update

TimetableDesigner.Core/BaseGroup.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace TimetableDesigner.Core
+{
+    public abstract class BaseGroup : IUnit
+    {
+        #region FIELDS
+
+        private string _name;
+        private string _shortName;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        public string Name
+        {
+            get => _name;
+            set => _name = value;
+        }
+        public string ShortName
+        {
+            get => _shortName;
+            set => _shortName = value;
+        }
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public BaseGroup()
+        {
+            _name = string.Empty;
+            _shortName = string.Empty;
+        }
+
+        #endregion
+    }
+}

TimetableDesigner.Core/Class.cs

@@ -6,14 +6,60 @@ using System.Threading.Tasks;
 
 namespace TimetableDesigner.Core
 {
+    [Serializable]
     public class Class
     {
+        #region FIELDS
+
+        private string _name;
+        private Teacher? _teacher;
+        private BaseGroup? _group;
+        private Classroom? _classroom;
+        private TimetableDay? _day;
+        private TimetableSpan? _slot;
+        private byte[] _color;
+
+        #endregion
+
+
+
         #region PROPERTIES
 
-        public string Name { get; set; }
+        public string Name
-        public Teacher? Teacher { get; set; }
+        {
-        public IGroup? Group { get; set; }
+            get => _name;
-        public Classroom? Classroom { get; set; }
+            set => _name = value;
+        }
+        public Teacher? Teacher
+        {
+            get => _teacher;
+            set => _teacher = value;
+        }
+        public BaseGroup? Group
+        {
+            get => _group;
+            set => _group = value;
+        }
+        public Classroom? Classroom
+        {
+            get => _classroom;
+            set => _classroom = value;
+        }
+        public TimetableDay? Day
+        {
+            get => _day;
+            set => _day = value;
+        }
+        public TimetableSpan? Slot
+        {
+            get => _slot;
+            set => _slot = value;
+        }
+        public byte[] Color
+        {
+            get => _color;
+            set => _color = value;
+        }
 
         #endregion
 
@@ -23,10 +69,13 @@ namespace TimetableDesigner.Core
 
         public Class()
         {
-            Name = string.Empty;
+            _name = string.Empty;
-            Teacher = null;
+            _teacher = null;
-            Group = null;
+            _group = null;
-            Classroom = null;
+            _classroom = null;
+            _day = null;
+            _slot = null;
+            _color = new byte[3] { 0xFA, 0x5A, 0x5A };
         }
 
         #endregion

TimetableDesigner.Core/Classroom.cs

@@ -7,14 +7,48 @@ using System.Threading.Tasks;
 
 namespace TimetableDesigner.Core
 {
-    public class Classroom
+    [Serializable]
+    public class Classroom : IUnit
     {
+        #region FIELDS
+
+        private string _name;
+        private string _shortName;
+        private string _description;
+        private bool _isCapacityLimited;
+        private uint _capacity;
+
+        #endregion
+
+
+
         #region PROPERTIES
 
-        public string Name { get; set; }
+        public string Name
-        public string Description { get; set; }
+        {
-        public bool IsCapacityLimited { get; set; }
+            get => _name;
-        public uint Capacity { get; set; }
+            set => _name = value;
+        }
+        public string ShortName
+        {
+            get => _shortName;
+            set => _shortName = value;
+        }
+        public string Description
+        {
+            get => _description;
+            set => _description = value;
+        }
+        public bool IsCapacityLimited
+        {
+            get => _isCapacityLimited;
+            set => _isCapacityLimited = value;
+        }
+        public uint Capacity
+        {
+            get => _capacity;
+            set => _capacity = value;
+        }
 
         #endregion
 
@@ -24,10 +58,11 @@ namespace TimetableDesigner.Core
 
         public Classroom()
         {
-            Name = string.Empty;
+            _name = string.Empty;
-            Description = string.Empty;
+            _shortName = string.Empty;
-            IsCapacityLimited = false;
+            _description = string.Empty;
-            Capacity = 1;
+            _isCapacityLimited = false;
+            _capacity = 1;
         }
 
         #endregion

TimetableDesigner.Core/Group.cs

@@ -6,13 +6,26 @@ using System.Threading.Tasks;
 
 namespace TimetableDesigner.Core
 {
-    public class Group : IGroup
+    [Serializable]
+    public class Group : BaseGroup
     {
+        #region FIELDS
+
+        private string _description;
+        private HashSet<Subgroup> _assignedSubgroups;
+
+        #endregion
+
+
+
         #region PROPERTIES
 
-        public string Name { get; set; }
+        public string Description
-        public string Description { get; set; }
+        {
-        public ICollection<Subgroup> AssignedSubgroups { get; set; }
+            get => _description;
+            set => _description = value;
+        }
+        public ICollection<Subgroup> AssignedSubgroups => _assignedSubgroups;
 
         #endregion
 
@@ -20,11 +33,10 @@ namespace TimetableDesigner.Core
 
         #region CONSTRUCTORS
 
-        public Group()
+        public Group() : base()
         {
-            Name = string.Empty;
+            _description = string.Empty;
-            Description = string.Empty;
+            _assignedSubgroups = new HashSet<Subgroup>();
-            AssignedSubgroups = new HashSet<Subgroup>();
         }
 
         #endregion

TimetableDesigner.Core/IUnit.cs

@@ -6,7 +6,7 @@ using System.Threading.Tasks;
 
 namespace TimetableDesigner.Core
 {
-    public interface IGroup
+    public interface IUnit
     {
         #region PROPERTIES
 

TimetableDesigner.Core/Project.cs

@@ -9,17 +9,47 @@ namespace TimetableDesigner.Core
     [Serializable]
     public class Project
     {
+        #region FIELDS
+
+        private Guid _guid;
+        private string _name;
+        private string _author;
+        private string _description;
+        private TimetableTemplate _timetableTemplate;
+        private HashSet<Classroom> _classrooms;
+        private HashSet<Teacher> _teachers;
+        private HashSet<Group> _groups;
+        private HashSet<Subgroup> _subgroups;
+        private HashSet<Class> _classes;
+
+        #endregion
+
+
+
         #region PROPERTIES
 
-        public string Name { get; set; }
+        public Guid Guid => _guid;
-        public string Author { get; set; }
+        public string Name
-        public string Description { get; set; }
+        {
-        public TimetableTemplate TimetableTemplate { get; set; }
+            get => _name;
-        public ICollection<Classroom> Classrooms { get; set; }
+            set => _name = value;
-        public ICollection<Teacher> Teachers { get; set; }
+        }
-        public ICollection<Group> Groups { get; set; }
+        public string Author
-        public ICollection<Subgroup> Subgroups { get; set; }
+        {
-        public ICollection<Class> Classes { get; set; }
+            get => _author;
+            set => _author = value;
+        }
+        public string Description
+        {
+            get => _description;
+            set => _description = value;
+        }
+        public TimetableTemplate TimetableTemplate => _timetableTemplate;
+        public ICollection<Classroom> Classrooms => _classrooms;
+        public ICollection<Teacher> Teachers => _teachers;
+        public ICollection<Group> Groups => _groups;
+        public ICollection<Subgroup> Subgroups => _subgroups;
+        public ICollection<Class> Classes => _classes;
 
         #endregion
 
@@ -29,14 +59,16 @@ namespace TimetableDesigner.Core
 
         public Project() 
         {
-            Name = string.Empty;
+            _guid = Guid.NewGuid();
-            Author = string.Empty;
+            _name = string.Empty;
-            Description = string.Empty;
+            _author = string.Empty;
-            TimetableTemplate = new TimetableTemplate();
+            _description = string.Empty;
-            Classrooms = new HashSet<Classroom>();
+            _timetableTemplate = new TimetableTemplate();
-            Teachers = new HashSet<Teacher>();
+            _classrooms = new HashSet<Classroom>();
-            Groups = new HashSet<Group>();
+            _teachers = new HashSet<Teacher>();
-            Subgroups = new HashSet<Subgroup>();
+            _groups = new HashSet<Group>();
+            _subgroups = new HashSet<Subgroup>();
+            _classes = new HashSet<Class>();
         }
 
         #endregion

TimetableDesigner.Core/Subgroup.cs

@@ -6,22 +6,13 @@ using System.Threading.Tasks;
 
 namespace TimetableDesigner.Core
 {
-    public class Subgroup : IGroup
+    [Serializable]
+    public class Subgroup : BaseGroup
     {
-        #region PROPERTIES
-
-        public string Name { get; set; }
-
-        #endregion
-
-
-
         #region CONSTRUCTORS
 
-        public Subgroup()
+        public Subgroup() : base()
-        {
+        { }
-            Name = string.Empty;
-        }
 
         #endregion
     }

TimetableDesigner.Core/Teacher.cs

@@ -3,16 +3,42 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
+using TimetableDesigner.Customs;
 
 namespace TimetableDesigner.Core
 {
-    public class Teacher
+    [Serializable]
+    public class Teacher : IUnit
     {
+        #region FIELDS
+
+        private string _name;
+        private string _shortName;
+        private string _description;
+        private JsonSerializableDictionary<TimetableDay, TimetableSpanCollection> _availabilityHours;
+
+        #endregion
+
+
+
         #region PROPERTIES
 
-        public string Name { get; set; }
+        public string Name
-        public string Description { get; set; }
+        {
-        public IDictionary<TimetableDay, TimetableSpanCollection> AvailabilityHours { get; set; }
+            get => _name;
+            set => _name = value;
+        }
+        public string ShortName
+        {
+            get => _shortName;
+            set => _shortName = value;
+        }
+        public string Description
+        {
+            get => _description;
+            set => _description = value;
+        }
+        public IDictionary<TimetableDay, TimetableSpanCollection> AvailabilityHours => _availabilityHours;
 
         #endregion
 
@@ -22,9 +48,10 @@ namespace TimetableDesigner.Core
 
         public Teacher()
         {
-            Name = string.Empty;
+            _name = string.Empty;
-            Description = string.Empty;
+            _shortName = string.Empty;
-            AvailabilityHours = new Dictionary<TimetableDay, TimetableSpanCollection>();
+            _description = string.Empty;
+            _availabilityHours = new JsonSerializableDictionary<TimetableDay, TimetableSpanCollection>();
         }
 
         #endregion

TimetableDesigner.Core/TimetableDay.cs

@@ -9,9 +9,21 @@ namespace TimetableDesigner.Core
     [Serializable]
     public class TimetableDay
     {
+        #region FIELDS
+
+        private string _name;
+
+        #endregion
+
+
+
         #region PROPERTIES
 
-        public string Name { get; set; }
+        public string Name
+        {
+            get => _name;
+            set => _name = value;
+        }
 
         #endregion
 
@@ -20,8 +32,8 @@ namespace TimetableDesigner.Core
         #region CONSTRUCTORS
 
         public TimetableDay(string name) 
-        { 
+        {
-            Name = name;
+            _name = name;
         }
 
         #endregion

TimetableDesigner.Core/TimetableDesigner.Core.csproj

@@ -6,4 +6,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\TimetableDesigner.Customs\TimetableDesigner.Customs.csproj" />
+  </ItemGroup>
+
 </Project>

TimetableDesigner.Core/TimetableSpan.cs

@@ -1,14 +1,24 @@
 using System;
+using System.Diagnostics;
 
 namespace TimetableDesigner.Core
 {
     [Serializable]
     public class TimetableSpan
     {
+        #region FIELDS
+
+        private TimeOnly _from;
+        private TimeOnly _to;
+
+        #endregion
+
+
+
         #region PROPERTIES
 
-        public TimeOnly From { get; private set; }
+        public TimeOnly From => _from;
-        public TimeOnly To { get; private set; }
+        public TimeOnly To => _to;
 
         #endregion
 
@@ -20,11 +30,11 @@ namespace TimetableDesigner.Core
         {
             if (to <= from)
             {
-                throw new ArgumentException("\"to\" cannot be less or equal to \"from\"");
+                throw new ArgumentException("Ending value (\"to\") of TimetableSpan have to be greater than starting value (\"from\")");
             }
 
-            From = from;
+            _from = from;
-            To = to;
+            _to = to;
         }
 
         #endregion
@@ -33,27 +43,33 @@ namespace TimetableDesigner.Core
 
         #region PUBLIC METHODS
 
-        internal TimetableSpanCollision CheckCollision(TimetableSpan slot)
+        public override bool Equals(object? obj) => obj is TimetableSpan slot && From == slot.From && To == slot.To;
+
+        public override int GetHashCode() => HashCode.Combine(From, To);
+
+        public override string? ToString() => $"{From} - {To}";
+
+        public TimetableSpanCollision CheckCollision(TimetableSpan slot)
         {
             if (slot.To <= this.From)
             {
                 return TimetableSpanCollision.CheckedSlotBefore;
             }
-            else if (this.To <= slot.From) 
+            else if (this.To <= slot.From)
             {
                 return TimetableSpanCollision.CheckedSlotAfter;
             }
             else
             {
-                if (this.From < slot.From && slot.To < this.To)
+                if (this.From <= slot.From && slot.To <= this.To)
                 {
                     return TimetableSpanCollision.CheckedSlotIn;
                 }
-                else if (this.From < slot.From && slot.From < this.To && this.To < slot.To)
+                else if (this.From < slot.From && slot.From < this.To && this.To <= slot.To)
                 {
                     return TimetableSpanCollision.CheckedSlotFromIn;
                 }
-                else if (slot.From < this.From && this.From < slot.To && slot.To < this.To)
+                else if (slot.From < this.From && this.From < slot.To && slot.To <= this.To)
                 {
                     return TimetableSpanCollision.CheckedSlotToIn;
                 }
@@ -64,12 +80,6 @@ namespace TimetableDesigner.Core
             }
         }
 
-        public override bool Equals(object? obj) => obj is TimetableSpan slot && From == slot.From && To == slot.To;
-
-        public override int GetHashCode() => HashCode.Combine(From, To);
-
-        public override string? ToString() => $"{From}-{To}";
-
         #endregion
     }
 }

TimetableDesigner.Core/TimetableSpanCollection.cs

@@ -7,11 +7,12 @@ using System.Threading.Tasks;
 
 namespace TimetableDesigner.Core
 {
+    [Serializable]
     public class TimetableSpanCollection : ICollection<TimetableSpan>
     {
         #region FIELDS
 
-        private IList<TimetableSpan> _list;
+        private List<TimetableSpan> _list;
 
         #endregion
 
@@ -20,7 +21,7 @@ namespace TimetableDesigner.Core
         #region PROPERTIES
 
         public int Count => _list.Count;
-        public bool IsReadOnly => _list.IsReadOnly;
+        public bool IsReadOnly => ((ICollection<TimetableSpan>)_list).IsReadOnly;
 
         #endregion
 

TimetableDesigner.Core/TimetableSpanCollision.cs

@@ -6,7 +6,7 @@ using System.Threading.Tasks;
 
 namespace TimetableDesigner.Core
 {
-    internal enum TimetableSpanCollision
+    public enum TimetableSpanCollision
     {
         CheckedSlotBefore,
         CheckedSlotAfter,

TimetableDesigner.Core/TimetableTemplate.cs

@@ -20,8 +20,8 @@ namespace TimetableDesigner.Core
 
         #region PROPERTIES
 
-        public IEnumerable<TimetableDay> Days => _days;
+        public ICollection<TimetableDay> Days => _days;
-        public IEnumerable<TimetableSpan> Slots => _slots;
+        public ICollection<TimetableSpan> Slots => _slots;
 
         #endregion
 
@@ -36,19 +36,5 @@ namespace TimetableDesigner.Core
         }
 
         #endregion
-
-
-
-        #region PUBLIC METHODS
-
-        public void AddDay(TimetableDay name) => _days.Add(name);
-
-        public bool RemoveDay(TimetableDay day) => _days.Remove(day);
-
-        public void AddSlot(TimetableSpan slot) => _slots.Add(slot);
-
-        public bool RemoveSlot(TimetableSpan slot) => _slots.Remove(slot);
-
-        #endregion
     }
 }

TimetableDesigner.Customs/JsonSerializableDictionary.cs

@@ -0,0 +1,14 @@
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace TimetableDesigner.Customs
+{
+    [JsonArray]
+    public class JsonSerializableDictionary<TKey, TValue> : Dictionary<TKey, TValue> where TKey : notnull
+    {
+    }
+}

TimetableDesigner.Customs/TimetableDesigner.Customs.csproj

@@ -6,4 +6,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+  </ItemGroup>
+
 </Project>

TimetableDesigner.Scheduler/Scheduler.cs

@@ -0,0 +1,7 @@
+namespace TimetableDesigner.Scheduler
+{
+    public class Class1
+    {
+
+    }
+}

TimetableDesigner.Scheduler/TimetableDesigner.Scheduler.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net7.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

TimetableDesigner.Tests/TimetableTest.cs

@@ -42,12 +42,9 @@ namespace TimetableDesigner.Tests
         {
             TimetableTemplate model = new TimetableTemplate();
 
-            TimetableDay day = new TimetableDay
+            TimetableDay day = new TimetableDay("Monday");
-            {
-                Name = "Monday"
-            };
 
-            model.AddDay(day);
+            model.Days.Add(day);
 
             Assert.AreEqual(1, model.Days.Count());
             Assert.AreEqual(day, model.Days.ToList()[0]);
@@ -60,7 +57,7 @@ namespace TimetableDesigner.Tests
 
             TimetableSpan slot = new TimetableSpan(new TimeOnly(8, 0), new TimeOnly(9, 0));
 
-            model.AddSlot(slot);
+            model.Slots.Add(slot);
 
             Assert.AreEqual(1, model.Slots.Count());
             Assert.AreEqual(new TimetableSpan(new TimeOnly(8, 0), new TimeOnly(9, 0)), model.Slots.ToList()[0]);
@@ -74,8 +71,8 @@ namespace TimetableDesigner.Tests
             TimetableSpan slot1 = new TimetableSpan(new TimeOnly(8, 15), new TimeOnly(9, 0));
             TimetableSpan slot2 = new TimetableSpan(new TimeOnly(9, 15), new TimeOnly(10, 0));
 
-            model.AddSlot(slot1);
+            model.Slots.Add(slot1);
-            model.AddSlot(slot2);
+            model.Slots.Add(slot2);
 
             Assert.AreEqual(2, model.Slots.Count());
             Assert.AreEqual(new TimetableSpan(new TimeOnly(8, 15), new TimeOnly(9, 0)), model.Slots.ToList()[0]);
@@ -90,8 +87,8 @@ namespace TimetableDesigner.Tests
             TimetableSpan slot1 = new TimetableSpan(new TimeOnly(8, 0), new TimeOnly(9, 0));
             TimetableSpan slot2 = new TimetableSpan(new TimeOnly(9, 0), new TimeOnly(10, 0));
 
-            model.AddSlot(slot1);
+            model.Slots.Add(slot1);
-            model.AddSlot(slot2);
+            model.Slots.Add(slot2);
 
             Assert.AreEqual(2, model.Slots.Count());
             Assert.AreEqual(new TimetableSpan(new TimeOnly(8, 0), new TimeOnly(9, 0)), model.Slots.ToList()[0]);
@@ -107,8 +104,8 @@ namespace TimetableDesigner.Tests
             TimetableSpan slot1 = new TimetableSpan(new TimeOnly(8, 0), new TimeOnly(9, 30));
             TimetableSpan slot2 = new TimetableSpan(new TimeOnly(8, 30), new TimeOnly(10, 0));
 
-            model.AddSlot(slot1);
+            model.Slots.Add(slot1);
-            model.AddSlot(slot2);
+            model.Slots.Add(slot2);
 
             Assert.Fail();
         }
@@ -123,9 +120,9 @@ namespace TimetableDesigner.Tests
             TimetableSpan slot2 = new TimetableSpan(new TimeOnly(10, 0), new TimeOnly(11, 0));
             TimetableSpan slot3 = new TimetableSpan(new TimeOnly(8, 59), new TimeOnly(10, 1));
 
-            model.AddSlot(slot1);
+            model.Slots.Add(slot1);
-            model.AddSlot(slot2);
+            model.Slots.Add(slot2);
-            model.AddSlot(slot3);
+            model.Slots.Add(slot3);
 
             Assert.Fail();
         }
@@ -143,13 +140,13 @@ namespace TimetableDesigner.Tests
             TimetableSpan slot6 = new TimetableSpan(new TimeOnly(9, 0), new TimeOnly(10, 0));
             TimetableSpan slot7 = new TimetableSpan(new TimeOnly(11, 0), new TimeOnly(12, 0));
 
-            model.AddSlot(slot1);
+            model.Slots.Add(slot1);
-            model.AddSlot(slot2);
+            model.Slots.Add(slot2);
-            model.AddSlot(slot3);
+            model.Slots.Add(slot3);
-            model.AddSlot(slot4);
+            model.Slots.Add(slot4);
-            model.AddSlot(slot5);
+            model.Slots.Add(slot5);
-            model.AddSlot(slot6);
+            model.Slots.Add(slot6);
-            model.AddSlot(slot7);
+            model.Slots.Add(slot7);
 
             List<TimetableSpan> slots = model.Slots.ToList();
 

TimetableDesigner/App.config

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<configuration>
+    <configSections>
+        <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
+            <section name="TimetableDesigner.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
+        </sectionGroup>
+    </configSections>
+    <userSettings>
+        <TimetableDesigner.Properties.Settings>
+            <setting name="RecentProjectsCount" serializeAs="String">
+                <value>10</value>
+            </setting>
+        </TimetableDesigner.Properties.Settings>
+    </userSettings>
+</configuration>

TimetableDesigner/App.xaml

@@ -2,7 +2,7 @@
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              ShutdownMode="OnMainWindowClose"
-             StartupUri="Views/MainWindow.xaml">
+             Startup="OnStartup">
     <Application.Resources>
         <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>

TimetableDesigner/App.xaml.cs

@@ -1,25 +1,88 @@
-using System;
+global using TimetableDesigner.Services;
+using Microsoft.ML.Data;
+using System;
 using System.Collections.Generic;
 using System.ComponentModel.Design;
 using System.Configuration;
 using System.Data;
+using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
 using System.Windows;
-using TimetableDesigner.Services;
+using TimetableDesigner.Services.FileDialog;
 using TimetableDesigner.Services.MessageBox;
 using TimetableDesigner.Services.Project;
+using TimetableDesigner.Services.Scheduler;
 using TimetableDesigner.Services.TabNavigation;
+using TimetableDesigner.ViewModels.Views;
+using TimetableDesigner.Views;
 
 namespace TimetableDesigner
 {
     public partial class App : Application
     {
+        #region FIELDS
+
+        private IMessageBoxService _messageBoxService;
+        private IFileDialogService _fileDialogService;
+        private ITabNavigationService _tabNavigationService;
+        private IProjectService _projectService;
+        private ISchedulerService _schedulerService;
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
         public App()
         {
-            ServiceProvider.Instance.AddService<IMessageBoxService>(new MessageBoxService());
+            _messageBoxService = new MessageBoxService();
-            ServiceProvider.Instance.AddService<ITabNavigationService>(new TabNavigationService());
+            _fileDialogService = new FileDialogService();
-            ServiceProvider.Instance.AddService<IProjectService>(new ProjectService());
+            _tabNavigationService = new TabNavigationService();
+            _projectService = new ProjectService();
+            _schedulerService = new SchedulerService(_projectService);
+
+            ServiceProvider.Instance.AddService(_messageBoxService);
+            ServiceProvider.Instance.AddService(_fileDialogService);
+            ServiceProvider.Instance.AddService(_tabNavigationService);
+            ServiceProvider.Instance.AddService(_projectService);
+            ServiceProvider.Instance.AddService(_schedulerService);
         }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private void OnStartup(object sender, StartupEventArgs e)
+        {
+            if (!Directory.Exists(Globals.Path.ApplicationData))
+            {
+                Directory.CreateDirectory(Globals.Path.ApplicationData);
+            }
+
+            _projectService.LoadRecentProjectsList();
+
+            MainWindow mainWindow = new MainWindow();
+            mainWindow.Show();
+
+            if (e.Args.Length > 0 && File.Exists(e.Args[0]))
+            {
+                _projectService.Load(e.Args[0]);
+            }
+            else
+            {
+                TabItem welcomeTab = new TabItem()
+                {
+                    Title = TimetableDesigner.Properties.Resources.Tabs_Welcome,
+                    ViewModel = new WelcomeViewVM()
+                };
+                _tabNavigationService.AddAndActivate(welcomeTab);
+            }
+        }
+
+        #endregion
     }
 }

TimetableDesigner/Commands/RelayCommand.cs

@@ -39,10 +39,7 @@ namespace TimetableDesigner.Commands
         
         public bool CanExecute(object parameter) => _canExecute == null || _canExecute((T)parameter);
 
-        public void Execute(object parameter)
+        public void Execute(object parameter) => _execute((T)parameter);
-        {
-            _execute((T)parameter);
-        }
 
