/*
    *  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;
  
  
  /**
   * A SyntaxChecker which verifies that a value is a Jpeg according to RFC 4517.
   * <p>
   * The JFIF (Jpeg File Interchange Format) specify that a jpeg image starts with
   * the following bytes :
   * <pre>
   * 0xFF 0xD8 (SOI, Start Of Image)
   * 0xFF 0xE0 (App0 for JFIF) or 0xDD 0xE1 (App1 for Exif)
   * 0xNN 0xNN (Header length)
   * "JFIF\0" (JFIF string with an ending \0)
   * some other bytes which are related to the image.
   * <pre>
   * 
   * We will check for those 11 bytes, except the length.
   * 
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  @SuppressWarnings("serial")
  public final class JpegSyntaxChecker extends SyntaxChecker
  {
      /**
       * A static instance of JpegSyntaxChecker
       */
      public static final JpegSyntaxChecker INSTANCE = new JpegSyntaxChecker( SchemaConstants.JPEG_SYNTAX );
      
      /**
       * A static Builder for this class
       */
      public static final class Builder extends SCBuilder<JpegSyntaxChecker>
      {
          /**
           * The Builder constructor
           */
          private Builder()
          {
              super( SchemaConstants.JPEG_SYNTAX );
          }
          
          
          /**
           * Create a new instance of JpegSyntaxChecker
           * @return A new instance of JpegSyntaxChecker
           */
          @Override
          public JpegSyntaxChecker build()
          {
              return new JpegSyntaxChecker( oid );
          }
      }
  
      
      /**
       * Creates a new instance of JpegSyntaxChecker.
       * 
       * @param oid The OID to use for this SyntaxChecker
       */
      private JpegSyntaxChecker( 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 )
     {
         if ( value == null )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, "null" ) );
             }
             
             return false;
         }
 
         // The value must be a byte array
         if ( !( value instanceof byte[] ) )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
             }
             
             return false;
         }
 
         byte[] bytes = ( byte[] ) value;
 
         // The header must be at least 11 bytes long
         if ( bytes.length < 11 )
         {
             if ( LOG.isDebugEnabled() )
             {
                 LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
             }
             
             return false;
         }
 
         // SOI or APP0 or APP1 format
         if ( ( bytes[0] == ( byte ) 0x00FF )
             && ( bytes[1] == ( byte ) 0x00D8 )
             && ( bytes[2] == ( byte ) 0x00FF ) )
         {
             // JFIF format
             if ( ( bytes[3] == ( byte ) 0x00E0 )
                 && ( bytes[6] == 'J' )
                 && ( bytes[7] == 'F' )
                 && ( bytes[8] == 'I' )
                 && ( bytes[9] == 'F' )
                 && ( bytes[10] == 0x00 ) )
             {
                 if ( LOG.isDebugEnabled() )
                 {
                     LOG.debug( I18n.msg( I18n.MSG_04489_SYNTAX_VALID, value ) );
                 }
                 
                 return true;
             }
         // EXIF Format
             else if ( ( bytes[3] == ( byte ) 0x00E1 ) 
                     && ( bytes[6] == 'E' )
                     && ( bytes[7] == 'x' )
                     && ( bytes[8] == 'i' )
                     && ( bytes[9] == 'f' )
                     && ( bytes[10] == 0x00 ) )
             {
                 if ( LOG.isDebugEnabled() )
                 {
                     LOG.debug( I18n.msg( I18n.MSG_04489_SYNTAX_VALID, value ) );
                 }
                 
                 return true;
             }
         }
 
         if ( LOG.isDebugEnabled() )
         {
             LOG.debug( I18n.err( I18n.ERR_04488_SYNTAX_INVALID, value ) );
         }
         
         return false;
     }
 }