/*

  * Entagged Audio Tag library

  * Copyright (c) 2003-2005 Rapha�l Slinckx <raphael@slinckx.net>

  * Copyright (c) 2004-2005 Christian Laireiter <liree@web.de>

  * 

  * This library is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public

  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *  

  * This library is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  * Lesser General Public License for more details.

  * 

  * You should have received a copy of the GNU Lesser General Public

  * License along with this library; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  */

 package org.jaudiotagger.tag.vorbiscomment;

 import org.jaudiotagger.audio.exceptions.CannotReadException;

 import org.jaudiotagger.audio.generic.Utils;

 import org.jaudiotagger.audio.ogg.util.VorbisHeader;

 import org.jaudiotagger.fix.Fix;

 import org.jaudiotagger.logging.ErrorMessage;

 import java.io.IOException;

 import java.util.logging.Logger;

 /**

  * Create the VorbisCommentTag by reading from the raw packet data

  * <p/>

  * <p>This is in the same format whether encoded with Ogg or Flac

  * except the framing bit is only present when used within Ogg Vorbis

  * <p/>

  * <pre>

  * From the http://xiph.org/vorbis/doc/Vorbis_I_spec.html#vorbis-spec-comment

  * Read decodes the packet data using the following algorithm:

  *  [vendor_length] = read an unsigned integer of 32 bits

  *  [vendor_string] = read a UTF-8 vector as [vendor_length] octets

  *  [user_comment_list_length] = read an unsigned integer of 32 bits

  *  iterate [user_comment_list_length] times {

  *      5) [length] = read an unsigned integer of 32 bits

  *      6) this iteration's user comment = read a UTF-8 vector as [length] octets

  *    }

  *  [framing_bit] = read a single bit as boolean

  *  if ( [framing_bit] unset or end-of-packet ) then ERROR

  *  done.

  * </pre>

  */

 public class VorbisCommentReader

 {

     // Logger Object

     public static Logger logger = Logger.getLogger("org.jaudiotagger.tag.vorbiscomment.VorbisCommentReader");

     public static final int FIELD_VENDOR_LENGTH_POS = 0;

     public static final int FIELD_VENDOR_STRING_POS = 4;

     public static final int FIELD_VENDOR_LENGTH_LENGTH = 4;

     public static final int FIELD_USER_COMMENT_LIST_LENGTH = 4;

     public static final int FIELD_COMMENT_LENGTH_LENGTH = 4;

     private Fix fix;

     public VorbisCommentReader()

     {

     }

     public VorbisCommentReader(Fix fix)

     {

         this.fix = fix;

     }

     /**

      * @param rawdata

      * @return logical representation of VorbisCommentTag

      * @throws IOException

      * @throws CannotReadException

      */

     public VorbisCommentTag read(byte[] rawdata, boolean isFramingBit) throws IOException, CannotReadException

     {

         VorbisCommentTag tag = new VorbisCommentTag();

         byte[] b = new byte[FIELD_VENDOR_LENGTH_LENGTH];

         System.arraycopy(rawdata, FIELD_VENDOR_LENGTH_POS, b, FIELD_VENDOR_LENGTH_POS, FIELD_VENDOR_LENGTH_LENGTH);

         int pos = FIELD_VENDOR_LENGTH_LENGTH;

         int vendorStringLength = Utils.getIntLE(b);

         b = new byte[vendorStringLength];

         System.arraycopy(rawdata, pos, b, 0, vendorStringLength);

         pos += vendorStringLength;

         tag.setVendor(new String(b, VorbisHeader.CHARSET_UTF_8));

         b = new byte[FIELD_USER_COMMENT_LIST_LENGTH];

         System.arraycopy(rawdata, pos, b, 0, FIELD_USER_COMMENT_LIST_LENGTH);

         pos += FIELD_USER_COMMENT_LIST_LENGTH;

         int userComments = Utils.getIntLE(b);

         logger.info("Number of user comments:" + userComments);

         if (fix == Fix.FIX_OGG_VORBIS_COMMENT_NOT_COUNTING_EMPTY_COLUMNS)

         {

             userComments++;

         }

         for (int i = 0; i < userComments; i++)

         {

             b = new byte[FIELD_COMMENT_LENGTH_LENGTH];

             System.arraycopy(rawdata, pos, b, 0, FIELD_COMMENT_LENGTH_LENGTH);

             pos += FIELD_COMMENT_LENGTH_LENGTH;

             int commentLength = Utils.getIntLE(b);

             logger.info("Next Comment Length:" + commentLength);

             b = new byte[commentLength];

             System.arraycopy(rawdata, pos, b, 0, commentLength);

             pos += commentLength;

             VorbisCommentTagField fieldComment = new VorbisCommentTagField(b);

             logger.info("Adding:" + fieldComment.getId());

             tag.add(fieldComment);

         }

         //Check framing bit, only exists when vorbisComment used within OggVorbis       

         if (isFramingBit)

         {

             if ((rawdata[pos] & 0x01) != 1)

             {

                 throw new CannotReadException(ErrorMessage.OGG_VORBIS_NO_FRAMING_BIT.getMsg((rawdata[pos] & 0x01)));

             }

         }

         return tag;

     }

 }