/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 package org.apache.myfaces.webapp;

 import java.util.Enumeration;

 import javax.faces.context.ExceptionHandler;

 import javax.faces.context.ExternalContext;

 import javax.faces.context.FacesContext;

 import javax.servlet.ServletContext;

 import javax.servlet.ServletContextAttributeEvent;

 import javax.servlet.ServletContextAttributeListener;

 import javax.servlet.ServletContextEvent;

 import javax.servlet.ServletContextListener;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletRequestAttributeEvent;

 import javax.servlet.ServletRequestAttributeListener;

 import javax.servlet.ServletRequestEvent;

 import javax.servlet.ServletRequestListener;

 import javax.servlet.http.HttpSessionAttributeListener;

 import javax.servlet.http.HttpSessionBindingEvent;

 import javax.servlet.http.HttpSessionEvent;

 import javax.servlet.http.HttpSessionListener;

 import org.apache.myfaces.config.ManagedBeanDestroyer;

 import org.apache.myfaces.context.ReleaseableExternalContext;

 import org.apache.myfaces.context.servlet.StartupFacesContextImpl;

 import org.apache.myfaces.context.servlet.StartupServletExternalContextImpl;

 import org.apache.myfaces.shared.context.ExceptionHandlerImpl;

 import org.apache.myfaces.spi.ViewScopeProvider;

 /**

  * Listens to

  *   - removing, replacing of attributes in context, session and request

  *   - destroying of context, session and request

  * for the ManagedBeanDestroyer to assure right destruction of managed beans in those scopes.

  * 

  * This listener is not registered in a tld or web.xml, but will be called by StartupServletContextListener.

  * 

  * @author Jakob Korherr (latest modification by $Author$)

  * @version $Revision$ $Date$

  * @since 2.0

  */

 public class ManagedBeanDestroyerListener implements 

         HttpSessionAttributeListener, HttpSessionListener,

         ServletContextListener, ServletContextAttributeListener,

         ServletRequestListener, ServletRequestAttributeListener

 {

     /**

      * The instance of the ManagedBeanDestroyerListener created by

      * StartupServletContextListener is stored under this key in the

      * ApplicationMap.

      */

     public static final String APPLICATION_MAP_KEY = "org.apache.myfaces.ManagedBeanDestroyerListener";

     private ManagedBeanDestroyer _destroyer = null;

     private ViewScopeProvider _viewScopeHandler = null;

     /**

      * Sets the ManagedBeanDestroyer instance to use.

      *  

      * @param destroyer

      */

     public void setManagedBeanDestroyer(ManagedBeanDestroyer destroyer)

     {

         _destroyer = destroyer;

     }

     public void setViewScopeHandler(ViewScopeProvider listener)

     {

         _viewScopeHandler = listener;

     }

     /* Session related methods ***********************************************/

     public void attributeAdded(HttpSessionBindingEvent event)

     {

         // noop

     }

     public void attributeRemoved(HttpSessionBindingEvent event)

     {

         if (_destroyer != null)

         {

             _destroyer.destroy(event.getName(), event.getValue());

         }

     }

     public void attributeReplaced(HttpSessionBindingEvent event)

     {

         if (_destroyer != null)

         {

             _destroyer.destroy(event.getName(), event.getValue());

         }

     }

     public void sessionCreated(HttpSessionEvent event)

     {

         // noop

     }

     @SuppressWarnings("unchecked")

     public void sessionDestroyed(HttpSessionEvent event)

     {

         // MYFACES-3040 @PreDestroy Has Called 2 times

         // attributeRemoved receives the event too, so it does not 

         // have sense to handle it here. Unfortunately, it is not possible to 

         // handle it first and then on attributeRemoved, so the best bet is

         // let the code in just one place.

