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

//
// This is the protocol between the master server and the
// individual servers.
//

public class pongProtocol {

  //
  // processCommand -- process the command from the client.
  //

  public static boolean processCommand(int command, 
			               ObjectInputStream serialIn,
			               ObjectOutputStream serialOut,
				       grimReaperThread reaper) {

    pongIdentity pongID;

    //
    // All objects must first contain a pongIdentity object so we don't
    // have to keep track of who's coming from where.
    //

    if ((pongID = getPongID(reaper, serialIn)) == null) {
      sendCommand(Pong.SERVER_NAK, serialOut);
      return false;
    }
    switch (command) {
      case Pong.SERVER_LOGIN:
	if (reaper.serverListGet(pongID.clientName) != null) {
	  sendCommand(Pong.SERVER_ALREADY_LOGGED_IN, serialOut);
	  return false;
        }
	reaper.serverListPut(pongID.clientName, pongID);
        sendCommand(Pong.SERVER_ACK, serialOut);
        break;
      case Pong.SERVER_LOGOUT:
	if (reaper.serverListGet(pongID.clientName) == null) {
	  sendCommand(Pong.SERVER_NOT_LOGGED_IN, serialOut);
	  return false;
        }
        sendCommand(Pong.SERVER_ACK, serialOut);
	reaper.serverListRemove(pongID.clientName);
        break;
      case Pong.SERVER_LIST:
	if (reaper.serverListGet(pongID.clientName) == null) {
	  sendCommand(Pong.SERVER_NOT_LOGGED_IN, serialOut);
	  return false;
        }
        try {
          serialOut.writeObject(reaper.serverList); 
        }
	catch (IOException e) {
          sendCommand(Pong.SERVER_NAK, serialOut);
        }
        break;
      case Pong.SERVER_PING:
        sendCommand(Pong.SERVER_ACK, serialOut);
        break;
      default:
        sendCommand(Pong.SERVER_NAK, serialOut);
        break;
    }
    return true;
  }

  static void sendCommand(int command, ObjectOutputStream serialOut) {
    try {
      serialOut.writeObject(new Integer(command));
    }
    catch (IOException e) {
      return;
    }
  }

  static pongIdentity getPongID(grimReaperThread reaper, ObjectInputStream serialIn) {

    pongIdentity pongID;

    try {
      pongID = (pongIdentity) serialIn.readObject();
    }
    catch (IOException e) {
      return null;
    }
    catch (ClassNotFoundException e) {
      return null;
    }
    reaper.serverListUpdate(pongID.clientName);	// update last time heard from
    return pongID;
  }
}