/*
  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.weblogic;

import java.io.IOException;
import java.lang.reflect.Method;
import java.util.concurrent.atomic.AtomicReference;

import org.granite.gravity.AbstractChannel;
import org.granite.gravity.AsyncHttpContext;
import org.granite.gravity.Gravity;
import org.granite.logging.Logger;

import weblogic.servlet.http.AbstractAsyncServlet;
import weblogic.servlet.http.RequestResponseKey;

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

        private static final Logger log = Logger.getLogger(WebLogicChannel.class);
        
        // For WebLogic 9.1 compatibility.
        private static Method isValid = null;
        static {
                try {
                        isValid = RequestResponseKey.class.getDeclaredMethod("isValid");
                }
                catch (Throwable t) {
                }
        }
    
    private final AtomicReference<RequestResponseKey> key = new AtomicReference<RequestResponseKey>();

    
        public WebLogicChannel(Gravity gravity, String id, WebLogicChannelFactory factory, String clientType) {
                super(gravity, id, factory, clientType);
        }
        
        public void setRequestResponseKey(RequestResponseKey key) {
        if (log.isDebugEnabled())
            log.debug("Channel: %s got new asyncContext: %s", getId(), key);
        
        // Set this channel's request/response key.
        RequestResponseKey previousKey = this.key.getAndSet(key);
        
        // Normally, we should have only two cases here:
        //
        // 1) this.key == null && key != null -> new (re)connect message.
        // 2) this.key != null && key == null -> timeout.
        //
        // Not sure about what should be done if this.key != null && key != null, so
        // warn about this case and close this.key if it is not the same as the key
        // parameter.
        if (previousKey != null) {
                if (key != null) {
                        log.warn(
                                "Got a new non null key %s while current key %s isn't null",
                                key, this.key.get()
                        );
                }
                if (previousKey != key) {
                        try {
                                previousKey.getResponse().getOutputStream().close();
                        }
                        catch (Exception e) {
                                log.debug(e, "Error while closing key");
                        }
                }
        }
        
        // Try to queue receiver if the new asyncContext isn't null.
        if (key != null)
                queueReceiver();
        }

        @Override
        protected boolean hasAsyncHttpContext() {
                return key.get() != null;
        }

        @Override
        protected AsyncHttpContext acquireAsyncHttpContext() {
                RequestResponseKey key = this.key.getAndSet(null);
                if (key == null || !isValid(key))
                        return null;

                try {
                        AbstractAsyncServlet.notify(key, this);
                }
                catch (IOException e) {
                        throw new RuntimeException(e);
                }
                
                return null;
        }

        @Override
        protected void releaseAsyncHttpContext(AsyncHttpContext context) {
                // This method shouldn't be called in a WebLogic environment, anyway...
                try {
                        if (context != null)
                                context.getResponse().getOutputStream().close();
                }
                catch (Exception e) {
                        log.warn(e, "Could not release asyncHttpContext for channel: %s", this);
                }
        }

        @Override
        public void destroy() {
                try {
                        super.destroy();
                }
                finally {
                        close();
                }
        }
        
        public void close() {
                RequestResponseKey key = this.key.getAndSet(null);
                if (key != null) {
                        try {
                                key.getResponse().getOutputStream().close();
                        }
                        catch (Exception e) {
                                log.debug(e, "Could not close key: %s for channel: %s", key, this);
                        }
                }
        }
        
        private static boolean isValid(RequestResponseKey key) {
                if (isValid != null) try {
                        return (Boolean)isValid.invoke(key);
                }
                catch (Exception e) {
                        return false;
                }
                return true;
        }
}