/*
    *  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.schema.comparators;
  
  
  import org.apache.directory.api.i18n.I18n;
  import org.apache.directory.api.ldap.model.exception.LdapException;
  import org.apache.directory.api.ldap.model.exception.LdapInvalidDnException;
  import org.apache.directory.api.ldap.model.name.Dn;
  import org.apache.directory.api.ldap.model.schema.LdapComparator;
  import org.apache.directory.api.ldap.model.schema.SchemaManager;
  
  
  /**
   * Compare two DNs
   * 
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class DnComparator extends LdapComparator<Object>
  {
      /** The serial version UID */
      private static final long serialVersionUID = 2L;
  
      /** A reference to the schema manager */
      private SchemaManager schemaManager;
  
      /**
       * Creates a new instance of DnComparator.
       *
       * @param oid The Comparator's OID
       */
      public DnComparator( String oid )
      {
          super( oid );
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public int compare( Object obj0, Object obj1 )
      {
          Dn dn0 = null;
          Dn dn1 = null;
  
          try
          {
              dn0 = getDn( obj0 );
              dn1 = getDn( obj1 );
          }
          catch ( LdapException e )
          {
              // -- what do we do here ?
              return -1;
          }
  
          int dn0Size = dn0.getRdns().size();
          int dn1Size = dn1.getRdns().size();
          
          // check the equality first, cause
          // when both DNs are equal checking isAncestorOf() returns true
          if ( dn0.equals( dn1 ) )
          {
              return 0;
          }
          else if ( dn0Size > dn1Size )
          {
              return -1;
          }
          else if ( dn1Size > dn0Size )
          {
              return 1;
          }
  
          return dn0.getNormName().compareTo( dn1.getNormName() );
      }
  
  
      private Dn getDn( Object obj ) throws LdapInvalidDnException
      {
          Dn dn;
 
         if ( obj instanceof Dn )
         {
             dn = ( Dn ) obj;
 
             dn = dn.isSchemaAware() ? dn : dn.apply( schemaManager );
         }
         else if ( obj instanceof String )
         {
             dn = new Dn( schemaManager, ( String ) obj );
         }
         else
         {
             throw new IllegalStateException( I18n.err( I18n.ERR_04218, obj == null ? null : obj.getClass() ) );
         }
 
         return dn;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void setSchemaManager( SchemaManager schemaManager )
     {
         this.schemaManager = schemaManager;
     }
 }