/*

  * $Id: ScopeELResolver.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.ArrayList;

 import java.util.Collections;

 import java.util.Iterator;

 import java.util.List;

 import java.util.Map;

 import javax.el.ELContext;

 import javax.el.ELResolver;

 import org.apache.tiles.request.Request;

 /**

  * Resolves beans in request, session and application scope.

  *

  * @version $Rev: 1049676 $ $Date: 2010-12-16 06:38:54 +1100 (Thu, 16 Dec 2010) $

  * @since 2.2.1

  */

 public class ScopeELResolver extends ELResolver {

     /**

      * The length of the suffix: "Scope".

      */

     private static final int SUFFIX_LENGTH = 5;

     /** {@inheritDoc} */

     @Override

     public Class<?> getCommonPropertyType(ELContext context, Object base) {

         // only resolve at the root of the context

         if (base != null) {

             return null;

         }

         return Map.class;

     }

     /** {@inheritDoc} */

     @Override

     public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context,

             Object base) {

         if (base != null) {

             List<FeatureDescriptor> retValue = Collections.emptyList();

             return retValue.iterator();

         }

         List<FeatureDescriptor> list = new ArrayList<FeatureDescriptor>();

         Request request = (Request) context

                 .getContext(Request.class);

         for (String scope : request.getAvailableScopes()) {

             FeatureDescriptor descriptor = new FeatureDescriptor();

             descriptor.setDisplayName(scope + "Scope");

             descriptor.setExpert(false);

             descriptor.setHidden(false);

             descriptor.setName(scope + "Scope");

             descriptor.setPreferred(true);

             descriptor.setShortDescription("");

             descriptor.setValue("type", Map.class);

             descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);

             list.add(descriptor);

         }

         return list.iterator();

     }

     /** {@inheritDoc} */

     @Override

     public Class<?> getType(ELContext context, Object base, Object property) {

         if (base != null || property == null || !(property instanceof String)

                 || !((String) property).endsWith("Scope")) {

             return null;

         }

         return Map.class;

     }

     /** {@inheritDoc} */

     @Override

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

         if (base != null) {

             return null;

         }

         Object retValue = null;

         String propertyString = (String) property;

         if (property instanceof String && propertyString.endsWith("Scope")) {

             Request request = (Request) context

                     .getContext(Request.class);

             retValue = request.getContext(propertyString.substring(0,

                     propertyString.length() - SUFFIX_LENGTH));

         }

         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.

     }

 }