Mediator example

mediator.cs

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

public class Program
{
    public class Person
    {
        public string Name { get; }

        public Person(string name)
        {
            Name = name;
        }

        public void Notify(string message)
        {
            Console.WriteLine(message);
        }
    }

    // Mediator class repsonsible for sending messages and notifying participants
    public class ChatRoom
    {
        private IList<Person> _participants = new List<Person>();

        public void RegisterParticipant(Person person)
        {
            _participants.Add(person);
        }

        public void SendGroupMessage(string senderName)
        {
            var participants = _participants.Where(e => e.Name != senderName);

            foreach (var participant in participants)
            {
                participant.Notify($"{senderName} says hello to {participant.Name}");
            }
        }

        public void SendPrivateMessage(string senderName, string listenerName)
        {
            var participant = _participants.First(e => e.Name == senderName);

            participant.Notify($"{senderName} says hello {participant.Name}");
        }
    }

    public static void Main()
    {
        // ChatRoom is our mediator instance
        var chatRoom = new ChatRoom();

        // Register chat participants
        chatRoom.RegisterParticipant(new Person("John"));
        chatRoom.RegisterParticipant(new Person("Sajid"));
        chatRoom.RegisterParticipant(new Person("Rebecca"));
        chatRoom.RegisterParticipant(new Person("Mo"));

        // The mediator decouples communication between the chat participants
        chatRoom.SendGroupMessage("John");
        chatRoom.SendGroupMessage("Mo");

        chatRoom.SendPrivateMessage("John", "Mo");
        chatRoom.SendPrivateMessage("Rebecca", "Sajid");


        // Console output:

        // John says hello Sajid
        // John says hello Rebecca
        // John says hello Mo

        // Mo says hello John
        // Mo says hello Sajid
        // Mo says hello Rebecca

        // John says hello Mo
        // Rebecca says hello Sajid
    }
}