backfill: implement marking read

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

pkg/connector/backfill.go

@@ -218,9 +218,17 @@ func (t *TelegramClient) FetchMessages(ctx context.Context, fetchParams bridgev2
 		return nil, err
 	}
 
-	var markRead bool // TODO implement
 	messages := msgs.GetMessages()
 
+	portal, err := t.main.Bridge.GetPortalByKey(ctx, fetchParams.Portal.PortalKey)
+	if err != nil {
+		return nil, err
+	}
+
+	// If the first message is the last read message, mark the chat as read
+	// during backfill.
+	markRead := fetchParams.Forward && portal.Metadata.(*PortalMetadata).ReadUpTo == messages[0].GetID()
+
 	var cursor networkid.PaginationCursor
 	if len(messages) > 0 {
 		cursor = ids.MakePaginationCursorID(messages[len(messages)-1].GetID())
@@ -248,11 +256,6 @@ func (t *TelegramClient) FetchMessages(ctx context.Context, fetchParams bridgev2
 		}
 		message := msg.(*tg.Message)
 
-		portal, err := t.main.Bridge.GetPortalByKey(ctx, fetchParams.Portal.PortalKey)
-		if err != nil {
-			return nil, err
-		}
-
 		sender := t.getEventSender(message)
 		intent := portal.GetIntentFor(ctx, sender, t.userLogin, bridgev2.RemoteEventBackfill)
 		converted, err := t.convertToMatrix(ctx, portal, intent, message)

pkg/connector/config.go

@@ -146,6 +146,7 @@ type GhostMetadata struct {
 
 type PortalMetadata struct {
 	IsSuperGroup bool `json:"is_supergroup,omitempty"`
+	ReadUpTo     int  `json:"read_up_to,omitempty"`
 }
 
 type MessageMetadata struct {

pkg/connector/sync.go

@@ -94,6 +94,9 @@ func (t *TelegramClient) handleDialogs(ctx context.Context, dialogs tg.ModifiedM
 			log.Err(err).Msg("Failed to get portal")
 			continue
 		}
+		if dialog.UnreadCount == 0 && !dialog.UnreadMark {
+			portal.Metadata.(*PortalMetadata).ReadUpTo = dialog.TopMessage
+		}
 
 		// If this is a DM, make sure that the user isn't deleted.
 		if user, ok := dialog.Peer.(*tg.PeerUser); ok {