Behavioral Pattern - Mediator Pattern

Definition:

Mediator defines an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.

UML Diagram:

Sample code:

Mediator:

public enum BillerType
    {
        Vodafone = 1,
        BESCOM = 2,
        TataIndicom = 3,
        Airtel = 4
    }
    public interface IBillPayAgent : IDisposable
    {
       
        bool PayBill(double amount);
    }
    public class BillPayAgent : IBillPayAgent
    {
        private BillerType _billerType;
        public BillPayAgent(BillerType billerType)
        {
            this._billerType = billerType;
        }
        private IBiller Biller
        {
            get { return BillerFactory.GetFactory(_billerType); }
        }
        public bool PayBill(double amount)
        {
            using (Biller)
            {
                Biller.ReceiveAmount(amount);
            }
            return true;
        }

        public void Dispose()
        {
            Dispose(true);
        }

        ~BillPayAgent()
        {
            Dispose(false);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
                GC.SuppressFinalize(this);
        }
    }

Supplier:

    public class IBiller : IDisposable
    {
        public virtual void ReceiveAmount(double amount)
        {
            Console.WriteLine("Received Amount: " + amount.ToString());
        }

        public void Dispose()
        {
            Dispose(true);
        }

        ~IBiller()
        {
            Dispose(false);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
                GC.SuppressFinalize(this);
        }
    }

    public sealed class Vodafone : IBiller
    {
        public override void ReceiveAmount(double amount)
        {
            Console.WriteLine("Greetings from Vodafone");
            base.ReceiveAmount(amount);
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
                GC.SuppressFinalize(this);
            base.Dispose(disposing);
        }
    }

    public sealed class TataIndicom : IBiller
    {
        public override void ReceiveAmount(double amount)
        {
            Console.WriteLine("Greetings from TataIndicom");
            base.ReceiveAmount(amount);
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
                GC.SuppressFinalize(this);
            base.Dispose(disposing);
        }
    }

    public sealed class BESCOM : IBiller
    {
        public override void ReceiveAmount(double amount)
        {
            Console.WriteLine("Greetings from BESCOM");
            base.ReceiveAmount(amount);
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
                GC.SuppressFinalize(this);
            base.Dispose(disposing);
        }
    }

    public sealed class Airtel : IBiller
    {
        public override void ReceiveAmount(double amount)
        {
            Console.WriteLine("Greetings from Airtel");
            base.ReceiveAmount(amount);
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
                GC.SuppressFinalize(this);
            base.Dispose(disposing);
        }
    }

Consumer:

public class Consumer : IDisposable
    {
        private IBillPayAgent billPayAgent = default(IBillPayAgent);
       
        public void DoShopping()
        {
            Console.WriteLine("I am doing shopping");
        }

        public void PayEBBill(double amount)
        {
            using (billPayAgent = new BillPayAgent(BillerType.BESCOM))
            {
                billPayAgent.PayBill(amount);
            }
        }

        public void PayMobileBill(double amount,BillerType billerType)
        {
            using (billPayAgent = new BillPayAgent(billerType))
            {
                billPayAgent.PayBill(amount);
            }
        }

        public void Dispose()
        {
            Dispose(true);
        }

        ~Consumer()
        {
            Dispose(false);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
                GC.SuppressFinalize(this);
        }
    }