Initial commit

Assets/_Project/Scripts/Code/CommandLayer/CommandManager.cs

@@ -0,0 +1,73 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class CommandManager
+{
+    private static CommandManager instance;
+
+    private LinkedList<ICommand> commandStack = new LinkedList<ICommand>();
+    private LinkedList<ICommand> redoStack = new LinkedList<ICommand>();
+
+    private int maxCapacity = 100; // added to prevent memory leak in the long run
+
+    private CommandManager()
+    {
+    }
+
+    public static CommandManager getInstance()
+    {
+        if (instance == null)
+        {
+            instance = new CommandManager();
+        }
+        return instance;
+    }
+
+    public void setMaxCapacity(int capacity)
+    {
+        maxCapacity = capacity;
+    }
+
+    public void executeCommand(ICommand command)
+    {
+        command.execute();
+
+        commandStack.AddFirst(command);
+        redoStack.Clear();
+        if (commandStack.Count > maxCapacity)
+        {
+            commandStack.RemoveLast();
+        }
+    }
+
+    public void undo()
+    {
+        if (commandStack.Count > 0)
+        {
+            ICommand command = commandStack.First.Value;
+            commandStack.RemoveFirst();
+            command.undo();
+            redoStack.AddFirst(command);
+        }
+    }
+
+    public ICommand redo()
+    {
+        if (redoStack.Count > 0)
+        {
+            ICommand command = redoStack.First.Value;
+            redoStack.RemoveFirst();
+            command.execute();
+            commandStack.AddFirst(command);
+            return command;
+        }
+        return null;
+    }
+
+    public void clearHistory()
+    {
+        commandStack.Clear();
+        redoStack.Clear();
+    }
+}