Fix edge cases around 2nd order relations and threads (#3437)

* Fix tests oversimplifying threads fixtures

* Check for unsigned thread_id in MatrixEvent::threadRootId

* Fix threads order being racy

* Make Sonar happier

* Iterate

spec/integ/matrix-client-event-timeline.spec.ts

@@ -1274,6 +1274,7 @@ describe("MatrixClient event timelines", function () {
             THREAD_ROOT.event_id,
             THREAD_REPLY.event_id,
             THREAD_REPLY2.getId(),
+            THREAD_ROOT_REACTION.getId(),
             THREAD_REPLY3.getId(),
         ]);
     });
@@ -1322,7 +1323,7 @@ describe("MatrixClient event timelines", function () {
             request.respond(200, function () {
                 return {
                     original_event: root,
-                    chunk: [replies],
+                    chunk: replies,
                     // no next batch as this is the oldest end of the timeline
                 };
             });
@@ -1479,7 +1480,7 @@ describe("MatrixClient event timelines", function () {
                     user: userId,
                     type: "m.room.message",
                     content: {
-                        "body": "thread reply",
+                        "body": "thread2 reply",
                         "msgtype": "m.text",
                         "m.relates_to": {
                             // We can't use the const here because we change server support mode for test
@@ -1499,7 +1500,7 @@ describe("MatrixClient event timelines", function () {
                     user: userId,
                     type: "m.room.message",
                     content: {
-                        "body": "thread reply",
+                        "body": "thread reply2",
                         "msgtype": "m.text",
                         "m.relates_to": {
                             // We can't use the const here because we change server support mode for test
@@ -1567,7 +1568,7 @@ describe("MatrixClient event timelines", function () {
                 // Test adding a second event to the first thread
                 const thread = room.getThread(THREAD_ROOT.event_id!)!;
                 thread.initialEventsFetched = true;
-                const prom = emitPromise(room, ThreadEvent.NewReply);
+                const prom = emitPromise(room, ThreadEvent.Update);
                 respondToEvent(THREAD_ROOT_UPDATED);
                 respondToEvent(THREAD_ROOT_UPDATED);
                 respondToEvent(THREAD_ROOT_UPDATED);

spec/unit/event-timeline-set.spec.ts

@@ -142,13 +142,6 @@ describe("EventTimelineSet", () => {
     });
 
     describe("addEventToTimeline", () => {
-        let thread: Thread;
-
-        beforeEach(() => {
-            (client.supportsThreads as jest.Mock).mockReturnValue(true);
-            thread = new Thread("!thread_id:server", messageEvent, { room, client });
-        });
-
         it("Adds event to timeline", () => {
             const liveTimeline = eventTimelineSet.getLiveTimeline();
             expect(liveTimeline.getEvents().length).toStrictEqual(0);
@@ -167,6 +160,15 @@ describe("EventTimelineSet", () => {
                 eventTimelineSet.addEventToTimeline(messageEvent, liveTimeline, true, false);
             }).not.toThrow();
         });
+    });
+
+    describe("addEventToTimeline (thread timeline)", () => {
+        let thread: Thread;
+
+        beforeEach(() => {
+            (client.supportsThreads as jest.Mock).mockReturnValue(true);
+            thread = new Thread("!thread_id:server", messageEvent, { room, client });
+        });
 
         it("should not add an event to a timeline that does not belong to the timelineSet", () => {
             const eventTimelineSet2 = new EventTimelineSet(room);
@@ -197,7 +199,14 @@ describe("EventTimelineSet", () => {
             const liveTimeline = eventTimelineSetForThread.getLiveTimeline();
             expect(liveTimeline.getEvents().length).toStrictEqual(0);
 
-            eventTimelineSetForThread.addEventToTimeline(messageEvent, liveTimeline, {
+            const normalMessage = utils.mkMessage({
+                room: roomId,
+                user: userA,
+                msg: "Hello!",
+                event: true,
+            });
+
+            eventTimelineSetForThread.addEventToTimeline(normalMessage, liveTimeline, {
                 toStartOfTimeline: true,
             });
             expect(liveTimeline.getEvents().length).toStrictEqual(0);
@@ -336,7 +345,9 @@ describe("EventTimelineSet", () => {
         });
 
         it("should return true if the timeline set is not for a thread and the event is a thread root", () => {
+            const thread = new Thread(messageEvent.getId()!, messageEvent, { room, client });
             const eventTimelineSet = new EventTimelineSet(room, {}, client);
+            messageEvent.setThread(thread);
             expect(eventTimelineSet.canContain(messageEvent)).toBeTruthy();
         });
 

