package org.crosswire.community.events;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.CometEvent;
import org.apache.catalina.CometProcessor;

public class EventBus extends HttpServlet implements CometProcessor {
	
private MessageSender messageSender = null;
private static final Integer TIMEOUT = 60 * 1000;

@Override
public void destroy() {
    messageSender.running = false;
    messageSender = null;

}

@Override
public void init() throws ServletException {
    messageSender = new MessageSender();
    Thread messageSenderThread = new Thread(messageSender, "MessageSender[" + getServletContext().getContextPath() + "]");
    messageSenderThread.setDaemon(true);
    messageSenderThread.start();

}

public void event(final CometEvent event) throws IOException, ServletException {
    HttpServletRequest request = event.getHttpServletRequest();
    HttpServletResponse response = event.getHttpServletResponse();
    if (event.getEventType() == CometEvent.EventType.BEGIN) {
        request.setAttribute("org.apache.tomcat.comet.timeout", TIMEOUT);
        log("Begin for session: " + request.getSession(true).getId());
        messageSender.setConnection(response);
        Weatherman weatherman = new Weatherman(95118, 32408);
        new Thread(weatherman).start();
    } else if (event.getEventType() == CometEvent.EventType.ERROR) {
        log("Error for session: " + request.getSession(true).getId());
        event.close();
    } else if (event.getEventType() == CometEvent.EventType.END) {
        log("End for session: " + request.getSession(true).getId());
        event.close();
    } else if (event.getEventType() == CometEvent.EventType.READ) {
        throw new UnsupportedOperationException("This servlet does not accept data");
    }

}


private class MessageSender implements Runnable {

    protected boolean running = true;
    protected final ArrayList<String> messages = new ArrayList<String>();
    private ServletResponse connection;
    private synchronized void setConnection(ServletResponse connection){
        this.connection = connection;
        notify();
    }
    public void send(String message) {
        synchronized (messages) {
            messages.add(message);
            log("Message added #messages=" + messages.size());
            messages.notify();
        }
    }
    public void run() {
        while (running) {
            if (messages.size() == 0) {
                try {
                    synchronized (messages) {
                        messages.wait();
                    }
                } catch (InterruptedException e) {
                    // Ignore
                }
            }
            String[] pendingMessages = null;
            synchronized (messages) {
                pendingMessages = messages.toArray(new String[0]);
                messages.clear();
            }
            try {
                if (connection == null){
                    try{
                        synchronized(this){
                            wait();
                        }
                    } catch (InterruptedException e){
                        // Ignore
                    }
                }
                PrintWriter writer = connection.getWriter();
                for (int j = 0; j < pendingMessages.length; j++) {
                    final String forecast = pendingMessages[j] + "<br>";
                    writer.println(forecast);
                    log("Writing:" + forecast);
                }
                writer.flush();
                writer.close();
                connection = null;
                log("Closing connection");
            } catch (IOException e) {
                log("IOExeption sending message", e);
            }
        }
    }
}



private class Weatherman implements Runnable{

    private final List<URL> zipCodes;
    private final String YAHOO_WEATHER = "http://weather.yahooapis.com/forecastrss?p=";

    public Weatherman(Integer... zips) {
        zipCodes = new ArrayList<URL>(zips.length);
        for (Integer zip : zips) {
            try {
                zipCodes.add(new URL(YAHOO_WEATHER + zip));
            } catch (Exception e) {
                // dont add it if it sucks
            }
        }
    }

   public void run() {
       int i = 0;
       while (i >= 0) {
           int j = i % zipCodes.size();
           try {
               URL zipUrl = zipCodes.get(j);
               messageSender.send(zipUrl.toString());
               Thread.sleep(30000L);
           } catch (Exception e) {
               // just eat it, eat it
           }
           i++;
       }
   }
}

/*
private void log(String msg) {
	System.err.println(msg);
}

private void log(String msg, Exception e) {
	System.err.println(msg + e.toString());
}
*/

}