Implement deep-linking for threads (matrix.to) (#7003)

src/MatrixClientPeg.ts

@@ -295,6 +295,7 @@ class MatrixClientPegClass implements IMatrixClientPeg {
 
         const notifTimelineSet = new EventTimelineSet(null, {
             timelineSupport: true,
+            pendingEvents: false,
         });
         // XXX: what is our initial pagination token?! it somehow needs to be synchronised with /sync.
         notifTimelineSet.getLiveTimeline().setPaginationToken("", EventTimeline.BACKWARDS);

src/components/structures/RightPanel.tsx

@@ -75,6 +75,8 @@ interface IState {
     groupRoomId?: string;
     groupId?: string;
     event: MatrixEvent;
+    initialEvent?: MatrixEvent;
+    initialEventHighlighted?: boolean;
 }
 
 @replaceableComponent("structures.RightPanel")
@@ -209,6 +211,8 @@ export default class RightPanel extends React.Component<IProps, IState> {
                 groupId: payload.groupId,
                 member: payload.member,
                 event: payload.event,
+                initialEvent: payload.initialEvent,
+                initialEventHighlighted: payload.highlighted,
                 verificationRequest: payload.verificationRequest,
                 verificationRequestPromise: payload.verificationRequestPromise,
                 widgetId: payload.widgetId,
@@ -244,7 +248,7 @@ export default class RightPanel extends React.Component<IProps, IState> {
         }
     };
 
-    render() {
+    public render(): JSX.Element {
         let panel = <div />;
         const roomId = this.props.room ? this.props.room.roomId : undefined;
 
@@ -327,6 +331,8 @@ export default class RightPanel extends React.Component<IProps, IState> {
                     resizeNotifier={this.props.resizeNotifier}
                     onClose={this.onClose}
                     mxEvent={this.state.event}
+                    initialEvent={this.state.initialEvent}
+                    initialEventHighlighted={this.state.initialEventHighlighted}
                     permalinkCreator={this.props.permalinkCreator}
                     e2eStatus={this.props.e2eStatus} />;
                 break;

src/components/structures/RoomView.tsx

@@ -92,6 +92,8 @@ import SpaceStore from "../../stores/SpaceStore";
 
 import { logger } from "matrix-js-sdk/src/logger";
 import { EventTimeline } from 'matrix-js-sdk/src/models/event-timeline';
+import { dispatchShowThreadEvent } from '../../dispatcher/dispatch-actions/threads';
+import { fetchInitialEvent } from "../../utils/EventUtils";
 
 const DEBUG = false;
 let debuglog = function(msg: string) {};
@@ -321,7 +323,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         });
     };
 
-    private onRoomViewStoreUpdate = (initial?: boolean) => {
+    private onRoomViewStoreUpdate = async (initial?: boolean): Promise<void> => {
         if (this.unmounted) {
             return;
         }
@@ -349,8 +351,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
             roomLoading: RoomViewStore.isRoomLoading(),
             roomLoadError: RoomViewStore.getRoomLoadError(),
             joining: RoomViewStore.isJoining(),
-            initialEventId: RoomViewStore.getInitialEventId(),
-            isInitialEventHighlighted: RoomViewStore.isInitialEventHighlighted(),
             replyToEvent: RoomViewStore.getQuotingEvent(),
             // we should only peek once we have a ready client
             shouldPeek: this.state.matrixClientIsReady && RoomViewStore.shouldPeek(),
@@ -362,6 +362,39 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
             wasContextSwitch: RoomViewStore.getWasContextSwitch(),
         };
 
+        const initialEventId = RoomViewStore.getInitialEventId();
+        if (initialEventId) {
+            const room = this.context.getRoom(roomId);
+            let initialEvent = room?.findEventById(initialEventId);
+            // The event does not exist in the current sync data
+            // We need to fetch it to know whether to route this request
+            // to the main timeline or to a threaded one
+            // In the current state, if a thread does not exist in the sync data
+            // We will only display the event targeted by the `matrix.to` link
+            // and the root event.
+            // The rest will be lost for now, until the aggregation API on the server
+            // becomes available to fetch a whole thread
+            if (!initialEvent) {
+                initialEvent = await fetchInitialEvent(
+                    this.context,
+                    roomId,
+                    initialEventId,
+                );
+            }
+
+            const thread = initialEvent?.getThread();
+            if (thread && !initialEvent?.isThreadRoot) {
+                dispatchShowThreadEvent(
+                    thread.rootEvent,
+                    initialEvent,
+                    RoomViewStore.isInitialEventHighlighted(),
+                );
+            } else {
+                newState.initialEventId = initialEventId;
+                newState.isInitialEventHighlighted = RoomViewStore.isInitialEventHighlighted();
+            }
+        }
+
         // Add watchers for each of the settings we just looked up
         this.settingWatchers = this.settingWatchers.concat([
             SettingsStore.watchSetting("showReadReceipts", roomId, (...[,,, value]) =>

