using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Command
{
    /// <summary>

    /// MainApp startup class for Structural 

    /// Command Design Pattern.
    /// Encapsulate a request as an object, thereby letting you parameterize clients with different requests,
    /// queue or log requests, and support undoable operations.

    /// </summary>

    class MainApp
    {
        /// <summary>

        /// Entry point into console application.

        /// </summary>

        static void Main()
        {
            // Create receiver, command, and invoker

            Receiver receiver = new Receiver();
            Command command = new ConcreteCommand(receiver);
            Invoker invoker = new Invoker();

            // Set and execute command

            invoker.SetCommand(command);
            invoker.ExecuteCommand();

            // Wait for user

            Console.ReadKey();
        }
    }

    /// <summary>

    /// The 'Command' abstract class

    /// </summary>

    abstract class Command
    {
        protected Receiver receiver;

        // Constructor

        public Command(Receiver receiver)
        {
            this.receiver = receiver;
        }

        public abstract void Execute();
    }

    /// <summary>

    /// The 'ConcreteCommand' class

    /// </summary>

    class ConcreteCommand : Command
    {
        // Constructor

        public ConcreteCommand(Receiver receiver) :
            base(receiver)
        {
        }

        public override void Execute()
        {
            receiver.Action();
        }
    }

    /// <summary>

    /// The 'Receiver' class

    /// </summary>

    class Receiver
    {
        public void Action()
        {
            Console.WriteLine("Called Receiver.Action()");
        }
    }

    /// <summary>

    /// The 'Invoker' class

    /// </summary>

    class Invoker
    {
        private Command _command;

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

        public void ExecuteCommand()
        {
            _command.Execute();
        }
    }
}