/*
    * 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.ExternalContext;
  import javax.faces.context.FacesContext;
  import javax.faces.event.PreDestroyCustomScopeEvent;
  import javax.faces.event.PreDestroyViewMapEvent;
  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.HttpSession;
  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.config.RuntimeConfig;
  import org.apache.myfaces.config.annotation.LifecycleProvider;
  
  /**
   * 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: bommel $)
   * @version $Revision: 1187700 $ $Date: 2011-10-22 07:19:37 -0500 (Sat, 22 Oct 2011) $
   * @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;
  
      /**
       * Sets the ManagedBeanDestroyer instance to use.
       *  
       * @param destroyer
       */
      public void setManagedBeanDestroyer(ManagedBeanDestroyer destroyer)
      {
          _destroyer = destroyer;
      }
  
      /* 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);
             }
         }*/
     }
     
     /* 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);
             }
         }
     }
 
 }