/*
    *  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 Number according to RFC 4512.
   * 
   * From RFC 4512 :
   * number  = DIGIT | ( LDIGIT 1*DIGIT )
   * DIGIT   = %x30 | LDIGIT       ; "0"-"9"
   * LDIGIT  = %x31-39             ; "1"-"9"
   * 
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  @SuppressWarnings("serial")
  public class NumberSyntaxChecker extends SyntaxChecker
  {
      /** A logger for this class */
      private static final Logger LOG = LoggerFactory.getLogger( NumberSyntaxChecker.class );
  
  
      /**
       * Creates a new instance of NumberSyntaxChecker.
       */
      public NumberSyntaxChecker()
      {
          super( SchemaConstants.NUMBER_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 should have at least one char
          if ( strValue.length() == 0 )
          {
              LOG.debug( "Syntax invalid for '{}'", value );
              return false;
          }
  
          // Check that each char is either a digit or a space
          for ( int i = 0; i < strValue.length(); i++ )
          {
              switch ( strValue.charAt( i ) )
              {
                  case '0':
                  case '1':
                  case '2':
                  case '3':
                  case '4':
                 case '5':
                 case '6':
                 case '7':
                 case '8':
                 case '9':
                     continue;
 
                 default:
                     LOG.debug( "Syntax invalid for '{}'", value );
                     return false;
             }
         }
 
         if ( ( strValue.charAt( 0 ) == '0' ) && strValue.length() > 1 )
         {
             // A number can't start with a '0' unless it's the only
             // number
             LOG.debug( "Syntax invalid for '{}'", value );
             return false;
         }
 
         LOG.debug( "Syntax valid for '{}'", value );
         return true;
     }
 }