/*
    * 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;
  
  import java.io.IOException;
  
  import javax.el.ValueExpression;
  import javax.faces.component.UIComponent;
  import javax.faces.component.ValueHolder;
  import javax.faces.context.FacesContext;
  import javax.faces.convert.Converter;
  import javax.faces.view.ValueHolderAttachedObjectHandler;
  import javax.faces.view.facelets.ComponentHandler;
  import javax.faces.view.facelets.ConverterHandler;
  import javax.faces.view.facelets.FaceletContext;
  import javax.faces.view.facelets.MetaRuleset;
  import javax.faces.view.facelets.TagAttribute;
  import javax.faces.view.facelets.TagException;
  import javax.faces.view.facelets.TagHandlerDelegate;
  
  import org.apache.myfaces.view.facelets.FaceletCompositionContext;
  import org.apache.myfaces.view.facelets.tag.MetaRulesetImpl;
  
  /**
   * Handles setting a Converter instance on a ValueHolder. Will wire all attributes set to the Converter instance
   * created/fetched. Uses the "binding" attribute for grabbing instances to apply attributes to. <p> Will only
   * set/create Converter is the passed UIComponent's parent is null, signifying that it wasn't restored from an existing
   * tree.</p>
   * 
   * @author Leonardo Uribe (latest modification by $Author$)
   * @version $Revision$ $Date$
   *
   * @since 2.0
   */
  public class ConverterTagHandlerDelegate extends TagHandlerDelegate implements ValueHolderAttachedObjectHandler
  {
      private ConverterHandler _delegate;
      
      public ConverterTagHandlerDelegate(ConverterHandler delegate)
      {
          _delegate = delegate;
      }
  
      /**
       * Set Converter instance on parent ValueHolder if it's not being restored.
       * <ol>
       * <li>Cast to ValueHolder</li>
       * <li>If "binding" attribute was specified, fetch/create and re-bind to expression.</li>
       * <li>Otherwise, call {@link #createConverter(FaceletContext) createConverter}.</li>
       * <li>Call setAttributes(FaceletContext, Object) on Converter instance.</li>
       * <li>Set the Converter on the ValueHolder</li>
       * <li>If the ValueHolder has a localValue, convert it and set the value</li>
       * </ol>
       * 
       * See ValueHolder
       * See Converter
       * See #createConverter(FaceletContext)
       * See javax.faces.view.facelets.FaceletHandler#apply(javax.faces.view.facelets.FaceletContext,
       *     javax.faces.component.UIComponent)
       */
      @Override
      public void apply(FaceletContext ctx, UIComponent parent) throws IOException
      {
          // only process if it's been created
          if (!ComponentHandler.isNew(parent))
          {
              return;
          }
          if (parent instanceof ValueHolder)
          {
              applyAttachedObject(ctx.getFacesContext(), parent);
          }
          else if (UIComponent.isCompositeComponent(parent))
          {
              if (getFor() == null)
              {
                  throw new TagException(_delegate.getTag(), "is nested inside a composite component"
                          + " but does not have a for attribute.");
              }
              FaceletCompositionContext mctx = FaceletCompositionContext.getCurrentInstance(ctx);
              mctx.addAttachedObjectHandler(parent, _delegate);
          }
          else
         {
             throw new TagException(_delegate.getTag(),
                     "Parent not composite component or an instance of ValueHolder: " + parent);
         }      
     }
 
     /**
      * Create a Converter instance
      * 
      * @param ctx
      *            FaceletContext to use
      * @return Converter instance, cannot be null
      */
     protected Converter createConverter(FaceletContext ctx)
     {
         if (_delegate.getConverterId(ctx) == null)
         {
             throw new TagException(_delegate.getTag(),
                                     "Default behavior invoked of requiring a converter-id passed in the "
                                     + "constructor, must override ConvertHandler(ConverterConfig)");
         }
         return ctx.getFacesContext().getApplication().createConverter(_delegate.getConverterId(ctx));
     }
 
     @Override
     public MetaRuleset createMetaRuleset(Class type)
     {
         return new MetaRulesetImpl(_delegate.getTag(), type).ignore("binding").ignore("for");
     }
 
     public void applyAttachedObject(FacesContext context, UIComponent parent)
     {
         // Retrieve the current FaceletContext from FacesContext object
         FaceletContext faceletContext = (FaceletContext) context.getAttributes().get(
                 FaceletContext.FACELET_CONTEXT_KEY);
         
         // cast to a ValueHolder
         ValueHolder vh = (ValueHolder) parent;
         ValueExpression ve = null;
         Converter c = null;
         if (_delegate.getBinding() != null)
         {
             ve = _delegate.getBinding().getValueExpression(faceletContext, Converter.class);
             c = (Converter) ve.getValue(faceletContext);
         }
         if (c == null)
         {
             c = this.createConverter(faceletContext);
             if (ve != null)
             {
                 ve.setValue(faceletContext, c);
             }
         }
         if (c == null)
         {
             throw new TagException(_delegate.getTag(), "No Converter was created");
         }
         _delegate.setAttributes(faceletContext, c);
         vh.setConverter(c);
         Object lv = vh.getLocalValue();
         FacesContext faces = faceletContext.getFacesContext();
         if (lv instanceof String)
         {
             vh.setValue(c.getAsObject(faces, parent, (String) lv));
         }
     }
 
     public String getFor()
     {
         TagAttribute forAttribute = _delegate.getTagAttribute("for");
         
         if (forAttribute == null)
         {
             return null;
         }
         else
         {
             return forAttribute.getValue();
         }
     }
 }