         #endregion
 

TimetableDesigner/Controls/ClassControl.xaml

@@ -0,0 +1,355 @@
+<UserControl x:Class="TimetableDesigner.Controls.ClassControl"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
+             xmlns:local="clr-namespace:TimetableDesigner.Controls"
+             xmlns:s="clr-namespace:System;assembly=mscorlib"
+             xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
+             mc:Ignorable="d" 
+             x:Name="control"
+             MinWidth="100"
+             d:DesignHeight="450" d:DesignWidth="800">
+    <Border BorderBrush="Black"
+            BorderThickness="1" 
+            CornerRadius="8"
+            Padding="2">
+        <Border.Background>
+            <SolidColorBrush Color="{Binding Color, Converter={StaticResource ByteArrayToColorConverter}}"/>
+        </Border.Background>
+        <Grid Margin="5">
+            <Grid.RowDefinitions>
+                <RowDefinition/>
+                <RowDefinition/>
+            </Grid.RowDefinitions>
+            <Grid Grid.Row="0">
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition/>
+                    <ColumnDefinition Width="Auto"/>
+                    <ColumnDefinition Width="Auto"/>
+                    <ColumnDefinition Width="Auto"/>
+                    <ColumnDefinition Width="Auto"/>
+                </Grid.ColumnDefinitions>
+                <TextBlock Grid.Column="0"
+                       Text="{Binding Name}"
+                       VerticalAlignment="Center"
+                       TextTrimming="CharacterEllipsis">
+                    <TextBlock.Visibility>
+                        <Binding Path="IsChecked"
+                                 ElementName="EditButton"
+                                 Converter="{StaticResource BooleanToVisibilityConverter}">
+                            <Binding.ConverterParameter>
+                                <s:Boolean>
+                                    true
+                                </s:Boolean>
+                            </Binding.ConverterParameter>
+                        </Binding>
+                    </TextBlock.Visibility>
+                    <TextBlock.Background>
+                        <SolidColorBrush Color="Transparent"/>
+                    </TextBlock.Background>
+                    <TextBlock.Style>
+                        <Style TargetType="TextBlock">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                             Value="True">
+                                    <Setter Property="Foreground" Value="Black"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                             Value="False">
+                                    <Setter Property="Foreground" Value="White"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </TextBlock.Style>
+                </TextBlock>
+                <TextBox Grid.Column="0" 
+                         Margin="2"
+                         Text="{Binding Name}"
+                         MaxLines="1"
+                         VerticalAlignment="Center"
+                         Visibility="{Binding IsChecked, ElementName=EditButton, Converter={StaticResource BooleanToVisibilityConverter}}">
+                    <TextBox.Background>
+                        <SolidColorBrush Color="Transparent"/>
+                    </TextBox.Background>
+                    <TextBox.Style>
+                        <Style TargetType="TextBox">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                             Value="True">
+                                    <Setter Property="Foreground" Value="Black"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                             Value="False">
+                                    <Setter Property="Foreground" Value="White"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </TextBox.Style>
+                </TextBox>
+                <xctk:ColorPicker Grid.Column="1"
+                                  SelectedColor="{Binding Color, Converter={StaticResource ByteArrayToColorConverter}}"
+                                  Margin="2"
+                                  Width="20"
+                                  UsingAlphaChannel="False"
+                                  ShowStandardColors="False"
+                                  ShowDropDownButton="False"
+                                  Visibility="{Binding IsChecked, ElementName=EditButton, Converter={StaticResource BooleanToVisibilityConverter}}"/>
+                <Button Grid.Column="2"
+                        Margin="2"
+                        Background="Transparent"
+                        BorderBrush="Transparent"
+                        Visibility="{Binding IsChecked, ElementName=EditButton, Converter={StaticResource BooleanToVisibilityConverter}}"
+                        Click="RemoveButton_Click">
+                    <Button.Content>
+                        <Image Width="15"
+                               Height="15">
+                            <Image.Style>
+                                <Style TargetType="Image">
+                                    <Style.Triggers>
+                                        <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                            <Setter Property="Source" Value="{StaticResource RemoveBlackImage}"/>
+                                        </DataTrigger>
+                                        <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                            <Setter Property="Source" Value="{StaticResource RemoveWhiteImage}"/>
+                                        </DataTrigger>
+                                    </Style.Triggers>
+                                </Style>
+                            </Image.Style>
+                        </Image>
+                    </Button.Content>
+                </Button>
+                <Button Grid.Column="3"
+                        Margin="2"
+                        Background="Transparent"
+                        BorderBrush="Transparent"
+                        Visibility="{Binding IsChecked, ElementName=EditButton, Converter={StaticResource BooleanToVisibilityConverter}}"
+                        Click="CloneButton_Click">
+                    <Button.Content>
+                        <Image Width="15"
+                               Height="15">
+                            <Image.Style>
+                                <Style TargetType="Image">
+                                    <Style.Triggers>
+                                        <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                            <Setter Property="Source" Value="{StaticResource CloneBlackImage}"/>
+                                        </DataTrigger>
+                                        <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                            <Setter Property="Source" Value="{StaticResource CloneWhiteImage}"/>
+                                        </DataTrigger>
+                                    </Style.Triggers>
+                                </Style>
+                            </Image.Style>
+                        </Image>
+                    </Button.Content>
+                </Button>
+                <ToggleButton Grid.Column="4"
+                              x:Name="EditButton"
+                              Margin="2"
+                              Background="Transparent"
+                              BorderBrush="Transparent">
+                    <ToggleButton.Content>
+                        <Image Width="15"
+                               Height="15">
+                            <Image.Style>
+                                <Style TargetType="Image">
+                                    <Style.Triggers>
+                                        <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                            <Setter Property="Source" Value="{StaticResource EditBlackImage}"/>
+                                        </DataTrigger>
+                                        <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                            <Setter Property="Source" Value="{StaticResource EditWhiteImage}"/>
+                                        </DataTrigger>
+                                    </Style.Triggers>
+                                </Style>
+                            </Image.Style>
+                        </Image>
+                    </ToggleButton.Content>
+                </ToggleButton>
+            </Grid>
+            <Grid Grid.Row="1">
+                <Grid.Visibility>
+                    <Binding Path="IsChecked"
+                                 ElementName="EditButton"
+                                 Converter="{StaticResource BooleanToVisibilityConverter}">
+                        <Binding.ConverterParameter>
+                            <s:Boolean>
+                                true
+                            </s:Boolean>
+                        </Binding.ConverterParameter>
+                    </Binding>
+                </Grid.Visibility>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition x:Name="GroupPreviewColumn"/>
+                    <ColumnDefinition x:Name="TeacherPreviewColumn"/>
+                    <ColumnDefinition x:Name="ClassroomPreviewColumn"/>
+                </Grid.ColumnDefinitions>
+                <Image Grid.Column="0"
+                       HorizontalAlignment="Center"
+                       VerticalAlignment="Center"
+                       Width="20"
+                       Height="20"
+                       ToolTip="{Binding Group.Name}">
+                    <Image.Style>
+                        <Style TargetType="Image">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                    <Setter Property="Source" Value="{StaticResource GroupBlackImage}"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                    <Setter Property="Source" Value="{StaticResource GroupWhiteImage}"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </Image.Style>
+                </Image>
+                <Image Grid.Column="1"
+                       HorizontalAlignment="Center"
+                       VerticalAlignment="Center"
+                       Width="20"
+                       Height="20"
+                       ToolTip="{Binding Teacher.Name}">
+                    <Image.Style>
+                        <Style TargetType="Image">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                    <Setter Property="Source" Value="{StaticResource TeacherBlackImage}"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                    <Setter Property="Source" Value="{StaticResource TeacherWhiteImage}"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </Image.Style>
+                </Image>
+                <Image Grid.Column="2"
+                       HorizontalAlignment="Center"
+                       VerticalAlignment="Center"
+                       Width="20"
+                       Height="20"
+                       ToolTip="{Binding Classroom.Name}">
+                    <Image.Style>
+                        <Style TargetType="Image">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                    <Setter Property="Source" Value="{StaticResource ClassroomBlackImage}"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                    <Setter Property="Source" Value="{StaticResource ClassroomWhiteImage}"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </Image.Style>
+                </Image>
+            </Grid>
+            <Grid Grid.Row="1"
+                  Margin="5"
+                  Visibility="{Binding IsChecked, ElementName=EditButton, Converter={StaticResource BooleanToVisibilityConverter}}">
+                <Grid.RowDefinitions>
+                    <RowDefinition Height="Auto" x:Name="GroupEditRow"/>
+                    <RowDefinition Height="Auto" x:Name="TeacherEditRow"/>
+                    <RowDefinition Height="Auto" x:Name="ClassroomEditRow"/>
+                </Grid.RowDefinitions>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="Auto"/>
+                    <ColumnDefinition/>
+                </Grid.ColumnDefinitions>
+                <Image Grid.Row="0"
+                       Grid.Column="0"
+                       Width="20"
+                       Height="20">
+                    <Image.Style>
+                        <Style TargetType="Image">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                    <Setter Property="Source" Value="{StaticResource GroupBlackImage}"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                    <Setter Property="Source" Value="{StaticResource GroupWhiteImage}"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </Image.Style>
+                </Image>
+                <ComboBox Grid.Row="0"
+                          Grid.Column="1"
+                          Margin="5,0,0,0"
+                          SelectedItem="{Binding Group, Mode=TwoWay}"
+                          DisplayMemberPath="Name">
+                    <ComboBox.Resources>
+                        <CollectionViewSource x:Key="Groups" Source="{Binding ElementName=control, Path=ProjectService.ProjectViewModel.Groups}"/>
+                        <CollectionViewSource x:Key="Subgroups" Source="{Binding ElementName=control, Path=ProjectService.ProjectViewModel.Subgroups}"/>
+                    </ComboBox.Resources>
+                    <ComboBox.ItemsSource>
+                        <CompositeCollection>
+                            <CollectionContainer Collection="{Binding Source={StaticResource Groups}}"/>
+                            <CollectionContainer Collection="{Binding Source={StaticResource Subgroups}}"/>
+                        </CompositeCollection>
+                    </ComboBox.ItemsSource>
+                </ComboBox>
+                <Image Grid.Row="1"
+                       Width="20"
+                       Height="20">
+                    <Image.Style>
+                        <Style TargetType="Image">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                    <Setter Property="Source" Value="{StaticResource TeacherBlackImage}"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                    <Setter Property="Source" Value="{StaticResource TeacherWhiteImage}"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </Image.Style>
+                </Image>
+                <ComboBox Grid.Row="1"
+                          Grid.Column="1"
+                          Margin="5,2,0,2"
+                          SelectedItem="{Binding Teacher, Mode=TwoWay}"
+                          ItemsSource="{Binding ElementName=control, Path=ProjectService.ProjectViewModel.Teachers}"
+                          DisplayMemberPath="Name"/>
+                <Image Grid.Row="2"
+                       Width="20"
+                       Height="20">
+                    <Image.Style>
+                        <Style TargetType="Image">
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="True">
+                                    <Setter Property="Source" Value="{StaticResource ClassroomBlackImage}"/>
+                                </DataTrigger>
+                                <DataTrigger Binding="{Binding Color, Converter={StaticResource ColorBrightnessIsHigherToBooleanConverter}, ConverterParameter=130}"
+                                                     Value="False">
+                                    <Setter Property="Source" Value="{StaticResource ClassroomWhiteImage}"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </Image.Style>
+                </Image>
+                <ComboBox Grid.Row="2"
+                          Grid.Column="1"
+                          Margin="5,0,0,0"
+                          SelectedItem="{Binding Classroom, Mode=TwoWay}"
+                          ItemsSource="{Binding ElementName=control, Path=ProjectService.ProjectViewModel.Classrooms}"
+                          DisplayMemberPath="Name"/>
+            </Grid>
+        </Grid>
+    </Border>
+</UserControl>

TimetableDesigner/Controls/ClassControl.xaml.cs

@@ -0,0 +1,119 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+using TimetableDesigner.Core;
+using TimetableDesigner.Services;
+using TimetableDesigner.Services.Project;
+using TimetableDesigner.Services.TabNavigation;
+using TimetableDesigner.ViewModels.Models;
+using TimetableDesigner.ViewModels.Models.Base;
+using TimetableDesigner.ViewModels.Views;
+
+namespace TimetableDesigner.Controls
+{
+    public partial class ClassControl : UserControl
+    {
+        #region FIELDS
+
+        private IProjectService _projectService;
+        private ITabNavigationService _tabNavigationService;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        private static DependencyProperty RemoveButtonCommandProperty = DependencyProperty.Register(
+            "RemoveButtonCommand",
+            typeof(ICommand),
+            typeof(ClassControl),
+            new PropertyMetadata(null)
+        );
+        public ICommand RemoveButtonCommand
+        {
+            get => (ICommand)GetValue(RemoveButtonCommandProperty);
+            set => SetValue(RemoveButtonCommandProperty, value);
+        }
+
+        private static DependencyProperty RemoveButtonCommandParameterProperty = DependencyProperty.Register(
+            "RemoveButtonCommandParameter",
+            typeof(object),
+            typeof(ClassControl),
+            new PropertyMetadata(null)
+        );
+        public object RemoveButtonCommandParameter
+        {
+            get => GetValue(RemoveButtonCommandParameterProperty);
+            set => SetValue(RemoveButtonCommandParameterProperty, value);
+        }
+
+        private static DependencyProperty CloneButtonCommandProperty = DependencyProperty.Register(
+            "CloneButtonCommand",
+            typeof(ICommand),
+            typeof(ClassControl),
+            new PropertyMetadata(null)
+        );
+        public ICommand CloneButtonCommand
+        {
+            get => (ICommand)GetValue(CloneButtonCommandProperty);
+            set => SetValue(CloneButtonCommandProperty, value);
+        }
+
+        private static DependencyProperty CloneButtonCommandParameterProperty = DependencyProperty.Register(
+            "CloneButtonCommandParameter",
+            typeof(object),
+            typeof(ClassControl),
+            new PropertyMetadata(null)
+        );
+        public object CloneButtonCommandParameter
+        {
+            get => GetValue(CloneButtonCommandParameterProperty);
+            set => SetValue(CloneButtonCommandParameterProperty, value);
+        }
+
+
+        public IProjectService ProjectService => _projectService;
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public ClassControl()
+        {
+            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
+            _tabNavigationService = ServiceProvider.Instance.GetService<ITabNavigationService>();
+
+            InitializeComponent();
+        }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private void RemoveButton_Click(object sender, RoutedEventArgs e) => RemoveButtonCommand?.Execute(RemoveButtonCommandParameter);
+
+        private void CloneButton_Click(object sender, RoutedEventArgs e) => CloneButtonCommand?.Execute(CloneButtonCommandParameter);
+
+        #endregion
+
+    }
+}

TimetableDesigner/Controls/DynamicGrid.xaml

@@ -0,0 +1,10 @@
+<UserControl x:Class="TimetableDesigner.Controls.DynamicGrid"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
+             xmlns:local="clr-namespace:TimetableDesigner.Controls"
+             mc:Ignorable="d" 
+             d:DesignHeight="450" d:DesignWidth="800">
+    <Grid x:Name="BaseGrid"/>
+</UserControl>

