/*

  * 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 org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.apache.myfaces.config.ManagedBeanBuilder;

 import org.apache.myfaces.util.ContainerUtils;

 import org.apache.myfaces.shared_impl.util.ClassUtils;

 import javax.faces.FactoryFinder;

 import javax.servlet.ServletContext;

 import javax.servlet.ServletContextEvent;

 import javax.servlet.ServletContextListener;

 /**

  * Initialise the MyFaces system.

  * <p>

  * This context listener is registered by the JSP TLD file for the standard

  * JSF "f" components. Normally, servlet containers will automatically load

  * and process .tld files at startup time, and therefore register and run

  * this class automatically.

  * <p>

  * Some very old servlet containers do not do this correctly, so in those

  * cases this listener may be registered manually in web.xml. Registering

  * it twice (ie in both .tld and web.xml) will result in a harmless warning

  * message being generated. Very old versions of MyFaces Core do not register

  * the listener in the .tld file, so those also need a manual entry in web.xml.

  * However all versions since at least 1.1.2 have this entry in the tld.

  * 

  * @author Manfred Geiler (latest modification by $Author: lu4242 $)

  * @version $Revision: 924403 $ $Date: 2010-03-17 13:28:20 -0500 (Wed, 17 Mar 2010) $

  */

 public class StartupServletContextListener extends AbstractMyFacesListener

     implements ServletContextListener

 {

     static final String FACES_INIT_DONE = StartupServletContextListener.class.getName() + ".FACES_INIT_DONE";

     /*comma delimited list of plugin classes which can be hooked into myfaces*/

     static final String FACES_INIT_PLUGINS = "org.apache.myfaces.FACES_INIT_PLUGINS";

     private static final byte FACES_INIT_PHASE_PREINIT = 0;

     private static final byte FACES_INIT_PHASE_POSTINIT = 1;

     private static final byte FACES_INIT_PHASE_PREDESTROY = 2;

     private static final byte FACES_INIT_PHASE_POSTDESTROY = 3;

     private static final Log log = LogFactory.getLog(StartupServletContextListener.class);

     private FacesInitializer _facesInitializer;

     private ServletContext _servletContext;

     /**

      * the central initialisation event dispatcher which calls

      * our listeners

      * @param event

      * @param operation

      */

     private void dispatchInitializationEvent(ServletContextEvent event, int operation) {

         String [] pluginEntries = (String []) _servletContext.getAttribute(FACES_INIT_PLUGINS);

         if(pluginEntries == null) {

             String plugins = (String) _servletContext.getInitParameter(FACES_INIT_PLUGINS);

             log.info("Checking for plugins:"+FACES_INIT_PLUGINS);

             if(plugins == null) return;

             log.info("Plugins found");

             pluginEntries = plugins.split(",");

             _servletContext.setAttribute(FACES_INIT_PLUGINS, pluginEntries);

         }

         //now we process the plugins

         for(String plugin: pluginEntries) {

             log.info("Processing plugin:"+plugin);

             try {

                 //for now the initializers have to be stateless to

                 //so that we do not have to enforce that the initializer

                 //must be serializable

                 Class pluginClass = ClassUtils.getContextClassLoader().loadClass(plugin);

                 if (pluginClass == null)

                 {

                     pluginClass = this.getClass().getClassLoader().loadClass(plugin);

                 }

                 StartupListener initializer = (StartupListener) pluginClass.newInstance();

                 switch(operation) {

                     case FACES_INIT_PHASE_PREINIT:

                         initializer.preInit(event);

                         break;

                     case FACES_INIT_PHASE_POSTINIT:

                         initializer.postInit(event);

                         break;

                     case FACES_INIT_PHASE_PREDESTROY:

                         initializer.preDestroy(event);

                         break;

                     default:

                         initializer.postDestroy(event);

                         break;

                 }

             } catch (ClassNotFoundException e) {

                 log.error(e);

             } catch (IllegalAccessException e) {

                 log.error(e);

             } catch (InstantiationException e) {

                 log.error(e);

             }

         }

         log.info("Processing plugins done");

     }

     public void contextInitialized(ServletContextEvent event)

     {

         if (_servletContext != null)

         {

             throw new IllegalStateException("context is already initialized");

         }

         _servletContext = event.getServletContext();

         Boolean b = (Boolean) _servletContext.getAttribute(FACES_INIT_DONE);

         if (b == null || b.booleanValue() == false)

         {

             dispatchInitializationEvent(event, FACES_INIT_PHASE_PREINIT);

             getFacesInitializer().initFaces(_servletContext);

             dispatchInitializationEvent(event, FACES_INIT_PHASE_POSTINIT);

             _servletContext.setAttribute(FACES_INIT_DONE, Boolean.TRUE);

         }

         else

         {

             log.info("MyFaces already initialized");

         }

     }

     protected FacesInitializer getFacesInitializer()

     {

         if (_facesInitializer == null)

         {

             if (ContainerUtils.isJsp21()) 

             {

                 _facesInitializer = new Jsp21FacesInitializer();

             } 

             else 

             {

                 _facesInitializer = new Jsp20FacesInitializer();

             }

         }

         return _facesInitializer;

     }

     /**

      * configure the faces initializer

      * 

      * @param facesInitializer

      */

     public void setFacesInitializer(FacesInitializer facesInitializer)

     {

         if (_facesInitializer != null && _facesInitializer != facesInitializer && _servletContext != null)

         {

             _facesInitializer.destroyFaces(_servletContext);

         }

         _facesInitializer = facesInitializer;

         if (_servletContext != null)

         {

             facesInitializer.initFaces(_servletContext);

         }

     }

     public void contextDestroyed(ServletContextEvent event)

     {

         doPredestroy(event);

         if (_facesInitializer != null && _servletContext != null)

         {

             _facesInitializer.destroyFaces(_servletContext);

         }

         FactoryFinder.releaseFactories();

         dispatchInitializationEvent(event, FACES_INIT_PHASE_POSTDESTROY);

         _servletContext = null;

     }

     private void doPredestroy(ServletContextEvent event) {

            ServletContext ctx = event.getServletContext();

            dispatchInitializationEvent(event, FACES_INIT_PHASE_PREDESTROY);

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

            while(attributes.hasMoreElements()) 

            {

                String name = attributes.nextElement();

                Object value = ctx.getAttribute(name);

                doPreDestroy(value, name, ManagedBeanBuilder.APPLICATION);

            }

     }

 }