/*
    * 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;
  
  import java.security.AccessController;
  import java.security.PrivilegedActionException;
  
  import javax.faces.FacesException;
  import javax.faces.context.ExternalContext;
  
  import org.apache.myfaces.spi.impl.DefaultWebConfigProviderFactory;
  import org.apache.myfaces.spi.impl.SpiUtils;
  
  /**
   * SPI to provide a WebConfigProviderFactory implementation and thus
   * a custom WebConfigProvider instance.
   *
   * @author Jakob Korherr
   * @author Leonardo Uribe
   * @since 2.0.3
   */
  public abstract class WebConfigProviderFactory
  {
  
      protected static final String FACTORY_DEFAULT = DefaultWebConfigProviderFactory.class.getName();
  
      private static final String FACTORY_KEY = WebConfigProviderFactory.class.getName();
  
      public static WebConfigProviderFactory getWebConfigProviderFactory(ExternalContext ctx)
      {
          WebConfigProviderFactory factory = (WebConfigProviderFactory) ctx.getApplicationMap().get(FACTORY_KEY);
          if (factory != null)
          {
              // use cached instance
              return factory;
          }
  
          // create new instance from service entry
          try
          {
  
              if (System.getSecurityManager() != null)
              {
                  final ExternalContext ectx = ctx;
                  factory = (WebConfigProviderFactory) AccessController.doPrivileged(
                          new java.security.PrivilegedExceptionAction<Object>()
                          {
                              public Object run() throws PrivilegedActionException
                              {
                                  //return DiscoverSingleton.find(
                                  return SpiUtils.build(ectx,
                                          WebConfigProviderFactory.class,
                                          FACTORY_DEFAULT);
                              }
                          });
              }
              else
              {
                  factory = (WebConfigProviderFactory)
                          SpiUtils.build(ctx, WebConfigProviderFactory.class, FACTORY_DEFAULT);
              }
          }
          catch (PrivilegedActionException pae)
          {
              throw new FacesException(pae);
          }
  
          if (factory != null)
          {
              // cache instance on ApplicationMap
              setWebConfigProviderFactory(ctx, factory);
          }
  
          return factory;
      }
  
      public static void setWebConfigProviderFactory(ExternalContext ctx, WebConfigProviderFactory factory)
      {
          ctx.getApplicationMap().put(FACTORY_KEY, factory);
      }
  
      public abstract WebConfigProvider getWebConfigProvider(ExternalContext externalContext);
  
 }