/*
    * 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 javax.el.ELException;
  import javax.faces.FacesException;
  import javax.faces.component.UIComponent;
  import javax.faces.view.facelets.FaceletContext;
  import javax.faces.view.facelets.FaceletException;
  import javax.faces.view.facelets.TagAttribute;
  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.JSFFaceletTag;
  
  /**
   * Sets the specified name and attribute on the parent UIComponent. If the "value" specified is not a literal, it will
   * instead set the ValueExpression on the UIComponent. 
   * 
   * See javax.faces.component.UIComponent#getAttributes()
   * See javax.faces.component.UIComponent#setValueExpression(java.lang.String, javax.el.ValueExpression)
   * @author Jacob Hookom
   * @version $Id$
   */
  @JSFFaceletTag(
          name = "f:attribute",
          bodyContent = "empty", 
          tagClass="org.apache.myfaces.taglib.core.AttributeTag")
  public final class AttributeHandler extends TagHandler
      implements javax.faces.view.facelets.AttributeHandler
  {
      private final TagAttribute _name;
  
      private final TagAttribute _value;
  
      /**
       * @param config
       */
      public AttributeHandler(TagConfig config)
      {
          super(config);
          _name = getRequiredAttribute("name");
          _value = getRequiredAttribute("value");
      }
  
      /*
       * (non-Javadoc)
       * 
       * 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 (parent == null)
          {
              throw new TagException(this.tag, "Parent UIComponent was null");
          }
  
          // only process if the parent is new to the tree
          if (parent.getParent() == null)
          {
              String n = _name.getValue(ctx);
              if (!parent.getAttributes().containsKey(n))
              {
                  if (_value.isLiteral())
                  {
                      parent.getAttributes().put(n, _value.getValue());
                  }
                  else
                  {
                      parent.setValueExpression(n, _value.getValueExpression(ctx, Object.class));
                  }
              }
          }
      }
  
      public String getAttributeName(FaceletContext ctx)
      {
          return _name.getValue(ctx);
     }
 }