package org.jaudiotagger.tag.mp4.field;

 import org.jaudiotagger.audio.generic.Utils;

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

 import org.jaudiotagger.tag.FieldDataInvalidException;

 import org.jaudiotagger.tag.mp4.Mp4FieldKey;

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

 import java.io.UnsupportedEncodingException;

 import java.nio.ByteBuffer;

 /**

  * Represents a single byte as a number

  * <p/>

  * <p>Usually single byte fields are used as a boolean field, but not always so we dont do this conversion

  */

 public class Mp4TagByteField extends Mp4TagTextField

 {

     //Holds the actual size of the data content as held in the databoxitem, this is required when creating new

     //items because we cant accurately work out the size by looking at the content because sometimes field must be longer

     //than is actually required to hold the value

     //e.g byte data length seems to be 1 for pgap and cpil but 2 for tmpo, so we stored the dataSize

     //when we loaded the value so if greater than 1 we pad the value.

     private int realDataLength;

     //Preserved from data from file

     private byte[] bytedata;

     /**

      * Create new field

      * <p/>

      * Assume length of 1 which is correct for most but not all byte fields

      *

      * @param id

      * @param value is a String representation of a number

      */

     public Mp4TagByteField(Mp4FieldKey id, String value) throws FieldDataInvalidException

     {

         this(id, value, 1);

     }

     /**

      * Create new field with known length

      *

      * @param id

      * @param value is a String representation of a number

      */

     public Mp4TagByteField(Mp4FieldKey id, String value, int realDataLength) throws FieldDataInvalidException

     {

         super(id.getFieldName(), value);

         this.realDataLength = realDataLength;

         //Check that can actually be store dnumercially, otherwise will have big problems

         //when try and save the field

         try

         {

             Long.parseLong(value);

         }

         catch (NumberFormatException nfe)

         {

             throw new FieldDataInvalidException("Value of:" + value + " is invalid for field:" + id);

         }

     }

     /**

      * Construct from rawdata from audio file

      *

      * @param id

      * @param raw

      * @throws UnsupportedEncodingException

      */

     public Mp4TagByteField(String id, ByteBuffer raw) throws UnsupportedEncodingException

     {

         super(id, raw);

     }

     public Mp4FieldType getFieldType()

     {

         return Mp4FieldType.BYTE;

     }

     /**

      * Return raw data bytes

      * <p/>

      * TODO this code should be done better so generalised to any length

      *

      * @return

      * @throws UnsupportedEncodingException

      */

     protected byte[] getDataBytes() throws UnsupportedEncodingException

     {

         //Write original data

         if (bytedata != null)

         {

             return bytedata;

         }

         //new field, lets hope the realDataLength is correct

         switch (realDataLength)

         {

             case 2:

             {

                 //Save as two bytes

                 Short shortValue = new Short(content);

                 byte rawData[] = Utils.getSizeBEInt16(shortValue);

                 return rawData;

             }

             case 1:

             {

                 //Save as 1 bytes

                 Short shortValue = new Short(content);

                 byte rawData[] = new byte[1];

                 rawData[0] = shortValue.byteValue();

                 return rawData;

             }

             case 4:

             {

                 //Assume could be int

                 Integer intValue = new Integer(content);

                 byte rawData[] = Utils.getSizeBEInt32(intValue);

                 return rawData;

             }

             default:

             {

                 //TODO

                 throw new RuntimeException(id + ":" + realDataLength + ":" + "Dont know how to write byte fields of this length");

             }

         }

     }

     protected void build(ByteBuffer data) throws UnsupportedEncodingException

     {

         //Data actually contains a 'Data' Box so process data using this

         Mp4BoxHeader header = new Mp4BoxHeader(data);

         Mp4DataBox databox = new Mp4DataBox(header, data);

         dataSize = header.getDataLength();

         //Needed for subsequent write

         realDataLength = dataSize - Mp4DataBox.PRE_DATA_LENGTH;

         bytedata = databox.getByteData();

         content = databox.getContent();

     }

 }