/*

  * 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 javax.el.ELContext;

 import javax.faces.context.FacesContext;

 import java.beans.FeatureDescriptor;

 import java.util.Iterator;

 import java.util.Map;

 import java.util.Arrays;

 /**

  * <p>

  * This composite el resolver will be used at the top level resolver for faces

  * ({@link javax.faces.application.Application#getELResolver()})

  * and jsp (the one we add with {@link javax.servlet.jsp.JspApplicationContext#addELResolver(javax.el.ELResolver)}.

  * It keeps track of its scope to let the variable resolver {@link org.apache.myfaces.el.VariableResolverImpl}

  * know in which scope it is executed. This is

  * necessarry to call either the faces or the jsp resolver head.

  * </p>

  * <p>

  * This implementation does nothing if there is no actual faces context. This is necessarry since we registered our

  * resolvers into the jsp engine. Therefore we have to make sure that jsp only pages where no faces context is available

  * are still working

  * </p>

  *

  * @author Mathias Broekelmann (latest modification by $Author$)

  * @version $Revision$ $Date$

  */

 public final class FacesCompositeELResolver extends org.apache.myfaces.el.CompositeELResolver

 {

     private final Scope _scope;

     public enum Scope

     {

         Faces, JSP, NONE

     }

     public static final String SCOPE = "org.apache.myfaces.el.unified.resolver.FacesCompositeELResolver.Scope";

     public FacesCompositeELResolver(final Scope scope)

     {

         if (scope == null)

         {

             throw new IllegalArgumentException("scope must not be one of " + Arrays.toString(Scope.values()));

         }

         _scope = scope;

     }

     private static FacesContext facesContext(final ELContext context)

     {

         FacesContext facesContext = (FacesContext)context.getContext(FacesContext.class);

         if (facesContext == null)

         {

             facesContext = FacesContext.getCurrentInstance();

         }

         return facesContext;

     }

     @Override

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

     {

         final FacesContext facesContext = facesContext(context);

         if (facesContext == null)

         {

             return null;

         }

         final Map<Object, Object> requestMap = facesContext.getAttributes();

         Scope prevScope = null;

         try

         {

             prevScope = getScope(requestMap);

             setScope(requestMap);

             return super.getCommonPropertyType(context, base);

         }

         finally

         {

             if(prevScope != null)

             {

                 setScope(requestMap, prevScope);

             }

             else

             {

                 unsetScope(requestMap);

             }

         }

     }

     @Override

     public Iterator<FeatureDescriptor> getFeatureDescriptors(final ELContext context, final Object base)

     {

         final FacesContext facesContext = facesContext(context);

         if (facesContext == null)

         {

             return null;

         }

         final Map<Object, Object> requestMap = facesContext.getAttributes();

         Scope prevScope = null;

         try

         {

             prevScope = getScope(requestMap);

             setScope(requestMap);

             return super.getFeatureDescriptors(context, base);

         }

         finally

         {

             if(prevScope != null)

             {

                 setScope(requestMap, prevScope);

             }

             else

             {

                 unsetScope(requestMap);

             }

         }

     }

     @Override

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

     {

         final FacesContext facesContext = facesContext(context);

         if (facesContext == null)

         {

             return null;

         }

         final Map<Object, Object> requestMap = facesContext.getAttributes();

         Scope prevScope = null;

         try

         {

             prevScope = getScope(requestMap);

             setScope(requestMap);

             return super.getType(context, base, property);

         }

         finally

         {

             if(prevScope != null)

             {

                 setScope(requestMap, prevScope);

             }

             else

             {

                 unsetScope(requestMap);

             }

         }

     }

     @Override

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

     {

         final FacesContext facesContext = facesContext(context);

         if (facesContext == null)

         {

             return null;

         }

         final Map<Object, Object> requestMap = facesContext.getAttributes();

         Scope prevScope = null;

         try

         {

             prevScope = getScope(requestMap);

             setScope(requestMap);

             return super.getValue(context, base, property);

         }

         finally

         {

             if(prevScope != null)

             {

                 setScope(requestMap, prevScope);

             }

             else

             {

                 unsetScope(requestMap);

             }

         }

     }

     @Override

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

     {

         final FacesContext facesContext = facesContext(context);

         if (facesContext == null)

         {

             return false;

         }

         final Map<Object, Object> requestMap = facesContext.getAttributes();

         Scope prevScope = null;

         try

         {

             prevScope = getScope(requestMap);

             setScope(requestMap);

             return super.isReadOnly(context, base, property);

         }

         finally

         {

             if(prevScope != null)

             {

                 setScope(requestMap, prevScope);

             }

             else

             {

                 unsetScope(requestMap);

             }

         }

     }

     @Override

     public void setValue(final ELContext context, final Object base, final Object property, final Object val)

     {

         final FacesContext facesContext = facesContext(context);

         if (facesContext == null)

         {

             return;

         }

         final Map<Object, Object> requestMap = facesContext.getAttributes();

         Scope prevScope = null;

         try

         {

             prevScope = getScope(requestMap);

             setScope(requestMap);

             super.setValue(context, base, property, val);

         }

         finally

         {

             if(prevScope != null)

             {

                 setScope(requestMap, prevScope);

             }

             else

             {

                 unsetScope(requestMap);

             }

         }

     }

     private void setScope(final Map<Object, Object> attributes)

     {

         attributes.put(SCOPE, _scope);

     }

     private Scope getScope(final Map<Object, Object> attributes)

     {

         return (Scope) attributes.get(SCOPE);

     }

     private void setScope(final Map<Object, Object> attributes, Scope prevScope)

     {

         attributes.put(SCOPE, prevScope);

     }

     private static void unsetScope(final Map<Object, Object> attributes)

     {

         //attributes.remove(SCOPE);

         attributes.put(SCOPE, Scope.NONE);

     }

 }