/*

  * 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.generic;

 import org.jaudiotagger.audio.AudioFile;

 import org.jaudiotagger.audio.exceptions.CannotReadException;

 import org.jaudiotagger.audio.exceptions.InvalidAudioFrameException;

 import org.jaudiotagger.audio.exceptions.ReadOnlyFileException;

 import org.jaudiotagger.tag.Tag;

 import org.jaudiotagger.tag.TagException;

 import org.jaudiotagger.logging.ErrorMessage;

 import java.io.File;

 import java.io.IOException;

 import java.io.RandomAccessFile;

 import java.util.logging.Logger;

 import java.util.logging.Level;

 /*

  * This abstract class is the skeleton for tag readers. It handles the creation/closing of

  * the randomaccessfile objects and then call the subclass method getEncodingInfo and getTag.

  * These two method have to be implemented in the subclass.

  * 

  *@author        Raphael Slinckx

  *@version        $Id: AudioFileReader.java,v 1.8 2008/11/21 10:32:48 paultaylor Exp $

  *@since        v0.02

  */

 public abstract class AudioFileReader

 {

     // Logger Object

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

     private static final int MINIMUM_SIZE_FOR_VALID_AUDIO_FILE = 150;

     /*

     * Returns the encoding info object associated wih the current File.

     * The subclass can assume the RAF pointer is at the first byte of the file.

     * The RandomAccessFile must be kept open after this function, but can point

     * at any offset in the file.

     *

     * @param raf The RandomAccessFile associtaed with the current file

     * @exception IOException is thrown when the RandomAccessFile operations throw it (you should never throw them manually)

     * @exception CannotReadException when an error occured during the parsing of the encoding infos

     */

     protected abstract GenericAudioHeader getEncodingInfo(RandomAccessFile raf) throws CannotReadException, IOException;

     /*

       * Same as above but returns the Tag contained in the file, or a new one.

       *

       * @param raf The RandomAccessFile associted with the current file

       * @exception IOException is thrown when the RandomAccessFile operations throw it (you should never throw them manually)

       * @exception CannotReadException when an error occured during the parsing of the tag

       */

     protected abstract Tag getTag(RandomAccessFile raf) throws CannotReadException, IOException;

     /*

       * Reads the given file, and return an AudioFile object containing the Tag

       * and the encoding infos present in the file. If the file has no tag, an

       * empty one is returned. If the encodinginfo is not valid , an exception is thrown.

       *

       * @param f The file to read

       * @exception CannotReadException If anything went bad during the read of this file

       */

     public AudioFile read(File f) throws CannotReadException, IOException, TagException, ReadOnlyFileException, InvalidAudioFrameException

     {

         if (!f.canRead())

         {

             throw new CannotReadException(ErrorMessage.GENERAL_READ_FAILED_FILE_TOO_SMALL.getMsg(f.getAbsolutePath()));

         }

         if (f.length() <= MINIMUM_SIZE_FOR_VALID_AUDIO_FILE)

         {

             throw new CannotReadException(ErrorMessage.GENERAL_READ_FAILED_FILE_TOO_SMALL.getMsg(f.getAbsolutePath()));

         }

         RandomAccessFile raf = null;

         try

         {

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

             raf.seek(0);

             GenericAudioHeader info = getEncodingInfo(raf);

             raf.seek(0);

             Tag tag = getTag(raf);

             return new AudioFile(f, info, tag);

         }

         catch (CannotReadException cre)

         {

             throw cre;

         }

         catch (Exception e)

         {

             //TODO is this masking exceptions, i.e NullBoxIDException get converted to CannotReadException

             throw new CannotReadException(f.getAbsolutePath()+":" + e.getMessage(), e);

         }

         finally

         {

             try

             {

                 if (raf != null)

                 {

                     raf.close();

                 }

             }

             catch (Exception ex)

             {

                 logger.log(Level.WARNING, ErrorMessage.GENERAL_READ_FAILED_UNABLE_TO_CLOSE_RANDOM_ACCESS_FILE.getMsg(f.getAbsolutePath()));

             }

         }

     }

 }