/*

  * 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.AbstractTagCreator;

 import org.jaudiotagger.audio.generic.Utils;

 import org.jaudiotagger.audio.mp4.Mp4NotMetaFieldKey;

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

 import org.jaudiotagger.tag.FieldKey;

 import org.jaudiotagger.tag.KeyNotFoundException;

 import org.jaudiotagger.tag.Tag;

 import org.jaudiotagger.tag.TagField;

 import org.jaudiotagger.tag.mp4.field.Mp4TagCoverField;

 import java.io.ByteArrayOutputStream;

 import java.io.IOException;

 import java.io.UnsupportedEncodingException;

 import java.nio.ByteBuffer;

 import java.util.Iterator;

 /**

  * Create raw content of mp4 tag data, concerns itself with atoms upto the ilst atom

  * <p/>

  * <p>This level is was selected because the ilst atom can be recreated without reference to existing mp4 fields

  * but fields above this level are dependent upon other information that is not held in the tag.

  * <p/>

  * <pre>

  * |--- ftyp

  * |--- moov

  * |......|

  * |......|----- mvdh

  * |......|----- trak

  * |......|----- udta

  * |..............|

  * |..............|-- meta

  * |....................|

  * |....................|-- hdlr

  * |....................|-- ilst

  * |....................|.. ..|

  * |....................|.....|---- @nam (Optional for each metadatafield)

  * |....................|.....|.......|-- data

  * |....................|.....|....... ecetera

  * |....................|.....|---- ---- (Optional for reverse dns field)

  * |....................|.............|-- mean

  * |....................|.............|-- name

  * |....................|.............|-- data

  * |....................|................ ecetere

  * |....................|-- free

  * |--- free

  * |--- mdat

  * </pre>

  */

 public class Mp4TagCreator extends AbstractTagCreator

 {

     /**

      * Convert tagdata to rawdata ready for writing to file

      *

      * @param tag

      * @param padding TODO padding parameter currently ignored

      * @return

      * @throws UnsupportedEncodingException

      */

     public ByteBuffer convert(Tag tag, int padding) throws UnsupportedEncodingException

     {

         try

         {

             //Add metadata raw content

             ByteArrayOutputStream baos = new ByteArrayOutputStream();

             Iterator<TagField> it = tag.getFields();

             boolean processedArtwork = false;

             while (it.hasNext())

             {

                 TagField frame = it.next();

                 //To ensure order is maintained dont process artwork until iterator hits it.

                 if (frame instanceof Mp4TagCoverField)

                 {

                     if (processedArtwork)

                     {

                         //ignore

                     }

                     else

                     {

                         processedArtwork = true;

                         //Because each artwork image is held within the tag as a seperate field, but when

                         //they are written they are all held under a single covr box we need to do some checks

                         //and special processing here if we have any artwork image (this code only neccessary

                         //if we have more than 1 but do it anyway even if only have 1 image)

                         ByteArrayOutputStream covrDataBaos = new ByteArrayOutputStream();

                         try

                         {

                             for (TagField artwork : tag.getFields(FieldKey.COVER_ART))

                             {

                                 covrDataBaos.write(((Mp4TagField) artwork).getRawContentDataOnly());

                             }

                         }

                         catch (KeyNotFoundException knfe)

                         {

                             //This cannot happen

                             throw new RuntimeException("Unable to find COVERART Key");

                         }

                         //Now create the parent Data

                         byte[] data = covrDataBaos.toByteArray();

                         baos.write(Utils.getSizeBEInt32(Mp4BoxHeader.HEADER_LENGTH + data.length));

                         baos.write(Utils.getDefaultBytes(Mp4FieldKey.ARTWORK.getFieldName(), "ISO-8859-1"));

                         baos.write(data);

                     }

                 }

                 else

                 {                     

                     baos.write(frame.getRawContent());

                 }

             }

             //Wrap into ilst box

             ByteArrayOutputStream ilst = new ByteArrayOutputStream();

             ilst.write(Utils.getSizeBEInt32(Mp4BoxHeader.HEADER_LENGTH + baos.size()));

             ilst.write(Utils.getDefaultBytes(Mp4NotMetaFieldKey.ILST.getFieldName(), "ISO-8859-1"));

             ilst.write(baos.toByteArray());

             //Put into ByteBuffer

             ByteBuffer buf = ByteBuffer.wrap(ilst.toByteArray());

             buf.rewind();

             return buf;

         }

         catch (IOException ioe)

         {

             //Should never happen as not writing to file at this point

             throw new RuntimeException(ioe);

         }

     }

 }