mediator pattern in csharp

main.cs
// Define mediator interface
public interface IMediator
{
    void Notify(object sender, string ev);
}

// Define concrete mediator
public class ConcreteMediator : IMediator
{
    private Component1 component1;
    private Component2 component2;

    public ConcreteMediator(Component1 component1, Component2 component2)
    {
        this.component1 = component1;
        this.component1.SetMediator(this);
        this.component2 = component2;
        this.component2.SetMediator(this);
    }

    public void Notify(object sender, string ev)
    {
        if (ev == "A")
        {
            Console.WriteLine("Mediator reacts on A and triggers following operations:");
            this.component2.DoC();
        }
        if (ev == "D")
        {
            Console.WriteLine("Mediator reacts on D and triggers following operations:");
            this.component1.DoB();
            this.component2.DoC();
        }
    }
}

// Define components
public class BaseComponent
{
    protected IMediator mediator;

    public BaseComponent(IMediator mediator = null)
    {
        this.mediator = mediator;
    }

    public void SetMediator(IMediator mediator)
    {
        this.mediator = mediator;
    }
}

public class Component1 : BaseComponent
{
    public void DoA()
    {
        Console.WriteLine("Component 1 does A.");
        this.mediator.Notify(this, "A");
    }

    public void DoB()
    {
        Console.WriteLine("Component 1 does B.\n");
        this.mediator.Notify(this, "B");
    }
}

public class Component2 : BaseComponent
{
    public void DoC()
    {
        Console.WriteLine("Component 2 does C.");
        this.mediator.Notify(this, "C");
    }

    public void DoD()
    {
        Console.WriteLine("Component 2 does D.");
        this.mediator.Notify(this, "D");
    }
}

// Example usage
public class Client
{
    static void Main(string[] args)
    {
        Component1 component1 = new Component1();
        Component2 component2 = new Component2();

        ConcreteMediator mediator = new ConcreteMediator(component1, component2);

        Console.WriteLine("Client triggers operation A.");
        component1.DoA();

        Console.WriteLine("\nClient triggers operation D.");
        component2.DoD();
    }
}
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