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

public class chatpeer2 {

 public static void main(String args[]) throws Exception {
   
  int                           ioPort = 1111, receiverPort = ioPort;
  DatagramSocket      ioSocket;
  String                      toName = "localhost";
  String                      userIn;
  byte                        sendBuffer[] = new byte[128];
  DatagramPacket      sendPacket   = new DatagramPacket(sendBuffer, 128);
  BufferedReader        in                  = new BufferedReader(
                                                            new InputStreamReader(System.in));
  Vector                     chatlist          = new Vector();

  if (args.length > 0) toName = args[0];
  if (toName.equals("localhost")) receiverPort = 2222; 
  try { ioSocket = new DatagramSocket(ioPort); }
  catch (Exception e) {
    ioPort = 2222; receiverPort = 1111;
    ioSocket = new DatagramSocket(ioPort);
  }

  System.out.println("chatpeer2 on port " + ioPort + ". ctrl-c to quit.");

  new receiver(ioSocket, chatlist, receiverPort);    // Start receiver

  chatlist.addElement(toName);

  while ((userIn=in.readLine())!=null) {
     sendBuffer = userIn.getBytes();
     for (int i=0; i<chatlist.size(); i++) {
       sendPacket = new DatagramPacket( sendBuffer, userIn.length(),
                                   InetAddress.getByName((String)(chatlist.elementAt(i))), 
                                   receiverPort);
       ioSocket.send(sendPacket);
     }
  }
  System.exit(0);                                     // Exit, stopping receiver
 }
}

class receiver implements Runnable {

  DatagramSocket ioSocket;
  Vector chatlist;

  int receiverPort;

 receiver(DatagramSocket ioSocket, Vector chatlist, int receiverPort) {
   this.ioSocket = ioSocket;
   this.chatlist = chatlist;

   this.receiverPort = receiverPort;

   new Thread(this).start();
 }

 public void run() {
   byte receiveBuffer[] = new byte[128];
   DatagramPacket sendPacket, receivePacket;
 
   while(true) {
     receivePacket = new DatagramPacket(receiveBuffer, 128);
     try { ioSocket.receive(receivePacket); }
     catch (Exception e) {}
     System.out.println( "Received " + new String(receivePacket.getData(), 0, 
                                                                            receivePacket.getLength()));
     String chatname = receivePacket.getAddress().getHostName();
     if(!chatlist.contains(chatname)) chatlist.addElement(chatname);

     for (int i=0; i<chatlist.size(); i++) {                                // Forward received to all chatters in list
       if(!((String)(chatlist.elementAt(i))).equals(chatname))   // Avoid looping to chatter
         try { 
           sendPacket = new DatagramPacket(receiveBuffer, receivePacket.getLength(),
                                  InetAddress.getByName((String)(chatlist.elementAt(i))), 
                                  receiverPort);
           ioSocket.send(sendPacket); 
         }
         catch(Exception ee) {}
     } 

  }
 }
}