using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var mediator = new ConcreteMediator();

        mediator.RegisterComponent<Database>();

        mediator.RegisterComponent<Logger>();

        var notifier = mediator.RegisterComponent<Notifier>();

        notifier.Send("Hello Pattern!");

    }

}

​

public class ConcreteMediator : Mediator

{

    List<Component> components = new List<Component>();

    public T RegisterComponent<T>() where T : Component, new()

    {

        var c = new T();

        c.SetMediator(this);

        components.Add(c);

        return c;

    }

    public override void Send(string message, Component component)

    {

        if (component.GetType() == typeof(Notifier))

        {

            components.Where(c => c != component).ToList().ForEach(c => c.HandleMessage(message, component));

        }

        else if (component.GetType() == typeof(Database))

        {

            components.Where(c => c.GetType() == typeof(Notifier) || c.GetType() == typeof(Logger)).ToList().ForEach(c => c.HandleMessage(message, component));

        }

    }

}

​

public class Database : Component

{

    public override void HandleMessage(string message, Component sender)

    {

        // NB "\n" manda a capo, "\t" inserisce un tab

        Console.WriteLine("Database\n received:\t\"{0}\" \n from:\t\t\"{1}\"", message, sender);

        this.mediator.Send("Database saved correctly", this);

    }

}

​

public class Logger : Component

{

    public override void HandleMessage(string message, Component sender)

    {

        Console.WriteLine("Logger\n received:\t\"{0}\" \n from:\t\t\"{1}\"", message, sender);

    }

}

​

public class Notifier : Component

{

    public override void HandleMessage(string message, Component sender)

    {

        Console.WriteLine("Notifier\n received:\t\"{0}\" \n from:\t\t\"{1}\"", message, sender);

    }

}

​

public abstract class Mediator

{

    public abstract void Send(string message, Component component);

}

​

public abstract class Component

{

    protected Mediator mediator;

    internal void SetMediator(Mediator mediator) => this.mediator = mediator;

    public virtual void Send(string message)

    {

        this.mediator.Send(message, this);

    }

    public abstract void HandleMessage(string message, Component sender);

}