using System;

public class Program

{

    public static string encryptedCookie = "QWE";

    public static bool IsCorrectlyEncrypted = true;

    public static string Username = "CevaUsername";

    public static bool IsExpired = true;

    public static void Main()

    {

        var loginController = new LoginController();

        loginController.Login();

    }

    public class LoginController

    {   

        private readonly Logger logger;

        private readonly Decryptor decryptor;

        public LoginController()

        {

            this.logger = new Logger();

            this.decryptor = new Decryptor();

        }

        public bool Login()

        {

            var cookie = encryptedCookie; // actually get the cookie from the HttpRequest

            this.logger.Log(string.Format("Trying to log in user with cookie {0}", cookie));

            if (cookie == null)

            {

                this.logger.Log("Cookie not found");

                return false; // please pretend that return false is actually a redirect to login :D

            }

            else

            {

                var decryptedCookie = this.decryptor.Decrypt(cookie);

                if (decryptedCookie == null)

                {

                    this.logger.Log("Invalid cookie");

                    return false;

                }

                else 

                {

                    if (decryptedCookie.IsExpired)

                    {

                        this.logger.Log("Expired cookie");

                        return false;

                    }

                    else

                    {

                        this.logger.Log(string.Format("Successfully logged in user {0}", decryptedCookie.Username));

                        return true; // set some state to reflect the user is authenticated

                    }

                }

            }

        }

    }

    public class Logger

    {

        public void Log(string message)

        {

            Console.WriteLine(message);

        }

    }

    public class Decryptor

    {

        public Cookie Decrypt(string input)

        {

            return IsCorrectlyEncrypted ? new Cookie(Username, IsExpired) : null;

        }

    }

    public class Cookie

    {

        public Cookie(string username, bool isExpired)

        {

            this.Username = username;

            this.IsExpired = isExpired;

        }

        public string Username { get; private set; }

        public bool IsExpired { get; private set; } 

    }

}