/*
  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.tomcat;

import java.util.concurrent.atomic.AtomicReference;

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

import org.apache.catalina.CometEvent;
import org.granite.gravity.AbstractChannel;
import org.granite.gravity.AbstractGravityServlet;
import org.granite.gravity.AsyncHttpContext;
import org.granite.gravity.Gravity;
import org.granite.logging.Logger;

import flex.messaging.messages.Message;

/**
 * @author Franck WOLFF
 */
public class TomcatChannel extends AbstractChannel {

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

    private final AtomicReference<CometEvent> event = new AtomicReference<CometEvent>();

    
    public TomcatChannel(Gravity gravity, String id, TomcatChannelFactory factory, String clientType) {
        super(gravity, id, factory, clientType);
    }
    
    public void setCometEvent(CometEvent event) {
        if (log.isDebugEnabled())
            log.debug("Channel: %s got new event: %s", getId(), EventUtil.toString(event));
        
        // Set this channel's event.
        CometEvent previousEvent = this.event.getAndSet(event);

        // Normally, we should have only two cases here:
        //
        // 1) this.event == null && event != null -> new (re)connect message.
        // 2) this.event != null && event == null -> timeout.
        //
        // Not sure about what should be done if this.event != null && event != null, so
        // warn about this case and close this.event if it is not the same as the event
        // parameter.
        if (previousEvent != null) {
                if (event != null) {
                        log.warn(
                                "Got a new non null event %s while current event %s isn't null",
                                EventUtil.toString(event), EventUtil.toString(this.event.get())
                        );
                }
                if (previousEvent != event) {
                        try {
                                previousEvent.close();
                        }
                        catch (Exception e) {
                                log.debug(e, "Error while closing event");
                        }
                }
        }
        
        // Try to queue receiver if the new event isn't null.
        if (event != null)
                queueReceiver();
    }
    
    @Override
        protected boolean hasAsyncHttpContext() {
        return event.get() != null;
        }

        @Override
        protected AsyncHttpContext acquireAsyncHttpContext() {

                CometEvent event = this.event.getAndSet(null);
                if (event == null)
                        return null;

        AsyncHttpContext context = null;
        
        try {
                HttpServletRequest request = null;
                HttpServletResponse response = null;
                try {
                        request = event.getHttpServletRequest();
                        response = event.getHttpServletResponse();
                } catch (Exception e) {
                        log.warn(e, "Illegal event: %s", EventUtil.toString(event));
                        return null;
                }
                if (request == null || response == null) {
                        log.warn("Illegal event (request or response is null): %s", EventUtil.toString(event));
                        return null;
                }
        
                Message requestMessage = AbstractGravityServlet.getConnectMessage(request);
                if (requestMessage == null) {
                        log.warn("No request message while running channel: %s", getId());
                        return null;
                }
                        
                context = new AsyncHttpContext(request, response, requestMessage, event);
        }
        finally {
                if (context == null) {
                        try {
                                event.close();
                        }
                        catch (Exception e) {
                                log.debug(e, "Error while closing event: %s", EventUtil.toString(event));
                        }
                }
        }
        
        return context;
        }

        @Override
        protected void releaseAsyncHttpContext(AsyncHttpContext context) {
                try {
                        if (context != null && context.getObject() != null)
                                ((CometEvent)context.getObject()).close();
                }
                catch (Exception e) {
                        log.warn(e, "Could not release event for channel: %s", this);
                }
        }

        @Override
        public void destroy() {
                try {
                        super.destroy();
                }
                finally {
                        close();
                }
        }
        
        public void close() {
                CometEvent event = this.event.getAndSet(null);
                if (event != null) {
                        try {
                                event.close();
                        }
                        catch (Exception e) {
                                log.debug(e, "Could not close event: %s for channel: %s", EventUtil.toString(event), this);
                        }
                }
        }
}