move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/telegram/uploader/part.go

@@ -0,0 +1,82 @@
+package uploader
+
+import (
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/constant"
+)
+
+// https://core.telegram.org/api/files#uploading-files
+const (
+	// Use upload.saveBigFilePart in case the full size of the file is more than 10 MB
+	// and upload.saveFilePart for smaller files.
+	bigFileLimit = constant.UploadMaxSmallSize
+
+	// Each part should have a sequence number, file_part, with a value ranging from 0 to 3,999.
+	partsLimit = constant.UploadMaxParts
+
+	defaultPartSize = 128 * 1024 // 128 KB
+	// The file’s binary content is then split into parts. All parts must have the same size (part_size)
+	// and the following conditions must be met:
+
+	// `part_size % 1024 = 0` (divisible by 1KB)
+	paddingPartSize = constant.UploadPadding
+
+	// MaximumPartSize is maximum size of single part.
+	MaximumPartSize = constant.UploadMaxPartSize
+)
+
+func checkPartSize(partSize int) error {
+	switch {
+	case partSize == 0:
+		return errors.New("is equal to zero")
+	case partSize%paddingPartSize != 0:
+		return errors.Errorf("%d is not divisible by %d", partSize, paddingPartSize)
+	case MaximumPartSize%partSize != 0:
+		return errors.Errorf("%d is not divisible by %d", MaximumPartSize, partSize)
+	}
+
+	return nil
+}
+
+func computeParts(partSize, total int) int {
+	if total <= 0 {
+		return 0
+	}
+
+	parts := total / partSize
+	if total%partSize != 0 {
+		parts++
+	}
+	return parts
+}
+
+func (u *Uploader) initUpload(upload *Upload) error {
+	big := upload.totalBytes > bigFileLimit
+	totalParts := computeParts(u.partSize, int(upload.totalBytes))
+	if !big && totalParts > partsLimit {
+		return errors.Errorf(
+			"part size is too small: total size = %d, part size = %d, %d / %d > %d",
+			upload.totalBytes, u.partSize, upload.totalBytes, u.partSize, partsLimit,
+		)
+	}
+
+	if upload.id == 0 {
+		id, err := u.id()
+		if err != nil {
+			return errors.Wrap(err, "id generation")
+		}
+
+		upload.id = id
+		upload.partSize = u.partSize
+	} else if upload.partSize != u.partSize {
+		return errors.Errorf(
+			"previous upload has part size %d, but uploader size is %d",
+			upload.partSize, u.partSize,
+		)
+	}
+
+	upload.big = big
+	upload.totalParts = totalParts
+	return nil
+}