/*
    *  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.Chars;
  import org.apache.directory.api.util.Strings;
  
  
  /**
   * A SyntaxChecker which verifies that a value is an Integer according to RFC 4517.
   * 
   * From RFC 4517 :
   * 
   * <pre>
   * Integer = ( HYPHEN LDIGIT *DIGIT ) | number
   * 
   * From RFC 4512 :
   * number  = DIGIT | ( LDIGIT 1*DIGIT )
   * DIGIT   = %x30 | LDIGIT       ; "0"-"9"
   * LDIGIT  = %x31-39             ; "1"-"9"
   * HYPHEN  = %x2D                ; hyphen ("-")
   * </pre>
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  @SuppressWarnings("serial")
  public final class IntegerSyntaxChecker extends SyntaxChecker
  {
      /**
       * A static instance of IntegerSyntaxChecker
       */
      public static final IntegerSyntaxChecker INSTANCE = new IntegerSyntaxChecker( SchemaConstants.INTEGER_SYNTAX );
      
      /**
       * A static Builder for this class
       */
      public static final class Builder extends SCBuilder<IntegerSyntaxChecker>
      {
          /**
           * The Builder constructor
           */
          private Builder()
          {
              super( SchemaConstants.INTEGER_SYNTAX );
          }
          
          
          /**
           * Create a new instance of IntegerSyntaxChecker
           * @return A new instance of IntegerSyntaxChecker
           */
          @Override
          public IntegerSyntaxChecker build()
          {
              return new IntegerSyntaxChecker( oid );
          }
      }
  
      
      /**
       * Creates a new instance of IntegerSyntaxChecker.
       * 
       * @param oid The OID to use for this SyntaxChecker
       */
      private IntegerSyntaxChecker( 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();
         }
 
         if ( strValue.length() == 0 )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
             }
             
             return false;
         }
 
         // The first char must be either a '-' or in [0..9].
         // If it's a '0', then there should be any other char after
         int pos = 0;
         char c = strValue.charAt( pos );
 
         if ( c == '-' )
         {
             pos = 1;
         }
         else if ( !Chars.isDigit( c ) )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
             }
             
             return false;
         }
         else if ( c == '0' )
         {
             if ( strValue.length() > 1 )
             {
                 if ( LOG.isDebugEnabled() )
                 {
                     LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
                 }
                 
                 return false;
             }
             else
             {
                 if ( LOG.isDebugEnabled() )
                 {
                     LOG.debug( I18n.msg( I18n.MSG_04489_SYNTAX_VALID, value ) );
                 }
                 
                 return true;
             }
         }
 
         // We must have at least a digit which is not '0'
         if ( !Chars.isDigit( strValue, pos ) || Strings.isCharASCII( strValue, pos, '0' ) )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
             }
             
             return false;
         }
         else
         {
             pos++;
         }
 
         while ( Chars.isDigit( strValue, pos ) )
         {
             pos++;
         }
 
         boolean result = pos == strValue.length();
 
         if ( LOG.isDebugEnabled() )
         {
             if ( result )
             {
                 LOG.debug( I18n.msg( I18n.MSG_04489_SYNTAX_VALID, value ) );
             }
             else
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
             }
         }
 
         return result;
     }
 }