/*
    *  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
    *  
   *    https://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 transient SchemaManager schemaManager;
  
      /**
       * Creates a new instance of DnComparator.
       * 
       * @param oid The Comparator's OID
       */
      public DnComparator( String oid )
      {
          super( oid );
      }
  
  
      /**
       * Compare two String DNs
       *  
       * @param dn1 The first DN
       * @param dn2 The second DN
       * 
       * @return -1 i the first DN is inferior to the second DN, 1 if the second DN is superior, 0 of they are equal
       */
      public int compare( String dn1, String dn2 )
      {
          if ( dn1 == null )
          {
              if ( dn2 == null )
              {
                  return 0;
              }
              else
              {
                  return -1;
              }
          }
          
          return dn1.compareTo( dn2 );
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public int compare( Object obj0, Object obj1 )
      {
          if ( ( obj0 instanceof String ) && ( obj1 instanceof String ) )
          {
              return compare( ( String ) obj0, ( String ) 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;
         }
 
         for ( int i = dn0Size - 1; i >= 0; i-- )
         {
             int comp = dn0.getRdn( i ).compareTo( dn1.getRdn( i ) );
             
             if ( comp != 0 )
             {
                 return comp;
             }
         }
         
         return 0;
     }
 
 
     private Dn getDn( Object obj ) throws LdapInvalidDnException
     {
         Dn dn;
 
         if ( obj instanceof Dn )
         {
             dn = ( Dn ) obj;
 
             dn = dn.isSchemaAware() ? dn : new Dn( schemaManager, dn );
         }
         else if ( obj instanceof String )
         {
             dn = new Dn( schemaManager, ( String ) obj );
         }
         else
         {
             throw new IllegalStateException( I18n.err( I18n.ERR_13720_CANNOT_HANDLE_DN_COMPARISONS, obj == null ? null : obj.getClass() ) );
         }
 
         return dn;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void setSchemaManager( SchemaManager schemaManager )
     {
         this.schemaManager = schemaManager;
     }
 }