src/models/event.ts

@@ -579,9 +579,18 @@ export class MatrixEvent extends TypedEventEmitter<MatrixEventEmittedEvents, Mat
         const relatesTo = this.getWireContent()?.["m.relates_to"];
         if (relatesTo?.rel_type === THREAD_RELATION_TYPE.name) {
             return relatesTo.event_id;
-        } else {
-            return this.getThread()?.id || this.threadId;
         }
+        if (this.thread) {
+            return this.thread.id;
+        }
+        if (this.threadId !== undefined) {
+            return this.threadId;
+        }
+        const unsigned = this.getUnsigned();
+        if (typeof unsigned[UNSIGNED_THREAD_ID_FIELD.name] === "string") {
+            return unsigned[UNSIGNED_THREAD_ID_FIELD.name];
+        }
+        return undefined;
     }
 
     /**
@@ -593,7 +602,7 @@ export class MatrixEvent extends TypedEventEmitter<MatrixEventEmittedEvents, Mat
         // Bundled relationships only returned when the sync response is limited
         // hence us having to check both bundled relation and inspect the thread
         // model
-        return !!threadDetails || this.getThread()?.id === this.getId();
+        return !!threadDetails || this.threadRootId === this.getId();
     }
 
     public get replyEventId(): string | undefined {

src/models/room.ts

@@ -1957,7 +1957,7 @@ export class Room extends ReadReceipt<RoomEmittedEvents, RoomEventHandlerMap> {
             }
         }
 
-        this.on(ThreadEvent.NewReply, this.onThreadNewReply);
+        this.on(ThreadEvent.Update, this.onThreadUpdate);
         this.on(ThreadEvent.Delete, this.onThreadDelete);
         this.threadsReady = true;
     }
@@ -2055,7 +2055,7 @@ export class Room extends ReadReceipt<RoomEmittedEvents, RoomEventHandlerMap> {
         }
     }
 
-    private onThreadNewReply(thread: Thread): void {
+    private onThreadUpdate(thread: Thread): void {
         this.updateThreadRootEvents(thread, false, true);
     }
 
@@ -2113,12 +2113,13 @@ export class Room extends ReadReceipt<RoomEmittedEvents, RoomEventHandlerMap> {
             };
         }
 
-        // A thread relation is always only shown in a thread
+        // A thread relation (1st and 2nd order) is always only shown in a thread
-        if (event.isRelation(THREAD_RELATION_TYPE.name)) {
+        const threadRootId = event.threadRootId;
+        if (threadRootId != undefined) {
             return {
                 shouldLiveInRoom: false,
                 shouldLiveInThread: true,
-                threadId: event.threadRootId,
+                threadId: threadRootId,
             };
         }
 
@@ -2149,15 +2150,6 @@ export class Room extends ReadReceipt<RoomEmittedEvents, RoomEventHandlerMap> {
             };
         }
 
-        const unsigned = event.getUnsigned();
-        if (typeof unsigned[UNSIGNED_THREAD_ID_FIELD.name] === "string") {
-            return {
-                shouldLiveInRoom: false,
-                shouldLiveInThread: true,
-                threadId: unsigned[UNSIGNED_THREAD_ID_FIELD.name],
-            };
-        }
-
         // We've exhausted all scenarios,
         // we cannot assume that it lives in the main timeline as this may be a relation for an unknown thread
         // adding the event in the wrong timeline causes stuck notifications and can break ability to send read receipts
@@ -2890,12 +2882,9 @@ export class Room extends ReadReceipt<RoomEmittedEvents, RoomEventHandlerMap> {
     private findThreadRoots(events: MatrixEvent[]): Set<string> {
         const threadRoots = new Set<string>();
         for (const event of events) {
-            if (event.isRelation(THREAD_RELATION_TYPE.name)) {
+            const threadRootId = event.threadRootId;
-                threadRoots.add(event.relationEventId ?? "");
+            if (threadRootId != undefined) {
-            }
+                threadRoots.add(threadRootId);
-            const unsigned = event.getUnsigned();
-            if (typeof unsigned[UNSIGNED_THREAD_ID_FIELD.name] === "string") {
-                threadRoots.add(unsigned[UNSIGNED_THREAD_ID_FIELD.name]!);
             }
         }
         return threadRoots;