TimetableDesigner/Controls/DynamicGrid.xaml.cs

@@ -0,0 +1,602 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.Drawing.Drawing2D;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
+using System.Windows.Data;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Threading;
+using static TimetableDesigner.ViewModels.Views.TimetableEditorViewVM;
+
+namespace TimetableDesigner.Controls
+{
+    public partial class DynamicGrid : UserControl
+    {
+        #region FIELDS
+
+        private Border[,]? _contentCells;
+        private Border[]? _columnHeadersCells;
+        private Border[]? _rowHeadersCells;
+        private List<DispatcherOperation> _dispatcherOperations;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        private static DependencyProperty ColumnsProperty = DependencyProperty.Register(
+            "Columns", 
+            typeof(int), 
+            typeof(DynamicGrid), 
+            new PropertyMetadata(0, new PropertyChangedCallback(OnLayoutChanged))
+        );
+        public int Columns
+        {
+            get => (int)GetValue(ColumnsProperty);
+            set => SetValue(ColumnsProperty, value);
+        }
+
+        private static DependencyProperty RowsProperty = DependencyProperty.Register(
+            "Rows", 
+            typeof(int), 
+            typeof(DynamicGrid), 
+            new PropertyMetadata(0, new PropertyChangedCallback(OnLayoutChanged))
+        );
+        public int Rows
+        {
+            get => (int)GetValue(RowsProperty);
+            set => SetValue(RowsProperty, value);
+        }
+
+
+        private static DependencyProperty ColumnHeadersSourceProperty = DependencyProperty.Register(
+            "ColumnHeadersSource", 
+            typeof(IEnumerable), 
+            typeof(DynamicGrid),
+            new PropertyMetadata(new PropertyChangedCallback(OnColumnHeadersChanged))
+        );
+        public IEnumerable ColumnHeadersSource
+        {
+            get => (IEnumerable)GetValue(ColumnHeadersSourceProperty);
+            set => SetValue(ColumnHeadersSourceProperty, value);
+        }
+
+
+        private static DependencyProperty ColumnHeadersTemplateProperty = DependencyProperty.Register(
+            "ColumnHeadersTemplate",
+            typeof(DataTemplate),
+            typeof(DynamicGrid),
+            new PropertyMetadata(new PropertyChangedCallback(OnColumnHeadersChanged))
+        );
+        public DataTemplate ColumnHeadersTemplate
+        {
+            get => (DataTemplate)GetValue(ColumnHeadersTemplateProperty);
+            set => SetValue(ColumnHeadersTemplateProperty, value);
+        }
+
+
+        private static DependencyProperty RowHeadersSourceProperty = DependencyProperty.Register(
+            "RowHeadersSource", 
+            typeof(IEnumerable), 
+            typeof(DynamicGrid),
+            new PropertyMetadata(new PropertyChangedCallback(OnRowHeadersChanged))
+        );
+        public IEnumerable RowHeadersSource
+        {
+            get => (IEnumerable)GetValue(RowHeadersSourceProperty);
+            set => SetValue(RowHeadersSourceProperty, value);
+        }
+
+        private static DependencyProperty RowHeadersTemplateProperty = DependencyProperty.Register(
+            "RowHeadersTemplate",
+            typeof(DataTemplate),
+            typeof(DynamicGrid),
+            new PropertyMetadata(new PropertyChangedCallback(OnRowHeadersChanged))
+        );
+        public DataTemplate RowHeadersTemplate
+        {
+            get => (DataTemplate)GetValue(RowHeadersTemplateProperty);
+            set => SetValue(RowHeadersTemplateProperty, value);
+        }
+
+
+        private static DependencyProperty ItemsSourceProperty = DependencyProperty.Register(
+            "ItemsSource", 
+            typeof(IEnumerable), 
+            typeof(DynamicGrid),
+            new PropertyMetadata(new PropertyChangedCallback(OnItemsChanged))
+        );
+        public IEnumerable ItemsSource
+        {
+            get => (IEnumerable)GetValue(ItemsSourceProperty);
+            set => SetValue(ItemsSourceProperty, value);
+        }
+
+        private static DependencyProperty ItemTemplateProperty = DependencyProperty.Register(
+            "ItemTemplate", 
+            typeof(DataTemplate), 
+            typeof(DynamicGrid),
+            new PropertyMetadata(new PropertyChangedCallback(OnItemsChanged))
+        );
+        public DataTemplate ItemTemplate
+        {
+            get => (DataTemplate)GetValue(ItemTemplateProperty);
+            set => SetValue(ItemTemplateProperty, value);
+        }
+
+        private static DependencyProperty CellBorderThicknessProperty = DependencyProperty.Register(
+            "CellBorderThickness", 
+            typeof(Thickness), 
+            typeof(DynamicGrid), 
+            new PropertyMetadata(new Thickness(0), new PropertyChangedCallback(OnCellBorderThicknessChanged))
+        );
+        public Thickness CellBorderThickness
+        {
+            get => (Thickness)GetValue(CellBorderThicknessProperty);
+            set => SetValue(CellBorderThicknessProperty, value);
+        }
+
+        private static DependencyProperty CellBorderBrushProperty = DependencyProperty.Register(
+            "CellBorderBrush", 
+            typeof(Brush), 
+            typeof(DynamicGrid), 
+            new PropertyMetadata(Brushes.Black, new PropertyChangedCallback(OnCellBorderBrushChanged))
+        );
+        public Brush CellBorderBrush
+        {
+            get => (Brush)GetValue(CellBorderBrushProperty);
+            set => SetValue(CellBorderBrushProperty, value);
+        }
+
+        private static DependencyProperty HeaderCellBorderThicknessProperty = DependencyProperty.Register(
+            "HeaderCellBorderThickness",
+            typeof(Thickness?),
+            typeof(DynamicGrid),
+            new PropertyMetadata(null, new PropertyChangedCallback(OnHeaderCellBorderThicknessChanged))
+        );
+        public Thickness HeaderCellBorderThickness
+        {
+            get
+            {
+                Thickness? headerThickness = (Thickness)GetValue(HeaderCellBorderThicknessProperty);
+                if (headerThickness is null)
+                {
+                    return CellBorderThickness;
+                }
+                else
+                {
+                    return headerThickness.Value;
+                }
+            }
+            set => SetValue(HeaderCellBorderThicknessProperty, value);
+        }
+
+        private static DependencyProperty HeaderCellBorderBrushProperty = DependencyProperty.Register(
+            "HeaderCellBorderBrush",
+            typeof(Brush),
+            typeof(DynamicGrid),
+            new PropertyMetadata(null, new PropertyChangedCallback(OnHeaderCellBorderBrushChanged))
+        );
+        public Brush? HeaderCellBorderBrush
+        {
+            get
+            {
+                Brush headerBrush = (Brush)GetValue(HeaderCellBorderBrushProperty);
+                if (headerBrush is null)
+                {
+                    headerBrush = CellBorderBrush;
+                }
+                return headerBrush;
+            }
+            set => SetValue(HeaderCellBorderBrushProperty, value);
+        }
+
+        private static DependencyProperty StrechHeaderCellsToContentCellsSizeProperty = DependencyProperty.Register(
+            "StrechHeaderCellsToContentCellsSize",
+            typeof(bool),
+            typeof(DynamicGrid),
+            new PropertyMetadata(false, new PropertyChangedCallback(OnStrechHeaderCellsToContentCellsSizeChanged))
+        );
+        public bool StrechHeaderCellsToContentCellsSize
+        {
+            get => (bool)GetValue(StrechHeaderCellsToContentCellsSizeProperty);
+            set => SetValue(StrechHeaderCellsToContentCellsSizeProperty, value);
+        }
+
+        #endregion
+
+
+
+        #region EVENTS
+
+        private static DependencyProperty ItemMovedCommandProperty = DependencyProperty.Register(
+            "ItemMovedCommand",
+            typeof(ICommand),
+            typeof(DynamicGrid),
+            new PropertyMetadata(null)
+        );
+        public ICommand ItemMovedCommand
+        {
+            get => (ICommand)GetValue(ItemMovedCommandProperty);
+            set => SetValue(ItemMovedCommandProperty, value);
+        }
+
+        private static DependencyProperty ItemMovedCommandParameterProperty = DependencyProperty.Register(
+            "ItemMovedCommandParameter",
+            typeof(object),
+            typeof(DynamicGrid),
+            new PropertyMetadata(null)
+        );
+        public object ItemMovedCommandParameter
+        {
+            get => (object)GetValue(ItemMovedCommandParameterProperty);
+            set => SetValue(ItemMovedCommandParameterProperty, value);
+        }
+
+        [Browsable(true)]
+        [Category("Action")]
+        [Description("Invoked when item moved to another cell")]
+        public event EventHandler ItemMoved;
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public DynamicGrid()
+        {
+            _columnHeadersCells = null;
+            _rowHeadersCells = null;
+            _contentCells = null;
+            _dispatcherOperations = new List<DispatcherOperation>();
+
+            InitializeComponent();
+        }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private void LayoutRefresh()
+        {
+            BaseGrid.Children.Clear();
+            BaseGrid.ColumnDefinitions.Clear();
+            BaseGrid.RowDefinitions.Clear();
+
+            if (Rows <= 0 || Columns <= 0)
+            {
+                _rowHeadersCells = null;
+                _columnHeadersCells = null;
+                _contentCells = null;
+                return;
+            }
+            else
+            {
+                _rowHeadersCells = null;
+                _columnHeadersCells = null;
+                _contentCells = new Border[Rows, Columns];
+            }
+
+            bool columnHeaders = ColumnHeadersSource != null && ColumnHeadersSource.Cast<object>().Any();
+            short columnHeadersNum = Convert.ToInt16(columnHeaders);
+
+            bool rowHeaders = RowHeadersSource != null && RowHeadersSource.Cast<object>().Any();
+            short rowHeadersNum = Convert.ToInt16(rowHeaders);
+
+            if (columnHeaders)
+            {
+                RowDefinition columnHeaderRow = new RowDefinition();
+                if (!StrechHeaderCellsToContentCellsSize)
+                {
+                    columnHeaderRow.Height = GridLength.Auto;
+                }
+                BaseGrid.RowDefinitions.Add(columnHeaderRow);
+                _columnHeadersCells = new Border[Columns];
+
+                for (int column = 0; column < Columns; column++)
+                {
+                    Border border = new Border()
+                    {
+                        BorderBrush = HeaderCellBorderBrush,
+                        BorderThickness = HeaderCellBorderThickness,
+                    };
+                    Grid.SetColumn(border, column + rowHeadersNum);
+                    Grid.SetRow(border, 0);
+                    BaseGrid.Children.Add(border);
+                    _columnHeadersCells[column] = border;
+                }
+                ColumnHeadersRefresh();
+            }
+
+            if (rowHeaders)
+            {
+                ColumnDefinition rowHeaderColumn = new ColumnDefinition();
+                if (!StrechHeaderCellsToContentCellsSize)
+                {
+                    rowHeaderColumn.Width = GridLength.Auto;
+                }
+                BaseGrid.ColumnDefinitions.Add(rowHeaderColumn);
+                _rowHeadersCells = new Border[Rows];
+
+                for (int row = 0; row < Rows; row++)
+                {
+                    Border border = new Border()
+                    {
+                        BorderBrush = HeaderCellBorderBrush,
+                        BorderThickness = HeaderCellBorderThickness,
+                    };
+                    Grid.SetColumn(border, 0);
+                    Grid.SetRow(border, row + columnHeadersNum);
+                    BaseGrid.Children.Add(border);
+                    _rowHeadersCells[row] = border;
+                }
+                RowHeadersRefresh();
+            }
+
+            for (int _ = 0; _ < Rows; _++)
+            {
+                BaseGrid.RowDefinitions.Add(new RowDefinition()
+                {
+                    Height = GridLength.Auto,
+                });
+            }
+            for (int _ = 0; _ < Columns; _++)
+            {
+                BaseGrid.ColumnDefinitions.Add(new ColumnDefinition()
+                {
+                    Width = GridLength.Auto,
+                });
+            }
+
+            for (int row = 0; row < Rows; row++)
+            {
+                for (int column = 0; column < Columns; column++)
+                {
+                    Border border = new Border()
+                    {
+                        BorderBrush = CellBorderBrush,
+                        BorderThickness = CellBorderThickness,
+                    };
+                    Grid.SetColumn(border, column + rowHeadersNum);
+                    Grid.SetRow(border, row + columnHeadersNum);
+
+                    UniformGrid grid = new UniformGrid()
+                    {
+                        Rows = 1,
+                        AllowDrop = true,
+                        Background = Brushes.Transparent,
+                    };
+                    grid.Drop += OnItemMoved;
+
+                    border.Child = grid;
+
+                    BaseGrid.Children.Add(border);
+                    _contentCells[row, column] = border;
+                }
+            }
+            ItemsRefresh();
+        }
+
+        private void ColumnHeadersRefresh(bool switched = false) => HeadersRefresh(switched, ColumnHeadersSource, _columnHeadersCells, ColumnHeadersTemplate);
+        private void RowHeadersRefresh(bool switched = false) => HeadersRefresh(switched, RowHeadersSource, _rowHeadersCells, RowHeadersTemplate);
+        private void HeadersRefresh(bool switched, IEnumerable headerSource, Border[]? headerCells, DataTemplate headerTemplate)
+        {
+            if (switched)
+            {
+                LayoutRefresh();
+            }
+
+            if (headerSource is not null && headerCells is not null)
+            {
+                IEnumerable<object> headersSourceCollection = headerSource.Cast<object>();
+                for (int index = 0; index < headerCells.Length; index++)
+                {
+                    headerCells[index].Child = null;
+                    if (index < headersSourceCollection.Count())
+                    {
+                        object headerItem = headersSourceCollection.ElementAt(index);
+
+                        FrameworkElement? control = null;
+                        if (headerTemplate is not null)
+                        {
+                            control = headerTemplate.LoadContent() as FrameworkElement;
+                            if (control is not null)
+                            {
+                                control.DataContext = headerItem;
+                            }
+                        }
+                        control ??= new Label()
+                        {
+                            Content = headerItem.ToString()
+                        };
+
+                        headerCells[index].Child = control;
+                    }
+                }
+            }
+        }
+
+        private void CellBorderRefresh(CellBorderRefreshProperty mode, CellBorderRefreshType type)
+        {
+            if ((type & CellBorderRefreshType.Headers) == CellBorderRefreshType.Headers)
+            {
+                List<IEnumerable<Border>> headerCellsCollection = new List<IEnumerable<Border>>();
+                if (_columnHeadersCells is not null) headerCellsCollection.Add(_columnHeadersCells);
+                if (_rowHeadersCells is not null) headerCellsCollection.Add(_rowHeadersCells);
+                foreach (IEnumerable<Border> cells in headerCellsCollection)
+                {
+                    foreach (Border cell in cells)
+                    {
+                        if ((mode & CellBorderRefreshProperty.Thickness) == CellBorderRefreshProperty.Thickness) cell.BorderThickness = HeaderCellBorderThickness;
+                        if ((mode & CellBorderRefreshProperty.Brush) == CellBorderRefreshProperty.Brush) cell.BorderBrush = HeaderCellBorderBrush;
+                    }
+                }
+            }
+            if ((type & CellBorderRefreshType.Content) == CellBorderRefreshType.Content && _contentCells is not null)
+            {
+                foreach (Border cell in _contentCells)
+                {
+                    if ((mode & CellBorderRefreshProperty.Thickness) == CellBorderRefreshProperty.Thickness) cell.BorderThickness = CellBorderThickness;
+                    if ((mode & CellBorderRefreshProperty.Brush) == CellBorderRefreshProperty.Brush) cell.BorderBrush = CellBorderBrush;
+                }
+            }
+        }
+
+        private void ItemsRefresh()
+        {
+            if (ItemsSource is not null && _contentCells is not null)
+            {
+                foreach (DispatcherOperation operation in _dispatcherOperations)
+                {
+                    operation.Abort();
+                }
+                _dispatcherOperations.Clear();
+
+                foreach (Border cell in _contentCells)
+                {
+                    ((UniformGrid)cell.Child).Children.Clear();
+                }
+
+                IEnumerable<object> itemsSourceCollection = ItemsSource.Cast<object>();
+                foreach (object item in itemsSourceCollection)
+                {
+                    FrameworkElement? control = null;
+                    if (ItemTemplate is not null)
+                    {
+                        control = ItemTemplate.LoadContent() as FrameworkElement;
+                        if (control is not null)
+                        {
+                            control.DataContext = item;
+                        }
+                    }
+                    control ??= new Label()
+                    {
+                        Content = item.ToString()
+                    };
+
+                    DispatcherOperation operation = Dispatcher.BeginInvoke(() =>
+                    {
+                        int row = GetRow(control);
+                        int column = GetColumn(control);
+                        Border cell = _contentCells[row, column];
+                        UniformGrid cellGrid = (UniformGrid)cell.Child;
+                        if (!cellGrid.Children.Contains(control))
+                        {
+                            cellGrid.Children.Add(control);
+                        }
+                    }, DispatcherPriority.Loaded);
+                    _dispatcherOperations.Add(operation);
+                }
+            }
+        }
+
+        private void OnItemMoved(object sender, DragEventArgs e)
+        {
+            UniformGrid? target = sender as UniformGrid;
+            object item = e.Data.GetData(DataFormats.Serializable);
+            if (target is not null && item is UIElement element && _contentCells is not null)
+            {
+                int x = 0;
+                int y = 0;
+                for (x = 0; x < _contentCells.GetLength(0); x++)
+                {
+                    for (y = 0; y < _contentCells.GetLength(1); y++)
+                    {
+                        if (_contentCells[x, y].Child.Equals(target))
+                        {
+                            goto LoopEnd;
+                        }
+                    }
+                }
+                LoopEnd:
+                if (x != GetRow(element) || y != GetColumn(element))
+                {
+                    SetRow(element, x);
+                    SetColumn(element, y);
+                    ItemMoved?.Invoke(this, EventArgs.Empty);
+                    ItemMovedCommand?.Execute(ItemMovedCommandParameter);
+                }
+            }
+        }
+
+        private void HeaderRowColumnSizeRefresh()
+        {
+            GridLength size;
+            if (StrechHeaderCellsToContentCellsSize)
+            {
+                size = new GridLength(1, GridUnitType.Star);
+            }
+            else
+            {
+                size = GridLength.Auto;
+            }
+
+            if (BaseGrid.RowDefinitions.Count > 1 && ColumnHeadersSource is not null)
+            {
+                BaseGrid.RowDefinitions[0].Height = size;
+            }
+            if (BaseGrid.ColumnDefinitions.Count > 1 && RowHeadersSource is not null)
+            {
+                BaseGrid.ColumnDefinitions[0].Width = size;
+            }
+        }
+
+        private static void OnLayoutChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).LayoutRefresh();
+        private static void OnColumnHeadersChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).ColumnHeadersRefresh((args.OldValue is null && args.NewValue is not null) || (args.OldValue is not null && args.NewValue is null));
+        private static void OnRowHeadersChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).RowHeadersRefresh((args.OldValue is null && args.NewValue is not null) || (args.OldValue is not null && args.NewValue is null));
+        private static void OnItemsChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).ItemsRefresh();
+        private static void OnCellBorderThicknessChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).CellBorderRefresh(CellBorderRefreshProperty.Thickness, obj.GetValue(HeaderCellBorderThicknessProperty) is null ? CellBorderRefreshType.Headers | CellBorderRefreshType.Content : CellBorderRefreshType.Content);
+        private static void OnCellBorderBrushChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).CellBorderRefresh(CellBorderRefreshProperty.Brush, obj.GetValue(HeaderCellBorderBrushProperty) is null ? CellBorderRefreshType.Headers | CellBorderRefreshType.Content : CellBorderRefreshType.Content);
+        private static void OnHeaderCellBorderThicknessChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).CellBorderRefresh(CellBorderRefreshProperty.Thickness, CellBorderRefreshType.Headers);
+        private static void OnHeaderCellBorderBrushChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).CellBorderRefresh(CellBorderRefreshProperty.Brush, CellBorderRefreshType.Headers);
+        private static void OnStrechHeaderCellsToContentCellsSizeChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) => ((DynamicGrid)obj).HeaderRowColumnSizeRefresh();
+
+        #endregion
+
+
+
+        #region COLUMN/ROW SET/GET STATIC METHODS
+
+        private static DependencyProperty ColumnProperty = DependencyProperty.RegisterAttached("Column", typeof(int), typeof(DynamicGrid), new PropertyMetadata(0));
+        public static int GetColumn(UIElement element) => (int)element.GetValue(ColumnProperty);
+        public static void SetColumn(UIElement element, int value) => element.SetValue(ColumnProperty, value);
+
+        private static DependencyProperty RowProperty = DependencyProperty.RegisterAttached("Row", typeof(int), typeof(DynamicGrid), new PropertyMetadata(0));
+        public static int GetRow(UIElement element) => (int)element.GetValue(RowProperty);
+        public static void SetRow(UIElement element, int value) => element.SetValue(RowProperty, value);
+
+        #endregion
+
+
+
+        #region ENUMS
+
+        [Flags]
+        private enum CellBorderRefreshProperty
+        {
+            Brush = 1,
+            Thickness = 2,
+        }
+
+        [Flags]
+        private enum CellBorderRefreshType
+        {
+            Headers = 1,
+            Content = 2,
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/Controls/TimetableEditorControl.xaml

@@ -1,34 +0,0 @@
-<UserControl x:Class="TimetableDesigner.Controls.TimetableEditorControl"
-             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
-             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
-             xmlns:local="clr-namespace:TimetableDesigner.Controls"
-             mc:Ignorable="d" 
-             d:DesignHeight="450" d:DesignWidth="800">
-    <Grid>
-        <Grid.ColumnDefinitions>
-            <ColumnDefinition/>
-            <ColumnDefinition Width="Auto"/>
-        </Grid.ColumnDefinitions>
-        <ItemsControl Grid.Column="0" ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path=_projectService.ProjectViewModel}">
-            <ItemsControl.ItemsPanel>
-                <ItemsPanelTemplate>
-                    <UniformGrid Grid.Column="0" 
-                                 Rows="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path=_projectService.ProjectViewModel.TimetableTemplate.Slots.Count, Converter={StaticResource IntegerAddConstantConverter}, ConverterParameter=1}"
-                                 Columns="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path=_projectService.ProjectViewModel.TimetableTemplate.Days.Count, Converter={StaticResource IntegerAddConstantConverter}, ConverterParameter=1}"/>
-                </ItemsPanelTemplate>
-            </ItemsControl.ItemsPanel>
-            <ItemsControl.ItemTemplate>
-                <DataTemplate>
-
-                </DataTemplate>
-            </ItemsControl.ItemTemplate>
-        </ItemsControl>
-        <ScrollViewer Grid.Column="1">
-            <StackPanel>
-                
-            </StackPanel>
-        </ScrollViewer>
-    </Grid>
-</UserControl>

TimetableDesigner/Controls/TimetableEditorControl.xaml.cs

@@ -1,55 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Data;
-using System.Windows.Documents;
-using System.Windows.Input;
-using System.Windows.Media;
-using System.Windows.Media.Imaging;
-using System.Windows.Navigation;
-using System.Windows.Shapes;
-using TimetableDesigner.Services;
-using TimetableDesigner.Services.Project;
-using TimetableDesigner.ViewModels.Models;
-
-namespace TimetableDesigner.Controls
-{
-    public partial class TimetableEditorControl : UserControl
-    {
-        #region FIELDS
-
-        private IProjectService _projectService;
-
-        #endregion
-
-
-
-        #region PROPERTIES
-
-        public IGroupViewModel Group 
-        {
-            get => (IGroupViewModel)GetValue(GroupProperty);
-            set => SetValue(GroupProperty, value);
-        }
-        public static readonly DependencyProperty GroupProperty = DependencyProperty.Register("Group", typeof(IGroupViewModel), typeof(TimetableEditorControl));
-
-        #endregion
-
-
-
-        #region CONSTRUCTORS
-
-        public TimetableEditorControl()
-        {
-            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
-
-            InitializeComponent();
-        }
-
-        #endregion
-    }
-}

TimetableDesigner/Converters/BooleanToGridColumnRowVisibilityConverter.cs

@@ -0,0 +1,51 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Data;
+
+namespace TimetableDesigner.Converters
+{
+    class BooleanToGridColumnRowVisibilityConverter : IValueConverter
+    {
+        private static GridLength _notVisible = new GridLength(0, GridUnitType.Pixel);
+        private static GridLength _visible = new GridLength(1, GridUnitType.Star);
+
+        // (bool)parameter - reverse output
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is null || value.GetType() != typeof(bool))
+            {
+                return new GridLength(1, GridUnitType.Star);
+            }
+            bool isVisible = (bool)value;
+
+            bool reverse = false;
+            if (parameter is not null && parameter.GetType() == typeof(bool))
+            {
+                reverse = (bool)parameter;
+            }
+
+            return isVisible ^ reverse ? _visible : _notVisible;
+        }
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is null || value.GetType() != typeof(GridLength))
+            {
+                return true;
+            }
+            GridLength visibility = (GridLength)value;
+
+            bool reverse = false;
+            if (parameter is not null && parameter.GetType() == typeof(bool))
+            {
+                reverse = (bool)parameter;
+            }
+
+            return visibility != _notVisible ^ reverse;
+        }
+    }
+}

TimetableDesigner/Converters/BooleanToVisibilityConverter.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Data;
+
+namespace TimetableDesigner.Converters
+{
+    public class BooleanToVisibilityConverter : IValueConverter
+    {
+        // (bool)parameter - reverse output
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is null || value.GetType() != typeof(bool))
+            {
+                return Visibility.Visible;
+            }
+            bool isVisible = (bool)value;
+
+            bool reverse = false;
+            if (parameter is not null && parameter.GetType() == typeof(bool))
+            {
+                reverse = (bool)parameter;
+            }
+
+            return isVisible ^ reverse ? Visibility.Visible : Visibility.Collapsed;
+        }
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is null || value.GetType() != typeof(Visibility))
+            {
+                return true;
+            }
+            Visibility visibility = (Visibility)value;
+
+            bool reverse = false;
+            if (parameter is not null && parameter.GetType() == typeof(bool))
+            {
+                reverse = (bool)parameter;
+            }
+
+            return visibility == Visibility.Visible ^ reverse;
+        }
+    }
+}

TimetableDesigner/Converters/ByteArrayToColorConverter.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Windows.Media;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+using System.Diagnostics;
+
+namespace TimetableDesigner.Converters
+{
+    public class ByteArrayToColorConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            byte[] bytes = (byte[])value;
+            Color color;
+            switch (bytes.Length)
+            {
+                case < 3: color = Colors.Red; break;
+                case 3: color = Color.FromRgb(bytes[0], bytes[1], bytes[2]); break;
+                case > 4: color = Color.FromArgb(bytes[0], bytes[1], bytes[2], bytes[3]); break;
+            }
+            return color;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            Color color = (Color)value;
+            List<byte> bytes = new List<byte>();
+
+            if (color.A != 0xFF) bytes.Add(color.A);
+            bytes.Add(color.R);
+            bytes.Add(color.G);
+            bytes.Add(color.B);
+
+            return bytes.ToArray();
+        }
+    }
+}

TimetableDesigner/Converters/ColorBrightnessIsHigherToBooleanConverter.cs

@@ -0,0 +1,39 @@
+using ControlzEx.Standard;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Drawing;
+using System.Globalization;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+
+namespace TimetableDesigner.Converters
+{
+    public class ColorBrightnessIsHigherToBooleanConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is byte[] color && (parameter is int min || (parameter is string minStr && int.TryParse(minStr, out min))))
+            {
+                int start = 0;
+                if (color.Length == 4)
+                {
+                    start = 1;
+                }
+                int result = (int)Math.Sqrt(color[start] * color[start] * .241 +
+                                            color[start + 1] * color[start + 1] * .691 +
+                                            color[start + 2] * color[start + 2] * .068);
+                return min < result;
+            }
+            return false;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

TimetableDesigner/Converters/IUnitVMToUnitNameConverter.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+using TimetableDesigner.Core;
+using TimetableDesigner.Properties;
+using TimetableDesigner.ViewModels.Models;
+using TimetableDesigner.ViewModels.Models.Base;
+
+namespace TimetableDesigner.Converters
+{
+    internal class IUnitVMToUnitNameConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is IUnitVM unit)
+            {
+                switch (unit)
+                {
+                    case ClassroomVM classroom: return Resources.Global_Classroom;
+                    case TeacherVM teacher: return Resources.Global_Teacher;
+                    case GroupVM group: return Resources.Global_Group;
+                    case SubgroupVM subgroup: return Resources.Global_Subgroup;
+                }
+            }
+            return string.Empty;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

TimetableDesigner/Converters/IntegerAddConstantConverter.cs

@@ -12,7 +12,7 @@ namespace TimetableDesigner.Converters
     {
         #region PUBLIC METHODS
 
-        public object Convert(object value, Type targetType, object parameter, CultureInfo culture) => (int)value + (int)parameter;
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture) => (int)value + int.Parse((string)parameter);
 
         public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) => (int)value - (int)parameter;
 

TimetableDesigner/Converters/TimetableDayToColumnNumberConverter.cs

@@ -0,0 +1,60 @@
+using System;
+using System.CodeDom;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+using TimetableDesigner.Core;
+using TimetableDesigner.Services;
+using TimetableDesigner.Services.Project;
+using TimetableDesigner.ViewModels.Models;
+
+namespace TimetableDesigner.Converters
+{
+    internal class TimetableDayToColumnNumberConverter : IValueConverter
+    {
+        #region FIELDS
+
+        private readonly IProjectService _projectService;
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public TimetableDayToColumnNumberConverter()
+        {
+            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
+        }
+
+        #endregion
+
+
+
+        #region PUBLIC METHODS
+
+        //value - TimetableDay
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is TimetableDay day)
+            {
+                return _projectService.ProjectViewModel.TimetableTemplate.Days.IndexOf(day);
+            }
+            return 0;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is int index && index >= 0)
+            {
+                return _projectService.ProjectViewModel.TimetableTemplate.Days[index];
+            }
+            return null;
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/Converters/TimetableSlotToRowNumberConverter.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+using TimetableDesigner.Core;
+using TimetableDesigner.Services.Project;
+using TimetableDesigner.Services;
+using System.Diagnostics;
+
+namespace TimetableDesigner.Converters
+{
+    internal class TimetableSlotToRowNumberConverter : IValueConverter
+    {
+        #region FIELDS
+
+        private readonly IProjectService _projectService;
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public TimetableSlotToRowNumberConverter()
+        {
+            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
+        }
+
+        #endregion
+
+
+
+        #region PUBLIC METHODS
+
+        //value - TimetableSlot
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is TimetableSpan slot)
+            {
+                return _projectService.ProjectViewModel.TimetableTemplate.Slots.IndexOf(slot);
+            }
+            return 0;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (value is int index && index >= 0)
+            {
+                return _projectService.ProjectViewModel.TimetableTemplate.Slots[index];
+            }
+            return null;
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/Converters/ViewModelToViewConverter.cs

@@ -19,12 +19,13 @@ namespace TimetableDesigner.Converters
 
         private static readonly Dictionary<Type, Type> _viewModelViewPairs = new Dictionary<Type, Type>
         {
-            { typeof(MainViewModel), typeof(MainWindow) },
+            { typeof(MainWindowVM), typeof(MainWindow) },
-            { typeof(WelcomeViewModel), typeof(WelcomeView) },
+            { typeof(WelcomeViewVM), typeof(WelcomeView) },
-            { typeof(ProjectSettingsViewModel), typeof(ProjectSettingsView) },
+            { typeof(ProjectSettingsViewVM), typeof(ProjectSettingsView) },
-            { typeof(ClassroomEditViewModel), typeof(ClassroomEditView) },
+            { typeof(ClassroomEditorViewVM), typeof(ClassroomEditorView) },
-            { typeof(TeacherEditViewModel), typeof(TeacherEditView) },
+            { typeof(TeacherEditorViewVM), typeof(TeacherEditorView) },
-            { typeof(GroupEditViewModel), typeof(GroupEditView) },
+            { typeof(GroupEditorViewVM), typeof(GroupEditorView) },
+            { typeof(TimetableEditorViewVM), typeof(TimetableEditorView) },
         };
 
         #endregion
@@ -35,7 +36,7 @@ namespace TimetableDesigner.Converters
 
         public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
         {
-            BaseViewViewModel? viewModel = value as BaseViewViewModel;
+            IViewVM? viewModel = value as IViewVM;
             if (viewModel is not null)
             {
                 Type view = _viewModelViewPairs[viewModel.GetType()];

TimetableDesigner/Globals/Path.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace TimetableDesigner.Globals
+{
+    public static class Path
+    {
+        public static readonly string ApplicationData = $"{Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)}\\TimetableDesigner";
+        public static readonly string RecentProjectsFile = $"{ApplicationData}\\recent";
+    }
+}

TimetableDesigner/Properties/Resources.Designer.cs

@@ -114,6 +114,114 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to During this class, other classes are taking place in this classroom.
+        /// </summary>
+        public static string Errors_ClassroomBusy {
+            get {
+                return ResourceManager.GetString("Errors.ClassroomBusy", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Class has no assigned classroom.
+        /// </summary>
+        public static string Errors_ClassroomNotAssigned {
+            get {
+                return ResourceManager.GetString("Errors.ClassroomNotAssigned", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to During this class, group, to which selected subgroup is assigned, already has other classes.
+        /// </summary>
+        public static string Errors_GroupAllBusy {
+            get {
+                return ResourceManager.GetString("Errors.GroupAllBusy", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to During this class, the selected group already has other classes.
+        /// </summary>
+        public static string Errors_GroupBusy {
+            get {
+                return ResourceManager.GetString("Errors.GroupBusy", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Class has no assigned group.
+        /// </summary>
+        public static string Errors_GroupNotAssigned {
+            get {
+                return ResourceManager.GetString("Errors.GroupNotAssigned", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to During this class, part of selected group already has other classes in subgroup.
+        /// </summary>
+        public static string Errors_GroupPartBusy {
+            get {
+                return ResourceManager.GetString("Errors.GroupPartBusy", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Class is not scheduled.
+        /// </summary>
+        public static string Errors_SlotNotAssigned {
+            get {
+                return ResourceManager.GetString("Errors.SlotNotAssigned", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to During this class, the selected teacher conducts other classes.
+        /// </summary>
+        public static string Errors_TeacherBusy {
+            get {
+                return ResourceManager.GetString("Errors.TeacherBusy", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Class has no assigned teacher.
+        /// </summary>
+        public static string Errors_TeacherNotAssigned {
+            get {
+                return ResourceManager.GetString("Errors.TeacherNotAssigned", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Selected teacher is not available during the class.
+        /// </summary>
+        public static string Errors_TeacherNotAvailable {
+            get {
+                return ResourceManager.GetString("Errors.TeacherNotAvailable", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to All files.
+        /// </summary>
+        public static string Global_AllFiles {
+            get {
+                return ResourceManager.GetString("Global.AllFiles", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Classroom.
+        /// </summary>
+        public static string Global_Classroom {
+            get {
+                return ResourceManager.GetString("Global.Classroom", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to New classroom.
         /// </summary>
@@ -150,6 +258,15 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Group.
+        /// </summary>
+        public static string Global_Group {
+            get {
+                return ResourceManager.GetString("Global.Group", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to no project loaded.
         /// </summary>
@@ -159,6 +276,33 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to TimetableEditor project file.
+        /// </summary>
+        public static string Global_ProjectFiletypeDescription {
+            get {
+                return ResourceManager.GetString("Global.ProjectFiletypeDescription", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Subgroup.
+        /// </summary>
+        public static string Global_Subgroup {
+            get {
+                return ResourceManager.GetString("Global.Subgroup", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Teacher.
+        /// </summary>
+        public static string Global_Teacher {
+            get {
+                return ResourceManager.GetString("Global.Teacher", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Delete.
         /// </summary>
@@ -231,6 +375,51 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Class name.
+        /// </summary>
+        public static string Main_Errors_ClassName {
+            get {
+                return ResourceManager.GetString("Main.Errors.ClassName", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Day.
+        /// </summary>
+        public static string Main_Errors_Day {
+            get {
+                return ResourceManager.GetString("Main.Errors.Day", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Description.
+        /// </summary>
+        public static string Main_Errors_Description {
+            get {
+                return ResourceManager.GetString("Main.Errors.Description", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Slot.
+        /// </summary>
+        public static string Main_Errors_Slot {
+            get {
+                return ResourceManager.GetString("Main.Errors.Slot", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Source.
+        /// </summary>
+        public static string Main_Errors_Source {
+            get {
+                return ResourceManager.GetString("Main.Errors.Source", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Project is loaded. Do you want to save?.
         /// </summary>
@@ -240,6 +429,97 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Edit.
+        /// </summary>
+        public static string Main_Ribbon_Edit {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Timetable.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Autoschedule all unscheduled classes.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Following classes could not be scheduled.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule_Message_FollowingClassesCouldNotBeScheduled {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule.Message.FollowingClassesCouldNotBeSchedul" +
+                        "ed", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to more.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule_Message_More {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule.Message.More", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to There is no unscheduled classes.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule_Message_NoUnscheduledClasses {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule.Message.NoUnscheduledClasses", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Successfully scheduled classes.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule_Message_SuccessfullyScheduled {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule.Message.SuccessfullyScheduled", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Classroom.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule_Message_UnitClassroom {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule.Message.UnitClassroom", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Group.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule_Message_UnitGroup {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule.Message.UnitGroup", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Teacher.
+        /// </summary>
+        public static string Main_Ribbon_Edit_Timetable_Autoschedule_Message_UnitTeacher {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.Edit.Timetable.Autoschedule.Message.UnitTeacher", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Export.
         /// </summary>
@@ -286,38 +566,47 @@ namespace TimetableDesigner.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to New/Open.
+        ///   Looks up a localized string similar to New.
         /// </summary>
-        public static string Main_Ribbon_File_NewOpen {
+        public static string Main_Ribbon_File_New {
             get {
-                return ResourceManager.GetString("Main.Ribbon.File.NewOpen", resourceCulture);
+                return ResourceManager.GetString("Main.Ribbon.File.New", resourceCulture);
             }
         }
         
