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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.io.Serializable;

import java.util.Map;

import javax.el.ValueExpression;

import javax.faces.component.UIComponent;
import javax.faces.el.ValueBinding;

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


/**
 * Change specialization for change in attributes.
 * While applying this Change, the specified attribute state is  restored.
 * @version $Name:  $ ($Revision: adfrt/faces/adf-faces-api/src/main/java/oracle/adf/view/faces/change/AttributeComponentChange.java#0 $) $Date: 10-nov-2005.19:09:56 $
 */
public class AttributeComponentChange extends ComponentChange
{
  /**
   * Constructs an AttributeChange with the given attributeName and
   *  attributeValue.
   * @param attributeName The name of the attribute for which the value needs
   *         to be restored.
   * @param attributeValue The value of the attribute that needs to be restored.
   *         This value should be of type java.io.Serializable in order to be
   *         persisted.  If the value is of type ValueExpression or ValueBinding,
   *         the component's ValueBinding or ValueExpression for the attribute
   *         will be updated and the current attribute value, if any, removed so
   *         that the new ValueExpression or ValueBinding can take precedence.
   * @throws IllegalArgumentException if specified attributeName were to be null or
   *         the specified attributeValue isn't serializable
   */
  public AttributeComponentChange(
    String attributeName,
    Object attributeValue
    )
  {
    if ((attributeName == null) || (attributeName.length() == 0))
      throw new IllegalArgumentException(_LOG.getMessage(
        "CANNOT_CONSTRUCT_ATTRIBUTECHANGE_WITH_NULL_NAME"));

    if (attributeValue != null && !(attributeValue instanceof Serializable))
      throw new IllegalArgumentException(_LOG.getMessage(
        "UNSERIALIZABLE_VALUE", attributeValue));

    _attributeName = attributeName;
    _attributeValue = attributeValue;
  }

  /**
   * Returns the name of the attribute that represents this Change.
   */
  public String getAttributeName()
  {
    return _attributeName;
  }

  /**
   * Returns the value of the attribute corresponding to this AttributeChange.
   */
  public Object getAttributeValue()
  {
    return _attributeValue;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  @SuppressWarnings("deprecation")
  public void changeComponent(UIComponent uiComponent)
  {
    Map attributeMap = uiComponent.getAttributes();

    // if the attributevalue is a ValueExpression or ValueBinding, use the
    // appropriate setValueExpression/setValueBinding call and remove the
    // current attribute value, if any, so that the ValueExpression/ValueBinding
    // can take precedence
    if (_attributeValue instanceof ValueExpression)
    {
      uiComponent.setValueExpression(_attributeName, (ValueExpression)_attributeValue);
      attributeMap.remove(_attributeName);
    }
    else if (_attributeValue instanceof ValueBinding)
    {
      uiComponent.setValueBinding(_attributeName, (ValueBinding)_attributeValue);
      attributeMap.remove(_attributeName);
    }
    else
    {
      attributeMap.put(_attributeName, _attributeValue);
    }
  }

  @Override
  public String toString()
  {
    return super.toString() + "[attribute=" + _attributeName +
           ",value=" + _attributeValue + "]";
  }
  
  @Override
  public int hashCode()
  {
    int hashCode = _attributeName.hashCode();
    
    if (_attributeValue != null)
      hashCode += 37 * _attributeValue.hashCode();
    
    return hashCode;
  }
  
  @Override
  public boolean equals(Object o)
  {
    if (o == this)
      return true;
    
    if (!(o instanceof AttributeComponentChange))
      return false;
    
    AttributeComponentChange other = (AttributeComponentChange)o;
    
    return _attributeName.equals(other._attributeName) &&
           ((_attributeValue == null)
             ? other._attributeValue == null
             : _attributeValue.equals(other._attributeValue));
  }

  private final String _attributeName;

  //=-=pu: Should we disallow non-serializable values during construction itself
  //      and throw IllegalArgumentException ?
  // Current known cases:
  //  The focusPath attribute of a tree, which is considered as a persistible
  //    Change takes a value that is a java.util.List. (-ve)
  //  treeState of a tree is a org.apache.myfaces.trinidad.model.PathSet that
  //    implements serializable. (+ve)
  //  selectionState of a table is org.apache.myfaces.trinidad.model.RowKeySet that
  //    implements externalizable. (+ve)
  private final Object _attributeValue;
  private static final TrinidadLogger _LOG = TrinidadLogger.createTrinidadLogger(
    AttributeComponentChange.class);
  private static final long serialVersionUID = 1L;
}