Mediator Design Pattern Example

ChatRoom.cs

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

namespace MediatorPattern
{
    //Concrete Mediator
    public class ChatRoom : IChatRoom
    {
        private Dictionary<string, Participant> participants = 
            new Dictionary<string, Participant>();
        public void Register(Participant participant)
        {
            if (!participants.ContainsValue(participant))
                participants.Add(participant.Name, participant);
            participant.ChatRoom = this;
        }

        public void SendMessage(string from, string to, string message)
        {
            if (participants.Keys.Contains(to))
            {
                Participant participant = participants[to];
                participant.Receive(from, message);
            }
            else
            {
                Console.WriteLine("Participant not registered.");
            }
        }
    }
}

IChatRoom.cs

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

namespace MediatorPattern
{
    //Mediator
    public interface IChatRoom
    {
        void Register(Participant participant);
        void SendMessage(string from, string to, string message);

    }
}

Participant.cs

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

namespace MediatorPattern
{
    //Participant class (Colleague class) 
    public class Participant
    {
        public Participant(string name)
        {
            Name = name;
        }
        public ChatRoom ChatRoom { get; set; }
        public string Name { get; set; }
        public void Send(string to, string message)
        {
            ChatRoom.SendMessage(Name, to, message);
        }
        public void Receive(string from, string message)
        {
            Console.WriteLine("{0} to {1} - '{2}'", 
                from, Name, message);
        }
    }
    //Client class (entry point)
    class Program
    {
        static void Main(string[] args)
        {
            ChatRoom chatroom = new ChatRoom();
            List<string> people = new List<string>()
            { "Mitesh", "Sandeep", "Vikram", "Amit" };
            List<Participant> participants = new List<Participant>();
            foreach (string s in people)
                participants.Add(new Participant(s));
            
            foreach (Participant p in participants)
                chatroom.Register(p);

            participants.Find(x => x.Name.Equals("Mitesh")).
                Send("Sandeep", "Hey Sandeep, How are you?");
            participants.Find(x => x.Name.Equals("Vikram")).
                Send("Mitesh", "Where are you?");
            participants.Find(x => x.Name.Equals("Sandeep")).
                Send("Mitesh", "Hi Mitesh, i am good. Thanks");
            participants.Find(x => x.Name.Equals("Mitesh")).
                Send("Vikram", "I am at home");
            participants.Find(x => x.Name.Equals("Amit")).
                Send("Vikram", "Hi");

            Console.Read();
        }
    }
}

Program.cs

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

namespace MediatorPattern
{    
    //Client class (entry point)
    class Program
    {
        static void Main(string[] args)
        {
            ChatRoom chatroom = new ChatRoom();
            List<string> people = new List<string>()
            { "Mitesh", "Sandeep", "Vikram", "Amit" };
            List<Participant> participants = new List<Participant>();
            foreach (string s in people)
                participants.Add(new Participant(s));
            
            foreach (Participant p in participants)
                chatroom.Register(p);

            participants.Find(x => x.Name.Equals("Mitesh")).
                Send("Sandeep", "Hey Sandeep, How are you?");
            participants.Find(x => x.Name.Equals("Vikram")).
                Send("Mitesh", "Where are you?");
            participants.Find(x => x.Name.Equals("Sandeep")).
                Send("Mitesh", "Hi Mitesh, i am good. Thanks");
            participants.Find(x => x.Name.Equals("Mitesh")).
                Send("Vikram", "I am at home");
            participants.Find(x => x.Name.Equals("Amit")).
                Send("Vikram", "Hi");

            Console.Read();
        }
    }
}