/*
    * 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());
     }
 
 }