/*
  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.util.concurrent.atomic.AtomicReference;

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

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 AsyncChannel extends AbstractChannel {

    private static final Logger log = Logger.getLogger(AsyncChannel.class);
    
    private final AtomicReference<AsyncContext> asyncContext = new AtomicReference<AsyncContext>();

        public AsyncChannel(Gravity gravity, String id, AsyncChannelFactory factory, String clientType) {
        super(gravity, id, factory, clientType);
        }

        public void setAsyncContext(AsyncContext asyncContext) {
        if (log.isDebugEnabled())
            log.debug("Channel: %s got new asyncContext: %s", getId(), asyncContext);
        
        // Set this channel's async context.
        AsyncContext previousAsyncContext = this.asyncContext.getAndSet(asyncContext);

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

        @Override
        protected AsyncHttpContext acquireAsyncHttpContext() {

                AsyncContext asyncContext = this.asyncContext.getAndSet(null);
                if (asyncContext == null)
                        return null;

        AsyncHttpContext context = null;

        try {
                HttpServletRequest request = null;
                HttpServletResponse response = null;
                try {
                        request = (HttpServletRequest)asyncContext.getRequest();
                        response = (HttpServletResponse)asyncContext.getResponse();
                } catch (Exception e) {
                        log.warn("Illegal asyncContext: %s", asyncContext);
                        return null;
                }
                if (request == null || response == null) {
                        log.warn("Illegal asyncContext (request or response is null): %s", asyncContext);
                        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, asyncContext);
        }
        finally {
                if (context == null) {
                        try {
                                asyncContext.complete();
                        }
                        catch (Exception e) {
                                log.debug(e, "Error while closing asyncContext: %s", asyncContext);
                        }
                }
        }
        
        return context;
        }

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

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