/*

  * 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.config;

 import java.lang.reflect.InvocationTargetException;

 import java.util.Map;

 import java.util.Set;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 import javax.faces.component.UIViewRoot;

 import javax.faces.event.PreDestroyCustomScopeEvent;

 import javax.faces.event.PreDestroyViewMapEvent;

 import javax.faces.event.ScopeContext;

 import javax.faces.event.SystemEvent;

 import javax.faces.event.SystemEventListener;

 import org.apache.myfaces.config.annotation.LifecycleProvider;

 /**

  * Destroyes managed beans with the current LifecycleProvider.

  * This guarantees the invocation of the @PreDestroy methods.

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

  * @version $Revision$ $Date$

  * @since 2.0

  */

 public class ManagedBeanDestroyer implements SystemEventListener

 {

     private static Logger log = Logger.getLogger(ManagedBeanDestroyer.class.getName());

     private RuntimeConfig _runtimeConfig;

     private LifecycleProvider _lifecycleProvider;

     /**

      * Creates the ManagedBeanDestroyer for the given RuntimeConfig

      * and LifecycleProvider.

      * 

      * @param lifecycleProvider

      * @param runtimeConfig

      */

     public ManagedBeanDestroyer(LifecycleProvider lifecycleProvider,

                                 RuntimeConfig runtimeConfig)

     {

         _lifecycleProvider = lifecycleProvider;

         _runtimeConfig = runtimeConfig;

     }

     public boolean isListenerForSource(Object source)

     {

         // source of PreDestroyCustomScopeEvent is ScopeContext

         // and source of PreDestroyViewMapEvent is UIViewRoot

         return (source instanceof ScopeContext) || (source instanceof UIViewRoot);

     }

     /**

      * Listens to PreDestroyCustomScopeEvent and PreDestroyViewMapEvent

      * and invokes destroy() for every managed bean in the associated scope.

      */

     public void processEvent(SystemEvent event)

     {

         Map<String, Object> scope = null;

         if (event instanceof PreDestroyViewMapEvent)

         {

             UIViewRoot viewRoot = (UIViewRoot) ((PreDestroyViewMapEvent) event).getComponent();

             scope = viewRoot.getViewMap(false);

             if (scope == null)

             {

                 // view map does not exist --> nothing to destroy

                 return;

             }

         }

         else if (event instanceof PreDestroyCustomScopeEvent)

         {

             ScopeContext scopeContext = ((PreDestroyCustomScopeEvent) event).getContext();

             scope = scopeContext.getScope();

         }

         else

         {

             // wrong event

             return;

         }

         if (!scope.isEmpty())

         {

             Set<String> keySet = scope.keySet();

             String[] keys = keySet.toArray(new String[keySet.size()]);

             for (String key : keys)

             {

                 Object value = scope.get(key);

                 this.destroy(key, value);

             }

         }

     }

     /**

      * Checks if the given managed bean exists in the RuntimeConfig.

      * @param name

      * @return

      */

     public boolean isManagedBean(String name)

     {

         return (_runtimeConfig.getManagedBean(name) != null);

     }

     /**

      * Destroys the given managed bean.

      * @param name

      * @param instance

      */

     public void destroy(String name, Object instance)

     {

         if (instance != null && isManagedBean(name))

         {

             try

             {

                 _lifecycleProvider.destroyInstance(instance);

             } 

             catch (IllegalAccessException e)

             {

                 log.log(Level.SEVERE, "Could not access @PreDestroy method of managed bean " + name, e);

             } 

             catch (InvocationTargetException e)

             {

                 log.log(Level.SEVERE, "An Exception occured while invoking " +

                         "@PreDestroy method of managed bean " + name, e);

             }

         }

     }

 }