Initial refactoring to support CommandManager

Filtration.ObjectModel/Commands/CommandManager.cs

@@ -0,0 +1,62 @@
+using System.Collections.Generic;
+
+namespace Filtration.ObjectModel.Commands
+{
+    public interface ICommandManager
+    {
+        void ExecuteCommand(ICommand command);
+        void Undo(int undoLevels = 1);
+        void Redo(int redoLevels = 1);
+    }
+
+    public interface ICommandManagerInternal : ICommandManager
+    {
+        void SetScript(IItemFilterScriptInternal layout);
+    }
+
+    internal class CommandManager : ICommandManagerInternal
+    {
+        private readonly Stack<IUndoableCommand> _undoCommandStack = new Stack<IUndoableCommand>();
+        private readonly Stack<IUndoableCommand> _redoCommandStack = new Stack<IUndoableCommand>();
+        private IItemFilterScriptInternal _itemFilterScript;
+
+        public void SetScript(IItemFilterScriptInternal itemFilterScript)
+        {
+            _itemFilterScript = itemFilterScript;
+        }
+
+        public void ExecuteCommand(ICommand command)
+        {
+            command.Execute();
+            var undoableCommand = command as IUndoableCommand;
+            if (undoableCommand != null)
+            {
+                _undoCommandStack.Push(undoableCommand);
+                _redoCommandStack.Clear();
+            }
+            _itemFilterScript.SetIsDirty(true);
+        }
+
+        public void Undo(int undoLevels = 1)
+        {
+            for (var index = undoLevels; _undoCommandStack.Count > 0 && index > 0; --index)
+            {
+                var undoableCommand = _undoCommandStack.Pop();
+                undoableCommand.Undo();
+                _redoCommandStack.Push(undoableCommand);
+            }
+            _itemFilterScript.SetIsDirty(true);
+        }
+
+        public void Redo(int redoLevels = 1)
+        {
+            for (int index = redoLevels; _redoCommandStack.Count > 0 && index > 0; --index)
+            {
+                var undoableCommand = _redoCommandStack.Pop();
+                undoableCommand.Redo();
+                _undoCommandStack.Push(undoableCommand);
+            }
+            _itemFilterScript.SetIsDirty(true);
+        }
+    }
+}

Filtration.ObjectModel/Commands/ICommand.cs

@@ -0,0 +1,7 @@
+namespace Filtration.ObjectModel.Commands
+{
+    public interface ICommand
+    {
+        void Execute();
+    }
+}

Filtration.ObjectModel/Commands/IUndoableCommand.cs

@@ -0,0 +1,8 @@
+namespace Filtration.ObjectModel.Commands
+{
+    internal interface IUndoableCommand : ICommand
+    {
+        void Undo();
+        void Redo();
+    }
+}