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

class TcpChat
{
    static void Main(string[] args)
    {
        if(args.Length == 0)
        {
            Console.WriteLine("Basic TCP chat");
            Console.WriteLine();
            Console.WriteLine("Usage:");
            Console.WriteLine("tcpchat server <port>");
            Console.WriteLine("tcpchat client <url> <port>");
            return;
        }

        try
        {
            Run(args);
        }
        catch(IOException)
        {
            Console.WriteLine("--- Connection lost");
        }
        catch(SocketException ex)
        {
            Console.WriteLine("--- Can't connect: " + ex.Message);
        }
    }
    
    static void Run(string[] args)
    {
        TcpClient client;
        NetworkStream stream;
        byte[] buffer = new byte[256];
        var encoding = Encoding.ASCII;

        if(args[0].StartsWith("s", StringComparison.InvariantCultureIgnoreCase))
        {
            var port = int.Parse(args[1]);
            var listener = new TcpListener(IPAddress.Any, port);
            listener.Start();
            Console.WriteLine("--- Waiting for a connection...");
            client = listener.AcceptTcpClient();
        }
        else
        {
            var hostName = args[1];
            var port = int.Parse(args[2]);
            client = new TcpClient();
            client.Connect(hostName, port);
        }

        stream = client.GetStream();
        Console.WriteLine("--- Connected. Start typing! (exit with Ctrl-C)");

        while(true)
        {
            if(Console.KeyAvailable)
            {
                var lineToSend = Console.ReadLine();
                var bytesToSend = encoding.GetBytes(lineToSend + "\\r\\n");
                stream.Write(bytesToSend, 0, bytesToSend.Length);
                stream.Flush();
            }

            if (stream.DataAvailable)
            {
                var receivedBytesCount = stream.Read(buffer, 0, buffer.Length);
                var receivedString = encoding.GetString(buffer, 0, receivedBytesCount);
                Console.Write(receivedString);
            }
        }
    }
}