         /// <summary>
         ///   Looks up a localized string similar to New.
         /// </summary>
-        public static string Main_Ribbon_File_NewOpen_New {
+        public static string Main_Ribbon_File_New_New {
             get {
-                return ResourceManager.GetString("Main.Ribbon.File.NewOpen.New", resourceCulture);
+                return ResourceManager.GetString("Main.Ribbon.File.New.New", resourceCulture);
             }
         }
         
         /// <summary>
         ///   Looks up a localized string similar to Open.
         /// </summary>
-        public static string Main_Ribbon_File_NewOpen_Open {
+        public static string Main_Ribbon_File_Open {
             get {
-                return ResourceManager.GetString("Main.Ribbon.File.NewOpen.Open", resourceCulture);
+                return ResourceManager.GetString("Main.Ribbon.File.Open", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Open.
+        /// </summary>
+        public static string Main_Ribbon_File_Open_Open {
+            get {
+                return ResourceManager.GetString("Main.Ribbon.File.Open.Open", resourceCulture);
             }
         }
         
         /// <summary>
         ///   Looks up a localized string similar to Open recent.
         /// </summary>
-        public static string Main_Ribbon_File_NewOpen_OpenRecent {
+        public static string Main_Ribbon_File_Open_OpenRecent {
             get {
-                return ResourceManager.GetString("Main.Ribbon.File.NewOpen.OpenRecent", resourceCulture);
+                return ResourceManager.GetString("Main.Ribbon.File.Open.OpenRecent", resourceCulture);
             }
         }
         
@@ -483,6 +772,15 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Are you sure you want to delete this classroom. This operation is irreversible. Classroom will be unassigned for all classes..
+        /// </summary>
+        public static string Main_Treeview_Classrooms_Message_Remove {
+            get {
+                return ResourceManager.GetString("Main.Treeview.Classrooms.Message.Remove", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Edit timetable.
         /// </summary>
@@ -520,7 +818,16 @@ namespace TimetableDesigner.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Are you sure you want to delete this subgroup. This operation is irreversible. Subgroup will be unassigned for all groups..
+        ///   Looks up a localized string similar to Are you sure you want to delete this group. This operation is irreversible. Group will be unassigned for all classes..
+        /// </summary>
+        public static string Main_Treeview_Groups_Message_Remove {
+            get {
+                return ResourceManager.GetString("Main.Treeview.Groups.Message.Remove", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Are you sure you want to delete this subgroup. This operation is irreversible. Subgroup will be unassigned for all groups and classes..
         /// </summary>
         public static string Main_Treeview_Subgroups_Message_Remove {
             get {
@@ -546,6 +853,15 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Are you sure you want to delete this teacher. This operation is irreversible. Teacher will be unassigned for all classes..
+        /// </summary>
+        public static string Main_Treeview_Teachers_Message_Remove {
+            get {
+                return ResourceManager.GetString("Main.Treeview.Teachers.Message.Remove", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Error.
         /// </summary>
@@ -555,6 +871,15 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Information.
+        /// </summary>
+        public static string MessageBox_Information {
+            get {
+                return ResourceManager.GetString("MessageBox.Information", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Question.
         /// </summary>
@@ -564,6 +889,15 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Warning.
+        /// </summary>
+        public static string MessageBox_Warning {
+            get {
+                return ResourceManager.GetString("MessageBox.Warning", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Author.
         /// </summary>
@@ -681,6 +1015,15 @@ namespace TimetableDesigner.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Timetable editing.
+        /// </summary>
+        public static string Tabs_TimetableEdit {
+            get {
+                return ResourceManager.GetString("Tabs.TimetableEdit", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Welcome.
         /// </summary>
@@ -761,5 +1104,23 @@ namespace TimetableDesigner.Properties {
                 return ResourceManager.GetString("TeacherEdit.Name", resourceCulture);
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Autoschedule.
+        /// </summary>
+        public static string TimetableEditor_Autoschedule {
+            get {
+                return ResourceManager.GetString("TimetableEditor.Autoschedule", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Unscheduled.
+        /// </summary>
+        public static string TimetableEditor_Unscheduled {
+            get {
+                return ResourceManager.GetString("TimetableEditor.Unscheduled", resourceCulture);
+            }
+        }
     }
 }

TimetableDesigner/Properties/Resources.resx

@@ -135,6 +135,42 @@
   <data name="ClassroomEdit.Name" xml:space="preserve">
     <value>Name</value>
   </data>
+  <data name="Errors.ClassroomBusy" xml:space="preserve">
+    <value>During this class, other classes are taking place in this classroom</value>
+  </data>
+  <data name="Errors.ClassroomNotAssigned" xml:space="preserve">
+    <value>Class has no assigned classroom</value>
+  </data>
+  <data name="Errors.GroupAllBusy" xml:space="preserve">
+    <value>During this class, group, to which selected subgroup is assigned, already has other classes</value>
+  </data>
+  <data name="Errors.GroupBusy" xml:space="preserve">
+    <value>During this class, the selected group already has other classes</value>
+  </data>
+  <data name="Errors.GroupNotAssigned" xml:space="preserve">
+    <value>Class has no assigned group</value>
+  </data>
+  <data name="Errors.GroupPartBusy" xml:space="preserve">
+    <value>During this class, part of selected group already has other classes in subgroup</value>
+  </data>
+  <data name="Errors.SlotNotAssigned" xml:space="preserve">
+    <value>Class is not scheduled</value>
+  </data>
+  <data name="Errors.TeacherBusy" xml:space="preserve">
+    <value>During this class, the selected teacher conducts other classes</value>
+  </data>
+  <data name="Errors.TeacherNotAssigned" xml:space="preserve">
+    <value>Class has no assigned teacher</value>
+  </data>
+  <data name="Errors.TeacherNotAvailable" xml:space="preserve">
+    <value>Selected teacher is not available during the class</value>
+  </data>
+  <data name="Global.AllFiles" xml:space="preserve">
+    <value>All files</value>
+  </data>
+  <data name="Global.Classroom" xml:space="preserve">
+    <value>Classroom</value>
+  </data>
   <data name="Global.DefaultClassroomName" xml:space="preserve">
     <value>New classroom</value>
   </data>
@@ -147,9 +183,21 @@
   <data name="Global.DefaultTeacherName" xml:space="preserve">
     <value>New teacher</value>
   </data>
+  <data name="Global.Group" xml:space="preserve">
+    <value>Group</value>
+  </data>
   <data name="Global.NoProjectLoadedTitle" xml:space="preserve">
     <value>no project loaded</value>
   </data>
+  <data name="Global.ProjectFiletypeDescription" xml:space="preserve">
+    <value>TimetableEditor project file</value>
+  </data>
+  <data name="Global.Subgroup" xml:space="preserve">
+    <value>Subgroup</value>
+  </data>
+  <data name="Global.Teacher" xml:space="preserve">
+    <value>Teacher</value>
+  </data>
   <data name="GroupEdit.DeleteSubgroup" xml:space="preserve">
     <value>Delete</value>
   </data>
@@ -174,9 +222,54 @@
   <data name="GroupEdit.Subgroups" xml:space="preserve">
     <value>Subgroups</value>
   </data>
+  <data name="Main.Errors.ClassName" xml:space="preserve">
+    <value>Class name</value>
+  </data>
+  <data name="Main.Errors.Day" xml:space="preserve">
+    <value>Day</value>
+  </data>
+  <data name="Main.Errors.Description" xml:space="preserve">
+    <value>Description</value>
+  </data>
+  <data name="Main.Errors.Slot" xml:space="preserve">
+    <value>Slot</value>
+  </data>
+  <data name="Main.Errors.Source" xml:space="preserve">
+    <value>Source</value>
+  </data>
   <data name="Main.Message.SaveCurrentProject" xml:space="preserve">
     <value>Project is loaded. Do you want to save?</value>
   </data>
+  <data name="Main.Ribbon.Edit" xml:space="preserve">
+    <value>Edit</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable" xml:space="preserve">
+    <value>Timetable</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule" xml:space="preserve">
+    <value>Autoschedule all unscheduled classes</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule.Message.FollowingClassesCouldNotBeScheduled" xml:space="preserve">
+    <value>Following classes could not be scheduled</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule.Message.More" xml:space="preserve">
+    <value>more</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule.Message.NoUnscheduledClasses" xml:space="preserve">
+    <value>There is no unscheduled classes</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule.Message.SuccessfullyScheduled" xml:space="preserve">
+    <value>Successfully scheduled classes</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule.Message.UnitClassroom" xml:space="preserve">
+    <value>Classroom</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule.Message.UnitGroup" xml:space="preserve">
+    <value>Group</value>
+  </data>
+  <data name="Main.Ribbon.Edit.Timetable.Autoschedule.Message.UnitTeacher" xml:space="preserve">
+    <value>Teacher</value>
+  </data>
   <data name="Main.Ribbon.Export" xml:space="preserve">
     <value>Export</value>
   </data>
@@ -192,16 +285,19 @@
   <data name="Main.Ribbon.File" xml:space="preserve">
     <value>File</value>
   </data>
-  <data name="Main.Ribbon.File.NewOpen" xml:space="preserve">
+  <data name="Main.Ribbon.File.New" xml:space="preserve">
-    <value>New/Open</value>
-  </data>
-  <data name="Main.Ribbon.File.NewOpen.New" xml:space="preserve">
     <value>New</value>
   </data>
-  <data name="Main.Ribbon.File.NewOpen.Open" xml:space="preserve">
+  <data name="Main.Ribbon.File.New.New" xml:space="preserve">
+    <value>New</value>
+  </data>
+  <data name="Main.Ribbon.File.Open" xml:space="preserve">
     <value>Open</value>
   </data>
-  <data name="Main.Ribbon.File.NewOpen.OpenRecent" xml:space="preserve">
+  <data name="Main.Ribbon.File.Open.Open" xml:space="preserve">
+    <value>Open</value>
+  </data>
+  <data name="Main.Ribbon.File.Open.OpenRecent" xml:space="preserve">
     <value>Open recent</value>
   </data>
   <data name="Main.Ribbon.File.Save" xml:space="preserve">
@@ -258,6 +354,9 @@
   <data name="Main.Treeview.Classrooms.ContextMenu.Edit" xml:space="preserve">
     <value>Edit classroom</value>
   </data>
+  <data name="Main.Treeview.Classrooms.Message.Remove" xml:space="preserve">
+    <value>Are you sure you want to delete this classroom. This operation is irreversible. Classroom will be unassigned for all classes.</value>
+  </data>
   <data name="Main.Treeview.ContextMenu.EditTimetable" xml:space="preserve">
     <value>Edit timetable</value>
   </data>
@@ -270,8 +369,11 @@
   <data name="Main.Treeview.Groups.ContextMenu.Edit" xml:space="preserve">
     <value>Edit group</value>
   </data>
+  <data name="Main.Treeview.Groups.Message.Remove" xml:space="preserve">
+    <value>Are you sure you want to delete this group. This operation is irreversible. Group will be unassigned for all classes.</value>
+  </data>
   <data name="Main.Treeview.Subgroups.Message.Remove" xml:space="preserve">
-    <value>Are you sure you want to delete this subgroup. This operation is irreversible. Subgroup will be unassigned for all groups.</value>
+    <value>Are you sure you want to delete this subgroup. This operation is irreversible. Subgroup will be unassigned for all groups and classes.</value>
   </data>
   <data name="Main.Treeview.Teachers" xml:space="preserve">
     <value>Teachers</value>
@@ -279,12 +381,21 @@
   <data name="Main.Treeview.Teachers.ContextMenu.Edit" xml:space="preserve">
     <value>Edit teacher</value>
   </data>
+  <data name="Main.Treeview.Teachers.Message.Remove" xml:space="preserve">
+    <value>Are you sure you want to delete this teacher. This operation is irreversible. Teacher will be unassigned for all classes.</value>
+  </data>
   <data name="MessageBox.Error" xml:space="preserve">
     <value>Error</value>
   </data>
+  <data name="MessageBox.Information" xml:space="preserve">
+    <value>Information</value>
+  </data>
   <data name="MessageBox.Question" xml:space="preserve">
     <value>Question</value>
   </data>
+  <data name="MessageBox.Warning" xml:space="preserve">
+    <value>Warning</value>
+  </data>
   <data name="ProjectSettings.Author" xml:space="preserve">
     <value>Author</value>
   </data>
@@ -324,6 +435,9 @@
   <data name="Tabs.TeacherEdit" xml:space="preserve">
     <value>Teacher editing</value>
   </data>
+  <data name="Tabs.TimetableEdit" xml:space="preserve">
+    <value>Timetable editing</value>
+  </data>
   <data name="Tabs.Welcome" xml:space="preserve">
     <value>Welcome</value>
   </data>
@@ -351,4 +465,10 @@
   <data name="TeacherEdit.Name" xml:space="preserve">
     <value>Name</value>
   </data>
+  <data name="TimetableEditor.Autoschedule" xml:space="preserve">
+    <value>Autoschedule</value>
+  </data>
+  <data name="TimetableEditor.Unscheduled" xml:space="preserve">
+    <value>Unscheduled</value>
+  </data>
 </root>

TimetableDesigner/Properties/Settings.Designer.cs

@@ -0,0 +1,38 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace TimetableDesigner.Properties {
+    
+    
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator", "17.4.0.0")]
+    internal sealed partial class Settings : global::System.Configuration.ApplicationSettingsBase {
+        
+        private static Settings defaultInstance = ((Settings)(global::System.Configuration.ApplicationSettingsBase.Synchronized(new Settings())));
+        
+        public static Settings Default {
+            get {
+                return defaultInstance;
+            }
+        }
+        
+        [global::System.Configuration.UserScopedSettingAttribute()]
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+        [global::System.Configuration.DefaultSettingValueAttribute("10")]
+        public uint RecentProjectsCount {
+            get {
+                return ((uint)(this["RecentProjectsCount"]));
+            }
+            set {
+                this["RecentProjectsCount"] = value;
+            }
+        }
+    }
+}

TimetableDesigner/Properties/Settings.settings

@@ -0,0 +1,9 @@
+<?xml version='1.0' encoding='utf-8'?>
+<SettingsFile xmlns="http://schemas.microsoft.com/VisualStudio/2004/01/settings" CurrentProfile="(Default)" GeneratedClassNamespace="TimetableDesigner.Properties" GeneratedClassName="Settings">
+  <Profiles />
+  <Settings>
+    <Setting Name="RecentProjectsCount" Type="System.UInt32" Scope="User">
+      <Value Profile="(Default)">10</Value>
+    </Setting>
+  </Settings>
+</SettingsFile>

TimetableDesigner/Resources/Converters.xaml

@@ -5,4 +5,10 @@
     <c:IsNullToVisibilityConverter x:Key="IsNullToVisibilityConverter"/>
     <c:IsNotNullToBooleanConverter x:Key="IsNotNullToBooleanConverter"/>
     <c:IntegerAddConstantConverter x:Key="IntegerAddConstantConverter"/>
+    <c:TimetableDayToColumnNumberConverter x:Key="TimetableDayToColumnNumberConverter"/>
+    <c:TimetableSlotToRowNumberConverter x:Key="TimetableSlotToRowNumberConverter"/>
+    <c:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>
+    <c:ByteArrayToColorConverter x:Key="ByteArrayToColorConverter"/>
+    <c:IUnitVMToUnitNameConverter x:Key="IUnitVMToUnitNameConverter"/>
+    <c:ColorBrightnessIsHigherToBooleanConverter x:Key="ColorBrightnessIsHigherToBooleanConverter"/>
 </ResourceDictionary>

TimetableDesigner/Resources/Images.xaml

@@ -2,8 +2,8 @@
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     xmlns:s="clr-namespace:System;assembly=mscorlib">
     <BitmapImage x:Key="CloseImage" UriSource="Images/Close.png"/>
+    <BitmapImage x:Key="AutoscheduleImage" UriSource="Images/Autoschedule.png"/>
     <BitmapImage x:Key="AddImage" UriSource="Images/Add.png"/>
-    <BitmapImage x:Key="RemoveImage" UriSource="Images/Remove.png"/>
     <BitmapImage x:Key="ProjectImage" UriSource="Images/Project.png"/>
     <BitmapImage x:Key="ProjectSettingsImage" UriSource="Images/ProjectSettings.png"/>
     <BitmapImage x:Key="ClassroomImage" UriSource="Images/Classroom.png"/>
@@ -18,4 +18,19 @@
     <BitmapImage x:Key="RightArrowImage" UriSource="Images/RightArrow.png"/>
     <BitmapImage x:Key="GroupImage" UriSource="Images/Group.png"/>
     <BitmapImage x:Key="GroupAddImage" UriSource="Images/GroupAdd.png"/>
+    <BitmapImage x:Key="ErrorImage" UriSource="Images/Error.png"/>
+    <BitmapImage x:Key="WarningImage" UriSource="Images/Warning.png"/>
+    <BitmapImage x:Key="InfoImage" UriSource="Images/Info.png"/>
+    <BitmapImage x:Key="CloneBlackImage" UriSource="Images/CloneBlack.png"/>
+    <BitmapImage x:Key="CloneWhiteImage" UriSource="Images/CloneWhite.png"/>
+    <BitmapImage x:Key="ClassroomBlackImage" UriSource="Images/ClassroomBlack.png"/>
+    <BitmapImage x:Key="ClassroomWhiteImage" UriSource="Images/ClassroomWhite.png"/>
+    <BitmapImage x:Key="TeacherBlackImage" UriSource="Images/TeacherBlack.png"/>
+    <BitmapImage x:Key="TeacherWhiteImage" UriSource="Images/TeacherWhite.png"/>
+    <BitmapImage x:Key="GroupBlackImage" UriSource="Images/GroupBlack.png"/>
+    <BitmapImage x:Key="GroupWhiteImage" UriSource="Images/GroupWhite.png"/>
+    <BitmapImage x:Key="RemoveBlackImage" UriSource="Images/RemoveBlack.png"/>
+    <BitmapImage x:Key="RemoveWhiteImage" UriSource="Images/RemoveWhite.png"/>
+    <BitmapImage x:Key="EditBlackImage" UriSource="Images/EditBlack.png"/>
+    <BitmapImage x:Key="EditWhiteImage" UriSource="Images/EditWhite.png"/>
 </ResourceDictionary>

TimetableDesigner/Services/FileDialog/FileDialogService.cs

@@ -0,0 +1,78 @@
+using Microsoft.Win32;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Properties;
+
+namespace TimetableDesigner.Services.FileDialog
+{
+    public class FileDialogService : IFileDialogService
+    {
+        #region PUBLIC METHODS
+
+        public string? OpenFile() => OpenFile(new Dictionary<string, IEnumerable<string>>(), true);
+        public string? OpenFile(IDictionary<string, IEnumerable<string>> types, bool allowAllFiles = false)
+        {
+            OpenFileDialog fileDialog = new OpenFileDialog();
+            return BuildAndShowDialog(fileDialog, types, allowAllFiles);
+        }
+
+        public string? SaveFile() => SaveFile(new Dictionary<string, IEnumerable<string>>(), true);
+        public string? SaveFile(IDictionary<string, IEnumerable<string>> types, bool allowAllFiles = false)
+        {
+            SaveFileDialog fileDialog = new SaveFileDialog();
+            return BuildAndShowDialog(fileDialog, types, allowAllFiles);
+        }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private static string? BuildAndShowDialog(Microsoft.Win32.FileDialog fileDialog, IDictionary<string, IEnumerable<string>> types, bool allowAllFiles)
+        {
+            fileDialog.Filter = BuildFilterString(types, allowAllFiles);
+
+            if (fileDialog.ShowDialog() == true)
+            {
+                return fileDialog.FileName;
+            }
+            else
+            {
+                return null;
+            }
+        }
+
+        private static string BuildFilterString(IDictionary<string, IEnumerable<string>> types, bool allFiles)
+        {
+            List<string> typeStrings = new List<string>();
+            foreach (KeyValuePair<string, IEnumerable<string>> type in types) 
+            {
+                StringBuilder sb = new StringBuilder();
+                sb.Append($"{type.Key}|");
+
+                List<string> extensionStrings = new List<string>();
+                foreach (string extension in type.Value)
+                {
+                    extensionStrings.Add($"*.{extension}");
+                }
+
+                sb.Append(string.Join(';', extensionStrings));
+
+                typeStrings.Add(sb.ToString());
+            }
+
+            if (allFiles)
+            {
+                typeStrings.Add($"{Resources.Global_AllFiles}|*.*");
+            }
+
+            return string.Join(" | ", typeStrings);
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/Services/FileDialog/IFileDialogService.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace TimetableDesigner.Services.FileDialog
+{
+    public interface IFileDialogService : IService
+    {
+        string? OpenFile();
+        string? OpenFile(IDictionary<string, IEnumerable<string>> types, bool allowAllFiles = false);
+
+        string? SaveFile();
+        string? SaveFile(IDictionary<string, IEnumerable<string>> types, bool allowAllFiles = false);
+    }
+}

TimetableDesigner/Services/MessageBox/IMessageBoxService.cs

@@ -16,6 +16,12 @@ namespace TimetableDesigner.Services.MessageBox
         MessageBoxQuestionResult ShowQuestion(string message, bool hideCancelButton = false);
         MessageBoxQuestionResult ShowQuestion(string message, string title, bool hideCancelButton = false);
 
+        void ShowWarning(string message);
+        void ShowWarning(string message, string title);
+
+        void ShowInformation(string message);
+        void ShowInformation(string message, string title);
+
         #endregion
     }
 }

TimetableDesigner/Services/MessageBox/MessageBoxService.cs

@@ -34,6 +34,12 @@ namespace TimetableDesigner.Services.MessageBox
             }
         }
 
+        public void ShowWarning(string message) => ShowWarning(message, Resources.MessageBox_Warning);
+        public void ShowWarning(string message, string title) => System.Windows.Forms.MessageBox.Show(message, title, MessageBoxButtons.OK, MessageBoxIcon.Warning);
+
+        public void ShowInformation(string message) => ShowInformation(message, Resources.MessageBox_Information);
+        public void ShowInformation(string message, string title) => System.Windows.Forms.MessageBox.Show(message, title, MessageBoxButtons.OK, MessageBoxIcon.Information);
+
         #endregion
     }
 }

TimetableDesigner/Services/Project/IProjectService.cs

@@ -1,8 +1,11 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Data;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
+using TimetableDesigner.Customs;
 using TimetableDesigner.ViewModels.Models;
 
 namespace TimetableDesigner.Services.Project
@@ -12,7 +15,12 @@ namespace TimetableDesigner.Services.Project
         #region PROPERTIES
 
