/*
    * 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.custom.tabbedpane;
  
  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.TagHandler;
  
  import org.apache.myfaces.shared_tomahawk.util.ClassUtils;
  
  /**
   * Custom Facelets taghandler for the TabChangeListener class.
   *  
   * @since 1.1.7
   */
  public class TabChangeListenerTagHandler extends TagHandler
  {
      private final TagAttribute typeAttr;
  
      public TabChangeListenerTagHandler(TagConfig config)
      {
          super(config);
          typeAttr = getRequiredAttribute("type");
      }
  
      public void apply(FaceletContext faceletContext, UIComponent parent)
              throws IOException, FacesException, FaceletException, ELException
      {
          // only process this tag if the parent has just been created..
          if (parent.getParent() == null)
          {
              if (parent instanceof HtmlPanelTabbedPane)
              {
                  Object listenerRef;
                  if (typeAttr.isLiteral())
                  {
                      listenerRef = typeAttr.getValue();
                  }
                  else
                  {
                      listenerRef = typeAttr.getObject(faceletContext);
                  }
                  
                  if (listenerRef instanceof String)
                  {
                      String className = (String) listenerRef;
                      TabChangeListener listener = (TabChangeListener) ClassUtils.newInstance(className);
                      ((HtmlPanelTabbedPane) parent).addTabChangeListener(listener);
                  }
                  else if (listenerRef instanceof TabChangeListener)
                  {
                      TabChangeListener listener = (TabChangeListener) listenerRef;
                      ((HtmlPanelTabbedPane) parent).addTabChangeListener(listener);
                  }
                  else if (listenerRef == null)
                  {
                      throw new FaceletException("Property 'type' must not be null.");
                  }
                  else
                  {
                      throw new FaceletException(
                         "Property 'type' must be either a string (containing a class name) " +
                         "or a TabChangeListener instance.");
                  }
              }
              else
              {
                  throw new FaceletException(
                          "Component " + parent.getId() + " is not of type HtmlPanelTabbedPane");
              }
          }
      }
  }