/*
  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.servlet3;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

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

import org.granite.gravity.AbstractGravityServlet;
import org.granite.gravity.AsyncHttpContext;
import org.granite.gravity.Gravity;
import org.granite.gravity.GravityManager;
import org.granite.logging.Logger;
import org.granite.messaging.jmf.JMFDeserializer;
import org.granite.messaging.jmf.JMFSerializer;
import org.granite.messaging.jmf.JMFServletContextListener;
import org.granite.messaging.jmf.SharedContext;
import org.granite.util.ContentType;
import org.granite.util.UUIDUtil;

import flex.messaging.messages.Message;

/**
 * @author Franck WOLFF
 */
public class GravityAsyncServlet extends AbstractGravityServlet {

        private static final long serialVersionUID = 1L;

        private static final Logger log = Logger.getLogger(GravityAsyncServlet.class);
    
    protected SharedContext jmfSharedContext = null;
    
        @Override
        public void init(ServletConfig config) throws ServletException {
                super.init(config);
                
        jmfSharedContext = JMFServletContextListener.getSharedContext(config.getServletContext());
        }

        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
                
                if (!request.isAsyncSupported())
                        throw new ServletException("Asynchronous requests are not supported with this servlet. Please check your web.xml");

                if (request.isAsyncStarted())
                        throw new ServletException("Gravity Servlet3 implementation doesn't support dispatch(...) mode");

                Gravity gravity = GravityManager.getGravity(getServletContext());
                AsyncChannelFactory channelFactory = newAsyncChannelFactory(gravity, request.getContentType());
        
                try {
            initializeRequest(gravity, request, response);

            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 connect request is allowed on tunnel.");

                    AsyncChannel channel = gravity.getChannel(channelFactory, channelId);
                    if (channel == null)
                                throw new NullPointerException("No channel on tunnel connect");
                    
                    // Try to send pending messages if any (using current container thread).
                    if (!channel.runReceived(new AsyncHttpContext(request, response, amf3Request))) {
                            // No pending messages, wait for new ones or timeout.
                            setConnectMessage(request, amf3Request);
                                AsyncContext asyncContext = request.startAsync();
                                asyncContext.setTimeout(getLongPollingTimeout());
                                try {
                                        asyncContext.addListener(new AsyncRequestListener(channel));
                                        channel.setAsyncContext(asyncContext);
                                }
                                catch (Exception e) {
                                        log.error(e, "Error while setting async context. Closing context...");
                                        asyncContext.complete();
                                }
                    }
                    return;
                }

                if (amf3Responses == null)
                        amf3Responses = new Message[amf3Requests.length];
                amf3Responses[i] = amf3Response;
            }

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

            serialize(gravity, response, amf3Responses, request.getContentType());
        }
        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 {
                cleanupRequest(request);
        }
        }


        @Override
        public void destroy() {
                jmfSharedContext = null;

                super.destroy();
        }
        
        protected AsyncChannelFactory newAsyncChannelFactory(Gravity gravity, String contentType) throws ServletException {
                if (ContentType.JMF_AMF.mimeType().equals(contentType)) {
                if (jmfSharedContext == null)
                        throw JMFServletContextListener.newSharedContextNotInitializedException();
                        
                return new JMFAsyncChannelFactory(gravity, jmfSharedContext);
                }
                return new AsyncChannelFactory(gravity);
        }

        @Override
        protected Message[] deserialize(Gravity gravity, HttpServletRequest request) throws ClassNotFoundException, IOException, ServletException {
                if (ContentType.JMF_AMF.mimeType().equals(request.getContentType())) {
                        InputStream is = request.getInputStream();
                        try {
                                return deserializeJMFAMF(gravity, request, is);
                        }
                        finally {
                                is.close();
                        }
                }
                return super.deserialize(gravity, request);
        }

        @Override
        protected Message[] deserialize(Gravity gravity, HttpServletRequest request, InputStream is) throws ClassNotFoundException, IOException, ServletException {
                if (ContentType.JMF_AMF.mimeType().equals(request.getContentType()))
                        return deserializeJMFAMF(gravity, request, is);
                return super.deserialize(gravity, request, is);
        }
        
        protected Message[] deserializeJMFAMF(Gravity gravity, HttpServletRequest request, InputStream is) throws ClassNotFoundException, IOException, ServletException {
        if (jmfSharedContext == null)
                throw JMFServletContextListener.newSharedContextNotInitializedException();
        
        @SuppressWarnings("all") // JDK7 warning (Resource leak: 'deserializer' is never closed)...
                JMFDeserializer deserializer = new JMFDeserializer(is, jmfSharedContext);
        return (Message[])deserializer.readObject();
        }

        protected void serialize(Gravity gravity, HttpServletResponse response, Message[] messages, String contentType) throws IOException, ServletException {
                if (ContentType.JMF_AMF.mimeType().equals(contentType))
                        serializeJMFAMF(gravity, response, messages);
                else
                        super.serialize(gravity, response, messages);
        }

        protected void serializeJMFAMF(Gravity gravity, HttpServletResponse response, Message[] messages) throws IOException, ServletException {
        if (jmfSharedContext == null)
                throw JMFServletContextListener.newSharedContextNotInitializedException();
        
        OutputStream os = null;
                try {
            // For SDK 2.0.1_Hotfix2+ (LCDS 2.5+).
                        String dsId = null;
            for (Message message : messages) {
                    if ("nil".equals(message.getHeader(Message.DS_ID_HEADER))) {
                        if (dsId == null)
                                dsId = UUIDUtil.randomUUID();
                        message.getHeaders().put(Message.DS_ID_HEADER, dsId);
                    }
            }
                        
                response.setStatus(HttpServletResponse.SC_OK);
                response.setContentType(ContentType.JMF_AMF.mimeType());
                response.setDateHeader("Expire", 0L);
                response.setHeader("Cache-Control", "no-store");
                
                os = response.getOutputStream();

                @SuppressWarnings("all") // JDK7 warning (Resource leak: 'serializer' is never closed)...
            JMFSerializer serializer = new JMFSerializer(os, jmfSharedContext);
            serializer.writeObject(messages);
                
                os.flush();
                response.flushBuffer();
                }
                finally {
                        if (os != null)
                                os.close();
                }
        }
}