media/transfer: add function to directly download bytes

Signed-off-by: Sumner Evans <sumner.evans@automattic.com>

pkg/connector/chatinfo.go

@@ -151,8 +151,7 @@ func (t *TelegramClient) avatarFromPhoto(photo tg.PhotoClass) *bridgev2.Avatar {
 	return &bridgev2.Avatar{
 		ID: ids.MakeAvatarID(photo.GetID()),
 		Get: func(ctx context.Context) (data []byte, err error) {
-			data, _, err = media.NewTransferer(t.client.API()).WithPhoto(photo).Download(ctx)
-			return
+			return media.NewTransferer(t.client.API()).WithPhoto(photo).DownloadBytes(ctx)
 		},
 	}
 }

pkg/connector/client.go

@@ -556,8 +556,7 @@ func (t *TelegramClient) getUserInfoFromTelegramUser(ctx context.Context, u tg.U
 				if err != nil {
 					return nil, err
 				}
-				data, _, err = transferer.Download(ctx)
-				return
+				return transferer.DownloadBytes(ctx)
 			},
 		}
 	}

pkg/connector/media/transfer.go

@@ -83,7 +83,6 @@ func getLocationID(loc any) (locID store.TelegramFileLocationID) {
 
 // Transferer is a utility for downloading media from Telegram and uploading it
 // to Matrix.
-// TODO better name?
 type Transferer struct {
 	client downloader.Client
 
@@ -247,7 +246,7 @@ func (t *ReadyTransferer) Transfer(ctx context.Context, store *store.Container,
 		return file.MXC, nil, &t.inner.fileInfo, nil
 	}
 
-	data, _, err := t.Download(ctx)
+	data, err := t.DownloadBytes(ctx)
 	if err != nil {
 		return "", nil, nil, fmt.Errorf("downloading file failed: %w", err)
 	}
@@ -344,6 +343,13 @@ func (t *ReadyTransferer) Download(ctx context.Context) ([]byte, *event.FileInfo
 	return buf.Bytes(), &t.inner.fileInfo, nil
 }
 
+// DownloadBytes downloads the media from Telegram to a byte buffer.
+func (t *ReadyTransferer) DownloadBytes(ctx context.Context) ([]byte, error) {
+	var buf bytes.Buffer
+	_, err := downloader.NewDownloader().Download(t.inner.client, t.loc).Stream(ctx, &buf)
+	return buf.Bytes(), err
+}
+
 // DirectDownloadURL returns the direct download URL for the media.
 func (t *ReadyTransferer) DirectDownloadURL(ctx context.Context, loggedInUserID int64, portal *bridgev2.Portal, msgID int, thumbnail bool, telegramMediaID int64) (id.ContentURIString, *event.FileInfo, error) {
 	peerType, chatID, err := ids.ParsePortalID(portal.ID)

pkg/connector/telegram.go

@@ -477,8 +477,7 @@ func (t *TelegramClient) updateChannel(ctx context.Context, channel *tg.Channel)
 		avatar = &bridgev2.Avatar{
 			ID: ids.MakeAvatarID(photo.PhotoID),
 			Get: func(ctx context.Context) (data []byte, err error) {
-				data, _, err = media.NewTransferer(t.client.API()).WithChannelPhoto(channel.ID, channel.AccessHash, photo.PhotoID).Download(ctx)
-				return
+				return media.NewTransferer(t.client.API()).WithChannelPhoto(channel.ID, channel.AccessHash, photo.PhotoID).DownloadBytes(ctx)
 			},
 		}
 	}