/*

  * 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.beans.FeatureDescriptor;

 import java.util.Iterator;

 import javax.el.ELContext;

 import javax.el.ELException;

 import javax.el.ELResolver;

 import javax.faces.application.Resource;

 import javax.faces.application.ResourceHandler;

 import javax.faces.component.UIComponent;

 import javax.faces.context.FacesContext;

 import javax.faces.view.Location;

 import org.apache.myfaces.shared.renderkit.html.util.ResourceUtils;

 import org.apache.myfaces.shared.resource.ContractResource;

 import org.apache.myfaces.view.facelets.el.CompositeComponentELUtils;

 import org.apache.myfaces.view.facelets.el.ResourceELUtils;

 /**

  * See JSF 2.0 spec section 5.6.1.3 and 5.6.2.4

  * 

  * @author Leonardo Uribe

  *

  */

 public final class ResourceResolver extends ELResolver

 {

     private static final String LIBRARY_THIS = "this";

     /** Creates a new instance of ResourceBundleResolver */

     public ResourceResolver()

     {

     }

     @Override

     public Class<?> getCommonPropertyType(final ELContext context,

             final Object base)

     {

         return base == null ? Object.class : null;

     }

     @Override

     public Iterator<FeatureDescriptor> getFeatureDescriptors(

             final ELContext context, final Object base)

     {

         return null;

     }

     @Override

     public Class<?> getType(final ELContext context, final Object base,

             final Object property)

     {

         return null;

     }

     @Override

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

             final Object property)

     {

         if (base != null && property != null && base instanceof ResourceHandler)

         {

             String reference = (String) property;

             int colonIndex = (reference).indexOf(':');

             Resource resource;

             if (colonIndex == -1)

             {

                 // No library name, just create as a simple resource.

                 resource = ((ResourceHandler) base).createResource (reference);

             }

             else

             {

                 String contractName = null;

                 if (reference.lastIndexOf (':') != colonIndex)

                 {

                     // Max of one ":" allowed, so throw an exception.

                     throw new ELException ("Malformed resource reference found when " +

                         "resolving " + property);

                 }

                 else

                 {

                     // Otherwise, portion before the ":" is the library name.

                     String libraryName = reference.substring (0, colonIndex);

                     FacesContext facesContext = facesContext(context);

                     if (LIBRARY_THIS.equals(libraryName))

                     {

                         // note in this case we don't need to resolve to an specific 

                         // composite component, instead we need to find the libraryName of the

                         // composite component associated with the Location. For any composite component

                         // instance that is created under the same facelet it will be the same,

                         // so it is enought to get the first one matching the Location object.

                         Location location = ResourceELUtils.getResourceLocationForResolver(facesContext);

                         if (location != null)

                         {

                             // There are two options:

                             UIComponent cc = CompositeComponentELUtils.

                                     getCompositeComponentBasedOnLocation(facesContext, location);

                             Resource ccResource = (Resource) cc.getAttributes().get(

                                     Resource.COMPONENT_RESOURCE_KEY); 

                             libraryName = ccResource.getLibraryName();

                             contractName = ResourceUtils.getContractName(ccResource);

                         }

                         else

                         {

                             // JSF 2.2 "this" identifier can refer to a library or contract.

                             libraryName = ResourceELUtils.getResourceLibraryForResolver(facesContext);

                             contractName = ResourceELUtils.getResourceContractForResolver(facesContext);

                         }

                     }

                     try

                     {

                         if (contractName != null)

                         {

                             facesContext.getAttributes().put(ContractResource.CONTRACT_SELECTED, contractName);

                         }

                         resource = ((ResourceHandler) base).createResource(reference.substring(colonIndex+1),

                                 libraryName);

                     }

                     finally

                     {

                         if (contractName != null)

                         {

                             facesContext.getAttributes().remove(ContractResource.CONTRACT_SELECTED);

                         }

                     }

                 }

             }

             context.setPropertyResolved(true);

             if (resource != null)

             {

                 return resource.getRequestPath();

             }

         }

         return null;

     }

     // get the FacesContext from the ELContext

     private static FacesContext facesContext(final ELContext context)

     {

         return (FacesContext)context.getContext(FacesContext.class);

     }

     @Override

     public boolean isReadOnly(final ELContext context, final Object base,

             final Object property)

     {

         //Return false on all cases

         return false;

     }

     @Override

     public void setValue(final ELContext context, final Object base,

             final Object property, final Object val)

     {

         //No action takes place

     }

 }