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


namespace kmserv
{
  class Server
  {
        private TcpListener tcpListener;
        private Thread listenThread;
        private TcpClient tcpClient;

        public static void Main (string[] args)
        {

            Server kmserv = new Server(23569);
        }

        public Server(int port)
        {
            Console.WriteLine ("Starting kmserv on port "+port.ToString()+"...");
            this.tcpListener = new TcpListener(IPAddress.Any, port);
            this.listenThread = new Thread(new ThreadStart(ListenForClients));
            this.listenThread.Start();
        }

        private void ListenForClients()
        {
            this.tcpListener.Start();
            while (true)
            {
                //blocks until a client has connected to the server
                TcpClient client = this.tcpListener.AcceptTcpClient();
                //create a thread to handle communication
                //with connected client
                Thread clientThread = new Thread(new ParameterizedThreadStart(HandleClientComm));
                clientThread.Start(client);
            }
        }

        private void HandleClientComm(object client)
        {
            tcpClient = (TcpClient)client;
            NetworkStream clientStream = tcpClient.GetStream();

            byte[] message = new byte[40960];
            int bytesRead;
            while (true)
            {
                bytesRead = 0;
                try
                {
                    //blocks until a client sends a message
                    bytesRead = clientStream.Read(message, 0, 40960);
                }
                catch
                {
                    //a socket error has occured
                    break;
                }

                if (bytesRead == 0)
                {
                    //the client has disconnected from the server
                    break;
                }
                //message has successfully been received
                ASCIIEncoding encoder = new ASCIIEncoding();
                //System.Diagnostics.Debug.WriteLine(encoder.GetString(message, 0, bytesRead));
                Console.WriteLine(GetCurrentTime() + " " + tcpClient.Client.RemoteEndPoint.ToString() + " [RECEIVED] | "+ encoder.GetString(message,0,bytesRead).Replace("\n",""));
                string command = encoder.GetString(message,0,bytesRead);

                string reply=ParseCommand(command);
                SendReply(reply);
                Console.WriteLine(GetCurrentTime() + " " + tcpClient.Client.RemoteEndPoint.ToString() + " [SENT] | "+ reply);
            }

            tcpClient.Close();
        }

        private string ParseCommand(string command)
        {
            string reply="";
            string prefix = command.Substring(0,3);
            switch(prefix)
            {
            case "cmd":
                reply = ExecuteCommandSync(command.Substring(4));
                break;
            default:
                reply = "ERROR: Invalid Command";
                break;
            }
            return reply;
        }

        private void SendReply(string reply)
        {
            string tempEnd="\n";
            System.Net.Sockets.NetworkStream clientStream = tcpClient.GetStream();
            ASCIIEncoding encoder = new ASCIIEncoding();
            byte[] buffer = encoder.GetBytes(reply+tempEnd);

            clientStream.Write(buffer, 0 , buffer.Length);
            clientStream.Flush();
        }

        private string GetCurrentTime()
        {
            string date = System.DateTime.Now.Year.ToString() +"-";
            if (System.DateTime.Now.Month.ToString().Length==1)
                date +="0";
            date +=System.DateTime.Now.Month.ToString() + "-";
            if (System.DateTime.Now.Day.ToString().Length==1)
                date +="0";
            date+=System.DateTime.Now.Day.ToString();

            date +=" ";

            if (System.DateTime.Now.Hour.ToString().Length==1)
                date+="0";
            date += System.DateTime.Now.Hour.ToString()+":";
            if (System.DateTime.Now.Minute.ToString().Length==1)
                date+="0";
            date += System.DateTime.Now.Minute.ToString()+":";
            if (System.DateTime.Now.Second.ToString().Length==1)
                date+="0";
            date+=System.DateTime.Now.Second.ToString();
            return date;
        }


        public string ExecuteCommandSync(object command)
        {
            string result="";

            try
            {
                 // create the ProcessStartInfo using "cmd" as the program to be run,
                 // and "/c " as the parameters.
                 // Incidentally, /c tells cmd that we want it to execute the command that follows,
                 // and then exit.
                System.Diagnostics.ProcessStartInfo procStartInfo = new System.Diagnostics.ProcessStartInfo("cmd", "/c " + command.ToString().Replace("\n",""));
                //System.Diagnostics.ProcessStartInfo procStartInfo =   new System.Diagnostics.ProcessStartInfo();

                // The following commands are needed to redirect the standard output.
                // This means that it will be redirected to the Process.StandardOutput StreamReader.
                procStartInfo.RedirectStandardOutput = true;
                procStartInfo.UseShellExecute = false;
                // Do not create the black window.
                procStartInfo.CreateNoWindow = true;
                // Now we create a process, assign its ProcessStartInfo and start it
                System.Diagnostics.Process proc = new System.Diagnostics.Process();
                proc.StartInfo = procStartInfo;
                proc.Start();
                // Get the output into a string
                result = proc.StandardOutput.ReadToEnd();

            }
            catch (Exception objException)
            {
                result =  objException.Message.ToString();
            }
            return result;
        }

    }
}