/*

  * Entagged Audio Tag library

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

  * 

  * 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.audio.flac;

 import org.jaudiotagger.audio.exceptions.CannotReadException;

 import org.jaudiotagger.audio.flac.metadatablock.BlockType;

 import org.jaudiotagger.audio.flac.metadatablock.MetadataBlockDataStreamInfo;

 import org.jaudiotagger.audio.flac.metadatablock.MetadataBlockHeader;

 import org.jaudiotagger.audio.generic.GenericAudioHeader;

 import java.io.File;

 import java.io.IOException;

 import java.io.RandomAccessFile;

 import java.util.logging.Logger;

 /**

  * Read info from Flac file

  */

 public class FlacInfoReader

 {

     // Logger Object

     public static Logger logger = Logger.getLogger("org.jaudiotagger.audio.flac");

     private static final int NO_OF_BITS_IN_BYTE = 8;

     private static final int KILOBYTES_TO_BYTES_MULTIPLIER = 1000;

     public GenericAudioHeader read(RandomAccessFile raf) throws CannotReadException, IOException

     {

         FlacStreamReader flacStream = new FlacStreamReader(raf);

         flacStream.findStream();

         MetadataBlockDataStreamInfo mbdsi = null;

         boolean isLastBlock = false;

         //Search for StreamInfo Block, but even after we found it we still have to continue through all

         //the metadata blocks so that we can find the start of the audio frames which we need to calculate

         //the bitrate

         while (!isLastBlock)

         {

             MetadataBlockHeader mbh = MetadataBlockHeader.readHeader(raf);

             if (mbh.getBlockType() == BlockType.STREAMINFO)

             {

                 mbdsi = new MetadataBlockDataStreamInfo(mbh, raf);

                 if (!mbdsi.isValid())

                 {

                     throw new CannotReadException("FLAC StreamInfo not valid");

                 }

             }

             else

             {

                 raf.seek(raf.getFilePointer() + mbh.getDataLength());

             }

             isLastBlock = mbh.isLastBlock();

             mbh = null; //Free memory

         }

         if (mbdsi == null)

         {

             throw new CannotReadException("Unable to find Flac StreamInfo");

         }

         GenericAudioHeader info = new GenericAudioHeader();

         info.setLength(mbdsi.getLength());

         info.setPreciseLength(mbdsi.getPreciseLength());

         info.setChannelNumber(mbdsi.getChannelNumber());

         info.setSamplingRate(mbdsi.getSamplingRate());

         info.setEncodingType(mbdsi.getEncodingType());

         info.setExtraEncodingInfos("");

         info.setBitrate(computeBitrate(mbdsi.getPreciseLength(), raf.length() - raf.getFilePointer()));

         return info;

     }

     private int computeBitrate(float length, long size)

     {

         return (int) ((size / KILOBYTES_TO_BYTES_MULTIPLIER) * NO_OF_BITS_IN_BYTE / length);

     }

     /**

      * Count the number of metadatablocks, useful for debugging

      *

      * @param f

      * @return

      * @throws CannotReadException

      * @throws IOException

      */

     public int countMetaBlocks(File f) throws CannotReadException, IOException

     {

         RandomAccessFile raf = new RandomAccessFile(f, "r");

         FlacStreamReader flacStream = new FlacStreamReader(raf);

         flacStream.findStream();

         boolean isLastBlock = false;

         int count = 0;

         while (!isLastBlock)

         {

             MetadataBlockHeader mbh = MetadataBlockHeader.readHeader(raf);

             logger.info("Found block:" + mbh.getBlockType());

             raf.seek(raf.getFilePointer() + mbh.getDataLength());

             isLastBlock = mbh.isLastBlock();

             mbh = null; //Free memory

             count++;

         }

         raf.close();

         return count;

     }

 }