         Core.Project? Project { get; }
-        ProjectViewModel? ProjectViewModel { get; }
+        ProjectVM? ProjectViewModel { get; }
+
+        ObservableCollection<ProjectError> Errors { get; }
+
+        string? SavePath { get; }
+        ObservableDictionary<Guid, RecentProjectEntry> RecentProjects { get; }
 
         #endregion
 
@@ -21,11 +29,14 @@ namespace TimetableDesigner.Services.Project
         #region METHODS
 
         void New();
-
         void Load(string path);
-
         void Save(string path);
 
+        void RefreshErrors();
+
+        void LoadRecentProjectsList();
+        void SaveRecentProjectsList();
+
         #endregion
     }
 }

TimetableDesigner/Services/Project/ProjectError.cs

@@ -0,0 +1,92 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Customs;
+using TimetableDesigner.ViewModels.Models;
+using TimetableDesigner.ViewModels.Models.Base;
+
+namespace TimetableDesigner.Services.Project
+{
+    public class ProjectError : ObservableObject
+    {
+        #region FIELDS
+
+        private ProjectErrorType _type;
+        private IUnitVM _unit;
+        private ClassVM _class;
+        private string _description;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        public ProjectErrorType Type
+        {
+            get => _type;
+            set
+            {
+                if (_type != value)
+                {
+                    _type = value;
+                    NotifyPropertyChanged(nameof(Type));
+                }
+            }
+        }
+        public IUnitVM Unit
+        {
+            get => _unit;
+            set
+            {
+                if (_unit != value)
+                {
+                    _unit = value;
+                    NotifyPropertyChanged(nameof(Unit));
+                }
+            }
+        }
+        public ClassVM Class
+        {
+            get => _class;
+            set
+            {
+                if (value != _class)
+                {
+                    _class = value;
+                    NotifyPropertyChanged(nameof(Class));
+                }
+            }
+        }
+        public string Description
+        {
+            get => _description;
+            set
+            {
+                if (value != _description) 
+                { 
+                    _description = value;
+                    NotifyPropertyChanged(nameof(Description));
+                }
+            }
+        }
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public ProjectError(ProjectErrorType type, IUnitVM unit, ClassVM @class, string description)
+        {
+            Type = type;
+            Unit = unit;
+            Class = @class;
+            Description = description;
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/Services/Project/ProjectErrorType.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace TimetableDesigner.Services.Project
+{
+    public enum ProjectErrorType
+    {
+        Error,
+        Warning,
+        Information
+    }
+}

TimetableDesigner/Services/Project/ProjectService.cs

@@ -1,12 +1,20 @@
-using System;
+using Microsoft.VisualBasic;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Data;
+using System.Diagnostics;
+using System.IO;
 using System.Linq;
-using System.Text;
+using System.Windows.Input;
-using System.Threading.Tasks;
 using TimetableDesigner.Core;
 using TimetableDesigner.Customs;
 using TimetableDesigner.Properties;
 using TimetableDesigner.ViewModels.Models;
+using TimetableDesigner.ViewModels.Models.Base;
+using static System.Runtime.InteropServices.JavaScript.JSType;
 
 namespace TimetableDesigner.Services.Project
 {
@@ -15,7 +23,19 @@ namespace TimetableDesigner.Services.Project
         #region FIELDS
 
         private Core.Project? _project;
-        private ProjectViewModel? _projectViewModel;
+        private ProjectVM? _projectViewModel;
+
+        private string? _savePath;
+        private ObservableDictionary<Guid, RecentProjectEntry> _recentProjects;
+
+        private ObservableCollection<ProjectError> _errors;
+
+        private static readonly JsonSerializerSettings _serializationSettings = new JsonSerializerSettings()
+        {
+            Formatting = Formatting.Indented,
+            PreserveReferencesHandling = PreserveReferencesHandling.All,
+            NullValueHandling = NullValueHandling.Include,
+        };
 
         #endregion
 
@@ -35,7 +55,7 @@ namespace TimetableDesigner.Services.Project
                 }
             }
         }
-        public ProjectViewModel? ProjectViewModel
+        public ProjectVM? ProjectViewModel
         {
             get => _projectViewModel;
             private set
@@ -48,6 +68,44 @@ namespace TimetableDesigner.Services.Project
             } 
         }
 
+        public string? SavePath
+        {
+            get => _savePath;
+            private set
+            {
+                if (_savePath != value)
+                {
+                    _savePath = value;
+                    NotifyPropertyChanged(nameof(SavePath));
+                }
+            }
+        }
+        public ObservableDictionary<Guid, RecentProjectEntry> RecentProjects
+        {
+            get => _recentProjects;
+            private set
+            {
+                if (_recentProjects != value)
+                {
+                    _recentProjects = value;
+                    NotifyPropertyChanged(nameof(RecentProjects));
+                }
+            }
+        }
+
+        public ObservableCollection<ProjectError> Errors
+        {
+            get => _errors;
+            set
+            {
+                if (_errors != value)
+                {
+                    _errors = value;
+                    NotifyPropertyChanged(nameof(Errors));
+                }
+            }
+        }
+
         #endregion
 
 
@@ -56,8 +114,13 @@ namespace TimetableDesigner.Services.Project
 
         public ProjectService()
         {
-            _project = null;
+            Project = null;
-            _projectViewModel = null;
+            ProjectViewModel = null;
+
+            SavePath = null;
+            RecentProjects = new ObservableDictionary<Guid, RecentProjectEntry>();
+
+            Errors = new ObservableCollection<ProjectError>();
         }
 
         #endregion
@@ -72,17 +135,234 @@ namespace TimetableDesigner.Services.Project
             {
                 Name = Resources.Global_DefaultProjectName,
             };
-            ProjectViewModel = new ProjectViewModel(Project);
+            ProjectViewModel = new ProjectVM(Project);
+            SavePath = null;
+            RefreshErrors();
         }
 
-        public void Load(string path)
+        public async void Load(string path)
         {
+            using (FileStream stream = File.Open(path, FileMode.Open, FileAccess.Read))
+            using (StreamReader reader = new StreamReader(stream))
+            {
+                string content = reader.ReadToEnd();
 
+                Project = JsonConvert.DeserializeObject<Core.Project>(content, _serializationSettings);
+                ProjectViewModel = new ProjectVM(Project);
+            }
+            SavePath = path;
+            RefreshErrors();
         }
 
         public void Save(string path)
         {
+            using (FileStream stream = File.Open(path, FileMode.Create, FileAccess.Write))
+            using (StreamWriter writer = new StreamWriter(stream))
+            {
+                string content = JsonConvert.SerializeObject(Project, _serializationSettings);
 
+                writer.Write(content);
+            }
+            SavePath = path;
+
+            if (!RecentProjects.ContainsKey(Project.Guid))
+            {
+                if (RecentProjects.Count == Settings.Default.RecentProjectsCount)
+                {
+                    IEnumerable<ObservableKeyValuePair<Guid, RecentProjectEntry>> kvp = RecentProjects.Cast<ObservableKeyValuePair<Guid, RecentProjectEntry>>();
+                    RecentProjects.Remove(kvp.Where(x => x.Value.SaveDate <= kvp.Min(y => y.Value.SaveDate)).FirstOrDefault());
+                }
+                RecentProjects.Add(Project.Guid, new(Project.Name, DateTime.Now, SavePath));
+            }
+            else
+            {
+                RecentProjects[Project.Guid] = new(Project.Name, DateTime.Now, SavePath);
+            }
+            SaveRecentProjectsList();
+        }
+
+
+        public void RefreshErrors()
+        {
+            Errors.Clear();
+
+            foreach (ClassVM class1 in ProjectViewModel.Classes)
+            {
+                foreach (ClassVM class2 in ProjectViewModel.Classes)
+                {
+                    if (class1.Equals(class2))
+                    {
+                        continue;
+                    }
+
+                    if (class1.Day is not null
+                        &&
+                        class2.Day is not null
+                        &&
+                        class1.Day.Equals(class2.Day)
+                        &&
+                        class1.Slot is not null
+                        &&
+                        class2.Slot is not null
+                        &&
+                        class1.Slot.Equals(class2.Slot))
+                    {
+                        // same classroom at the same time
+                        bool classroomCondition = class1.Classroom is not null
+                                                  &&
+                                                  class2.Classroom is not null
+                                                  &&
+                                                  class1.Classroom.Equals(class2.Classroom);
+                        if (classroomCondition)
+                        {
+                            ProjectError newEntry = new ProjectError(ProjectErrorType.Error, class2.Classroom, class2, Resources.Errors_ClassroomBusy);
+                            Errors.Add(newEntry);
+                        }
+
+                        // same teacher at the same time
+                        bool teacherCondition = class1.Teacher is not null
+                                                &&
+                                                class2.Teacher is not null
+                                                &&
+                                                class1.Teacher.Equals(class2.Teacher);
+                        if (teacherCondition)
+                        {
+                            ProjectError newEntry = new ProjectError(ProjectErrorType.Error, class2.Teacher, class2, Resources.Errors_TeacherBusy);
+                            Errors.Add(newEntry);
+                        }
+
+                        // same group at the same time
+                        if (class1.Group is not null && class2.Group is not null)
+                        {
+                            if (class1.Group.Equals(class2.Group))
+                            {
+                                ProjectError newEntry = new ProjectError(ProjectErrorType.Error, class2.Group, class2, Resources.Errors_GroupBusy);
+                                Errors.Add(newEntry);
+                            }
+                            else if (class1.Group is GroupVM group1 && class2.Group is SubgroupVM subgroup2 && group1.AssignedSubgroups.Contains(subgroup2))
+                            {
+                                ProjectError newEntry = new ProjectError(ProjectErrorType.Error, class2.Group, class2, Resources.Errors_GroupPartBusy);
+                                Errors.Add(newEntry);
+                            }
+                            else if (class1.Group is SubgroupVM subgroup1 && class2.Group is GroupVM group2 && group2.AssignedSubgroups.Contains(subgroup1))
+                            {
+                                ProjectError newEntry = new ProjectError(ProjectErrorType.Error, class2.Group, class2, Resources.Errors_GroupAllBusy);
+                                Errors.Add(newEntry);
+                            }
+                        }
+                    }
+                }
+
+                bool teacherHoursCondition = class1.Teacher is not null
+                                             &&
+                                             class1.Day is not null
+                                             &&
+                                             class1.Slot is not null
+                                             &&
+                                             (
+                                                 !class1.Teacher.AvailabilityHours.ContainsKey(class1.Day)
+                                                 ||
+                                                 (
+                                                     class1.Teacher.AvailabilityHours.ContainsKey(class1.Day)
+                                                     &&
+                                                     !class1.Teacher.AvailabilityHours[class1.Day].Any(x => x.CheckCollision(class1.Slot) == TimetableSpanCollision.CheckedSlotIn)
+                                                 )
+                                             );
+                if (teacherHoursCondition)
+                {
+                    ProjectError newEntry = new ProjectError(ProjectErrorType.Warning, class1.Teacher, class1, Resources.Errors_TeacherNotAvailable);
+                    Errors.Add(newEntry);
+                }
+
+                bool teacherAssigned = class1.Teacher is not null;
+                bool classroomAssigned = class1.Classroom is not null;
+                bool groupAssigned = class1.Group is not null;
+
+                List<IUnitVM> assigned = new List<IUnitVM>();
+                if (groupAssigned)
+                {
+                    assigned.Add(class1.Group);
+                }
+                if (teacherAssigned)
+                {
+                    assigned.Add(class1.Teacher);
+                }
+                if (classroomAssigned)
+                {
+                    assigned.Add(class1.Classroom);
+                }
+                IUnitVM unit = assigned.FirstOrDefault();
+
+                if (!teacherAssigned)
+                {
+                    ProjectError newEntry = new ProjectError(ProjectErrorType.Warning, unit, class1, Resources.Errors_TeacherNotAssigned);
+                    Errors.Add(newEntry);
+                }
+                if (!classroomAssigned)
+                {
+                    ProjectError newEntry = new ProjectError(ProjectErrorType.Warning, unit, class1, Resources.Errors_ClassroomNotAssigned);
+                    Errors.Add(newEntry);
+                }
+                if (!groupAssigned)
+                {
+                    ProjectError newEntry = new ProjectError(ProjectErrorType.Warning, unit, class1, Resources.Errors_GroupNotAssigned);
+                    Errors.Add(newEntry);
+                }
+
+                if (class1.Slot is null || class1.Day is null)
+                {
+                    ProjectError newEntry = new ProjectError(ProjectErrorType.Information, unit, class1, Resources.Errors_SlotNotAssigned);
+                    Errors.Add(newEntry);
+                }
+            }
+        }
+
+
+        public void LoadRecentProjectsList()
+        {
+            RecentProjects.Clear();
+
+            if (!File.Exists(Globals.Path.RecentProjectsFile))
+            {
+                return;
+            }
+
+            string[] projects;
+            using (FileStream stream = File.Open(Globals.Path.RecentProjectsFile, FileMode.Open, FileAccess.Read))
+            using (StreamReader reader = new StreamReader(stream))
+            {
+                projects = reader.ReadToEnd().Split('\n');
+            }
+            foreach (string project in projects)
+            {
+                string[] projectData = project.Split(" : ");
+                if (projectData.Length < 4)
+                {
+                    continue;
+                }
+
+                string name = projectData[1];
+                string path = projectData[3];
+                if (Guid.TryParse(projectData[0], out Guid guid) && DateTime.TryParse(projectData[2], out DateTime saveDate) && !string.IsNullOrWhiteSpace(path) && File.Exists(path) && !string.IsNullOrWhiteSpace(name))
+                {
+                    RecentProjects.Add(guid, new(name, saveDate, path));
+                }
+            }
+        }
+
+        public void SaveRecentProjectsList()
+        {
+            List<string> lines = new List<string>();
+            foreach (ObservableKeyValuePair<Guid, RecentProjectEntry> project in RecentProjects)
+            {
+                lines.Add($"{project.Key} : {project.Value.Name} : {project.Value.SaveDate} : {project.Value.Path}");
+            }
+
+            using (FileStream stream = File.Open(Globals.Path.RecentProjectsFile, FileMode.Create, FileAccess.Write))
+            using (StreamWriter reader = new StreamWriter(stream))
+            {
+                reader.Write(string.Join('\n', lines));
+            }
         }
 
         #endregion

TimetableDesigner/Services/Project/RecentProjectEntry.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Customs;
+
+namespace TimetableDesigner.Services.Project
+{
+    public class RecentProjectEntry : ObservableObject
+    {
+        #region FIELDS
+
+        private string _name;
+        private DateTime _saveDate;
+        private string _path;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        public string Name
+        {
+            get => _name;
+            set
+            {
+                if (_name != value)
+                {
+                    _name = value;
+                    NotifyPropertyChanged(nameof(Name));
+                }
+            }
+        }
+        public DateTime SaveDate
+        {
+            get => _saveDate;
+            set
+            {
+                if (_saveDate != value)
+                {
+                    _saveDate = value;
+                    NotifyPropertyChanged(nameof(SaveDate));
+                }
+            }
+        }
+        public string Path
+        {
+            get => _path;
+            set
+            {
+                if (_path != value)
+                {
+                    _path = value;
+                    NotifyPropertyChanged(nameof(Path));
+                }
+            }
+        }
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public RecentProjectEntry(string name, DateTime saveDate, string path) 
+        { 
+            Name = name;
+            SaveDate = saveDate;
+            Path = path;
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/Services/Scheduler/ISchedulerService.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Core;
+using TimetableDesigner.ViewModels.Models;
+
+namespace TimetableDesigner.Services.Scheduler
+{
+    public interface ISchedulerService : IService
+    {
+        #region METHODS
+
+        (TimetableDay? Day, TimetableSpan? Slot) Schedule(ClassVM @class);
+
+        #endregion
+    }
+}

TimetableDesigner/Services/Scheduler/SchedulerService.cs

@@ -0,0 +1,201 @@
+using Microsoft.ML;
+using Microsoft.ML.Data;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.Data;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Xml.Linq;
+using TimetableDesigner.Core;
+using TimetableDesigner.Services.Project;
+using TimetableDesigner.ViewModels.Models;
+
+namespace TimetableDesigner.Services.Scheduler
+{
+    public class SchedulerService : ISchedulerService
+    {
+        #region FIELDS
+
+        private IProjectService _projectService;
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public SchedulerService(IProjectService projectService)
+        {
+            _projectService = projectService;
+        }
+
+        #endregion
+
+
+
+        #region PUBLIC METHODS
+
+        public (TimetableDay? Day, TimetableSpan? Slot) Schedule(ClassVM @class)
+        {
+            IEnumerable<(TimetableDay Day, TimetableSpan Slot)> freeSlots = GetFreeSlots(@class);
+
+            List<(TimetableDay Day, TimetableSpan Slot)> allMidBreaks = new List<(TimetableDay Day, TimetableSpan Slot)>();
+            List<(TimetableDay Day, TimetableSpan Slot)> secondTierBreaks = new List<(TimetableDay Day, TimetableSpan Slot)>();
+
+            IEnumerable<TimetableDay> days = freeSlots.Select(x => x.Day).Distinct();
+            foreach (TimetableDay day in days)
+            {
+                IEnumerable<int> unusedIndexes = freeSlots.Where(x => x.Day == day).Select(x => _projectService.ProjectViewModel.TimetableTemplate.Slots.IndexOf(x.Slot));
+                Debug.WriteLine(day.Name);
+                foreach (int unusedIndex in unusedIndexes)
+                {
+                    Debug.WriteLine(unusedIndex);
+                }
+                Debug.WriteLine("");
+
+                IEnumerable<(int Start, int End)> breaks = FindBreaks(unusedIndexes);
+                int last = _projectService.ProjectViewModel.TimetableTemplate.Slots.Count - 1;
+
+                IEnumerable<(int Start, int End)> midBreaks = breaks.Where(x => x.Start != 0 && x.End != last);
+                if (midBreaks.Any())
+                {
+                    allMidBreaks.Add((day, _projectService.ProjectViewModel.TimetableTemplate.Slots.ElementAt(midBreaks.First().Start)));
+                }
+                else
+                {
+                    (int start, int end) = breaks.First();
+                    int selIndex = start == 0 && end != last ? end : start;
+                    secondTierBreaks.Add((day, _projectService.ProjectViewModel.TimetableTemplate.Slots.ElementAt(selIndex)));
+                }
+            }
+
+            if (allMidBreaks.Any())
+            {
+                return allMidBreaks.First();
+            }
+
+            if (secondTierBreaks.Any())
+            {
+                Random rd = new Random();
+                return secondTierBreaks.ElementAt(rd.Next(secondTierBreaks.Count));
+            }
+
+            return (null, null);
+        }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private IEnumerable<(int Start, int End)> FindBreaks(IEnumerable<int> unusedIndexes)
+        {
+            unusedIndexes = unusedIndexes.Order();
+
+            int prev = unusedIndexes.ElementAt(0);
+            int first = unusedIndexes.ElementAt(0);
+            List<(int Start, int End)> breaks = new List<(int Start, int End)>();
+            foreach (int index in unusedIndexes.Skip(1))
+            {
+                if (prev + 1 != index)
+                {
+                    breaks.Add((first, prev));
+                    first = index;
+                }
+                prev = index;
+            }
+            breaks.Add((first, prev));
+            return breaks;
+        }
+
+        private Dictionary<TimetableDay, List<TimetableSpan>> CreateSlotsDictionary()
+        {
+            Dictionary<TimetableDay, List<TimetableSpan>> slotsDictionary = new Dictionary<TimetableDay, List<TimetableSpan>>();
+            foreach (TimetableDay day in _projectService.ProjectViewModel.TimetableTemplate.Days)
+            {
+                slotsDictionary[day] = new List<TimetableSpan>();
+                foreach (TimetableSpan slot in _projectService.ProjectViewModel.TimetableTemplate.Slots)
+                {
+                    slotsDictionary[day].Add(slot);
+                }
+            }
+            return slotsDictionary;
+        }
+
+        private IEnumerable<(TimetableDay Day, TimetableSpan Slot)> GetFreeSlots(ClassVM @class)
+        {
+            Dictionary<TimetableDay, List<TimetableSpan>> classroomFreeSlotsDict = CreateSlotsDictionary();
+            if (@class.Classroom is not null)
+            {
+                IEnumerable<ClassVM> classroomClasses = _projectService.ProjectViewModel.Classes.Where(x => x.Classroom == @class.Classroom).Where(x => x.Day is not null && x.Slot is not null);
+                foreach (ClassVM classroomClass in classroomClasses)
+                {
+                    classroomFreeSlotsDict[classroomClass.Day].Remove(classroomClass.Slot);
+                }
+            }
+            ICollection<(TimetableDay Day, TimetableSpan Slot)> classroomFreeSlots = new List<(TimetableDay Day, TimetableSpan Slot)>();
+            foreach (KeyValuePair<TimetableDay, List<TimetableSpan>> pair in classroomFreeSlotsDict)
+            {
+                foreach (TimetableSpan slot in pair.Value)
+                {
+                    classroomFreeSlots.Add((pair.Key, slot));
+                }
+            }
+
+            Dictionary<TimetableDay, List<TimetableSpan>> teacherFreeSlotsDict = CreateSlotsDictionary();
+            if (@class.Teacher is not null)
+            {
+                IEnumerable<ClassVM> teacherClasses = _projectService.ProjectViewModel.Classes.Where(x => x.Teacher == @class.Teacher).Where(x => x.Day is not null && x.Slot is not null);
+                foreach (ClassVM teacherClass in teacherClasses)
+                {
+                    teacherFreeSlotsDict[teacherClass.Day].Remove(teacherClass.Slot);
+                }
+            }
+            ICollection<(TimetableDay Day, TimetableSpan Slot)> teacherFreeSlots = new List<(TimetableDay Day, TimetableSpan Slot)>();
+            foreach (KeyValuePair<TimetableDay, List<TimetableSpan>> pair in teacherFreeSlotsDict)
+            {
+                foreach (TimetableSpan slot in pair.Value)
+                {
+                    teacherFreeSlots.Add((pair.Key, slot));
+                }
+            }
+
+            Dictionary<TimetableDay, List<TimetableSpan>> groupFreeSlotsDict = CreateSlotsDictionary();
+            if (@class.Group is not null)
+            {
+                IEnumerable<ClassVM> groupClasses;
+                if (@class.Group is SubgroupVM subgroup)
+                {
+                    IEnumerable<GroupVM> groups = _projectService.ProjectViewModel.Groups.Where(x => x.AssignedSubgroups.Contains(subgroup));
+                    groupClasses = _projectService.ProjectViewModel.Classes.Where(x => (x.Group is GroupVM group && groups.Contains(group)) || x.Group == subgroup);
+                }
+                else
+                {
+                    GroupVM group = @class.Group as GroupVM;
+                    groupClasses = _projectService.ProjectViewModel.Classes.Where(x => x.Group == group || (x.Group is SubgroupVM subgroup && group.AssignedSubgroups.Contains(subgroup)));
+                }
+                groupClasses = groupClasses.Where(x => x.Day is not null && x.Slot is not null);
+                foreach (ClassVM groupClass in groupClasses)
+                {
+                    groupFreeSlotsDict[groupClass.Day].Remove(groupClass.Slot);
+                }
+            }
+            ICollection<(TimetableDay Day, TimetableSpan Slot)> groupFreeSlots = new List<(TimetableDay Day, TimetableSpan Slot)>();
+            foreach (KeyValuePair<TimetableDay, List<TimetableSpan>> pair in groupFreeSlotsDict)
+            {
+                foreach (TimetableSpan slot in pair.Value)
+                {
+                    groupFreeSlots.Add((pair.Key, slot));
+                }
+            }
+
+            return classroomFreeSlots.Intersect(teacherFreeSlots).Intersect(groupFreeSlots);
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/Services/TabNavigation/TabItem.cs

@@ -21,7 +21,7 @@ namespace TimetableDesigner.Services.TabNavigation
         private ImageSource _image;
         private string _title;
         private bool _isClosable;
-        private BaseViewViewModel _viewModel;
+        private IViewVM _viewModel;
 
         #endregion
 
@@ -65,7 +65,7 @@ namespace TimetableDesigner.Services.TabNavigation
                 }
             }
         }
-        public BaseViewViewModel ViewModel
+        public IViewVM ViewModel
         {
             get => _viewModel;
             set

TimetableDesigner/Services/TabNavigation/TabNavigationService.cs

@@ -73,7 +73,7 @@ namespace TimetableDesigner.Services.TabNavigation
         public void Close(TabItem item) => Close(new List<TabItem>() { item });
         public void Close(IEnumerable<TabItem> items)
         {
-            TabItem selected = SelectedTab;
+            TabItem? selected = SelectedTab;
             while (items.Contains(selected) && selected != null)
             {
                 int nextIndex = Tabs.IndexOf(selected) + 1;
@@ -102,7 +102,7 @@ namespace TimetableDesigner.Services.TabNavigation
                     }
                 }
             }
-            foreach (TabItem item in items)
+            foreach (TabItem item in items.ToList())
             {
                 Tabs.Remove(item);
             }

