feat(upload): add support for streamed uploads of Big File

[Streamed uploads](https://core.telegram.org/api/files#streamed-uploads)
- A total_stream_size variable must be used to keep track of the total
number of bytes read from the stream.

- upload.saveBigFilePart must always be used, even if the stream turns
out to be smaller than 10MB.

- The file_total_parts field must be set to -1 for all parts except for
the last one, using the following logic:

telegram/uploader/big.go

@@ -53,14 +53,22 @@ func (u *Uploader) bigLoop(ctx context.Context, threads int, upload *Upload) err
 	r := syncio.NewReader(upload.from)
 	g.Go(func(ctx context.Context) error {
 		last := false
+		totalStreamSize := 0
 
 		for {
 			buf := u.pool.GetSize(u.partSize)
 
 			n, err := io.ReadFull(r, buf.Buf)
+			if n > 0 {
+				totalStreamSize += n
+			}
 			switch {
 			case errors.Is(err, io.ErrUnexpectedEOF):
 				last = true
+				if upload.totalParts == -1 {
+					totalParts := (totalStreamSize + u.partSize - 1) / u.partSize
+					upload.totalParts = int(totalParts)
+				}
 			case errors.Is(err, io.EOF):
 				u.pool.Put(buf)
 

telegram/uploader/helpers.go

@@ -60,6 +60,8 @@ func (u *Uploader) FromFS(ctx context.Context, filesystem fs.FS, path string) (_
 // FromReader uploads file from given io.Reader.
 // NB: totally stream should not exceed the limit for
 // small files (10 MB as docs says, may be a bit bigger).
+// Support For Big Files
+// https://core.telegram.org/api/files#streamed-uploads
 func (u *Uploader) FromReader(ctx context.Context, name string, f io.Reader) (tg.InputFileClass, error) {
 	return u.Upload(ctx, NewUpload(name, f, -1))
 }

telegram/uploader/uploader.go

@@ -82,6 +82,10 @@ func (u *Uploader) Upload(ctx context.Context, upload *Upload) (tg.InputFileClas
 	if err := u.initUpload(upload); err != nil {
 		return nil, err
 	}
+	if upload.totalBytes == -1 {
+		upload.big = true
+		upload.totalParts = -1
+	}
 
 	if !upload.big {
 		return u.uploadSmall(ctx, upload)