/*

  * $Id: ModularTilesInitializer.java 1297705 2012-03-06 20:44:30Z nlebas $

  *

  * 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.tiles.extras.module;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.List;

 import java.util.jar.Attributes;

 import java.util.jar.Manifest;

 import javax.servlet.ServletContext;

 import org.apache.tiles.definition.DefinitionsFactoryException;

 import org.apache.tiles.request.ApplicationContext;

 import org.apache.tiles.request.ApplicationResource;

 import org.apache.tiles.request.reflect.ClassUtil;

 import org.apache.tiles.request.servlet.wildcard.WildcardServletApplicationContext;

 import org.apache.tiles.startup.TilesInitializer;

 /**

  * Loads Tiles modules, initializes them and destroy them at the end.<br>

  * It loads all META-INF/MANIFEST.MF files, checks for the "Tiles-Initializer"

  * property that must contain a valid class name of a {@link TilesInitializer}.

  * After that, initializes all found initializers, one by one. When the

  * {@link #destroy()} method is called, all the initializers are then destroyed.

  *

  * @version $Rev: 1297705 $ $Date: 2012-03-07 07:44:30 +1100 (Wed, 07 Mar 2012) $

  * @since 2.2.1

  */

 public class ModularTilesInitializer implements TilesInitializer {

     /**

      * The initializers to use.

      */

     private List<TilesInitializer> initializers;

     /** {@inheritDoc} */

     public void initialize(ApplicationContext preliminaryContext) {

         ApplicationContext applicationContext = new WildcardServletApplicationContext(

                 (ServletContext) preliminaryContext.getContext());

         loadInitializers(applicationContext);

         for (TilesInitializer initializer : initializers) {

             initializer.initialize(preliminaryContext);

         }

     }

     /** {@inheritDoc} */

     public void destroy() {

         for (TilesInitializer initializer : initializers) {

             initializer.destroy();

         }

     }

     /**

      * Load all the initializers from manifest files.

      *

      * @param applicationContext The application context.

      */

     private void loadInitializers(ApplicationContext applicationContext) {

         initializers = new ArrayList<TilesInitializer>();

         try {

             Collection<ApplicationResource> resources = applicationContext

                     .getResources("classpath*:META-INF/MANIFEST.MF");

             ApplicationResource mainResource = applicationContext.getResource("/META-INF/MANIFEST.MF");

             if (mainResource != null) {

                 resources.add(mainResource);

             }

             for (ApplicationResource resource : resources) {

                 InputStream stream = resource.getInputStream();

                 try {

                     Manifest manifest = new Manifest(stream);

                     Attributes attributes = manifest.getMainAttributes();

                     if (attributes != null) {

                         String initializerName = attributes.getValue("Tiles-Initializer");

                         if (initializerName != null) {

                             TilesInitializer initializer = (TilesInitializer) ClassUtil

                                     .instantiate(initializerName);

                             initializers.add(initializer);

                         }

                     }

                 } finally {

                     stream.close();

                 }

             }

         } catch (IOException e) {

             throw new DefinitionsFactoryException("Error getting manifest files", e);

         }

     }

 }