using System;

​

public class HttpRequest

{

    public string Username {get; set;}

    public string Password {get; set;}

}

​

public abstract class Handler

{

    private Handler next;

    public Handler(Handler next)

    {

        this.next = next;

    }

    protected abstract bool DoHandle(HttpRequest request);

    public void Handle(HttpRequest request) {

        if(DoHandle(request))

            return;

        if(next != null)

            next.Handle(request);

    }

}

​

public class Authenticator: Handler

{

    public Authenticator(Handler handler): base(handler)

    {

    }

    protected override bool DoHandle(HttpRequest request) 

    {

        Console.WriteLine("Authenticating request");

        return !(request.Username == "admin" && request.Password == "1234");

    }

}

​

public class Logger: Handler

{

    public Logger(Handler handler): base(handler)

    {

    }

    protected override bool DoHandle(HttpRequest request) 

    {

        Console.WriteLine("Logging request");

        return false;

    }

}

​

public class Compressor: Handler

{

    public Compressor(Handler handler): base(handler)

    {

    }

    protected override bool DoHandle(HttpRequest request) 

    {

        Console.WriteLine("Compressing request");

        return false;

    }

}

​

public class WebServer

{

    private Handler handler;

    public WebServer(Handler handler) 

    {

        this.handler = handler;

    }

    public void Handle(HttpRequest request) {

        handler.Handle(request);

    }

}

​

public class Program

{

    public static void Main()

    {

        var logger = new Logger(null);

        var compressor = new Compressor(logger);

        var authenticator = new Authenticator(compressor);

        var webserver = new WebServer(authenticator);

        webserver.Handle(new HttpRequest(){Username = "admin", Password = "1234"});

    }

}