/*
    *  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.i18n.I18n;
  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;
  
  
  /**
   * 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 final class DerefAliasSyntaxChecker extends SyntaxChecker
  {
      /**
       * A static instance of DerefAliasSyntaxChecker
       */
      public static final DerefAliasSyntaxChecker INSTANCE = 
          new DerefAliasSyntaxChecker( SchemaConstants.DEREF_ALIAS_SYNTAX );
      
      /**
       * A static Builder for this class
       */
      public static final class Builder extends SCBuilder<DerefAliasSyntaxChecker>
      {
          /**
           * The Builder constructor
           */
          private Builder()
          {
              super( SchemaConstants.DEREF_ALIAS_SYNTAX );
          }
          
          
          /**
           * Create a new instance of DerefAliasSyntaxChecker
           * @return A new instance of DerefAliasSyntaxChecker
           */
          @Override
          public DerefAliasSyntaxChecker build()
          {
              return new DerefAliasSyntaxChecker( oid );
          }
      }
  
      /**
       * Creates a new instance of DerefAliasSyntaxChecker.
       * 
       * @param oid The OID to use for this SyntaxChecker
       */
      private DerefAliasSyntaxChecker( String oid )
      {
          super( oid );
      }
  
      
      /**
       * @return An instance of the Builder for this class
       */
      public static Builder builder()
      {
          return new Builder();
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
     public boolean isValidSyntax( Object value )
     {
         String strValue;
 
         if ( value == null )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, "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.toLowerCaseAscii( strValue ) );
 
         return "never".equals( strValue ) || "finding".equals( strValue ) || "searching".equals( strValue ) || "always"
             .equals( strValue );
     }
 }