         /*

         if (_destroyer != null)

         {

             HttpSession session = event.getSession();

             Enumeration<String> attributes = session.getAttributeNames();

             if (!attributes.hasMoreElements())

             {

                 // nothing to do

                 return;

             }

             while (attributes.hasMoreElements())

             {

                 String name = attributes.nextElement();

                 Object value = session.getAttribute(name);

                 _destroyer.destroy(name, value);

             }

         }*/

         // If we don't propagate this event, CDI will do for us but outside JSF control

         // so when @PreDestroy methods are called there will not be an active FacesContext.

         // The trick here is ensure clean the affected scopes to avoid duplicates.

         // Remember cdi session scope is different from jsf session scope, because in

         // jsf case the beans are stored under a session attribute, so it has the problem

         // with attributeRemoved, but on cdi a wrapper is used instead, avoiding the problem.

         if (_viewScopeHandler != null)

         {

             FacesContext facesContext = FacesContext.getCurrentInstance();

             if (facesContext != null)

             {

                 _viewScopeHandler.onSessionDestroyed();

             }

             else

             {

                 // In case no FacesContext is available, we are on session invalidation

                 // through timeout. In that case, create a dummy FacesContext for this one

                 // like the one used in startup or shutdown and invoke the destroy method.

                 try

                 {

                     ServletContext servletContext = event.getSession().getServletContext();

                     ExternalContext externalContext = new StartupServletExternalContextImpl(servletContext, false);

                     ExceptionHandler exceptionHandler = new ExceptionHandlerImpl();

                     facesContext = new StartupFacesContextImpl(externalContext, 

                             (ReleaseableExternalContext) externalContext, exceptionHandler, false);

                     _viewScopeHandler.onSessionDestroyed();

                 }

                 finally

                 {

                     facesContext.release();

                 }

             }

         }

     }

     /* Context related methods ***********************************************/

     public void attributeAdded(ServletContextAttributeEvent event)

     {

         // noop

     }

     public void attributeRemoved(ServletContextAttributeEvent event)

     {

         if (_destroyer != null)

         {

             _destroyer.destroy(event.getName(), event.getValue());

         }

     }

     public void attributeReplaced(ServletContextAttributeEvent event)

     {

         if (_destroyer != null)

         {

             _destroyer.destroy(event.getName(), event.getValue());

         }

     }

     public void contextInitialized(ServletContextEvent event)

     {

         // noop

     }

     @SuppressWarnings("unchecked")

     public void contextDestroyed(ServletContextEvent event)

     {

         if (_destroyer != null)

         {

             ServletContext ctx = event.getServletContext();

             Enumeration<String> attributes = ctx.getAttributeNames();

             if (!attributes.hasMoreElements())

             {

                 // nothing to do

                 return;

             }

             while (attributes.hasMoreElements())

             {

                 String name = attributes.nextElement();

                 Object value = ctx.getAttribute(name);

                 _destroyer.destroy(name, value);

             }

         }

     }

     /* Request related methods ***********************************************/

     public void attributeAdded(ServletRequestAttributeEvent event)

     {

         // noop

     }

     public void attributeRemoved(ServletRequestAttributeEvent event)

     {

         if (_destroyer != null)

         {

             _destroyer.destroy(event.getName(), event.getValue());

         }

     }

     public void attributeReplaced(ServletRequestAttributeEvent event)

     {

         if (_destroyer != null)

         {

             _destroyer.destroy(event.getName(), event.getValue());

         }

     }

     public void requestInitialized(ServletRequestEvent event)

     {

         // noop

     }

     @SuppressWarnings("unchecked")

     public void requestDestroyed(ServletRequestEvent event)

     {

         if (_destroyer != null)

         {

             ServletRequest request = event.getServletRequest();

             Enumeration<String> attributes = request.getAttributeNames();

             if (!attributes.hasMoreElements())

             {

                 // nothing to do

                 return;

             }

             while (attributes.hasMoreElements())

             {

                 String name = attributes.nextElement();

                 Object value = request.getAttribute(name);

                 _destroyer.destroy(name, value);

             }

         }

     }

 }