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Public API for the Apache MyFaces Trinidad project
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/*
 * 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.trinidad.change;

import java.util.List;

import javax.faces.component.UIComponent;

import org.apache.myfaces.trinidad.logging.TrinidadLogger;


/**
 * Change specialization for adding a child component.
 * While applying this Change, the child component is re-created and added to
 *  the list of children. If a child component with an id same as the new child being added is 
 *  already present in the parent container, the new child is not added.
 * @version $Name:  $ ($Revision: adfrt/faces/adf-faces-api/src/main/java/oracle/adf/view/faces/change/AddChildComponentChange.java#0 $) $Date: 10-nov-2005.19:09:54 $
 */
public class AddChildComponentChange extends AddComponentChange 
{
  /**
   * Constructs an AddChildChange that appends the specified child component.
   * @param childComponent The child component that is to be appended.
   * @throws IllegalArgumentException if specified childComponent is null.
   */
  public AddChildComponentChange(UIComponent childComponent)
  {
    this(null,childComponent);
  }
  
  /**
   * Constructs an AddChildChange with the specified child component and the
   *  the identifier of the neighbour. If the neighbour is not found
   *  when applying this Change, or is null< the child is
   *  appended to the end of the list of children.
  *  @param insertBeforeId The identifier of the sibling before which this new 
  *         child is to be inserted.
   * @param childComponent The child component that is to be added.
   * @throws IllegalArgumentException if specified childComponent is null
   */
  public AddChildComponentChange(
    String insertBeforeId,
    UIComponent childComponent)
  {
    super(childComponent);
   
    _insertBeforeId = insertBeforeId;
  }
  
  /**
   * Returns the identifier of the sibling before which this new child needs to
   *  be inserted.
   */
  public String getInsertBeforeId()
  {
    return _insertBeforeId;
  }
  
  /**
   * {@inheritDoc}
   */
  @SuppressWarnings("unchecked")
  @Override
  public void changeComponent(UIComponent uiComponent)
  {
    UIComponent child = getComponent();
    
    if (child == null)
      return;
      
    String newChildId = child.getId();
    List children = uiComponent.getChildren();
    
    // If there were to be a child already with the ID same as the to-be-added child, it might have
    //  been added from previous change application, and further customizations might have happened
    //  on them. We just want to warn, abort the child addition, and not alter the component tree.
    UIComponent duplicateChild = ChangeUtils.getChildForId(uiComponent, newChildId);
  
    if (duplicateChild != null)
    {
      _LOG.info("ATTEMPT_ADD_CHILD_WITH_DUPLICATE_ID", newChildId);
      return;
    }
    
    if (_insertBeforeId == null)
    {
      // append the child
      children.add(child); 
    }
    else
    {
      int index = ChangeUtils.getChildIndexForId(uiComponent, _insertBeforeId);
      if(index == -1)
      {
        children.add(child);
      }
      else
      {
        children.add(index, child);
      }
    }
  }
  
  private final String _insertBeforeId;
  static private final TrinidadLogger _LOG =
    TrinidadLogger.createTrinidadLogger(AddChildComponentChange.class);
  private static final long serialVersionUID = 1L;
}