using System;
using System.Threading;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.IO;

namespace ServerFTP_IO
{
    public class server
    {
        ManualResetEvent tcpClientConnected = new ManualResetEvent(false);

        void ProcessIncomingData(object obj)
        {
            TcpClient client = (TcpClient)obj;
            StringBuilder sb = new StringBuilder();
            bool userauth = false;
            bool accessgranted = false;
            using (NetworkStream stream = client.GetStream())
            {
                int i;
                string[] tab = new string[2];

                while ((i = stream.ReadByte()) != 0)
                {
                    sb.Append((char)i);
                }
                tab = sb.ToString().Split(' ');
                switch (tab[0].ToUpper())
                {
                    case "USER":
                        {
                            accessgranted = true;
                            userauth = true;
                            Byte[] bytess = new Byte[256];
                            string username = tab[1];
                            if (username.Equals("anonymous"))
                            {
                                string rep = "331: Password is required to get access." + '\0';
                                stream.Write(Encoding.ASCII.GetBytes(rep), 0, rep.Length);

                                userauth = true;


                            }
                            else
                            {
                                string rep = "530: Access denied" + '\0';
                                stream.Write(Encoding.ASCII.GetBytes(rep), 0, rep.Length);
                            }
                            break;
                        }
                    case "PASS":
                        {

                            if (userauth)
                            {
                                string userpass = tab[1];
                                if (userpass.Contains("@") && !(userpass.StartsWith("@")) && !(userpass.EndsWith("@")) && (userpass.EndsWith(".com") || userpass.EndsWith(".pl")))
                                {
                                    string rep = " 230: Access granted. " + '\0';
                                    stream.Write(Encoding.ASCII.GetBytes(rep), 0, rep.Length);
                                    accessgranted = true;
                                }
                                else
                                {
                                    string rep = " 530: Access denied. " + '\0';
                                    stream.Write(Encoding.ASCII.GetBytes(rep), 0, rep.Length);

                                }
                            }
                            else
                            {
                                string rep = " User has not been specified yet. " + '\0';
                                stream.Write(Encoding.ASCII.GetBytes(rep), 0, rep.Length);

                            }
                            userauth = false;
                            break;
                        }

                    case "RETR":
                        {
                            if (accessgranted)
                            {
                                string path = @"C:\Users\Klaudia\Documents\hello.txt";
                                byte[] fileData = GetFileData(path);
                                stream.Write(fileData, 0, fileData.Length);

                            }

                            Console.WriteLine(sb.ToString());



                            //  string reply = "ack: " + sb.ToString() + '\0';
                            //    stream.Write(Encoding.ASCII.GetBytes(reply), 0, reply.Length);
                            break;
                        }
                }
            }
        }


        byte[] GetFileData(String path)
        {
            using (var sr = new StreamReader(path))
            {
                return ASCIIEncoding.ASCII.GetBytes(sr.ReadToEnd());
            }

        }
        void ProcessIncomingConnection(IAsyncResult ar)
        {
            TcpListener listener = (TcpListener)ar.AsyncState;
            TcpClient client = listener.EndAcceptTcpClient(ar);

            ThreadPool.QueueUserWorkItem(ProcessIncomingData, client);
            tcpClientConnected.Set();
        }

        public void start()
        {
            IPEndPoint endpoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 5000);
            TcpListener listener = new TcpListener(endpoint);
            listener.Start();

            while (true)
            {
                tcpClientConnected.Reset();
                listener.BeginAcceptTcpClient(new AsyncCallback(ProcessIncomingConnection), listener);
                tcpClientConnected.WaitOne();
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            server s = new server();
            s.start();
        }
    }
}