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

namespace Klient_FTP
{

    class Program
    {
        Int32 portPASV;
        String currentUser=String.Empty;
        static void SaveFile(String fileName, Byte[] Data)
        {
            BinaryWriter Writer = new BinaryWriter(File.OpenWrite(fileName));
            Writer.Write(Data);
            Writer.Flush();
            Writer.Close();
        }
        void Work(object obj)
        {
            Directory.CreateDirectory("C:/FTP");
            Directory.SetCurrentDirectory("C:/FTP");
            var message = ((object[])obj)[0].ToString() + " " + currentUser + '\0';

            IPEndPoint ep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 21);
            TcpClient client = new TcpClient();
            client.Connect(ep);
            StringBuilder sb = new StringBuilder();
            if (message.Contains("RETR"))
            {
                if (currentUser != String.Empty)
                {
                    NetworkStream strim = client.GetStream();
                    message = message.Insert(message.LastIndexOf('\0'), " " + currentUser);
                    strim.Write(Encoding.ASCII.GetBytes(message), 0, message.Length);
                    IPEndPoint fileEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), portPASV);
                    StringBuilder msg = new StringBuilder();
                    TcpClient fileClient = new TcpClient();
                    fileClient.Connect(fileEndPoint);
                    StringBuilder sbf = new StringBuilder();
                    using (NetworkStream fileStream = fileClient.GetStream())
                    {

                        int _tmp;
                        while ((_tmp = fileStream.ReadByte()) != 0)
                        {
                            sbf.Append((char)_tmp);
                        }
                    }

                    String[] splitMessage = message.Split(' ');
                    StringBuilder fileName = new StringBuilder(splitMessage[1]);
                    fileName.Insert(0, '\\');
                    StringBuilder XD = new StringBuilder(fileName.ToString().Substring(fileName.ToString().LastIndexOf("\\")));
                    SaveFile(Directory.GetCurrentDirectory() + XD, System.Text.Encoding.ASCII.GetBytes(sbf.ToString()));
                    fileClient.Close();
                    client.Close();
                    return;
                }
                else
                {
                    Console.WriteLine("530: Access denied. Provide password before using RETR.");
                    return;
                }


            }
            using (NetworkStream stream = client.GetStream())
            {
                Console.WriteLine("sent: " + message);
                stream.Write(Encoding.ASCII.GetBytes(message), 0, message.Length);
                int i;
                while ((i = stream.ReadByte()) != 0)
                {
                    sb.Append((char)i);
                }
            }
            if (message.Contains("PASV"))
            {

                String[] PASVtoparse = new String[6];
                PASVtoparse = sb.ToString().Split(',');
                IPAddress localAddress = IPAddress.Parse(PASVtoparse[0] + "." + PASVtoparse[1] + "." + PASVtoparse[2] + "." + PASVtoparse[3]);
                portPASV = Int32.Parse(PASVtoparse[4]) * 256 + Int32.Parse(PASVtoparse[5]);
                Console.WriteLine("Port: " + portPASV.ToString());
            }
            else if (message.Contains("PASS"))
            {
                String[] splitMessage = message.Split(' ');
                currentUser = splitMessage[1];
                Console.WriteLine("ID klienta: " + currentUser);

            }
            Console.WriteLine("response: \n" + sb.ToString());
            client.Close();
        }
        void start(string m)
        {
            ThreadPool.QueueUserWorkItem(Work, new object[] { m });
            Thread.Sleep(200);
        }

        static void Main(string[] args)
        {
            Program p = new Program();
            string message = string.Empty;
            while (true)
            {
                Console.Write("input: ");
                message = Console.ReadLine();
                if (message != "QUIT") p.start(message);
                else break;
            }
            //press any key to exit
            Console.ReadKey();
            Environment.Exit(0);
        }
    }
}