/*
    * $Id: TilesContextELResolver.java 1049676 2010-12-15 19:38:54Z apetrelli $
    *
    * 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.tiles.el;
  
  import java.beans.FeatureDescriptor;
  import java.util.Iterator;
  
  import javax.el.ELContext;
  import javax.el.ELResolver;
  
  import org.apache.tiles.request.ApplicationContext;
  import org.apache.tiles.request.Request;
  import org.apache.tiles.util.CombinedBeanInfo;
  
  /**
   * Resolves properties of {@link Request} and
   * {@link ApplicationContext}.
   *
   * @version $Rev: 1049676 $ $Date: 2010-12-16 06:38:54 +1100 (Thu, 16 Dec 2010) $
   * @since 2.2.1
   */
  public class TilesContextELResolver extends ELResolver {
  
      /**
       * Internal bean resolver to resolve beans in any context.
       */
      private ELResolver beanElResolver;
  
      /**
       * Constructor.
       *
       * @param beanElResolver The used bean resolver.
       */
      public TilesContextELResolver(ELResolver beanElResolver) {
          this.beanElResolver = beanElResolver;
      }
  
      /**
       * The beaninfos about {@link Request} and {@link ApplicationContext}.
       */
      private CombinedBeanInfo requestBeanInfo = new CombinedBeanInfo(
              Request.class, ApplicationContext.class);
  
      /** {@inheritDoc} */
      @Override
      public Class<?> getCommonPropertyType(ELContext context, Object base) {
          // only resolve at the root of the context
          if (base != null) {
              return null;
          }
  
          return String.class;
      }
  
      /** {@inheritDoc} */
      @Override
      public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context,
              Object base) {
          // only resolve at the root of the context
          if (base != null) {
              return null;
          }
  
          return requestBeanInfo.getDescriptors().iterator();
      }
  
      /** {@inheritDoc} */
      @Override
      public Class<?> getType(ELContext context, Object base, Object property) {
          // only resolve at the root of the context
          if (base != null) {
              return null;
          }
  
          Class<?> retValue = null;
          if (requestBeanInfo.getProperties(Request.class).contains(property)) {
              Request request = (Request) context
                      .getContext(Request.class);
              retValue = beanElResolver.getType(context, request, property);
          } else if (requestBeanInfo.getProperties(ApplicationContext.class).contains(property)) {
              ApplicationContext applicationContext = (ApplicationContext) context
                     .getContext(ApplicationContext.class);
             retValue = beanElResolver.getType(context, applicationContext, property);
         }
 
         if (retValue != null) {
             context.setPropertyResolved(true);
         }
 
         return retValue;
     }
 
     /** {@inheritDoc} */
     @Override
     public Object getValue(ELContext context, Object base, Object property) {
         // only resolve at the root of the context
         if (base != null) {
             return null;
         }
 
         Object retValue = null;
 
         if (requestBeanInfo.getProperties(Request.class).contains(property)) {
             Request request = (Request) context
                     .getContext(Request.class);
             retValue = beanElResolver.getValue(context, request, property);
         } else if (requestBeanInfo.getProperties(ApplicationContext.class)
                 .contains(property)) {
             ApplicationContext applicationContext = (ApplicationContext) context
                     .getContext(ApplicationContext.class);
             retValue = beanElResolver.getValue(context, applicationContext, property);
         }
 
         if (retValue != null) {
             context.setPropertyResolved(true);
         }
 
         return retValue;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean isReadOnly(ELContext context, Object base, Object property) {
         if (context == null) {
             throw new NullPointerException();
         }
 
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public void setValue(ELContext context, Object base, Object property,
             Object value) {
         // Does nothing for the moment.
     }
 }