import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;


/**
   This class listens for broadcast messages and reports them to the
   ReliableBroadcastProcss that spawned it.
   
   @author Tom Austin
 */
public class RBListenerThread extends Thread
{  
   //RB process that this class corresponds to.
   private ReliableBroadcastProcess rbp;
   
   //Network connection details.
   private int socketNum;
   private InetAddress address;

   /**
      Constructor.
      
      @param rbp  Process that this thread belongs to.
      @param address  Address of the broadcast group.
      @param socketNum  Socket on which to listen.
    */
   public RBListenerThread(ReliableBroadcastProcess rbp, InetAddress address, int socketNum)
   {
      this.rbp = rbp;
      this.address = address;
      this.socketNum = socketNum;
   }
   
   /**
      Starts the thread.  It will listen for broadcast messages and report
      them to its corresponding process.
      
      @see java.lang.Runnable#run()
    */
   public void run()
   {
      MulticastSocket socket;
      try
      {
         socket = new MulticastSocket(socketNum);
         socket.joinGroup(address);
   
         DatagramPacket packet;
         while (true)
         {
            byte[] buf = new byte[256];
            packet = new DatagramPacket(buf, buf.length);
            socket.receive(packet);
            String received = new String(packet.getData());
            
            //Here we parse the data received to construct a
            // new Message object from it.
            Message m = Message.parseTransmissionString(received.trim());
            
            //The message is passed to the RB process here.
            rbp.receive(m);
         }
      }
      catch (IOException e)
      {
         e.printStackTrace();
      }
   }

}