TimetableDesigner/Settings.cs

@@ -0,0 +1,28 @@
+namespace TimetableDesigner.Properties {
+    
+    
+    // This class allows you to handle specific events on the settings class:
+    //  The SettingChanging event is raised before a setting's value is changed.
+    //  The PropertyChanged event is raised after a setting's value is changed.
+    //  The SettingsLoaded event is raised after the setting values are loaded.
+    //  The SettingsSaving event is raised before the setting values are saved.
+    internal sealed partial class Settings {
+        
+        public Settings() {
+            // // To add event handlers for saving and changing settings, uncomment the lines below:
+            //
+            // this.SettingChanging += this.SettingChangingEventHandler;
+            //
+            // this.SettingsSaving += this.SettingsSavingEventHandler;
+            //
+        }
+        
+        private void SettingChangingEventHandler(object sender, System.Configuration.SettingChangingEventArgs e) {
+            // Add code to handle the SettingChangingEvent event here.
+        }
+        
+        private void SettingsSavingEventHandler(object sender, System.ComponentModel.CancelEventArgs e) {
+            // Add code to handle the SettingsSaving event here.
+        }
+    }
+}

TimetableDesigner/TimetableDesigner.csproj

@@ -16,29 +16,86 @@
 
   <ItemGroup>
     <None Remove="Resources\Images\Add.png" />
+    <None Remove="Resources\Images\Autoschedule.png" />
     <None Remove="Resources\Images\Classroom.png" />
     <None Remove="Resources\Images\ClassroomAdd.png" />
+    <None Remove="Resources\Images\ClassroomBlack.png" />
+    <None Remove="Resources\Images\ClassroomGrey.png" />
+    <None Remove="Resources\Images\ClassroomWhite.png" />
+    <None Remove="Resources\Images\CloneBlack.png" />
+    <None Remove="Resources\Images\CloneWhite.png" />
     <None Remove="Resources\Images\Close.png" />
     <None Remove="Resources\Images\CloseButtonImage.png" />
+    <None Remove="Resources\Images\EditBlack.png" />
+    <None Remove="Resources\Images\EditGrey.png" />
+    <None Remove="Resources\Images\EditWhite.png" />
+    <None Remove="Resources\Images\Error.png" />
     <None Remove="Resources\Images\Group.png" />
     <None Remove="Resources\Images\GroupAdd.png" />
+    <None Remove="Resources\Images\GroupBlack.png" />
+    <None Remove="Resources\Images\GroupGrey.png" />
+    <None Remove="Resources\Images\GroupWhite.png" />
+    <None Remove="Resources\Images\Info.png" />
     <None Remove="Resources\Images\New.png" />
     <None Remove="Resources\Images\Open.png" />
     <None Remove="Resources\Images\OpenRecent.png" />
     <None Remove="Resources\Images\Project.png" />
     <None Remove="Resources\Images\ProjectSettings.png" />
     <None Remove="Resources\Images\Remove.png" />
+    <None Remove="Resources\Images\RemoveBlack.png" />
+    <None Remove="Resources\Images\RemoveGrey.png" />
+    <None Remove="Resources\Images\RemoveWhite.png" />
     <None Remove="Resources\Images\RightArrow.png" />
     <None Remove="Resources\Images\Save.png" />
     <None Remove="Resources\Images\SaveAs.png" />
     <None Remove="Resources\Images\Teacher.png" />
     <None Remove="Resources\Images\TeacherAdd.png" />
+    <None Remove="Resources\Images\TeacherBlack.png" />
+    <None Remove="Resources\Images\TeacherGrey.png" />
+    <None Remove="Resources\Images\TeacherWhite.png" />
+    <None Remove="Resources\Images\Warning.png" />
   </ItemGroup>
 
   <ItemGroup>
     <Page Remove="Views\ProjectSettingsTabView.xaml" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Content Include="Resources\Images\Autoschedule.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\ClassroomBlack.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\ClassroomWhite.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\CloneBlack.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\CloneWhite.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\EditBlack.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\EditWhite.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\Error.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\GroupBlack.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\GroupWhite.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\Info.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+  </ItemGroup>
+
   <ItemGroup>
     <Content Include="Resources\Images\Classroom.png">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
@@ -70,7 +127,10 @@
     <Content Include="Resources\Images\ProjectSettings.png">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </Content>
-    <Content Include="Resources\Images\Remove.png">
+    <Content Include="Resources\Images\RemoveBlack.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\RemoveWhite.png">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </Content>
     <Content Include="Resources\Images\RightArrow.png">
@@ -88,11 +148,23 @@
     <Content Include="Resources\Images\TeacherAdd.png">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </Content>
+    <Content Include="Resources\Images\TeacherBlack.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\TeacherWhite.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
+    <Content Include="Resources\Images\Warning.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </Content>
   </ItemGroup>
 
   <ItemGroup>
     <PackageReference Include="Extended.Wpf.Toolkit" Version="4.5.0" />
     <PackageReference Include="Fluent.Ribbon" Version="9.0.4" />
+    <PackageReference Include="Microsoft.ML" Version="2.0.1" />
+    <PackageReference Include="Microsoft.Xaml.Behaviors.Wpf" Version="1.1.39" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
   </ItemGroup>
 
   <ItemGroup>
@@ -117,6 +189,11 @@
       <AutoGen>True</AutoGen>
       <DependentUpon>Resources.resx</DependentUpon>
     </Compile>
+    <Compile Update="Properties\Settings.Designer.cs">
+      <DesignTimeSharedInput>True</DesignTimeSharedInput>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>Settings.settings</DependentUpon>
+    </Compile>
   </ItemGroup>
 
   <ItemGroup>
@@ -130,4 +207,11 @@
     </EmbeddedResource>
   </ItemGroup>
 
+  <ItemGroup>
+    <None Update="Properties\Settings.settings">
+      <Generator>SettingsSingleFileGenerator</Generator>
+      <LastGenOutput>Settings.Designer.cs</LastGenOutput>
+    </None>
+  </ItemGroup>
+
 </Project>

TimetableDesigner/ViewModels/IModelVM.cs

@@ -3,11 +3,10 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
-using TimetableDesigner.Customs;
 
 namespace TimetableDesigner.ViewModels
 {
-    public abstract class BaseViewViewModel : ObservableObject
+    public interface IModelVM
     {
     }
 }

TimetableDesigner/ViewModels/IRemovableVM.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace TimetableDesigner.ViewModels.Models.Base
+{
+    public interface IRemovableVM : IUnitVM
+    {
+    }
+}

TimetableDesigner/ViewModels/IUnitEditorViewVM.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.ViewModels.Models.Base;
+
+namespace TimetableDesigner.ViewModels
+{
+    internal interface IUnitEditorViewVM : IViewVM
+    {
+        #region PROPERTIES
+
+        IUnitVM Unit { get; }
+
+        #endregion
+    }
+}

TimetableDesigner/ViewModels/IUnitVM.cs

@@ -5,13 +5,13 @@ using System.Text;
 using System.Threading.Tasks;
 using TimetableDesigner.Core;
 
-namespace TimetableDesigner.ViewModels.Models
+namespace TimetableDesigner.ViewModels.Models.Base
 {
-    public interface IGroupViewModel
+    public interface IUnitVM : IModelVM
     {
         #region PROPERTIES
-
+        
-        IGroup Group { get; }
+        IUnit Unit { get; }
         string Name { get; }
 
         #endregion

TimetableDesigner/ViewModels/IViewVM.cs

@@ -1,14 +1,12 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
-using TimetableDesigner.Customs;
 
 namespace TimetableDesigner.ViewModels
 {
-    public abstract class BaseModelViewModel : ObservableObject
+    public interface IViewVM
     {
     }
 }

TimetableDesigner/ViewModels/Models/BaseGroupVM.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Core;
+using TimetableDesigner.Customs;
+using TimetableDesigner.ViewModels.Models.Base;
+
+namespace TimetableDesigner.ViewModels.Models
+{
+    public abstract class BaseGroupVM : ObservableObject, IModelVM, IUnitVM
+    {
+        #region FIELDS
+
+        protected BaseGroup _baseGroup;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        IUnit IUnitVM.Unit => _baseGroup;
+        public BaseGroup BaseGroup => _baseGroup;
+
+        public string Name
+        {
+            get => _baseGroup.Name;
+            set
+            {
+                if (_baseGroup.Name != value)
+                {
+                    _baseGroup.Name = value;
+                    NotifyPropertyChanged(nameof(Name));
+                }
+            }
+        }
+        public string ShortName
+        {
+            get => _baseGroup.ShortName;
+            set
+            {
+                if (_baseGroup.ShortName != value)
+                {
+                    _baseGroup.ShortName = value;
+                    NotifyPropertyChanged(nameof(ShortName));
+                }
+            }
+        }
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public BaseGroupVM(BaseGroup baseGroup)
+        {
+            _baseGroup = baseGroup;
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/ViewModels/Models/ClassVM.cs

@@ -1,16 +1,20 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.Design;
+using System.Diagnostics;
+using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using TimetableDesigner.Core;
+using TimetableDesigner.Customs;
 using TimetableDesigner.Services;
 using TimetableDesigner.Services.Project;
+using TimetableDesigner.ViewModels.Models.Base;
 
 namespace TimetableDesigner.ViewModels.Models
 {
-    public class ClassViewModel : BaseModelViewModel
+    public class ClassVM : ObservableObject, IModelVM
     {
         #region FIELDS
 
@@ -38,7 +42,7 @@ namespace TimetableDesigner.ViewModels.Models
                 }
             }
         }
-        public TeacherViewModel? Teacher
+        public TeacherVM? Teacher
         {
             get => _projectService.ProjectViewModel?.Teachers.Where(vm => vm.Teacher == _class.Teacher).FirstOrDefault();
             set
@@ -47,18 +51,22 @@ namespace TimetableDesigner.ViewModels.Models
                 {
                     _class.Teacher = value?.Teacher;
                     NotifyPropertyChanged(nameof(Teacher));
+
+                    //REFRESH: Errors
+                    _projectService.RefreshErrors();
                 }
             }
         }
-        public IGroupViewModel? Group
+        public BaseGroupVM? Group
         {
             get
             {
-                if (_class.Group?.GetType() == typeof(GroupViewModel))
+
+                if (_class.Group?.GetType() == typeof(Group))
                 {
                     return _projectService.ProjectViewModel?.Groups.Where(vm => vm.Group == _class.Group).FirstOrDefault();
                 }
-                else if (_class.Group?.GetType() == typeof(SubgroupViewModel))
+                else if (_class.Group?.GetType() == typeof(Subgroup))
                 {
                     return _projectService.ProjectViewModel?.Subgroups.Where(vm => vm.Subgroup == _class.Group).FirstOrDefault();
                 }
@@ -69,14 +77,17 @@ namespace TimetableDesigner.ViewModels.Models
             }
             set
             {
-                if (_class.Group != value?.Group)
+                if (_class.Group != value?.BaseGroup)
                 {
-                    _class.Group = value?.Group;
+                    _class.Group = value?.BaseGroup;
                     NotifyPropertyChanged(nameof(Group));
+
+                    //REFRESH: Errors
+                    _projectService.RefreshErrors();
                 }
             }
         }
-        public ClassroomViewModel? Classroom
+        public ClassroomVM? Classroom
         {
             get => _projectService.ProjectViewModel?.Classrooms.Where(vm => vm.Classroom == _class.Classroom).FirstOrDefault();
             set
@@ -85,6 +96,45 @@ namespace TimetableDesigner.ViewModels.Models
                 {
                     _class.Classroom = value?.Classroom;
                     NotifyPropertyChanged(nameof(Classroom));
+
+                    //REFRESH: Errors
+                    _projectService.RefreshErrors();
+                }
+            }
+        }
+        public TimetableDay? Day
+        {
+            get => _class.Day;
+            set
+            {
+                if (value != _class.Day) 
+                {
+                    _class.Day = value;
+                    NotifyPropertyChanged(nameof(Day));
+                }
+            }
+        }
+        public TimetableSpan? Slot
+        {
+            get => _class.Slot;
+            set
+            {
+                if (value != _class.Slot)
+                {
+                    _class.Slot = value;
+                    NotifyPropertyChanged(nameof(Slot));
+                }
+            }
+        }
+        public byte[] Color
+        {
+            get => _class.Color;
+            set
+            {
+                if (value != _class.Color)
+                {
+                    _class.Color = value;
+                    NotifyPropertyChanged(nameof(Color));
                 }
             }
         }
@@ -95,7 +145,7 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region CONSTRUCTORS
 
-        public ClassViewModel(Class @class) 
+        public ClassVM(Class @class) 
         {
             _projectService = ServiceProvider.Instance.GetService<IProjectService>();
 

TimetableDesigner/ViewModels/Models/ClassroomVM.cs

@@ -4,10 +4,12 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using TimetableDesigner.Core;
+using TimetableDesigner.Customs;
+using TimetableDesigner.ViewModels.Models.Base;
 
 namespace TimetableDesigner.ViewModels.Models
 {
-    public class ClassroomViewModel : BaseModelViewModel
+    public class ClassroomVM : ObservableObject, IModelVM, IUnitVM, IRemovableVM
     {
         #region FIELDS
 
@@ -19,6 +21,7 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region PROPERTIES
 
+        IUnit IUnitVM.Unit => _classroom;
         public Classroom Classroom => _classroom;
 
         public string Name
@@ -76,7 +79,7 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region CONSTRUCTORS
 
-        public ClassroomViewModel(Classroom classroom)
+        public ClassroomVM(Classroom classroom)
         {
             _classroom = classroom;
         }

TimetableDesigner/ViewModels/Models/GroupVM.cs

@@ -5,53 +5,40 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using TimetableDesigner.Core;
+using TimetableDesigner.Customs;
 using TimetableDesigner.Services;
 using TimetableDesigner.Services.Project;
+using TimetableDesigner.ViewModels.Models.Base;
 
 namespace TimetableDesigner.ViewModels.Models
 {
-    public class GroupViewModel : BaseModelViewModel, IGroupViewModel
+    public class GroupVM : BaseGroupVM, IRemovableVM
     {
         #region FIELDS
 
         private IProjectService _projectService;
 
-        private Group _group;
-
         #endregion
 
 
 
         #region PROPERTIES
 
-        IGroup IGroupViewModel.Group => _group;
+        public Group Group => (Group)_baseGroup;
-        public Group Group => _group;
 
-        public string Name
-        {
-            get => _group.Name;
-            set
-            {
-                if (_group.Name != value)
-                {
-                    _group.Name = value;
-                    NotifyPropertyChanged(nameof(Name));
-                }
-            }
-        }
         public string Description
         {
-            get => _group.Description;
+            get => Group.Description;
             set
             {
-                if (_group.Description != value)
+                if (Group.Description != value)
                 {
-                    _group.Description = value;
+                    Group.Description = value;
                     NotifyPropertyChanged(nameof(Description));
                 }
             }
         }
-        public ObservableCollection<SubgroupViewModel> AssignedSubgroups => new ObservableCollection<SubgroupViewModel>(_projectService.ProjectViewModel.Subgroups.Where(vm => Group.AssignedSubgroups.Contains(vm.Subgroup)));
+        public ObservableCollection<SubgroupVM> AssignedSubgroups => new ObservableCollection<SubgroupVM>(_projectService.ProjectViewModel.Subgroups.Where(vm => Group.AssignedSubgroups.Contains(vm.Subgroup)));
 
         #endregion
 
@@ -59,10 +46,9 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region CONSTRUCTORS
 
-        public GroupViewModel(Group group)
+        public GroupVM(Group group) : base(group)
         {
             _projectService = ServiceProvider.Instance.GetService<IProjectService>();
-            _group = group;
         }
 
         #endregion
@@ -71,16 +57,22 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region PUBLIC METHODS
 
-        public void AddSubgroup(SubgroupViewModel subgroup)
+        public void AddSubgroup(SubgroupVM subgroup)
         {
             Group.AssignedSubgroups.Add(subgroup.Subgroup);
             NotifyPropertyChanged(nameof(AssignedSubgroups));
+
+            //REFRESH: Errors
+            _projectService.RefreshErrors();
         }
 
-        public void RemoveSubgroup(SubgroupViewModel subgroup)
+        public void RemoveSubgroup(SubgroupVM subgroup)
         {
             Group.AssignedSubgroups.Remove(subgroup.Subgroup);
             NotifyPropertyChanged(nameof(AssignedSubgroups));
+
+            //REFRESH: Errors
+            _projectService.RefreshErrors();
         }
 
         #endregion

TimetableDesigner/ViewModels/Models/ProjectVM.cs

@@ -0,0 +1,222 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Core;
+using TimetableDesigner.Customs;
+using TimetableDesigner.Services.Project;
+
+namespace TimetableDesigner.ViewModels.Models
+{
+    public class ProjectVM : ObservableObject, IModelVM
+    {
+        #region FIELDS
+
+        private Project _project;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        public Project Project => _project;
+
+        public string Name
+        {
+            get => Project.Name;
+            set
+            {
+                if (Project.Name != value)
+                {
+                    Project.Name = value;
+                    NotifyPropertyChanged(nameof(Name));
+                }
+            }
+        }
+        public string Author
+        {
+            get => Project.Author;
+            set
+            {
+                if (Project.Author != value)
+                {
+                    Project.Author = value;
+                    NotifyPropertyChanged(nameof(Author));
+                }
+            }
+        }
+        public string Description
+        {
+            get => Project.Description;
+            set
+            {
+                if (Project.Description != value)
+                {
+                    Project.Description = value;
+                    NotifyPropertyChanged(nameof(Description));
+                }
+            }
+        }
+        public TimetableTemplateVM TimetableTemplate { get; set; }
+        public ObservableCollection<ClassroomVM> Classrooms { get; set; }
+        public ObservableCollection<TeacherVM> Teachers { get; set; }
+        public ObservableCollection<GroupVM> Groups { get; set; }
+        public ObservableCollection<SubgroupVM> Subgroups { get; set; }
+        public ObservableCollection<ClassVM> Classes { get; set; }
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public ProjectVM(Project project)
+        {
+            _project = project;
+
+            TimetableTemplate = new TimetableTemplateVM(_project.TimetableTemplate);
+
+            Classrooms = new ObservableCollection<ClassroomVM>(_project.Classrooms.Select(item => new ClassroomVM(item)));
+            Classrooms.CollectionChanged += Classrooms_CollectionChanged;
+
+            Teachers = new ObservableCollection<TeacherVM>(_project.Teachers.Select(item => new TeacherVM(item)));
+            Teachers.CollectionChanged += Teachers_CollectionChanged;
+
+            Groups = new ObservableCollection<GroupVM>(_project.Groups.Select(item => new GroupVM(item)));
+            Groups.CollectionChanged += Groups_CollectionChanged;
+
+            Subgroups = new ObservableCollection<SubgroupVM>(_project.Subgroups.Select(item => new SubgroupVM(item)));
+            Subgroups.CollectionChanged += Subgroups_CollectionChanged;
+
+            Classes = new ObservableCollection<ClassVM>(_project.Classes.Select(item => new ClassVM(item)));
+            Classes.CollectionChanged += Classes_CollectionChanged;
+        }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private void Classrooms_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
+        {
+            if (e.OldItems is not null)
+            {
+                foreach (ClassroomVM vm in e.OldItems)
+                {
+                    foreach (ClassVM cvm in Classes.Where(x => x.Classroom == vm))
+                    {
+                        cvm.Classroom = null;
+                    }
+                    _project.Classrooms.Remove(vm.Classroom);
+                }
+            }
+
+            if (e.NewItems is not null)
+            {
+                foreach (ClassroomVM vm in e.NewItems)
+                {
+                    _project.Classrooms.Add(vm.Classroom);
+                }
+            }
+        }
+
+        private void Teachers_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
+        {
+            if (e.OldItems is not null)
+            {
+                foreach (TeacherVM vm in e.OldItems)
+                {
+                    foreach (ClassVM cvm in Classes.Where(x => x.Teacher == vm))
+                    {
+                        cvm.Teacher = null;
+                    }
+                    _project.Teachers.Remove(vm.Teacher);
+                }
+            }
+
+            if (e.NewItems is not null)
+            {
+                foreach (TeacherVM vm in e.NewItems)
+                {
+                    _project.Teachers.Add(vm.Teacher);
+                }
+            }
+        }
+
+        private void Groups_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
+        {
+            if (e.OldItems is not null)
+            {
+                foreach (GroupVM vm in e.OldItems)
+                {
+                    foreach (ClassVM cvm in Classes.Where(x => x.Group == vm))
+                    {
+                        cvm.Group = null;
+                    }
+                    _project.Groups.Remove(vm.Group);
+                }
+            }
+
+            if (e.NewItems is not null)
+            {
+                foreach (GroupVM vm in e.NewItems)
+                {
+                    _project.Groups.Add(vm.Group);
+                }
+            }
+        }
+
+        private void Subgroups_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
+        {
+            if (e.OldItems is not null)
+            {
+                foreach (SubgroupVM vm in e.OldItems)
+                {
+                    foreach (ClassVM cvm in Classes.Where(x => x.Group == vm))
+                    {
+                        cvm.Group = null;
+                    }
+                    foreach (GroupVM gvm in Groups.Where(x => x.AssignedSubgroups.Contains(vm)))
+                    {
+                        gvm.RemoveSubgroup(vm);
+                    }
+                    _project.Subgroups.Remove(vm.Subgroup);
+                }
+            }
+
+            if (e.NewItems is not null)
+            {
+                foreach (SubgroupVM vm in e.NewItems)
+                {
+                    _project.Subgroups.Add(vm.Subgroup);
+                }
+            }
+        }
+
+        private void Classes_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
+        {
+            if (e.OldItems is not null)
+            {
+                foreach (ClassVM vm in e.OldItems)
+                {
+                    _project.Classes.Remove(vm.Class);
+                }
+            }
+
+            if (e.NewItems is not null)
+            {
+                foreach (ClassVM vm in e.NewItems)
+                {
+                    _project.Classes.Add(vm.Class);
+                }
+            }
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/ViewModels/Models/ProjectViewModel.cs

@@ -1,188 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Collections.ObjectModel;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using TimetableDesigner.Core;
-
-namespace TimetableDesigner.ViewModels.Models
-{
-    public class ProjectViewModel : BaseModelViewModel
-    {
-        #region FIELDS
-
-        private Project _project;
-
-        #endregion
-
-
-
-        #region PROPERTIES
-
-        public Project Project => _project;
-
-        public string Name
-        {
-            get => Project.Name;
-            set
-            {
-                if (Project.Name != value)
-                {
-                    Project.Name = value;
-                    NotifyPropertyChanged(nameof(Name));
-                }
-            }
-        }
-        public string Author
-        {
-            get => Project.Author;
-            set
-            {
-                if (Project.Author != value)
-                {
-                    Project.Author = value;
-                    NotifyPropertyChanged(nameof(Author));
-                }
-            }
-        }
-        public string Description
-        {
-            get => Project.Description;
-            set
-            {
-                if (Project.Description != value)
-                {
-                    Project.Description = value;
-                    NotifyPropertyChanged(nameof(Description));
-                }
-            }
-        }
-        public TimetableTemplateViewModel TimetableTemplate { get; set; }
-        public ObservableCollection<ClassroomViewModel> Classrooms { get; set; }
-        public ObservableCollection<TeacherViewModel> Teachers { get; set; }
-        public ObservableCollection<GroupViewModel> Groups { get; set; }
-        public ObservableCollection<SubgroupViewModel> Subgroups { get; set; }
-
-        #endregion
-
-
-
-        #region CONSTRUCTORS
-
-        public ProjectViewModel(Project project)
-        {
-            _project = project;
-
-            TimetableTemplate = new TimetableTemplateViewModel(_project.TimetableTemplate);
-
-            Classrooms = new ObservableCollection<ClassroomViewModel>();
-            Classrooms.CollectionChanged += Classrooms_CollectionChanged;
-
-            Teachers = new ObservableCollection<TeacherViewModel>();
-            Teachers.CollectionChanged += Teachers_CollectionChanged;
-
-            Groups = new ObservableCollection<GroupViewModel>();
-            Groups.CollectionChanged += Groups_CollectionChanged;
-
-            Subgroups = new ObservableCollection<SubgroupViewModel>();
-            Subgroups.CollectionChanged += Subgroups_CollectionChanged;
-        }
-
-        #endregion
-
-
-
-        #region PRIVATE METHODS
-
-        private void Classrooms_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
-        {
-            IList<ClassroomViewModel>? added = e.NewItems as IList<ClassroomViewModel>;
-            IList<ClassroomViewModel>? removed = e.OldItems as IList<ClassroomViewModel>;
-            
-            if (removed is not null)
-            {
-                foreach (ClassroomViewModel vm in removed)
-                {
-                    _project.Classrooms.Remove(vm.Classroom);
-                }
-            }
-
-            if (added is not null)
-            {
-                foreach (ClassroomViewModel vm in added)
-                {
-                    _project.Classrooms.Add(vm.Classroom);
-                }
-            }
-        }
-
-        private void Teachers_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
-        {
-            IList<TeacherViewModel>? added = e.NewItems as IList<TeacherViewModel>;
-            IList<TeacherViewModel>? removed = e.OldItems as IList<TeacherViewModel>;
-
-            if (removed is not null)
-            {
-                foreach (TeacherViewModel vm in removed)
-                {
-                    _project.Teachers.Remove(vm.Teacher);
-                }
-            }
-
-            if (added is not null)
-            {
-                foreach (TeacherViewModel vm in added)
-                {
-                    _project.Teachers.Add(vm.Teacher);
-                }
-            }
-        }
-
-        private void Groups_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
-        {
-            IList<GroupViewModel>? added = e.NewItems as IList<GroupViewModel>;
-            IList<GroupViewModel>? removed = e.OldItems as IList<GroupViewModel>;
-
-            if (removed is not null)
-            {
-                foreach (GroupViewModel vm in removed)
-                {
-                    _project.Groups.Remove(vm.Group);
-                }
-            }
-
-            if (added is not null)
-            {
-                foreach (GroupViewModel vm in added)
-                {
-                    _project.Groups.Add(vm.Group);
-                }
-            }
-        }
-
-        private void Subgroups_CollectionChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
-        {
-            IList<SubgroupViewModel>? added = e.NewItems as IList<SubgroupViewModel>;
-            IList<SubgroupViewModel>? removed = e.OldItems as IList<SubgroupViewModel>;
-
-            if (removed is not null)
-            {
-                foreach (SubgroupViewModel vm in removed)
-                {
-                    _project.Subgroups.Remove(vm.Subgroup);
-                }
-            }
-
-            if (added is not null)
-            {
-                foreach (SubgroupViewModel vm in added)
-                {
-                    _project.Subgroups.Add(vm.Subgroup);
-                }
-            }
-        }
-
-        #endregion
-    }
-}

