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();
    }
}