import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.net.*;
import java.util.*;
import com.objectspace.jgl.*;

import com.oreilly.servlet.DaemonHttpServlet;

public class ModChatServlet extends DaemonHttpServlet {
//Initialize global variables
  HashMap msgHolder = new HashMap();

  public void init(ServletConfig config) throws ServletException {
    super.init(config);
  }
//Process the HTTP Get request

  public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
    res.setContentType("text/plain");
    PrintWriter out = res.getWriter();
    out.println(getNextMessage(req));
  }
//Process the HTTP Post request

  public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
    String message = req.getParameter("message");
    if(message != null) broadcastMessage(message);
    res.setStatus(res.SC_NO_CONTENT);
  }

//return the next new message
  public String getNextMessage(HttpServletRequest req){
    ModMessageSink MSink= new ModMessageSink();
    ModMessageSource source = new ModMessageSource();
    Thread t1 = new Thread(source);
    t1.start();
    return MSink.getNextMessage(source);
  }

//inform all currently listening clients that there is a new message
  public void broadcastMessage(String message){
    System.out.println("Adding new message...");
    msgHolder.add("daljeet", message);
//    source.sendMessage(message);
  }

  public void handleClient(Socket client){
  }

//Get Servlet information

  public String getServletInfo() {
    return "MDM.ChatServlet Information";
  }

class ModMessageSource extends Observable implements Runnable{
  public void run(){
    while (msgHolder.count("daljeet")==0){
      try{
        Thread.sleep(5000000);
        System.out.println("Thread going to sleep:");
      }
      catch(Exception e){;}
    }
    sendMessage((String)msgHolder.values("daljeet").nextElement());
    msgHolder.remove("daljeet");
  }
  public void sendMessage(String message){
    setChanged();
    notifyObservers(message);
  }
}

class ModMessageSink implements Observer{
  String message = null;

  synchronized public void update(Observable o, Object arg){
    message = (String) arg;
    notify();
  }

  synchronized public String getNextMessage(ModMessageSource source){
    source.addObserver(this);
    while (message == null){
      try{wait();}catch(Exception ignored) {}
    }
    source.deleteObserver(this);
    String messageCopy = message;
    message = null;
    return messageCopy;
  }
}
}