TimetableDesigner/ViewModels/Models/SubgroupVM.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Core;
+using TimetableDesigner.Customs;
+using TimetableDesigner.ViewModels.Models.Base;
+
+namespace TimetableDesigner.ViewModels.Models
+{
+    public class SubgroupVM : BaseGroupVM, IRemovableVM
+    {
+        #region PROPERTIES
+
+        public Subgroup Subgroup => (Subgroup)_baseGroup;
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public SubgroupVM(Subgroup subgroup) : base(subgroup)
+        { }
+
+        #endregion
+    }
+}

TimetableDesigner/ViewModels/Models/SubgroupViewModel.cs

@@ -1,51 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using TimetableDesigner.Core;
-
-namespace TimetableDesigner.ViewModels.Models
-{
-    public class SubgroupViewModel : BaseModelViewModel, IGroupViewModel
-    {
-        #region FIELDS
-
-        private Subgroup _subgroup;
-
-        #endregion
-
-
-
-        #region PROPERTIES
-
-        IGroup IGroupViewModel.Group => _subgroup;
-        public Subgroup Subgroup => _subgroup;
-
-        public string Name
-        {
-            get => _subgroup.Name;
-            set
-            {
-                if (_subgroup.Name != value)
-                {
-                    _subgroup.Name = value;
-                    NotifyPropertyChanged(nameof(Name));
-                }
-            }
-        }
-
-        #endregion
-
-
-
-        #region CONSTRUCTORS
-
-        public SubgroupViewModel(Subgroup subgroup)
-        {
-            _subgroup = subgroup;
-        }
-
-        #endregion
-    }
-}

TimetableDesigner/ViewModels/Models/TeacherVM.cs

@@ -6,13 +6,16 @@ using System.Text;
 using System.Threading.Tasks;
 using TimetableDesigner.Core;
 using TimetableDesigner.Customs;
+using TimetableDesigner.Services.Project;
+using TimetableDesigner.ViewModels.Models.Base;
 
 namespace TimetableDesigner.ViewModels.Models
 {
-    public class TeacherViewModel : BaseModelViewModel
+    public class TeacherVM : ObservableObject, IModelVM, IUnitVM, IRemovableVM
     {
         #region FIELDS
 
+        private IProjectService _projectService;
         private Teacher _teacher;
 
         #endregion
@@ -21,6 +24,7 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region PROPERTIES
 
+        IUnit IUnitVM.Unit => _teacher;
         public Teacher Teacher => _teacher;
 
         public string Name
@@ -55,8 +59,9 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region CONSTRUCTORS
 
-        public TeacherViewModel(Teacher teacher)
+        public TeacherVM(Teacher teacher)
         {
+            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
             _teacher = teacher;
         }
 
@@ -72,6 +77,9 @@ namespace TimetableDesigner.ViewModels.Models
             {
                 Teacher.AvailabilityHours.Add(day, new TimetableSpanCollection());
                 NotifyPropertyChanged(nameof(AvailabilityHours));
+
+                //REFRESH: Errors
+                _projectService.RefreshErrors();
             }
         }
 
@@ -79,6 +87,9 @@ namespace TimetableDesigner.ViewModels.Models
         {
             Teacher.AvailabilityHours.Remove(day);
             NotifyPropertyChanged(nameof(AvailabilityHours));
+
+            //REFRESH: Errors
+            _projectService.RefreshErrors();
         }
 
         public void AddHours(TimetableDay day, TimetableSpan hours) 
@@ -87,6 +98,9 @@ namespace TimetableDesigner.ViewModels.Models
             {
                 Teacher.AvailabilityHours[day].Add(hours);
                 NotifyPropertyChanged(nameof(AvailabilityHours));
+
+                //REFRESH: Errors
+                _projectService.RefreshErrors();
             }
         }
 
@@ -96,6 +110,9 @@ namespace TimetableDesigner.ViewModels.Models
             {
                 Teacher.AvailabilityHours[day].Remove(hours);
                 NotifyPropertyChanged(nameof(AvailabilityHours));
+
+                //REFRESH: Errors
+                _projectService.RefreshErrors();
             }
         }
 

TimetableDesigner/ViewModels/Models/TimetableTemplateVM.cs

@@ -5,10 +5,11 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using TimetableDesigner.Core;
+using TimetableDesigner.Customs;
 
 namespace TimetableDesigner.ViewModels.Models
 {
-    public class TimetableTemplateViewModel : BaseModelViewModel
+    public class TimetableTemplateVM : ObservableObject, IModelVM
     {
         #region FIELDS
 
@@ -31,7 +32,7 @@ namespace TimetableDesigner.ViewModels.Models
 
         #region CONSTRUCTORS
 
-        public TimetableTemplateViewModel(TimetableTemplate timetableTemplate)
+        public TimetableTemplateVM(TimetableTemplate timetableTemplate)
         {
             _timetableTemplate = timetableTemplate;
         }
@@ -44,25 +45,25 @@ namespace TimetableDesigner.ViewModels.Models
 
         public void AddDay(TimetableDay day)
         {
-            _timetableTemplate.AddDay(day);
+            _timetableTemplate.Days.Add(day);
             NotifyPropertyChanged(nameof(Days));
         }
 
         public void RemoveDay(TimetableDay day)
         {
-            _timetableTemplate.RemoveDay(day);
+            _timetableTemplate.Days.Remove(day);
             NotifyPropertyChanged(nameof(Days));
         }
 
         public void AddSlot(TimetableSpan slot)
         {
-            _timetableTemplate.AddSlot(slot);
+            _timetableTemplate.Slots.Add(slot);
             NotifyPropertyChanged(nameof(Slots));
         }
 
         public void RemoveSlot(TimetableSpan slot)
         {
-            _timetableTemplate.RemoveSlot(slot);
+            _timetableTemplate.Slots.Remove(slot);
             NotifyPropertyChanged(nameof(Slots));
         }
 

TimetableDesigner/ViewModels/Views/ClassroomEditorViewVM.cs

@@ -9,14 +9,15 @@ using TimetableDesigner.Properties;
 using TimetableDesigner.Services;
 using TimetableDesigner.Services.TabNavigation;
 using TimetableDesigner.ViewModels.Models;
+using TimetableDesigner.ViewModels.Models.Base;
 
 namespace TimetableDesigner.ViewModels.Views
 {
-    public class ClassroomEditViewModel : BaseViewViewModel
+    public class ClassroomEditorViewVM : ObservableObject, IViewVM, IUnitEditorViewVM
     {
         #region FIELDS
 
-        private ClassroomViewModel _classroom;
+        private ClassroomVM _classroom;
 
         #endregion
 
@@ -24,7 +25,8 @@ namespace TimetableDesigner.ViewModels.Views
 
         #region PROPERTIES
 
-        public ClassroomViewModel Classroom
+        IUnitVM IUnitEditorViewVM.Unit => Classroom;
+        public ClassroomVM Classroom
         {
             get => _classroom;
             set
@@ -62,10 +64,10 @@ namespace TimetableDesigner.ViewModels.Views
 
         #region CONSTRUCTORS
 
-        public ClassroomEditViewModel() : this(new ClassroomViewModel(new Classroom()))
+        public ClassroomEditorViewVM() : this(new ClassroomVM(new Classroom()))
         { }
 
-        public ClassroomEditViewModel(ClassroomViewModel classroom)
+        public ClassroomEditorViewVM(ClassroomVM classroom)
         {
             _classroom = classroom;
         }

TimetableDesigner/ViewModels/Views/GroupEditorViewVM.cs

@@ -14,17 +14,18 @@ using System.Windows.Input;
 using TimetableDesigner.Commands;
 using System.Diagnostics;
 using TimetableDesigner.Services.MessageBox;
+using TimetableDesigner.ViewModels.Models.Base;
 
 namespace TimetableDesigner.ViewModels.Views
 {
-    public class GroupEditViewModel : BaseViewViewModel
+    public class GroupEditorViewVM : ObservableObject, IViewVM, IUnitEditorViewVM
     {
         #region FIELDS
 
         private IProjectService _projectService;
         private IMessageBoxService _messageBoxService;
 
-        private GroupViewModel _group;
+        private GroupVM _group;
 
         private string _newSubgroupName;
 
@@ -34,7 +35,8 @@ namespace TimetableDesigner.ViewModels.Views
 
         #region PROPERTIES
 
-        public GroupViewModel Group
+        IUnitVM IUnitEditorViewVM.Unit => Group;
+        public GroupVM Group
         {
             get => _group;
             set
@@ -66,7 +68,7 @@ namespace TimetableDesigner.ViewModels.Views
             }
         }
 
-        public ObservableDictionary<SubgroupViewModel, bool> Subgroups => new ObservableDictionary<SubgroupViewModel, bool>(_projectService.ProjectViewModel.Subgroups.ToDictionary(sg => sg, Group.AssignedSubgroups.Contains));
+        public ObservableDictionary<SubgroupVM, bool> Subgroups => new ObservableDictionary<SubgroupVM, bool>(_projectService.ProjectViewModel.Subgroups.ToDictionary(sg => sg, Group.AssignedSubgroups.Contains));
 
         public string NewSubgroupName
         {
@@ -91,10 +93,10 @@ namespace TimetableDesigner.ViewModels.Views
 
         #region CONSTRUCTORS
 
-        public GroupEditViewModel() : this(new GroupViewModel(new Group()))
+        public GroupEditorViewVM() : this(new GroupVM(new Group()))
         { }
 
-        public GroupEditViewModel(GroupViewModel group)
+        public GroupEditorViewVM(GroupVM group)
         {
             _projectService = ServiceProvider.Instance.GetService<IProjectService>();
             _messageBoxService = ServiceProvider.Instance.GetService<IMessageBoxService>();
@@ -103,8 +105,8 @@ namespace TimetableDesigner.ViewModels.Views
             _newSubgroupName = string.Empty;
 
             AddSubgroupCommand = new RelayCommand<object>(args => AddSubgroup());
-            EditSubgroupAssignmentCommand = new RelayCommand<SubgroupViewModel>(EditSubgroupAssignment);
+            EditSubgroupAssignmentCommand = new RelayCommand<SubgroupVM>(EditSubgroupAssignment);
-            DeleteSubgroupCommand = new RelayCommand<SubgroupViewModel>(DeleteSubgroup);
+            DeleteSubgroupCommand = new RelayCommand<SubgroupVM>(DeleteSubgroup);
         }
 
         #endregion
@@ -119,7 +121,7 @@ namespace TimetableDesigner.ViewModels.Views
             {
                 Name = NewSubgroupName
             };
-            SubgroupViewModel subgroupViewModel = new SubgroupViewModel(subgroup);
+            SubgroupVM subgroupViewModel = new SubgroupVM(subgroup);
 
             _projectService.ProjectViewModel.Subgroups.Add(subgroupViewModel);
             Group.AddSubgroup(subgroupViewModel);
@@ -128,7 +130,7 @@ namespace TimetableDesigner.ViewModels.Views
             NewSubgroupName = string.Empty;
         }
 
-        private void EditSubgroupAssignment(SubgroupViewModel subgroup)
+        private void EditSubgroupAssignment(SubgroupVM subgroup)
         {
             bool assigned = Subgroups[subgroup];
             if (assigned)
@@ -142,12 +144,12 @@ namespace TimetableDesigner.ViewModels.Views
             NotifyPropertyChanged(nameof(Subgroups));
         }
 
-        private void DeleteSubgroup(SubgroupViewModel subgroup)
+        private void DeleteSubgroup(SubgroupVM subgroup)
         {
             MessageBoxQuestionResult result = _messageBoxService.ShowQuestion(Resources.GroupEdit_Message_SubgroupDelete, true);
             if (result == MessageBoxQuestionResult.Yes)
             {
-                foreach (GroupViewModel group in _projectService.ProjectViewModel.Groups)
+                foreach (GroupVM group in _projectService.ProjectViewModel.Groups)
                 {
                     group.RemoveSubgroup(subgroup);
                 }

TimetableDesigner/ViewModels/Views/MainViewModel.cs

@@ -1,271 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Collections.ObjectModel;
-using System.ComponentModel;
-using System.Diagnostics;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using System.Windows.Input;
-using TimetableDesigner.Commands;
-using System.Windows.Navigation;
-using TimetableDesigner.Core;
-using System.Windows;
-using TimetableDesigner.Properties;
-using System.Reflection;
-using TimetableDesigner.ViewModels.Models;
-using System.Windows.Data;
-using TimetableDesigner.Services.MessageBox;
-using System.ComponentModel.Design;
-using TimetableDesigner.Services;
-using TimetableDesigner.Services.TabNavigation;
-using TimetableDesigner.Services.Project;
-using System.Drawing;
-
-namespace TimetableDesigner.ViewModels.Views
-{
-    class MainViewModel : BaseViewViewModel
-    {
-        #region FIELDS
-
-        private IMessageBoxService _messageBoxService;
-        private ITabNavigationService _tabNavigationService;
-        private IProjectService _projectService;
-
-        #endregion
-
-
-
-        #region PROPERTIES
-
-        // Observable services
-        public IProjectService ProjectService => _projectService;
-        public ITabNavigationService TabNavigationService => _tabNavigationService;
-
-        // Tabs
-        public ObservableCollection<TabItem> Tabs => _tabNavigationService.Tabs;
-        public TabItem SelectedTab => _tabNavigationService.SelectedTab;
-
-        // Commands
-        public ICommand NewProjectCommand { get; set; }
-        public ICommand OpenProjectCommand { get; set; }
-        public ICommand ProjectSettingsCommand { get; set; }
-        public ICommand NewClassroomCommand { get; set; }
-        public ICommand EditClassroomCommand { get; set; }
-        public ICommand RemoveClassroomCommand { get; set; }
-        public ICommand NewTeacherCommand { get; set; }
-        public ICommand EditTeacherCommand { get; set; }
-        public ICommand RemoveTeacherCommand { get; set; }
-        public ICommand NewGroupCommand { get; set; }
-        public ICommand EditGroupCommand { get; set; }
-        public ICommand RemoveGroupCommand { get; set; }
-        public ICommand RemoveSubgroupCommand { get; set; }
-
-        // Others
-        public string Version { get; set; }
-
-        #endregion
-
-
-
-        #region CONSTRUCTORS
-
-        public MainViewModel()
-        {
-            _messageBoxService = ServiceProvider.Instance.GetService<IMessageBoxService>();
-            _tabNavigationService = ServiceProvider.Instance.GetService<ITabNavigationService>();
-            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
-
-            NewProjectCommand = new RelayCommand<object>(param => NewProject());
-            OpenProjectCommand = new RelayCommand<object>(param => OpenProject());
-            ProjectSettingsCommand = new RelayCommand<object>(param => ProjectSettings());
-            NewClassroomCommand = new RelayCommand<object>(param => NewClassroom());
-            EditClassroomCommand = new RelayCommand<ClassroomViewModel>(EditClassroom);
-            RemoveClassroomCommand = new RelayCommand<ClassroomViewModel>(DeleteClassroom);
-            NewTeacherCommand = new RelayCommand<object>(param => NewTeacher());
-            EditTeacherCommand = new RelayCommand<TeacherViewModel>(EditTeacher);
-            RemoveTeacherCommand = new RelayCommand<TeacherViewModel>(DeleteTeacher);
-            NewGroupCommand = new RelayCommand<object>(param => NewGroup());
-            EditGroupCommand = new RelayCommand<GroupViewModel>(EditGroup);
-            RemoveGroupCommand = new RelayCommand<GroupViewModel>(DeleteGroup);
-            RemoveSubgroupCommand = new RelayCommand<SubgroupViewModel>(DeleteSubgroup);
-
-            Version = Assembly.GetExecutingAssembly().GetName().Version.ToString();
-
-            TabItem welcomeTab = new TabItem()
-            {
-                Title = Resources.Tabs_Welcome,
-                ViewModel = new WelcomeViewModel()
-            };
-            _tabNavigationService.AddAndActivate(welcomeTab);
-        }
-
-        #endregion
-
-
-
-        #region PRIVATE METHODS
-
-        private void OpenProject()
-        {
-        }
-
-        private void NewProject()
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                MessageBoxQuestionResult result = _messageBoxService.ShowQuestion(Resources.Main_Message_SaveCurrentProject);
-
-                switch (result)
-                {
-                    case MessageBoxQuestionResult.Yes: break;
-                    case MessageBoxQuestionResult.No: break;
-                    default: return;
-                }
-            }
-            _tabNavigationService.CloseAll();
-            _projectService.New();
-            ProjectSettings();
-        }
-
-        private void ProjectSettings()
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                TabItem projectSettingsTab = new TabItem()
-                {
-                    Title = Resources.Tabs_ProjectSettings,
-                    IsClosable = true,
-                    ViewModel = new ProjectSettingsViewModel()
-                };
-                _tabNavigationService.AddAndActivate(projectSettingsTab);
-            }
-        }
-
-        private void NewClassroom()
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                Classroom classroom = new Classroom()
-                {
-                    Name = Resources.Global_DefaultClassroomName
-                };
-                ClassroomViewModel classroomVM = new ClassroomViewModel(classroom);
-                ProjectService.ProjectViewModel.Classrooms.Add(classroomVM);
-                EditClassroom(classroomVM);
-            }
-        }
-
-        private void EditClassroom(ClassroomViewModel classroomViewModel)
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                TabItem classroomEditTab = new TabItem()
-                {
-                    Title = $"{Resources.Tabs_ClassroomEdit}: {classroomViewModel.Name}",
-                    IsClosable = true,
-                    ViewModel = new ClassroomEditViewModel(classroomViewModel)
-                };
-                _tabNavigationService.AddAndActivate(classroomEditTab);
-            }  
-        }
-
-        private void DeleteClassroom(ClassroomViewModel classroomViewModel)
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                ProjectService.ProjectViewModel.Classrooms.Remove(classroomViewModel);
-            }
-        }
-
-        private void NewTeacher()
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                Teacher teacher = new Teacher()
-                {
-                    Name = Resources.Global_DefaultTeacherName
-                };
-                TeacherViewModel teacherVM = new TeacherViewModel(teacher);
-                ProjectService.ProjectViewModel.Teachers.Add(teacherVM);
-                EditTeacher(teacherVM);
-            }
-        }
-
-        private void EditTeacher(TeacherViewModel teacherViewModel)
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                TabItem teacherEditTab = new TabItem()
-                {
-                    Title = $"{Resources.Tabs_TeacherEdit}: {teacherViewModel.Name}",
-                    IsClosable = true,
-                    ViewModel = new TeacherEditViewModel(teacherViewModel)
-                };
-                _tabNavigationService.AddAndActivate(teacherEditTab);
-            }
-        }
-
-        private void DeleteTeacher(TeacherViewModel teacherViewModel)
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                ProjectService.ProjectViewModel.Teachers.Remove(teacherViewModel);
-            }
-        }
-
-        private void NewGroup()
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                Group group = new Group()
-                {
-                    Name = Resources.Global_DefaultGroupName
-                };
-                GroupViewModel groupVM = new GroupViewModel(group);
-                ProjectService.ProjectViewModel.Groups.Add(groupVM);
-                EditGroup(groupVM);
-            }
-        }
-
-        private void EditGroup(GroupViewModel groupViewModel)
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                TabItem groupEditTab = new TabItem()
-                {
-                    Title = $"{Resources.Tabs_GroupEdit}: {groupViewModel.Name}",
-                    IsClosable = true,
-                    ViewModel = new GroupEditViewModel(groupViewModel)
-                };
-                _tabNavigationService.AddAndActivate(groupEditTab);
-            }
-        }
-
-        private void DeleteGroup(GroupViewModel groupViewModel)
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                ProjectService.ProjectViewModel.Groups.Remove(groupViewModel);
-            }
-        }
-
-        private void DeleteSubgroup(SubgroupViewModel subgroupViewModel)
-        {
-            if (ProjectService.ProjectViewModel is not null)
-            {
-                MessageBoxQuestionResult result = _messageBoxService.ShowQuestion(Resources.Main_Treeview_Subgroups_Message_Remove, true);
-                if (result == MessageBoxQuestionResult.Yes)
-                {
-                    foreach (GroupViewModel group in ProjectService.ProjectViewModel.Groups)
-                    {
-                        group.RemoveSubgroup(subgroupViewModel);
-                    }
-                    _projectService.ProjectViewModel.Subgroups.Remove(subgroupViewModel);
-                }
-            }
-        }
-
-        #endregion
-    }
-}

