/*
    *  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.syntaxCheckers;
  
  
  import org.apache.directory.api.ldap.model.constants.SchemaConstants;
  import org.apache.directory.api.ldap.model.schema.SyntaxChecker;
  import org.apache.directory.api.util.Strings;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * A SyntaxChecker which verifies that a value is a valid DerefAlias. We
   * have four possible values :
   * <ul>
   * <li>NEVER</li>
   * <li>SEARCHING</li>
   * <li>FINDING</li>
   * <li>ALWAYS</li>
   * </ul>
   * The value is case insensitive
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  @SuppressWarnings("serial")
  public class DerefAliasSyntaxChecker extends SyntaxChecker
  {
      /** A logger for this class */
      private static final Logger LOG = LoggerFactory.getLogger( DerefAliasSyntaxChecker.class );
  
  
      /**
       * Creates a new instance of DerefAliasSyntaxChecker.
       */
      public DerefAliasSyntaxChecker()
      {
          super( SchemaConstants.DEREF_ALIAS_SYNTAX );
      }
  
  
      /**
       * {@inheritDoc}
       */
      public boolean isValidSyntax( Object value )
      {
          String strValue = null;
  
          if ( value == null )
          {
              LOG.debug( "Syntax invalid for 'null'" );
              return false;
          }
  
          if ( value instanceof String )
          {
              strValue = ( String ) value;
          }
          else if ( value instanceof byte[] )
          {
              strValue = Strings.utf8ToString( ( byte[] ) value );
          }
          else
          {
              strValue = value.toString();
          }
  
          strValue = Strings.trim( Strings.toLowerCase( strValue ) );
  
          return ( "never".equals( strValue ) ||
              "finding".equals( strValue ) ||
              "searching".equals( strValue ) || "always".equals( strValue ) );
      }
  }