/*
    *  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.directory.api.ldap.model.filter;
  
  
  import org.apache.directory.api.ldap.model.schema.AttributeType;
  
  
  /**
   * Abstract base class for leaf nodes within the expression filter tree.
   * 
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public abstract class LeafNode extends AbstractExprNode
  {
      /** attributeType on which this leaf is based */
      protected AttributeType attributeType;
  
      /** attribute on which this leaf is based */
      protected String attribute;
  
  
      /**
       * Creates a leaf node.
       * 
       * @param attributeType the attribute this node is based on
       * @param assertionType the type of this leaf node
       */
      protected LeafNode( AttributeType attributeType, AssertionType assertionType )
      {
          super( assertionType );
          this.attributeType = attributeType;
  
          if ( attributeType != null )
          {
              this.attribute = attributeType.getName();
              isSchemaAware = true;
          }
          else
          {
              throw new NullPointerException( "Cannot create a Node with a null Attribute" );
          }
      }
  
  
      /**
       * Creates a leaf node.
       * 
       * @param attributeType the attribute this node is based on
       * @param assertionType the type of this leaf node
       */
      protected LeafNode( String attribute, AssertionType assertionType )
      {
          super( assertionType );
          this.attributeType = null;
          this.attribute = attribute;
          isSchemaAware = false;
      }
  
  
      /**
       * Gets whether this node is a leaf - the answer is always true here.
       * 
       * @return true always
       */
      public final boolean isLeaf()
      {
          return true;
      }
  
  
      /**
       * Gets the attributeType this leaf node is based on.
       * 
       * @return the attributeType asserted
       */
      public final AttributeType getAttributeType()
      {
          return attributeType;
      }
  
  
     /**
      * Gets the attribute this leaf node is based on.
      * 
      * @return the attribute asserted
      */
     public final String getAttribute()
     {
         return attribute;
     }
 
 
     /**
      * Sets the attributeType this leaf node is based on.
      * 
      * @param attributeType the attributeType that is asserted by this filter node
      */
     public void setAttributeType( AttributeType attributeType )
     {
         this.attributeType = attributeType;
 
         if ( attributeType != null )
         {
             attribute = attributeType.getName();
             isSchemaAware = true;
         }
     }
 
 
     /**
      * Sets the attribute this leaf node is based on.
      * 
      * @param attribute the attribute that is asserted by this filter node
      */
     public void setAttribute( String attribute )
     {
         this.attribute = attribute;
         isSchemaAware = false;
     }
 
 
     /**
      * @see ExprNode#accept(
      *FilterVisitor)
      * 
      * @param visitor the filter expression tree structure visitor
      * @return The modified element
      */
     public final Object accept( FilterVisitor visitor )
     {
         if ( visitor.canVisit( this ) )
         {
             return visitor.visit( this );
         }
         else
         {
             return null;
         }
     }
 
 
     /**
      * @see Object#hashCode()
      * @return the instance's hash code 
      */
     public int hashCode()
     {
         int h = 37;
 
         h = h * 17 + super.hashCode();
 
         if ( attributeType != null )
         {
             h = h * 17 + attributeType.hashCode();
         }
         else
         {
             h = h * 17 + attribute.hashCode();
         }
 
         return h;
     }
 
 
     /**
      * @see java.lang.Object#equals(java.lang.Object)
      */
     public boolean equals( Object other )
     {
         if ( this == other )
         {
             return true;
         }
 
         if ( !( other instanceof LeafNode ) )
         {
             return false;
         }
 
         LeafNode otherNode = ( LeafNode ) other;
 
         if ( other.getClass() != this.getClass() )
         {
             return false;
         }
 
         if ( attributeType != null )
         {
             return attributeType.equals( otherNode.getAttributeType() );
         }
         else
         {
             return attribute.equalsIgnoreCase( otherNode.getAttribute() );
         }
     }
 }