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

namespace Client_ServerTest01
{
    class Server
    {
        const int Port = 2536;
        static void Main(string[] args)
        {
            Console.WriteLine("Start");
            bool ExitTrigger = true;

            IPEndPoint ipPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), Port);
            Socket listenSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            listenSocket.Bind(ipPoint);
            Console.WriteLine("Bilding");
            listenSocket.Listen(100);
            Console.WriteLine("Listening");
            Socket handler = listenSocket.Accept();
            Console.WriteLine("Ready!");
            while (ExitTrigger)
            {
                byte[] data = new byte[256];
                handler.Receive(data);
                int num = BitConverter.ToInt32(data, 0);
                if (num != 0)
                {
                    Console.WriteLine(num);
                    handler.Send(BitConverter.GetBytes(factorial(num)));
                }
                else
                {
                    handler.Shutdown(SocketShutdown.Both);
                    handler.Close();
                    Console.WriteLine("Closing");
                    ExitTrigger = false;
                }
            }
        }
      static int factorial(int num)
        {
            int result = 1;
            for (int i = 1; i <= num; i++)
            {
                result *= i;
            }
            return result;
        }
    }
}