/*
    *  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 java.util.HashSet;
  import java.util.Set;
  
  import org.apache.directory.api.ldap.model.constants.SchemaConstants;
  import org.apache.directory.api.ldap.model.schema.SyntaxChecker;
  import org.apache.directory.api.util.Chars;
  import org.apache.directory.api.util.Strings;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * A SyntaxChecker which verifies that a value is a DSEType according to 
   * http://tools.ietf.org/id/draft-ietf-asid-ldapv3-attributes-03.txt, par 6.2.1.5 :
   * 
   * <DSEType>    ::= '(' <sp>* <DSEBit> <sp>* <DSEBitList> ')'
   * <DSEBitList> ::= '$' <sp>* <DSEBit> <sp>* <DSEBitList> | e      
   * <DSEBit>     ::= 'root' | 'glue' | 'cp' | 'entry' | 'alias' | 'subr' |
   *                  'nssr' | 'supr' | 'xr' | 'admPoint' | 'subentry' |
   *                  'shadow' | 'zombie' | 'immSupr' | 'rhob' | 'sa'
   * 
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  @SuppressWarnings("serial")
  public class DseTypeSyntaxChecker extends SyntaxChecker
  {
      /** A logger for this class */
      private static final Logger LOG = LoggerFactory.getLogger( DseTypeSyntaxChecker.class );
  
      /** The DSE BITS keywords */
      private static final String[] DSE_BITS_STRINGS =
          {
              "root", "glue", "cp", "entry", "alias", "subr",
              "nssr", "supr", "xr", "admPoint", "subentry",
              "shadow", "zombie", "immSupr", "rhob", "sa"
      };
  
      /** The Set which contains the DESBits */
      private static final Set<String> DSE_BITS = new HashSet<String>();
  
      /** Initialization of the country set */
      static
      {
          for ( String country : DSE_BITS_STRINGS )
          {
              DSE_BITS.add( country );
          }
      }
  
  
      /**
       * 
       * Creates a new instance of DSETypeSyntaxChecker.
       *
       */
      public DseTypeSyntaxChecker()
      {
          super( SchemaConstants.DSE_TYPE_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();
         }
 
         // We must have at least '(cp)', '(xr)' or '(ca)'
         if ( strValue.length() < 4 )
         {
             LOG.debug( "Syntax invalid for '{}'", value );
             return false;
         }
 
         // Check the opening and closing parenthesis
         if ( ( strValue.charAt( 0 ) != '(' )
             || ( strValue.charAt( strValue.length() - 1 ) != ')' ) )
         {
             LOG.debug( "Syntax invalid for '{}'", value );
             return false;
         }
 
         Set<String> keywords = new HashSet<String>();
         int len = strValue.length() - 1;
         boolean needKeyword = true;
 
         // 
         for ( int i = 1; i < len; /* */)
         {
             // Skip spaces
             while ( ( i < len ) && ( strValue.charAt( i ) == ' ' ) )
             {
                 i++;
             }
 
             int pos = i;
 
             // Search for a keyword
             while ( ( i < len ) && Chars.isAlphaASCII( strValue, pos ) )
             {
                 pos++;
             }
 
             if ( pos == i )
             {
                 // No keyword : error
                 LOG.debug( "Syntax invalid for '{}'", value );
                 return false;
             }
 
             String keyword = strValue.substring( i, pos );
             i = pos;
 
             if ( !DSE_BITS.contains( keyword ) )
             {
                 // Unknown keyword
                 LOG.debug( "Syntax invalid for '{}'", value );
                 return false;
             }
 
             // Check that the keyword has not been met
             if ( keywords.contains( keyword ) )
             {
                 LOG.debug( "Syntax invalid for '{}'", value );
                 return false;
             }
 
             keywords.add( keyword );
             needKeyword = false;
 
             // Skip spaces
             while ( ( i < len ) && ( strValue.charAt( i ) == ' ' ) )
             {
                 i++;
             }
 
             // Do we have another keyword ?
             if ( ( i < len ) && ( strValue.charAt( i ) == '$' ) )
             {
                 // yes
                 i++;
                 needKeyword = true;
                 continue;
             }
         }
 
         // We are done
         if ( needKeyword )
         {
             LOG.debug( "Syntax invalid for '{}'", value );
         }
         else
         {
             LOG.debug( "Syntax valid for '{}'", value );
         }
 
         return !needKeyword;
     }
 }