TimetableDesigner/ViewModels/Views/MainWindowVM.cs

@@ -0,0 +1,387 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Input;
+using TimetableDesigner.Commands;
+using System.Windows.Navigation;
+using TimetableDesigner.Core;
+using System.Windows;
+using TimetableDesigner.Properties;
+using System.Reflection;
+using TimetableDesigner.ViewModels.Models;
+using System.Windows.Data;
+using TimetableDesigner.Services.MessageBox;
+using System.ComponentModel.Design;
+using TimetableDesigner.Services;
+using TimetableDesigner.Services.TabNavigation;
+using TimetableDesigner.Services.Project;
+using System.Drawing;
+using TimetableDesigner.ViewModels.Models.Base;
+using System.Collections;
+using TimetableDesigner.Customs;
+using Microsoft.Win32;
+using System.Windows.Forms;
+using TimetableDesigner.Services.FileDialog;
+using TimetableDesigner.Services.Scheduler;
+using static TimetableDesigner.ViewModels.Views.TimetableEditorViewVM;
+
+namespace TimetableDesigner.ViewModels.Views
+{
+    class MainWindowVM : ObservableObject, IViewVM
+    {
+        #region FIELDS
+
+        private IMessageBoxService _messageBoxService;
+        private IFileDialogService _fileDialogService;
+        private ITabNavigationService _tabNavigationService;
+        private IProjectService _projectService;
+        private ISchedulerService _schedulerService;
+
+        private IDictionary<string, IEnumerable<string>> _projectFileTypes = new Dictionary<string, IEnumerable<string>>()
+        {
+            { Resources.Global_ProjectFiletypeDescription, new List<string>() { "ttdp" } }
+        };
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        // Observable services
+        public IProjectService ProjectService => _projectService;
+        public ITabNavigationService TabNavigationService => _tabNavigationService;
+
+        // Tabs
+        public ObservableCollection<TabItem> Tabs => _tabNavigationService.Tabs;
+        public TabItem SelectedTab => _tabNavigationService.SelectedTab;
+
+        // Commands
+        public ICommand NewProjectCommand { get; set; }
+        public ICommand OpenProjectCommand { get; set; }
+        public ICommand OpenRecentProjectCommand { get; set; }
+        public ICommand SaveProjectCommand { get; set; }
+        public ICommand SaveAsProjectCommand { get; set; }
+        public ICommand ProjectSettingsCommand { get; set; }
+        public ICommand NewClassroomCommand { get; set; }
+        public ICommand NewTeacherCommand { get; set; }
+        public ICommand NewGroupCommand { get; set; }
+        public ICommand EditClassroomCommand { get; set; }
+        public ICommand EditTeacherCommand { get; set; }
+        public ICommand EditGroupCommand { get; set; }
+        public ICommand RemoveClassroomCommand { get; set; }
+        public ICommand RemoveTeacherCommand { get; set; }
+        public ICommand RemoveGroupCommand { get; set; }
+        public ICommand RemoveSubgroupCommand { get; set; }
+        public ICommand EditTimetableCommand { get; set; }
+        public ICommand AutoScheduleCommand { get; set; }
+
+        // Others
+        public string? Version { get; set; }
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public MainWindowVM()
+        {
+            _messageBoxService = ServiceProvider.Instance.GetService<IMessageBoxService>();
+            _fileDialogService = ServiceProvider.Instance.GetService<IFileDialogService>();
+            _tabNavigationService = ServiceProvider.Instance.GetService<ITabNavigationService>();
+            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
+            _schedulerService = ServiceProvider.Instance.GetService<ISchedulerService>();
+
+            NewProjectCommand = new RelayCommand<object>(param => NewProject());
+            OpenProjectCommand = new RelayCommand<object>(param => OpenProject());
+            OpenRecentProjectCommand = new RelayCommand<string>(OpenProject);
+            SaveProjectCommand = new RelayCommand<object>(param => SaveProject());
+            SaveAsProjectCommand = new RelayCommand<object>(param => SaveAsProject());
+            ProjectSettingsCommand = new RelayCommand<object>(param => ProjectSettings());
+            NewClassroomCommand = new RelayCommand<object>(param => NewClassroom());
+            NewTeacherCommand = new RelayCommand<object>(param => NewTeacher());
+            NewGroupCommand = new RelayCommand<object>(param => NewGroup());
+            EditClassroomCommand = new RelayCommand<ClassroomVM>(EditClassroom);
+            EditTeacherCommand = new RelayCommand<TeacherVM>(EditTeacher);
+            EditGroupCommand = new RelayCommand<GroupVM>(EditGroup);
+            RemoveClassroomCommand = new RelayCommand<ClassroomVM>(RemoveClassroom);
+            RemoveTeacherCommand = new RelayCommand<TeacherVM>(RemoveTeacher);
+            RemoveGroupCommand = new RelayCommand<GroupVM>(RemoveGroup);
+            RemoveSubgroupCommand = new RelayCommand<SubgroupVM>(RemoveSubgroup);
+            EditTimetableCommand = new RelayCommand<IUnitVM>(EditTimetable);
+            AutoScheduleCommand = new RelayCommand<object>(param => AutoSchedule());
+
+            Version = Assembly.GetExecutingAssembly().GetName().Version?.ToString();
+        }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private void NewProject()
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                MessageBoxQuestionResult result = _messageBoxService.ShowQuestion(Resources.Main_Message_SaveCurrentProject);
+
+                switch (result)
+                {
+                    case MessageBoxQuestionResult.Yes: SaveProject(); break;
+                    case MessageBoxQuestionResult.No: break;
+                    default: return;
+                }
+            }
+
+            _tabNavigationService.CloseAll();
+            _projectService.New();
+            ProjectSettings();
+        }
+
+        private void OpenProject()
+        {
+            string? path = _fileDialogService.OpenFile(_projectFileTypes);
+            if (path is not null)
+            {
+                OpenProject(path);
+            }
+        }
+
+        private void OpenProject(string path)
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                MessageBoxQuestionResult result = _messageBoxService.ShowQuestion(Resources.Main_Message_SaveCurrentProject);
+
+                switch (result)
+                {
+                    case MessageBoxQuestionResult.Yes: SaveProject(); break;
+                    case MessageBoxQuestionResult.No: break;
+                    default: return;
+                }
+            }
+
+            _projectService.Load(path);
+            _tabNavigationService.CloseAll();
+        }
+
+        private void SaveProject()
+        {
+            string? path = _projectService.SavePath;
+            if (_projectService.SavePath is null)
+            {
+                path = _fileDialogService.SaveFile(_projectFileTypes);
+            }
+            
+            if (path is not null)
+            {
+                _projectService.Save(path);
+            }
+        }
+        private void SaveAsProject()
+        {
+            string? path = _fileDialogService.SaveFile(_projectFileTypes);
+            if (path is not null)
+            {
+                _projectService.Save(path);
+            }
+        }
+
+        private void ProjectSettings()
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                TabItem projectSettingsTab = new TabItem()
+                {
+                    Title = Resources.Tabs_ProjectSettings,
+                    IsClosable = true,
+                    ViewModel = new ProjectSettingsViewVM()
+                };
+                _tabNavigationService.AddAndActivate(projectSettingsTab);
+            }
+        }
+
+        private void NewClassroom()
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                Classroom classroom = new Classroom()
+                {
+                    Name = Resources.Global_DefaultClassroomName
+                };
+                ClassroomVM classroomVM = new ClassroomVM(classroom);
+                ProjectService.ProjectViewModel.Classrooms.Add(classroomVM);
+                EditClassroom(classroomVM);
+            }
+        }
+        private void NewTeacher()
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                Teacher teacher = new Teacher()
+                {
+                    Name = Resources.Global_DefaultTeacherName
+                };
+                TeacherVM teacherVM = new TeacherVM(teacher);
+                ProjectService.ProjectViewModel.Teachers.Add(teacherVM);
+                EditTeacher(teacherVM);
+            }
+        }
+        private void NewGroup()
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                Group group = new Group()
+                {
+                    Name = Resources.Global_DefaultGroupName
+                };
+                GroupVM groupVM = new GroupVM(group);
+                ProjectService.ProjectViewModel.Groups.Add(groupVM);
+                EditGroup(groupVM);
+            }
+        }
+
+        private void EditClassroom(ClassroomVM classroom) => EditUnit(new ClassroomEditorViewVM(classroom), Resources.Tabs_ClassroomEdit);
+        private void EditTeacher(TeacherVM teacher) => EditUnit(new TeacherEditorViewVM(teacher), Resources.Tabs_TeacherEdit);
+        private void EditGroup(GroupVM group) => EditUnit(new GroupEditorViewVM(group), Resources.Tabs_GroupEdit);
+        private void EditUnit(IUnitEditorViewVM edit, string tabNamePrefix)
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                TabItem groupEditTab = new TabItem()
+                {
+                    Title = $"{tabNamePrefix}: {edit.Unit.Name}",
+                    IsClosable = true,
+                    ViewModel = edit
+                };
+                _tabNavigationService.AddAndActivate(groupEditTab);
+            }
+        }
+
+        private void RemoveClassroom(ClassroomVM classroom) => RemoveUnit(classroom, ProjectService.ProjectViewModel?.Classrooms, Resources.Main_Treeview_Classrooms_Message_Remove);
+        private void RemoveTeacher(TeacherVM teacher) => RemoveUnit(teacher, ProjectService.ProjectViewModel?.Teachers, Resources.Main_Treeview_Teachers_Message_Remove);
+        private void RemoveGroup(GroupVM group) => RemoveUnit(group, ProjectService.ProjectViewModel?.Groups, Resources.Main_Treeview_Groups_Message_Remove);
+        private void RemoveSubgroup(SubgroupVM subgroup) => RemoveUnit(subgroup, ProjectService.ProjectViewModel?.Subgroups, Resources.Main_Treeview_Subgroups_Message_Remove);
+        private void RemoveUnit(IRemovableVM unit, IList? collection, string questionMessage)
+        {
+            if (collection is not null)
+            {
+                MessageBoxQuestionResult result = _messageBoxService.ShowQuestion(questionMessage, true);
+                if (result == MessageBoxQuestionResult.Yes)
+                {
+                    collection.Remove(unit);
+                    _tabNavigationService.Close(_tabNavigationService.Tabs.Where(x => x.ViewModel is IUnitEditorViewVM model && model.Unit == unit));
+                }
+            }
+        }
+
+        private void EditTimetable(IUnitVM classUnit)
+        {
+            if (ProjectService.ProjectViewModel is not null)
+            {
+                TabItem timetableEditTab = new TabItem()
+                {
+                    Title = $"{Resources.Tabs_TimetableEdit}: {classUnit.Name}",
+                    IsClosable = true,
+                    ViewModel = new TimetableEditorViewVM(classUnit)
+                };
+                _tabNavigationService.AddAndActivate(timetableEditTab);
+            }
+        }
+
+        private void AutoSchedule()
+        {
+            IEnumerable<ClassVM> unscheduledClasses = _projectService.ProjectViewModel.Classes.Where(x => x.Day is null || x.Slot is null);
+            if (unscheduledClasses.Any())
+            {
+                List<ClassVM> errors = new List<ClassVM>();
+                int successCount = 0;
+                foreach (ClassVM @class in unscheduledClasses)
+                {
+                    (TimetableDay? day, TimetableSpan? slot) = _schedulerService.Schedule(@class);
+                    if (day is not null && slot is not null)
+                    {
+                        @class.Day = day;
+                        @class.Slot = slot;
+                        successCount++;
+                    }
+                    else
+                    {
+                        errors.Add(@class);
+                    }
+                }
+
+                //REFRESH: All editors & Errors
+                foreach (TimetableEditorViewVM editor in _tabNavigationService.Tabs.Select(x => x.ViewModel).OfType<TimetableEditorViewVM>().Distinct())
+                {
+                    editor.RefreshClasses(RefreshMode.Scheduled | RefreshMode.Unscheduled);
+                }
+                _projectService.RefreshErrors();
+
+                StringBuilder sb = new StringBuilder();
+                sb.Append($"{Resources.Main_Ribbon_Edit_Timetable_Autoschedule_Message_SuccessfullyScheduled}: {successCount}");
+                if (errors.Any())
+                {
+                    sb.AppendLine();
+                    sb.AppendLine();
+                    sb.Append($"{Resources.Main_Ribbon_Edit_Timetable_Autoschedule_Message_FollowingClassesCouldNotBeScheduled}:");
+                    sb.AppendLine();
+                    int deleted = 0;
+                    for (int i = 0; i < errors.Count && i < 5; i++)
+                    {
+                        ClassVM errorClass = errors[i];
+                        string unit;
+                        string unitName;
+                        if (errorClass.Group is not null)
+                        {
+                            unit = Resources.Main_Ribbon_Edit_Timetable_Autoschedule_Message_UnitGroup;
+                            unitName = errorClass.Group.Name;
+                        }
+                        else if (errorClass.Teacher is not null)
+                        {
+                            unit = Resources.Main_Ribbon_Edit_Timetable_Autoschedule_Message_UnitTeacher;
+                            unitName = errorClass.Teacher.Name;
+                        }
+                        else if (errorClass.Classroom is not null)
+                        {
+                            unit = Resources.Main_Ribbon_Edit_Timetable_Autoschedule_Message_UnitClassroom;
+                            unitName = errorClass.Classroom.Name;
+                        }
+                        else
+                        {
+                            deleted++;
+                            i--;
+                            _projectService.ProjectViewModel.Classes.Remove(errorClass);
+                            continue;
+                        }
+                        sb.Append($"- {errorClass.Name} ({unit}: {unitName})");
+                        sb.AppendLine();
+                    }
+                    if (errors.Count - deleted > 5)
+                    {
+                        sb.Append($"+ {errors.Count - deleted - 5} {Resources.Main_Ribbon_Edit_Timetable_Autoschedule_Message_More}");
+                    }
+
+                    _messageBoxService.ShowWarning(sb.ToString());
+                }
+                else
+                {
+                    _messageBoxService.ShowInformation(sb.ToString());
+                }
+            }
+            else
+            {
+                _messageBoxService.ShowInformation(Resources.Main_Ribbon_Edit_Timetable_Autoschedule_Message_NoUnscheduledClasses);
+            }
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/ViewModels/Views/ProjectSettingsViewVM.cs

@@ -19,7 +19,7 @@ using TimetableDesigner.ViewModels.Models;
 
 namespace TimetableDesigner.ViewModels.Views
 {
-    public class ProjectSettingsViewModel : BaseViewViewModel
+    public class ProjectSettingsViewVM : ObservableObject, IViewVM
     {
         #region FIELDS
 
@@ -37,7 +37,7 @@ namespace TimetableDesigner.ViewModels.Views
         #region PROPERTIES
 
         // Project
-        public ProjectViewModel? Project => _projectService.ProjectViewModel;
+        public ProjectVM? Project => _projectService.ProjectViewModel;
 
         // Fields
         public string NewDayName
@@ -81,7 +81,7 @@ namespace TimetableDesigner.ViewModels.Views
 
         #region CONSTRUCTORS
 
-        public ProjectSettingsViewModel()
+        public ProjectSettingsViewVM()
         {
             _messageBoxService = ServiceProvider.Instance.GetService<IMessageBoxService>();
             _projectService = ServiceProvider.Instance.GetService<IProjectService>();
@@ -115,7 +115,7 @@ namespace TimetableDesigner.ViewModels.Views
         {
             if (Project is not null)
             {
-                foreach (TeacherViewModel teacher in Project.Teachers)
+                foreach (TeacherVM teacher in Project.Teachers)
                 {
                     teacher.RemoveDay(day);
                 }
@@ -137,11 +137,19 @@ namespace TimetableDesigner.ViewModels.Views
 
                 try
                 {
+                    TimetableSpan? lastSlot = Project.TimetableTemplate.Slots.LastOrDefault();
+
                     Project.TimetableTemplate.AddSlot(new TimetableSpan(from, to));
 
+                    double offset = 0;
+                    if (lastSlot != null)
+                    {
+                        offset = (from - lastSlot.To).TotalMinutes;
+                    }
+
                     double delta = (to - from).TotalMinutes;
-                    DateTime newFrom = NewSlotTo.Value;
+                    DateTime newFrom = NewSlotTo.Value.AddMinutes(offset);
-                    DateTime newTo = NewSlotTo.Value.AddMinutes(delta);
+                    DateTime newTo = NewSlotTo.Value.AddMinutes(offset + delta);
                     NewSlotFrom = newFrom;
                     NewSlotTo = newTo;
                 }

TimetableDesigner/ViewModels/Views/TeacherEditorViewVM.cs

@@ -14,17 +14,18 @@ using TimetableDesigner.Services.MessageBox;
 using TimetableDesigner.Services.Project;
 using TimetableDesigner.Services.TabNavigation;
 using TimetableDesigner.ViewModels.Models;
+using TimetableDesigner.ViewModels.Models.Base;
 
 namespace TimetableDesigner.ViewModels.Views
 {
-    public class TeacherEditViewModel : BaseViewViewModel
+    public class TeacherEditorViewVM : ObservableObject, IViewVM, IUnitEditorViewVM
     {
         #region FIELDS
 
         private IMessageBoxService _messageBoxService;
         private IProjectService _projectService;
 
-        private TeacherViewModel _teacher;
+        private TeacherVM _teacher;
 
         private TimetableDay _selectedDay;
 
@@ -38,7 +39,8 @@ namespace TimetableDesigner.ViewModels.Views
 
         #region PROPERTIES
 
-        public TeacherViewModel Teacher
+        IUnitVM IUnitEditorViewVM.Unit => Teacher;
+        public TeacherVM Teacher
         {
             get => _teacher;
             set
@@ -50,7 +52,7 @@ namespace TimetableDesigner.ViewModels.Views
                 }
             }
         }
-        public TimetableTemplateViewModel? TimetableTemplate => _projectService.ProjectViewModel?.TimetableTemplate;
+        public TimetableTemplateVM? TimetableTemplate => _projectService.ProjectViewModel?.TimetableTemplate;
 
         public string Name
         {
@@ -65,7 +67,7 @@ namespace TimetableDesigner.ViewModels.Views
                     TabItem? tab = ServiceProvider.Instance.GetService<ITabNavigationService>().Tabs.Where(tab => tab.ViewModel == this).FirstOrDefault();
                     if (tab != null)
                     {
-                        tab.Title = $"{Resources.Tabs_ClassroomEdit}: {_teacher.Name}";
+                        tab.Title = $"{Resources.Tabs_TeacherEdit}: {_teacher.Name}";
                     }
                 }
             }
@@ -130,10 +132,10 @@ namespace TimetableDesigner.ViewModels.Views
 
         #region CONSTRUCTORS
 
-        public TeacherEditViewModel() : this(new TeacherViewModel(new Teacher()))
+        public TeacherEditorViewVM() : this(new TeacherVM(new Teacher()))
         { }
 
-        public TeacherEditViewModel(TeacherViewModel teacher)
+        public TeacherEditorViewVM(TeacherVM teacher)
         {
             _messageBoxService = ServiceProvider.Instance.GetService<IMessageBoxService>();
             _projectService = ServiceProvider.Instance.GetService<IProjectService>();

TimetableDesigner/ViewModels/Views/TimetableEditorViewVM.cs

@@ -0,0 +1,255 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using TimetableDesigner.Services;
+using TimetableDesigner.Services.Project;
+using TimetableDesigner.ViewModels.Models.Base;
+using TimetableDesigner.ViewModels.Models;
+using TimetableDesigner.Customs;
+using System.Collections.ObjectModel;
+using System.Windows.Input;
+using TimetableDesigner.Commands;
+using System.Windows;
+using System.Diagnostics;
+using TimetableDesigner.Core;
+using System.Xml.Linq;
+using TimetableDesigner.Services.TabNavigation;
+using System.Security.Policy;
+using TimetableDesigner.Converters;
+using System.Data;
+using static TimetableDesigner.ViewModels.Views.TimetableEditorViewVM;
+using TimetableDesigner.Services.Scheduler;
+
+namespace TimetableDesigner.ViewModels.Views
+{
+    public class TimetableEditorViewVM : ObservableObject, IViewVM
+    {
+        #region FIELDS
+
+        private IProjectService _projectService;
+        private ITabNavigationService _tabNavigationService;
+        private ISchedulerService _schedulerService;
+
+        private IUnitVM? _unit;
+
+        #endregion
+
+
+
+        #region PROPERTIES
+
+        public TimetableTemplateVM TimetableTemplate => _projectService.ProjectViewModel.TimetableTemplate;
+
+        public IUnitVM? Unit
+        {
+            get => _unit;
+            set
+            {
+                if (value != _unit)
+                {
+                    _unit = value;
+                    NotifyPropertyChanged(nameof(Unit));
+                }
+            }
+        }
+
+        public IEnumerable<ClassVM> AssignedClasses => _projectService.ProjectViewModel.Classes.Where(c => c.Classroom == Unit || c.Teacher == Unit || c.Group == Unit || (Unit is GroupVM g && c.Group is SubgroupVM s && g.AssignedSubgroups.Contains(s)));
+        public IEnumerable<ClassVM> ScheduledClasses => AssignedClasses.Where(c => c.Slot is not null && c.Day is not null);
+        public IEnumerable<ClassVM> UnscheduledClasses => AssignedClasses.Where(c => c.Slot is null || c.Day is null);
+
+        public ICommand AddClassCommand { get; set; }
+        public ICommand AutoScheduleCommand { get; set; }
+        public ICommand RemoveClassCommand { get; set; }
+        public ICommand CloneClassCommand { get; set; }
+        public ICommand RefreshScheduledClassesCommand { get; set; }
+        public ICommand RefreshUnscheduledClassesCommand { get; set; }
+        public ICommand RefreshAllClassesCommand { get; set; }
+
+        #endregion
+
+
+
+        #region CONSTRUCTORS
+
+        public TimetableEditorViewVM() : this(null)
+        { }
+
+        public TimetableEditorViewVM(IUnitVM? unit)
+        {
+            _projectService = ServiceProvider.Instance.GetService<IProjectService>();
+            _tabNavigationService = ServiceProvider.Instance.GetService<ITabNavigationService>();
+            _schedulerService = ServiceProvider.Instance.GetService<ISchedulerService>();
+
+            _unit = unit;
+
+            AddClassCommand = new RelayCommand<object>(arg => AddClass());
+            AutoScheduleCommand = new RelayCommand<object>(arg => AutoSchedule());
+            RemoveClassCommand = new RelayCommand<ClassVM>(RemoveClass);
+            CloneClassCommand = new RelayCommand<ClassVM>(CloneClass);
+            RefreshScheduledClassesCommand = new RelayCommand<object>(arg => RefreshClassesAndErrors(RefreshMode.Scheduled));
+            RefreshUnscheduledClassesCommand = new RelayCommand<object>(arg => RefreshClassesAndErrors(RefreshMode.Unscheduled));
+            RefreshAllClassesCommand = new RelayCommand<object>(arg => RefreshClassesAndErrors(RefreshMode.Scheduled | RefreshMode.Unscheduled));
+        }
+
+        #endregion
+
+
+
+        #region PUBLIC METHODS
+
+        public void RefreshClasses(RefreshMode mode)
+        {
+            if ((mode & RefreshMode.Scheduled) == RefreshMode.Scheduled)
+                NotifyPropertyChanged(nameof(ScheduledClasses));
+            if ((mode & RefreshMode.Unscheduled) == RefreshMode.Unscheduled)
+                NotifyPropertyChanged(nameof(UnscheduledClasses));
+        }
+
+        #endregion
+
+
+
+        #region PRIVATE METHODS
+
+        private void AddClass()
+        {
+            Class @class = new Class()
+            {
+                Name = "New class",
+                Teacher = _unit is TeacherVM t ? t.Teacher : null,
+                Classroom = _unit is ClassroomVM c ? c.Classroom : null,
+                Group = _unit is BaseGroupVM g ? g.BaseGroup : null,
+            };
+            ClassVM classVM = new ClassVM(@class);
+            _projectService.ProjectViewModel.Classes.Add(classVM);
+
+            //REFRESH: Unassigned classes of this unit & Errors
+            RefreshClasses(RefreshMode.Unscheduled);
+            _projectService.RefreshErrors();
+        }
+
+        private void AutoSchedule()
+        {
+            foreach (ClassVM @class in UnscheduledClasses)
+            {
+                (TimetableDay? day, TimetableSpan? slot) = _schedulerService.Schedule(@class);
+                @class.Day = day;
+                @class.Slot = slot;
+            }
+
+            //REFRESH: Scheduled & Errors
+            foreach (TimetableEditorViewVM editors in _tabNavigationService.Tabs.Select(x => x.ViewModel).OfType<TimetableEditorViewVM>().Distinct())
+            {
+                editors.RefreshClasses(RefreshMode.Scheduled | RefreshMode.Unscheduled);
+            }
+            _projectService.RefreshErrors();
+        }
+
+        private void RemoveClass(ClassVM @class)
+        {
+            Debug.WriteLine(@class.Name);
+            List<IUnitVM> units = new List<IUnitVM>();
+            if (@class.Teacher is not null)
+            {
+                units.Add(@class.Teacher);
+            }
+            if (@class.Classroom is not null)
+            {
+                units.Add(@class.Classroom);
+            }
+            if (@class.Group is not null)
+            {
+                units.Add(@class.Group);
+                if (@class.Group is SubgroupVM sg)
+                {
+                    units.AddRange(_projectService.ProjectViewModel.Groups.Where(x => x.AssignedSubgroups.Contains(sg)));
+                }
+            }
+
+            RefreshMode refreshMode = RefreshMode.Unscheduled;
+            if (@class.Day is not null && @class.Slot is not null)
+            {
+                refreshMode = RefreshMode.Scheduled;
+            }
+
+            _projectService.ProjectViewModel.Classes.Remove(@class);
+
+            //REFRESH: Assigned classes of units assigned to class & Errors
+            foreach (TimetableEditorViewVM editors in _tabNavigationService.Tabs.Select(x => x.ViewModel).OfType<TimetableEditorViewVM>().Where(x => units.Contains(x.Unit)).Distinct())
+            {
+                editors.RefreshClasses(refreshMode);
+            }
+            _projectService.RefreshErrors();
+        }
+
+        private void CloneClass(ClassVM @class)
+        {
+            List<IUnitVM> units = new List<IUnitVM>();
+            if (@class.Teacher is not null)
+            {
+                units.Add(@class.Teacher);
+            }
+            if (@class.Classroom is not null)
+            {
+                units.Add(@class.Classroom);
+            }
+            if (@class.Group is not null)
+            {
+                units.Add(@class.Group);
+                if (@class.Group is SubgroupVM sg)
+                {
+                    units.AddRange(_projectService.ProjectViewModel.Groups.Where(x => x.AssignedSubgroups.Contains(sg)));
+                }
+            }
+
+            RefreshMode refreshMode = RefreshMode.Unscheduled;
+            if (@class.Day is not null && @class.Slot is not null)
+            {
+                refreshMode = RefreshMode.Scheduled;
+            }
+
+            Class newClass = new Class()
+            {
+                Name = @class.Name,
+                Teacher = @class.Teacher?.Teacher,
+                Classroom = @class.Classroom?.Classroom,
+                Group = @class.Group?.BaseGroup,
+                Day = @class.Day,
+                Slot = @class.Slot,
+                Color = @class.Color,
+            };
+            ClassVM classVM = new ClassVM(newClass);
+            _projectService.ProjectViewModel.Classes.Add(classVM);
+
+            //REFRESH: Assigned classes of units assigned to class & Errors
+            foreach (TimetableEditorViewVM editors in _tabNavigationService.Tabs.Select(x => x.ViewModel).OfType<TimetableEditorViewVM>().Where(x => units.Contains(x.Unit)).Distinct())
+            {
+                editors.RefreshClasses(refreshMode);
+            }
+            _projectService.RefreshErrors();
+        }
+
+        private void RefreshClassesAndErrors(RefreshMode mode)
+        {
+            RefreshClasses(mode);
+            _projectService.RefreshErrors();
+        }
+
+        #endregion
+
+
+
+        #region ENUMS
+
+        [Flags]
+        public enum RefreshMode
+        {
+            Scheduled,
+            Unscheduled
+        }
+
+        #endregion
+    }
+}

TimetableDesigner/ViewModels/Views/WelcomeViewVM.cs

@@ -7,11 +7,11 @@ using TimetableDesigner.Customs;
 
 namespace TimetableDesigner.ViewModels.Views
 {
-    public class WelcomeViewModel : BaseViewViewModel
+    public class WelcomeViewVM : ObservableObject, IViewVM
     {
         #region CONSTRUCTORS
 
-        public WelcomeViewModel()
+        public WelcomeViewVM()
         { }
 
         #endregion