/*

  * Entagged Audio Tag library

  * Copyright (c) 2003-2005 Raphaël 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.tag.mp4;

 import org.jaudiotagger.audio.generic.Utils;

 import org.jaudiotagger.audio.mp4.atom.Mp4BoxHeader;

 import org.jaudiotagger.tag.TagField;

 import org.jaudiotagger.tag.mp4.atom.Mp4DataBox;

 import org.jaudiotagger.tag.mp4.field.Mp4FieldType;

 import java.io.ByteArrayOutputStream;

 import java.io.IOException;

 import java.io.UnsupportedEncodingException;

 import java.nio.ByteBuffer;

 import java.util.logging.Logger;

 /**

  * This abstract class represents a link between piece of data, and how it is stored as an mp4 atom

  * <p/>

  * Note there isnt a one to one correspondance between a tag field and a box because some fields are represented

  * by multiple boxes, for example many of the MusicBrainz fields use the '----' box, which in turn uses one of mean,

  * name and data box. So an instance of a tag field maps to one item of data such as 'Title', but it may have to read

  * multiple boxes to do this.   

  * <p/>

  * There are various subclasses that represent different types of fields               

  */

 public abstract class Mp4TagField implements TagField

 {

     // Logger Object

     public static Logger logger = Logger.getLogger("org.jaudiotagger.tag.mp4");

     protected String id;

     //Just used by reverese dns class, so it knows the size of its aprent so it can detect end correctly

     protected Mp4BoxHeader parentHeader;

     protected Mp4TagField(String id)

     {

         this.id = id;

     }

     /**

      * Used by subclasses that canot identify their id until after they have been built such as ReverseDnsField

      *

      * @param data

      * @throws UnsupportedEncodingException

      */

     protected Mp4TagField(ByteBuffer data) throws UnsupportedEncodingException

     {

         build(data);

     }

     /**

      * Used by reverese dns when reading from file, so can identify when there is a data atom

      *

      * @param parentHeader

      * @param data

      * @throws UnsupportedEncodingException

      */

     protected Mp4TagField(Mp4BoxHeader parentHeader, ByteBuffer data) throws UnsupportedEncodingException

     {

         this.parentHeader = parentHeader;

         build(data);

     }

     protected Mp4TagField(String id, ByteBuffer data) throws UnsupportedEncodingException

     {

         this(id);

         build(data);

     }

     /**

      * @return field identifier

      */

     public String getId()

     {

         return id;

     }

     public void isBinary(boolean b)

     {

         /* One cannot choose if an arbitrary block can be binary or not */

     }

     public boolean isCommon()

     {

         return id.equals(Mp4FieldKey.ARTIST.getFieldName()) || id.equals(Mp4FieldKey.ALBUM.getFieldName()) || id.equals(Mp4FieldKey.TITLE.getFieldName()) || id.equals(Mp4FieldKey.TRACK.getFieldName()) || id.equals(Mp4FieldKey.DAY.getFieldName()) || id.equals(Mp4FieldKey.COMMENT.getFieldName()) || id.equals(Mp4FieldKey.GENRE.getFieldName());

     }

     /**

      * @return field identifier as it will be held within the file

      */

     protected byte[] getIdBytes()

     {

         return Utils.getDefaultBytes(getId(), "ISO-8859-1");

     }

     /**

      * @return the data as it is held on file

      * @throws UnsupportedEncodingException

      */

     protected abstract byte[] getDataBytes() throws UnsupportedEncodingException;

     /**

      * @return the field type of this field

      */

     public abstract Mp4FieldType getFieldType();

     /**

      * Processes the data and sets the position of the data buffer to just after the end of this fields data

      * ready for processing next field.

      *

      * @param data

      * @throws UnsupportedEncodingException

      */

     protected abstract void build(ByteBuffer data) throws UnsupportedEncodingException;

     /**

      * Convert back to raw content, includes parent and data atom as views as one thing externally

      *

      * @return

      * @throws UnsupportedEncodingException

      */

     public byte[] getRawContent() throws UnsupportedEncodingException

     {

         logger.fine("Getting Raw data for:" + getId());

         try

         {

             //Create Data Box

             byte[] databox = getRawContentDataOnly();

             //Wrap in Parent box

             ByteArrayOutputStream outerbaos = new ByteArrayOutputStream();

             outerbaos.write(Utils.getSizeBEInt32(Mp4BoxHeader.HEADER_LENGTH + databox.length));

             outerbaos.write(Utils.getDefaultBytes(getId(), "ISO-8859-1"));

             outerbaos.write(databox);

             return outerbaos.toByteArray();

         }

         catch (IOException ioe)

         {

             //This should never happen as were not actually writing to/from a file

             throw new RuntimeException(ioe);

         }

     }

     /**

      * Get raw content for the data component only

      *

      * @return

      * @throws UnsupportedEncodingException

      */

     public byte[] getRawContentDataOnly() throws UnsupportedEncodingException

     {

         logger.fine("Getting Raw data for:" + getId());

         try

         {

             //Create Data Box

             ByteArrayOutputStream baos = new ByteArrayOutputStream();

             byte[] data = getDataBytes();

             baos.write(Utils.getSizeBEInt32(Mp4DataBox.DATA_HEADER_LENGTH + data.length));

             baos.write(Utils.getDefaultBytes(Mp4DataBox.IDENTIFIER, "ISO-8859-1"));

             baos.write(new byte[]{0});

             baos.write(new byte[]{0, 0, (byte) getFieldType().getFileClassId()});

             baos.write(new byte[]{0, 0, 0, 0});

             baos.write(data);

             return baos.toByteArray();

         }

         catch (IOException ioe)

         {

             //This should never happen as were not actually writing to/from a file

             throw new RuntimeException(ioe);

         }

     }

 }