/*
    * 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.context;
  
  import java.lang.reflect.Field;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  import javax.faces.FacesException;
  import javax.faces.FactoryFinder;
  import javax.faces.application.ApplicationFactory;
  import javax.faces.context.ExceptionHandlerFactory;
  import javax.faces.context.ExternalContext;
  import javax.faces.context.ExternalContextFactory;
  import javax.faces.context.FacesContext;
  import javax.faces.context.FacesContextFactory;
  import javax.faces.context.PartialViewContextFactory;
  import javax.faces.lifecycle.Lifecycle;
  import javax.faces.render.RenderKitFactory;
  
  import org.apache.myfaces.context.servlet.FacesContextImpl;
  import org.apache.myfaces.shared.util.ClassUtils;
  
  /**
   * DOCUMENT ME!
   * 
   * @author Manfred Geiler (latest modification by $Author$)
   * @version $Revision$ $Date$
   */
  public class FacesContextFactoryImpl extends FacesContextFactory
      implements ReleaseableFacesContextFactory
  {
      //private static final Log log = LogFactory.getLog(FacesContextFactoryImpl.class);
      private static final Logger log = Logger.getLogger(FacesContextFactoryImpl.class.getName());
      
      /**
       * Reference to factory to prevent unnecessary lookups
       */
      private final ExternalContextFactory _externalContextFactory;
      
      /**
       * Reference to factory to prevent unnecessary lookups
       */
      private final ExceptionHandlerFactory _exceptionHandlerFactory;
      
      private final ApplicationFactory _applicationFactory;
      
      private final RenderKitFactory _renderKitFactory;
      
      private final PartialViewContextFactory _partialViewContextFactory;
      
      /**
       * This var is assigned as the same as javax.faces.context.ExternalContext._firstInstance,
       * and since it is a static reference and does not change, we can cache it here safely.
       * 
       * We need
       */
      private final ThreadLocal<ExternalContext> _firstExternalContextInstance;
      
      @SuppressWarnings("unchecked")
      public FacesContextFactoryImpl()
      {
          super();
          ThreadLocal<ExternalContext> firstExternalContextInstance = null;
          try
          {
              Class clazz = ClassUtils.classForName("javax.faces.context._MyFacesExternalContextHelper");
              Field externalContextFirstInstance = clazz.getDeclaredField("firstInstance");
              externalContextFirstInstance.setAccessible(true);
              
              if (externalContextFirstInstance != null)
              {
                  if (firstExternalContextInstance == null)
                  {
                      firstExternalContextInstance = 
                          (ThreadLocal<ExternalContext>) externalContextFirstInstance.get(null);
                  }
              }
          }
          catch (SecurityException e)
          {
              // It could happen, but we can ignore it.
              if (log.isLoggable(Level.FINE))
             {
                 log.log(Level.FINE, "Cannot access field firstInstance"
                         + "from _MyFacesExternalContextHelper ", e);
             }
         }
         catch (Exception e)
         {
             if (log.isLoggable(Level.SEVERE))
             {
                 log.log(Level.SEVERE, "Cannot find field firstInstance"
                         + "from _MyFacesExternalContextHelper ", e);
             }
         }
         
         _firstExternalContextInstance = firstExternalContextInstance;
         
         _externalContextFactory = (ExternalContextFactory)
             FactoryFinder.getFactory(FactoryFinder.EXTERNAL_CONTEXT_FACTORY);
 
         _exceptionHandlerFactory = (ExceptionHandlerFactory)
             FactoryFinder.getFactory(FactoryFinder.EXCEPTION_HANDLER_FACTORY);
         
         _applicationFactory = (ApplicationFactory)
             FactoryFinder.getFactory(FactoryFinder.APPLICATION_FACTORY);
         
         _renderKitFactory = (RenderKitFactory)
             FactoryFinder.getFactory(FactoryFinder.RENDER_KIT_FACTORY);
 
         _partialViewContextFactory = (PartialViewContextFactory) 
             FactoryFinder.getFactory(FactoryFinder.PARTIAL_VIEW_CONTEXT_FACTORY);
     }
 
     @Override
     public FacesContext getFacesContext(Object context, Object request, Object response, Lifecycle lifecycle)
         throws FacesException
     {
         if (context == null)
         {
             throw new NullPointerException("context");
         }
         if (request == null)
         {
             throw new NullPointerException("request");
         }
         if (response == null)
         {
             throw new NullPointerException("response");
         }
         if (lifecycle == null)
         {
             throw new NullPointerException("lifecycle");
         }
         
         ExternalContext externalContext = _externalContextFactory.getExternalContext(context, request, response);
 
         ExternalContext defaultExternalContext = null;
         
         if (_firstExternalContextInstance != null)
         {
             defaultExternalContext = (ExternalContext)
                 externalContext.getRequestMap().remove(
                         ExternalContextFactoryImpl.EXTERNAL_CONTEXT_KEY);
             
             if (defaultExternalContext != null)
             {
                 // Initialize the firstExternalContext that old jsf 1.2 or lower
                 // implementations of ExternalContext should fall when call jsf 2.0
                 // methods.
                 _firstExternalContextInstance.set(defaultExternalContext);
             }
         }
         
         //if (context instanceof ServletContext)
         //{
             FacesContext facesContext;
             if (externalContext instanceof ReleaseableExternalContext)
             {
                 facesContext = new FacesContextImpl(externalContext, (ReleaseableExternalContext) externalContext,
                                                     this, _applicationFactory, _renderKitFactory, 
                                                     _partialViewContextFactory);
             }
             else if (defaultExternalContext != null && defaultExternalContext instanceof ReleaseableExternalContext)
             {
                 facesContext = new FacesContextImpl(externalContext,
                                                     (ReleaseableExternalContext) defaultExternalContext, this,
                                                     _applicationFactory, _renderKitFactory, 
                                                     _partialViewContextFactory);
             }
             else
             {
                 facesContext = new FacesContextImpl(externalContext, null, this,
                                                     _applicationFactory, _renderKitFactory, 
                                                     _partialViewContextFactory);
             }
             
             facesContext.setExceptionHandler(_exceptionHandlerFactory.getExceptionHandler());
             
             return facesContext;
             //return new FacesContextImpl((ServletContext)context, (ServletRequest)request, (ServletResponse)response);
         //}
 
         //throw new FacesException("Unsupported context type " + context.getClass().getName());
     }
 
     public void release()
     {
         if (_firstExternalContextInstance != null)
         {
             _firstExternalContextInstance.remove();
         }
     }
 }