public static int BytesPerPiece(this ITorrentInfo self, int pieceIndex)
{
if (self.IsV1Only())
{
if (pieceIndex < self.PieceCount() - 1)
{
return(self.PieceLength);
}
return((int)(self.Size - self.PieceIndexToByteOffset(pieceIndex)));
}
else if (self.IsV2Only())
{
for (int i = 0; i < self.Files.Count; i++)
{
var file = self.Files[i];
if (pieceIndex < file.StartPieceIndex || pieceIndex > file.EndPieceIndex)
{
continue;
}
var remainder = file.Length - (pieceIndex - file.StartPieceIndex) * self.PieceLength;
return((int)(remainder > self.PieceLength ? self.PieceLength : remainder));
}
throw new ArgumentOutOfRangeException(nameof(pieceIndex));
}
else
{
throw new NotSupportedException("hybrid torrents aren't supported");
}
}
/// <summary>
/// The number of pieces in the torrent
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static int PieceCount(this ITorrentInfo self)
{
if (self.IsV1Only())
{
return((int)((self.Size + self.PieceLength - 1) / self.PieceLength));
}
else if (self.IsV2Only())
{
return(self.Files[self.Files.Count - 1].EndPieceIndex + 1);
}
else
{
throw new NotSupportedException();
}
}
public static long PieceIndexToByteOffset(this ITorrentInfo self, int pieceIndex)
{
if (self.IsV1Only())
{
return((long)(long)self.PieceLength * pieceIndex);
}
else if (self.IsV2Only())
{
for (int i = 0; i < self.Files.Count; i++)
{
var file = self.Files[i];
if (pieceIndex < file.StartPieceIndex || pieceIndex > file.EndPieceIndex)
{
continue;
}
return(file.OffsetInTorrent + ((pieceIndex - file.StartPieceIndex) * (long)self.PieceLength));
}
throw new ArgumentOutOfRangeException(nameof(pieceIndex));
}
else
{
throw new NotSupportedException("Hybrid torrents aren't supported");
}
}
public static int ByteOffsetToPieceIndex(this ITorrentInfo self, long offset)
{
if (self.IsV1Only())
{
return((int)(offset / self.PieceLength));
}
else if (self.IsV2Only())
{
for (int i = 0; i < self.Files.Count; i++)
{
var file = self.Files[i];
if (offset < file.OffsetInTorrent || offset >= file.OffsetInTorrent + file.Length)
{
continue;
}
return(file.StartPieceIndex + (int)((offset - file.OffsetInTorrent) / self.PieceLength));
}
throw new ArgumentOutOfRangeException(nameof(offset));
}
else
{
throw new NotSupportedException("Hybrid torrents aren't supported");
}
}
public static int BlocksPerPiece(this ITorrentInfo self, int pieceIndex) => (BytesPerPiece(self, pieceIndex) + Constants.BlockSize - 1) / Constants.BlockSize;
static bool IsHybrid(this ITorrentInfo self) => self.InfoHashes.IsHybrid;
static bool IsV2Only(this ITorrentInfo self) => self.InfoHashes.V1 == null && self.InfoHashes.V2 != null;
