/*

  * 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 org.apache.myfaces.spi.impl.SpiUtils;

 import javax.faces.FacesException;

 import javax.faces.context.ExternalContext;

 import java.security.AccessController;

 import java.security.PrivilegedActionException;

 /**

  * SPI to provide a FacesFlowProviderFactory implementation and thus

  * a custom FacesFlowProvider instance.

  *

  * @author Leonardo Uribe

  * @since 2.2

  */

 public abstract class FacesFlowProviderFactory

 {

     protected static final String FACTORY_DEFAULT = 

         "org.apache.myfaces.spi.impl.DefaultFacesFlowProviderFactory";

     private static final String FACTORY_KEY = FacesFlowProviderFactory.class.getName();

     public static FacesFlowProviderFactory getFacesFlowProviderFactory(ExternalContext ctx)

     {

         FacesFlowProviderFactory factory

                 = (FacesFlowProviderFactory) 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 = (FacesFlowProviderFactory) AccessController.doPrivileged(

                         new java.security.PrivilegedExceptionAction<Object>()

                         {

                             public Object run() throws PrivilegedActionException

                             {

                                 return SpiUtils.build(ectx,

                                         FacesFlowProviderFactory.class,

                                         FACTORY_DEFAULT);

                             }

                         });

             }

             else

             {

                 factory = (FacesFlowProviderFactory) SpiUtils

                         .build(ctx, FacesFlowProviderFactory.class, FACTORY_DEFAULT);

             }

         }

         catch (PrivilegedActionException pae)

         {

             throw new FacesException(pae);

         }

         if (factory != null)

         {

             // cache instance on ApplicationMap

             setFacesFlowProviderFactory(ctx, factory);

         }

         return factory;

     }

     public static void setFacesFlowProviderFactory(ExternalContext ctx,

                                                           FacesFlowProviderFactory factory)

     {

         ctx.getApplicationMap().put(FACTORY_KEY, factory);

     }

     public abstract FacesFlowProvider getFacesFlowProvider(ExternalContext externalContext);

 }