/*
  GRANITE DATA SERVICES
  Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.

  This file is part of Granite Data Services.

  Granite Data Services is free software; you can redistribute it and/or modify
  it under the terms of the GNU Library General Public License as published by
  the Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  Granite Data Services is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
  for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

package org.granite.gravity.gae;

import java.io.IOException;
import java.util.List;

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

import org.granite.gravity.AbstractGravityServlet;
import org.granite.gravity.Gravity;
import org.granite.gravity.GravityManager;
import org.granite.logging.Logger;

import com.google.apphosting.api.DeadlineExceededException;

import flex.messaging.messages.AsyncMessage;
import flex.messaging.messages.Message;


/**
 * @author William DRAI
 */
public class GravityGAEServlet extends AbstractGravityServlet {

    private static final long serialVersionUID = 1L;

    private static final Logger log = Logger.getLogger(GravityGAEServlet.class);


    private static long GAE_TIMEOUT = 20000L;
    private static long GAE_POLLING_INTERVAL = 500L;


    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

                Gravity gravity = GravityManager.getGravity(getServletContext());
                GAEChannelFactory channelFactory = new GAEChannelFactory((GAEGravity)gravity);
                
                try {
                        // Setup context (thread local GraniteContext, etc.)
                        initializeRequest(gravity, request, response);
                        
                        // New Request.
                        Message[] amf3Requests = deserialize(gravity, request);

            log.debug(">> [AMF3 REQUESTS] %s", (Object)amf3Requests);

            Message[] amf3Responses = null;
            
            boolean accessed = false;
            for (int i = 0; i < amf3Requests.length; i++) {
                Message amf3Request = amf3Requests[i];
                
                // Ask gravity to create a specific response (will be null for connect request from tunnel).
                Message amf3Response = gravity.handleMessage(channelFactory, amf3Request);
                String channelId = (String)amf3Request.getClientId();
                
                // Mark current channel (if any) as accessed.
                if (!accessed)
                        accessed = gravity.access(channelId);
                
                // (Re)Connect message from tunnel.
                if (amf3Response == null) {
                    if (amf3Requests.length > 1)
                        throw new IllegalArgumentException("Only one request is allowed on tunnel.");

                        GAEChannel channel = gravity.getChannel(channelFactory, channelId);
                        if (channel == null)
                                throw new NullPointerException("No channel on connect");
                        
                        long pollingInterval = gravity.getGravityConfig().getExtra().get("gae/@polling-interval", Long.TYPE, GAE_POLLING_INTERVAL);

                    long initialTime = System.currentTimeMillis();
                    do {
                        // Get messages or wait
                        List<Message> messages = null;
                        synchronized (channel) {
                            // Get pending messages from client queue
                            messages = channel.takeMessages();
                        }
        
                        // Send the messages
                        if (messages != null) {
                                amf3Responses = messages.toArray(new Message[0]);
                                ((AsyncMessage)amf3Responses[i]).setCorrelationId(amf3Requests[i].getMessageId());
                                break;
                        }
                        
                        try {
                                Thread.sleep(pollingInterval);
                        }
                        catch (InterruptedException e) {
                                break;
                        }
                        catch (DeadlineExceededException e) {
                                break;
                        }
                    }
                    while (System.currentTimeMillis()-initialTime < GAE_TIMEOUT);
                    
                    if (amf3Responses == null)
                        amf3Responses = new Message[0];
                }
                else {
                        if (amf3Responses == null)
                                amf3Responses = new Message[amf3Requests.length];
                        amf3Responses[i] = amf3Response;
                }
            }

            log.debug("<< [AMF3 RESPONSES] %s", (Object)amf3Responses);

            serialize(gravity, response, amf3Responses);
                }
        catch (IOException e) {
            log.error(e, "Gravity message error");
            throw e;
        }
        catch (Exception e) {
            log.error(e, "Gravity message error");
            throw new ServletException(e);
        }
                finally {
                        // Cleanup context (thread local GraniteContext, etc.)
                        cleanupRequest(request);
                }
    }
}