Program.cs

using System;
using System.Collections.Generic;

namespace Command;

// Command interface
public interface ICommand
{
    void Execute();
    void Undo();
}

// Receiver
public class Light(string location)
{
    // Using C# 14 field keyword for cleaner implementation
    public string Location
    {
        get;
        init => field = value ?? throw new ArgumentNullException(nameof(value));
    } = location;

    public void TurnOn()
    {
        Console.WriteLine($"{Location} light is ON");
    }

    public void TurnOff()
    {
        Console.WriteLine($"{Location} light is OFF");
    }
}

// Concrete Commands
public class LightOnCommand(Light light) : ICommand
{
    public void Execute()
    {
        light.TurnOn();
    }

    public void Undo()
    {
        light.TurnOff();
    }
}

public class LightOffCommand(Light light) : ICommand
{
    public void Execute()
    {
        light.TurnOff();
    }

    public void Undo()
    {
        light.TurnOn();
    }
}

// Invoker
public class RemoteControl
{
    private ICommand command;
    private Stack<ICommand> commandHistory = [];

    public void SetCommand(ICommand command)
    {
        this.command = command;
    }

    public void PressButton()
    {
        command.Execute();
        commandHistory.Push(command);
    }

    public void PressUndo()
    {
        if (commandHistory.Count > 0)
        {
            ICommand lastCommand = commandHistory.Pop();
            lastCommand.Undo();
        }
        else
        {
            Console.WriteLine("Nothing to undo");
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("=== Command Pattern Demo ===");
        Console.WriteLine();

        // Receivers
        Light livingRoomLight = new Light("Living Room");
        Light kitchenLight = new Light("Kitchen");

        // Commands
        ICommand livingRoomOn = new LightOnCommand(livingRoomLight);
        ICommand livingRoomOff = new LightOffCommand(livingRoomLight);
        ICommand kitchenOn = new LightOnCommand(kitchenLight);
        ICommand kitchenOff = new LightOffCommand(kitchenLight);

        // Invoker
        RemoteControl remote = new RemoteControl();

        // Execute commands
        Console.WriteLine("Turning on living room light:");
        remote.SetCommand(livingRoomOn);
        remote.PressButton();

        Console.WriteLine();
        Console.WriteLine("Turning on kitchen light:");
        remote.SetCommand(kitchenOn);
        remote.PressButton();

        Console.WriteLine();
        Console.WriteLine("Turning off living room light:");
        remote.SetCommand(livingRoomOff);
        remote.PressButton();

        Console.WriteLine();
        Console.WriteLine("Undo last command:");
        remote.PressUndo();

        Console.WriteLine();
        Console.WriteLine("Undo previous command:");
        remote.PressUndo();

        Console.WriteLine();
        Console.WriteLine("Press any key to exit...");
        Console.ReadKey();
    }
}