/*

  * 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.spi.impl;

 import org.apache.myfaces.config.DefaultFacesConfigurationMerger;

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

 import org.apache.myfaces.spi.FacesConfigurationMerger;

 import org.apache.myfaces.spi.FacesConfigurationMergerFactory;

 import org.apache.myfaces.spi.ServiceProviderFinderFactory;

 import javax.faces.FacesException;

 import javax.faces.context.ExternalContext;

 import java.lang.reflect.InvocationTargetException;

 import java.security.AccessController;

 import java.security.PrivilegedActionException;

 import java.util.List;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 /**

  * @author Jakob Korherr

  */

 public class DefaultFacesConfigurationMergerFactory extends FacesConfigurationMergerFactory

 {

     public static final String FACES_CONFIGURATION_MERGER = FacesConfigurationMerger.class.getName();

     public static final String FACES_CONFIGURATION_MERGER_INSTANCE_KEY = FACES_CONFIGURATION_MERGER + ".INSTANCE";

     @Override

     public FacesConfigurationMerger getFacesConfigurationMerger(ExternalContext externalContext)

     {

         // check for cached instance

         FacesConfigurationMerger returnValue = (FacesConfigurationMerger)

                 externalContext.getApplicationMap().get(FACES_CONFIGURATION_MERGER_INSTANCE_KEY);

         if (returnValue == null)

         {

             final ExternalContext extContext = externalContext;

             try

             {

                 if (System.getSecurityManager() != null)

                 {

                     returnValue = AccessController.doPrivileged(

                             new java.security.PrivilegedExceptionAction<FacesConfigurationMerger>()

                             {

                                 public FacesConfigurationMerger run() throws ClassNotFoundException,

                                         NoClassDefFoundError,

                                         InstantiationException,

                                         IllegalAccessException,

                                         InvocationTargetException,

                                         PrivilegedActionException

                                 {

                                     return resolveFacesConfigurationMergerFromService(extContext);

                                 }

                             });

                 }

                 else

                 {

                     returnValue = resolveFacesConfigurationMergerFromService(extContext);

                 }

                 // cache the result on the ApplicationMap

                 externalContext.getApplicationMap().put(FACES_CONFIGURATION_MERGER_INSTANCE_KEY, returnValue);

             }

             catch (ClassNotFoundException e)

             {

                 // ignore

             }

             catch (NoClassDefFoundError e)

             {

                 // ignore

             }

             catch (InstantiationException e)

             {

                 getLogger().log(Level.SEVERE, "", e);

             }

             catch (IllegalAccessException e)

             {

                 getLogger().log(Level.SEVERE, "", e);

             }

             catch (InvocationTargetException e)

             {

                 getLogger().log(Level.SEVERE, "", e);

             }

             catch (PrivilegedActionException e)

             {

                 throw new FacesException(e);

             }

         }

         return returnValue;

     }

     private FacesConfigurationMerger resolveFacesConfigurationMergerFromService(ExternalContext externalContext)

             throws ClassNotFoundException,

                    NoClassDefFoundError,

                    InstantiationException,

                    IllegalAccessException,

                    InvocationTargetException,

                    PrivilegedActionException

     {

         // get all fitting SPI implementations (no need to cache this since it's only called once per JSF-app)

         List<String> classList = ServiceProviderFinderFactory.getServiceProviderFinder(externalContext)

                 .getServiceProviderList(FACES_CONFIGURATION_MERGER);

         // create the instance using decorator pattern

         return ClassUtils.buildApplicationObject(FacesConfigurationMerger.class,

                 classList, new DefaultFacesConfigurationMerger());

     }

     private Logger getLogger()

     {

         return Logger.getLogger(DefaultFacesConfigurationMergerFactory.class.getName());

     }

 }