////------------------------------------------------------------------------------------------------------------------------------
/// <inheritdoc/>
public IAudioTagOffset ReadFromStream(Stream stream, TagOrigin tagOrigin)
{
if (stream == null)
throw new ArgumentNullException("stream");
if (!stream.CanRead)
throw new InvalidOperationException("stream can not be read");
if (!stream.CanSeek)
throw new InvalidOperationException("stream can not be seeked");
StreamBuffer sb = stream as StreamBuffer ?? new StreamBuffer(stream);
long startOffset = FindIdentifier(sb, tagOrigin);
if (startOffset < 0)
return null;
long endOffset = 0;
if (tagOrigin == TagOrigin.End)
{
endOffset = startOffset + FooterIdentifierBytes.Length;
sb.Position = Math.Max(sb.Position - FooterIdentifierBytes.Length - Lyrics3v2Tag.TagSizeLength, 0);
string strTagSize = sb.ReadString(Lyrics3v2Tag.TagSizeLength);
long tagSize;
if (!Int64.TryParse(strTagSize, out tagSize))
{
#if DEBUG
throw new InvalidDataException(String.Format("Can't parse size value {0} before footer.", strTagSize));
#else
return null;
#endif
}
long currentPosition = sb.Position;
// The Lyrics3 block ends with a six character size descriptor and the string "LYRICS200".
// The size value includes the "LYRICSBEGIN" string, but does not include the 6 character size descriptor and the trailing "LYRICS200" string.
sb.Position = Math.Max(sb.Position - tagSize - Lyrics3v2Tag.TagSizeLength, 0);
startOffset = FindIdentifier(sb, TagOrigin.Start);
if (startOffset < 0)
{
// Header could be off
sb.Position = Math.Max(sb.Position - (tagSize - 5), 0);
if (sb.Position > 0)
{
startOffset = FindIdentifier(sb, TagOrigin.End);
if (startOffset < 0)
startOffset = sb.Position = currentPosition;
}
}
}
// Read the fields.
List<Lyrics3v2Field> fields = new List<Lyrics3v2Field>();
long bytesRead = HeaderIdentifierBytes.Length;
long streamLength = (endOffset > 0) ? endOffset : Math.Max(sb.Length, endOffset);
while (startOffset + bytesRead < streamLength)
{
long startPosition = sb.Position;
// Read field if needed.
Lyrics3v2Field field = Lyrics3v2Field.ReadFromStream(sb, streamLength - bytesRead);
if (field != null)
{
Lyrics3v2FieldParseEventArgs fieldParseEventArgs = new Lyrics3v2FieldParseEventArgs(field);
OnFieldParse(fieldParseEventArgs);
if (!fieldParseEventArgs.Cancel)
{
// Call after read event.
Lyrics3v2FieldParsedEventArgs parsedEventArgs = new Lyrics3v2FieldParsedEventArgs(field);
OnFieldParsed(parsedEventArgs);
fields.Add(field);
}
}
else
{
sb.Position = startPosition;
break;
}
bytesRead += (sb.Position - startPosition);
}
if (endOffset == 0)
{
// The Lyrics3 block ends with a six character size descriptor and the string "LYRICS200".
// The size value includes the "LYRICSBEGIN" string, but does not include the 6 character size descriptor and the trailing "LYRICS200" string.
string strTagSize = sb.ReadString(6);
long tagSize;
if (!Int64.TryParse(strTagSize, out tagSize))
{
#if DEBUG
throw new InvalidDataException(String.Format("Can't parse size value {0} before footer.", strTagSize));
#else
return null;
#endif
}
int bRead;
string footerIdentifier = sb.ReadString(FooterIdentifierBytes.Length, true, out bRead);
if (!String.Equals(footerIdentifier, Lyrics3v2Tag.FooterIdentifier))
{
#if DEBUG
throw new InvalidDataException(
String.Format("Footer identifier {0} not recognized; expected {1}", footerIdentifier, Lyrics3v2Tag.FooterIdentifier));
#else
sb.Position -= bRead;
#endif
}
endOffset = sb.Position;
}
#if DEBUG
long totalDataSize = (endOffset - startOffset) - Lyrics3v2Tag.TagSizeLength - FooterIdentifierBytes.Length;
//if (totalDataSize != bytesRead)
//{
// // If the amount of bytes we read doesn't match the size of the tag indicated in the header,
// throw new InvalidDataException(
// String.Format(
// "Amount of bytes read ({0}) does not match size indicated before footer ({1}).",
// totalDataSize,
// bytesRead));
//}
#endif
Lyrics3v2Tag tag = new Lyrics3v2Tag();
tag.SetFields(fields);
return new AudioTagOffset(tagOrigin, startOffset, endOffset, tag);
}
/// <summary>
/// Raises the <see cref="FieldParsed"/> event.
/// </summary>
/// <param name="e">The <see cref="AudioVideoLib.Tags.Lyrics3v2FieldParsedEventArgs"/> instance containing the event data.</param>
private void OnFieldParsed(Lyrics3v2FieldParsedEventArgs e)
{
EventHandler<Lyrics3v2FieldParsedEventArgs> eventHandlers = FieldParsed;
if (eventHandlers != null)
eventHandlers(this, e);
}
