package udpchatserver;

/**
 * Title: UDPChatServer
 * Description: UDPChatServer
 * Copyright:    Copyright (c) 2001
 * Company:
 * @author: Dan
 * @version 1.0
 */


import java.net.* ;
import java.io.* ;
import java.lang.* ;
import java.util.* ;

public class ChatServer{

//set the global variables which are passed/referenced by sub classes

static final int BUFFER_SIZE = 512;           //Sets Max Packet Size
private DatagramSocket ChatSocket = null;     //Socket to Communicate with
public Hashtable ClientsTable = new Hashtable();


public ChatServer(int Port) {


    int ServerPort = Port;


    //Create buffers to hold incoming & outgoing messages
    byte[] recievedBuffer = new byte[BUFFER_SIZE];
    byte[] sendBuffer = new byte[BUFFER_SIZE];
    while(true){
      try {
        //Sets up DatagramSocket on the Server Port
       ChatSocket = new DatagramSocket(ServerPort);
        System.out.println("Chat Server started on " + InetAddress.getLocalHost());
        do {
          //Block until a Datagram appears

          byte [] buf = new byte [BUFFER_SIZE];
          DatagramPacket IncomingPacket = new DatagramPacket(buf, buf.length);
          ChatSocket.receive(IncomingPacket);
          ChatServerThread ChatThread = new ChatServerThread(IncomingPacket, GetHashTable());
          ChatThread.start();

        }while(true);

      }catch (SocketException e) {

          System.err.println("Can't open OutToClientSocket");
          System.exit (1);

      }catch (IOException e) {

          System.err.println("Communication error");
          e.printStackTrace ();

      }finally {

          ChatSocket.close();
      }
    }
}

public Hashtable GetHashTable(){

      return ClientsTable;
}



public static void main (String args []) throws Exception {

ChatServer p;

int localport = -1;
int i = 0;
boolean error = false;
Integer parselocalport = new Integer(args[i]);

  try{
      localport = parselocalport.parseInt(args[i], 10);
  }

  catch(Exception e){
      System.err.println("Error: " + e.getMessage() + "\n");
      error = true;
   }

  if(localport <= 0){
      System.err.println("Error: Invalid Local Port Specification " + "\n");
      error = true;
  }

  try{
      if (args.length!=1)
      throw new IllegalArgumentException("Syntax: chatserver <port>");
  }

  catch (Exception ex){
      System.err.println(ex.getMessage());
      System.exit(1);
  }

  if(error)
    System.exit(-1);



  try{
      p = new ChatServer(Integer.parseInt(args[0]));
      p.ChatSocket.disconnect();
      }

  catch(Exception ex){

      System.err.println("Error: " + ex.getMessage());
      System.exit(1);
      }

  finally{

      System.out.println("Closing...");
  }

}
}