/// <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);
ApeHeader headerOrFooter = ReadHeader(sb, tagOrigin);
if (headerOrFooter == null)
return null;
// Don't throw an exception; just return here. The read header could be a false match.
if (headerOrFooter.Size > ApeTag.MaxAllowedSize)
return null;
ApeTag tag = new ApeTag(headerOrFooter.Version, headerOrFooter.Flags);
long startOffset, endOffset;
ApeHeader header = null, footer = null;
if (tag.IsHeader)
{
header = headerOrFooter;
startOffset = header.Position;
endOffset = Math.Min(startOffset + ApeTag.HeaderSize + header.Size, sb.Length);
if (endOffset > sb.Length)
{
#if DEBUG
throw new EndOfStreamException("Tag at start could not be read: stream is truncated.");
#else
return null;
#endif
}
tag.UseHeader = true;
}
else
{
footer = headerOrFooter;
endOffset = Math.Min(footer.Position + ApeTag.FooterSize, sb.Length);
startOffset = Math.Max(endOffset - footer.Size - (tag.UseHeader ? ApeTag.HeaderSize : 0), 0);
if (endOffset > sb.Length)
{
#if DEBUG
throw new EndOfStreamException("Tag at end could not be read: stream is truncated.");
#else
return null;
#endif
}
tag.UseFooter = true;
// Seek to the start of the tag.
sb.Seek(startOffset, SeekOrigin.Begin);
if (tag.UseHeader)
{
// Read the 'header' as if it was the start of the tag
header = ReadHeader(sb, TagOrigin.Start);
if (header == null)
{
// Size in the header could be off.
// Read the 'footer' as if it was at the end of the tag
sb.Seek(startOffset, SeekOrigin.Begin);
header = ReadHeader(sb, TagOrigin.End);
if (header == null)
{
tag.UseHeader = false;
sb.Seek(startOffset, SeekOrigin.Begin);
}
}
if (header != null)
{
startOffset = header.Position;
header.Size = (int)Math.Max(endOffset - (startOffset + ApeTag.HeaderSize), 0);
footer.Size = Math.Max(header.Size, footer.Size);
}
if (footer.Size > ApeTag.MaxAllowedSize)
{
#if DEBUG
throw new InvalidDataException(
String.Format("Size ({0}) is larger than the max allowed size ({1})", footer.Size, ApeTag.MaxAllowedSize));
#else
return null;
#endif
}
}
ValidateHeader(header, footer);
}
int totalSizeItems = Math.Max(headerOrFooter.Size - ApeTag.FooterSize, 0);
if ((sb.Length - sb.Position) < totalSizeItems)
{
#if DEBUG
throw new IndexOutOfRangeException(
String.Format("Ape field ({0}) is bigger than amount of bytes left in stream ({1}).", totalSizeItems, sb.Length - sb.Position));
#else
return null;
#endif
}
// Parse the individual frames.
List<ApeItem> items = new List<ApeItem>();
long bytesRead = 0;
while (bytesRead < totalSizeItems)
{
long startPosition = sb.Position;
ApeItem item = ApeItem.ReadFromStream(tag.Version, sb, totalSizeItems - bytesRead);
if (item != null)
{
ApeItemParseEventArgs parseEventArgs = new ApeItemParseEventArgs(item);
OnItemParse(parseEventArgs);
if (!parseEventArgs.Cancel)
{
if (parseEventArgs.Item != null)
item = parseEventArgs.Item;
if (item != null)
{
// Call after read event.
ApeItemParsedEventArgs parsedEventArgs = new ApeItemParsedEventArgs(item);
OnItemParsed(parsedEventArgs);
items.Add(parsedEventArgs.Item);
}
}
}
bytesRead += (sb.Position - startPosition);
}
#if DEBUG
//if (items.Count != headerOrFooter.FrameCount)
//throw new InvalidDataException("items.Count does not match FrameCount");
if (items.Count > ApeTag.MaxAllowedFields)
{
throw new InvalidDataException(
String.Format("Tag has more fields ('{0}') than the allowed max fields count ('{1}').", items.Count, ApeTag.MaxAllowedFields));
}
//if (bytesRead != totalSizeItems)
//{
// throw new InvalidDataException(
// String.Format("Amount of bytes read ({0}) does not match expected size ({1}).", bytesRead, totalSizeItems));
//}
#endif
if (tag.IsHeader && tag.UseFooter)
{
sb.Position += ApeTag.FooterSize;
footer = ReadHeader(sb, TagOrigin.End);
}
ValidateHeader(header, footer);
tag.SetItems(items);
return new AudioTagOffset(tagOrigin, startOffset, endOffset, tag);
}
/// <summary>
/// Raises the <see cref="ItemParsed"/> event.
/// </summary>
/// <param name="e">The <see cref="AudioVideoLib.Tags.ApeItemParsedEventArgs"/> instance containing the event data.</param>
private void OnItemParsed(ApeItemParsedEventArgs e)
{
EventHandler<ApeItemParsedEventArgs> eventHandlers = ItemParsed;
if (eventHandlers != null)
eventHandlers(this, e);
}
