/*

  * 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.el.unified.resolver;

 import java.lang.reflect.Constructor;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import javax.el.ELContext;

 import javax.el.ELException;

 import javax.el.PropertyNotFoundException;

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

 /**

  * See JSF 2.2 section 5.6.2.8

  */

 public class ImportHandlerResolver extends ScopedAttributeResolver

 {

     private static final Class EL_CLASS;

     private static final Constructor EL_CLASS_CONSTRUCTOR;

     private static final Method GET_IMPORT_HANDLER_METHOD;

     private static final Method IMPORT_HANDLER_RESOLVE_CLASS_METHOD;

     static

     {

         Class elClass = null;

         Class importHandlerClass = null;

         Constructor elClassConstructor = null;

         Method getImportHandlerMethod = null;

         Method importHandlerResolveClassMethod = null;

         try

         {

             // These classes will only be available with EL 3+

             elClass = ClassUtils.classForName("javax.el.ELClass");

             importHandlerClass = ClassUtils.classForName("javax.el.ImportHandler");

             getImportHandlerMethod = ELContext.class.getMethod("getImportHandler");

             if (elClass != null && importHandlerClass != null) 

             {

                 importHandlerResolveClassMethod = 

                     importHandlerClass.getDeclaredMethod("resolveClass", new Class[] {String.class});

                 elClassConstructor = elClass.getConstructor(Class.class);

             }

         }

         catch (SecurityException ex)

         {

             //No op

         }

         catch (ClassNotFoundException ex)

         {

             //No op

         } 

         catch (NoSuchMethodException e) 

         {

             // No op

         }

         EL_CLASS = elClass;

         GET_IMPORT_HANDLER_METHOD = getImportHandlerMethod;

         IMPORT_HANDLER_RESOLVE_CLASS_METHOD = importHandlerResolveClassMethod;

         EL_CLASS_CONSTRUCTOR = elClassConstructor;

     }

     /**

      * Creates a new instance of ImportHandlerResolver

      */

     public ImportHandlerResolver()

     {

     }

     /*

      * Handle the EL case for the name of an import class

      */

     @Override

     public Object getValue(final ELContext context, final Object base, final Object property)

         throws NullPointerException, PropertyNotFoundException, ELException

     {

         if (EL_CLASS != null && EL_CLASS_CONSTRUCTOR != null 

                         && GET_IMPORT_HANDLER_METHOD != null && IMPORT_HANDLER_RESOLVE_CLASS_METHOD != null ) 

         {

             Object importHandler = null;

             try 

             {

                 // In an EL 3+ environment, the ELContext will have a getImportHandler() method

                 importHandler = GET_IMPORT_HANDLER_METHOD.invoke(context);

                 if (importHandler != null) 

                 {

                     Class<?> clazz;

                     clazz = (Class<?>) IMPORT_HANDLER_RESOLVE_CLASS_METHOD

                         .invoke(importHandler, property.toString());

                     if (clazz != null) 

                     {

                         context.setPropertyResolved(true);

                         return EL_CLASS_CONSTRUCTOR.newInstance(clazz);

                     }

                 }

             } 

             catch (IllegalAccessException ex) 

             {

                 //No op

             } 

             catch (IllegalArgumentException ex) 

             {

                 //No op

             } 

             catch (InvocationTargetException ex) 

             {

                 //No op

             } 

             catch (SecurityException ex) 

             {

                 //No op

             } 

             catch (InstantiationException e) 

             {

                 //No op

             }

         }

         return null;

     }

 }