/*

  * 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.view.facelets.tag.jsf.core;

 import java.io.IOException;

 import java.io.Serializable;

 import javax.el.ELException;

 import javax.el.ValueExpression;

 import javax.faces.FacesException;

 import javax.faces.component.EditableValueHolder;

 import javax.faces.component.UIComponent;

 import javax.faces.context.FacesContext;

 import javax.faces.event.AbortProcessingException;

 import javax.faces.event.ValueChangeEvent;

 import javax.faces.event.ValueChangeListener;

 import javax.faces.view.EditableValueHolderAttachedObjectHandler;

 import javax.faces.view.facelets.ComponentHandler;

 import javax.faces.view.facelets.FaceletContext;

 import javax.faces.view.facelets.FaceletException;

 import javax.faces.view.facelets.TagAttribute;

 import javax.faces.view.facelets.TagAttributeException;

 import javax.faces.view.facelets.TagConfig;

 import javax.faces.view.facelets.TagException;

 import javax.faces.view.facelets.TagHandler;

 import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFFaceletAttribute;

 import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFFaceletTag;

 import org.apache.myfaces.view.facelets.FaceletCompositionContext;

 import org.apache.myfaces.view.facelets.util.ReflectionUtil;

 /**

  * Register an ValueChangeListener instance on the UIComponent associated with the closest parent UIComponent custom

  * action.<p/> See <a target="_new"

  * href="http://java.sun.com/j2ee/javaserverfaces/1.1_01/docs/tlddocs/f/valueChangeListener.html">tag documentation</a>.

  * 

  * @author Jacob Hookom

  * @version $Id$

  */

 @JSFFaceletTag(

         name = "f:valueChangeListener",

         bodyContent = "empty", 

         tagClass="org.apache.myfaces.taglib.core.ValueChangeListenerTag")

 public final class ValueChangeListenerHandler extends TagHandler

     implements EditableValueHolderAttachedObjectHandler

 {

     private static class LazyValueChangeListener implements ValueChangeListener, Serializable

     {

         private static final long serialVersionUID = 7613811124326963180L;

         private final String type;

         private final ValueExpression binding;

         public LazyValueChangeListener(String type, ValueExpression binding)

         {

             this.type = type;

             this.binding = binding;

         }

         public void processValueChange(ValueChangeEvent event) throws AbortProcessingException

         {

             ValueChangeListener instance = null;

             FacesContext faces = FacesContext.getCurrentInstance();

             if (faces == null)

             {

                 return;

             }

             if (this.binding != null)

             {

                 instance = (ValueChangeListener) binding.getValue(faces.getELContext());

             }

             if (instance == null && this.type != null)

             {

                 try

                 {

                     instance = (ValueChangeListener) ReflectionUtil.forName(this.type).newInstance();

                 }

                 catch (Exception e)

                 {

                     throw new AbortProcessingException("Couldn't Lazily instantiate ValueChangeListener", e);

                 }

                 if (this.binding != null)

                 {

                     binding.setValue(faces.getELContext(), instance);

                 }

             }

             if (instance != null)

             {

                 instance.processValueChange(event);

             }

         }

     }

     private final TagAttribute binding;

     private final String listenerType;

     public ValueChangeListenerHandler(TagConfig config)

     {

         super(config);

         this.binding = this.getAttribute("binding");

         TagAttribute type = this.getAttribute("type");

         if (type != null)

         {

             if (!type.isLiteral())

             {

                 throw new TagAttributeException(type, "Must be a literal class name of type ValueChangeListener");

             }

             else

             {

                 // test it out

                 try

                 {

                     ReflectionUtil.forName(type.getValue());

                 }

                 catch (ClassNotFoundException e)

                 {

                     throw new TagAttributeException(type, "Couldn't qualify ValueChangeListener", e);

                 }

             }

             this.listenerType = type.getValue();

         }

         else

         {

             this.listenerType = null;

         }

     }

     /**

      * See taglib documentation.

      * 

      * @see javax.faces.view.facelets.FaceletHandler#apply(javax.faces.view.facelets.FaceletContext, javax.faces.component.UIComponent)

      */

     public void apply(FaceletContext ctx, UIComponent parent) throws IOException, FacesException, FaceletException,

             ELException

     {

         if (!ComponentHandler.isNew(parent))

         {

             return;

         }

         if (parent instanceof EditableValueHolder)

         {

             applyAttachedObject(ctx.getFacesContext(), parent);

         }

         else if (UIComponent.isCompositeComponent(parent))

         {

             FaceletCompositionContext mctx = FaceletCompositionContext.getCurrentInstance(ctx);

             mctx.addAttachedObjectHandler(parent, this);

         }

         else

         {

             throw new TagException(this.tag,

                     "Parent not composite component or an instance of EditableValueHolder: " + parent);

         }

     }

     public void applyAttachedObject(FacesContext context, UIComponent parent)

     {

         // Retrieve the current FaceletContext from FacesContext object

         FaceletContext faceletContext = (FaceletContext) context.getAttributes().get(

                 FaceletContext.FACELET_CONTEXT_KEY);

         EditableValueHolder evh = (EditableValueHolder) parent;

         ValueExpression b = null;

         if (this.binding != null)

         {

             b = this.binding.getValueExpression(faceletContext, ValueChangeListener.class);

         }

         ValueChangeListener listener = new LazyValueChangeListener(this.listenerType, b);

         evh.addValueChangeListener(listener);

     }

     /**

      * TODO: Document me!

      */

     @JSFFaceletAttribute

     public String getFor()

     {

         TagAttribute forAttribute = getAttribute("for");

         if (forAttribute == null)

         {

             return null;

         }

         else

         {

             return forAttribute.getValue();

         }

     }

 }