Correctly mark received messages whose response came after /sync

include/timeline/TimelineItem.h

@@ -193,6 +193,7 @@ public:
         QString eventId() const { return event_id_; }
         void setEventId(const QString &event_id) { event_id_ = event_id; }
         void markReceived();
+        bool isReceived() { return isReceived_; };
         void setRoomId(QString room_id) { room_id_ = room_id; }
         void sendReadReceipt() const;
 
@@ -225,6 +226,10 @@ private:
         void setupAvatarLayout(const QString &userName);
         void setupSimpleLayout();
 
+        //! Whether or not the event associated with the widget
+        //! has been acknowledged by the server.
+        bool isReceived_ = false;
+
         QString replaceEmoji(const QString &body);
         QString event_id_;
         QString room_id_;

src/timeline/TimelineItem.cc

@@ -432,6 +432,7 @@ TimelineItem::TimelineItem(const mtx::events::RoomEvent<mtx::events::msg::Text>
 void
 TimelineItem::markReceived()
 {
+        isReceived_ = true;
         checkmark_->setText(CHECKMARK);
         checkmark_->setAlignment(Qt::AlignTop);
 

src/timeline/TimelineView.cc

@@ -602,11 +602,18 @@ TimelineView::updatePendingMessage(const std::string &txn_id, const QString &eve
 
                 if (msg.widget) {
                         msg.widget->setEventId(event_id);
-                        msg.widget->markReceived();
                         eventIds_[event_id] = msg.widget;
-                }
 
-                pending_sent_msgs_.append(msg);
+                        // If the response comes after we have received the event from sync
+                        // we've already marked the widget as received.
+                        if (!msg.widget->isReceived()) {
+                                msg.widget->markReceived();
+                                pending_sent_msgs_.append(msg);
+                        }
+                } else {
+                        nhlog::ui()->warn("[{}] received message response for invalid widget",
+                                          txn_id);
+                }
         }
 
         sendNextPendingMessage();
@@ -809,10 +816,10 @@ TimelineView::removePendingMessage(const std::string &txn_id)
         }
         for (auto it = pending_msgs_.begin(); it != pending_msgs_.end(); ++it) {
                 if (it->txn_id == txn_id) {
-                        int index = std::distance(pending_msgs_.begin(), it);
-                        pending_msgs_.removeAt(index);
+                        if (it->widget)
+                                it->widget->markReceived();
 
-                        nhlog::ui()->info("[{}] removed message before sync", txn_id);
+                        nhlog::ui()->info("[{}] received sync before message response", txn_id);
                         return;
                 }
         }