src/components/structures/ThreadPanel.tsx

@@ -67,6 +67,7 @@ const useFilteredThreadsTimelinePanel = ({
     const timelineSet = useMemo(() => new EventTimelineSet(null, {
         timelineSupport: true,
         unstableClientRelationAggregation: true,
+        pendingEvents: false,
     }), []);
 
     useEffect(() => {

src/components/structures/ThreadView.tsx

@@ -45,6 +45,8 @@ interface IProps {
     mxEvent: MatrixEvent;
     permalinkCreator?: RoomPermalinkCreator;
     e2eStatus?: E2EStatus;
+    initialEvent?: MatrixEvent;
+    initialEventHighlighted?: boolean;
 }
 
 interface IState {
@@ -102,19 +104,19 @@ export default class ThreadView extends React.Component<IProps, IState> {
             }
         }
         switch (payload.action) {
-            case Action.EditEvent: {
+            case Action.EditEvent:
                 // Quit early if it's not a thread context
                 if (payload.timelineRenderingType !== TimelineRenderingType.Thread) return;
                 // Quit early if that's not a thread event
                 if (payload.event && !payload.event.getThread()) return;
-                const editState = payload.event ? new EditorStateTransfer(payload.event) : null;
-                this.setState({ editState }, () => {
+                this.setState({
+                    editState: payload.event ? new EditorStateTransfer(payload.event) : null,
+                }, () => {
                     if (payload.event) {
                         this.timelinePanelRef.current?.scrollToEventIfNeeded(payload.event.getId());
                     }
                 });
                 break;
-            }
             case 'reply_to_event':
                 if (payload.context === TimelineRenderingType.Thread) {
                     this.setState({
@@ -131,7 +133,11 @@ export default class ThreadView extends React.Component<IProps, IState> {
         let thread = mxEv.getThread();
         if (!thread) {
             const client = MatrixClientPeg.get();
-            thread = new Thread([mxEv], this.props.room, client);
+            thread = new Thread(
+                [mxEv],
+                this.props.room,
+                client,
+            );
             mxEv.setThread(thread);
         }
         thread.on(ThreadEvent.Update, this.updateThread);
@@ -163,7 +169,22 @@ export default class ThreadView extends React.Component<IProps, IState> {
         this.timelinePanelRef.current?.refreshTimeline();
     };
 
+    private onScroll = (): void => {
+        if (this.props.initialEvent && this.props.initialEventHighlighted) {
+            dis.dispatch({
+                action: 'view_room',
+                room_id: this.props.room.roomId,
+                event_id: this.props.initialEvent?.getId(),
+                highlighted: false,
+                replyingToEvent: this.state.replyToEvent,
+            });
+        }
+    };
+
     public render(): JSX.Element {
+        const highlightedEventId = this.props.initialEventHighlighted
+            ? this.props.initialEvent?.getId()
+            : null;
         return (
             <RoomContext.Provider value={{
                 ...this.context,
@@ -197,6 +218,9 @@ export default class ThreadView extends React.Component<IProps, IState> {
                             permalinkCreator={this.props.permalinkCreator}
                             membersLoaded={true}
                             editState={this.state.editState}
+                            eventId={this.props.initialEvent?.getId()}
+                            highlightedEventId={highlightedEventId}
+                            onUserScroll={this.onScroll}
                         />
                     ) }
 

src/components/views/rooms/EventTile.tsx

@@ -574,7 +574,9 @@ export default class EventTile extends React.Component<IProps, IState> {
             <div
                 className="mx_ThreadInfo"
                 onClick={() => {
-                    dispatchShowThreadEvent(this.props.mxEvent);
+                    dispatchShowThreadEvent(
+                        this.props.mxEvent,
+                    );
                 }}
             >
                 <span className="mx_ThreadInfo_thread-icon" />

src/dispatcher/dispatch-actions/threads.ts

@@ -19,12 +19,18 @@ import { Action } from "../actions";
 import dis from '../dispatcher';
 import { SetRightPanelPhasePayload } from "../payloads/SetRightPanelPhasePayload";
 
-export const dispatchShowThreadEvent = (event: MatrixEvent) => {
+export const dispatchShowThreadEvent = (
+    rootEvent: MatrixEvent,
+    initialEvent?: MatrixEvent,
+    highlighted?: boolean,
+) => {
     dis.dispatch({
         action: Action.SetRightPanelPhase,
         phase: RightPanelPhases.ThreadView,
         refireParams: {
-            event,
+            event: rootEvent,
+            initialEvent,
+            highlighted,
         },
     });
 };

src/utils/EventUtils.ts

@@ -21,6 +21,9 @@ import shouldHideEvent from "../shouldHideEvent";
 import { getHandlerTile, haveTileForEvent } from "../components/views/rooms/EventTile";
 import SettingsStore from "../settings/SettingsStore";
 import { EventType } from "matrix-js-sdk/src/@types/event";
+import { MatrixClient } from 'matrix-js-sdk/src/client';
+import { Thread } from 'matrix-js-sdk/src/models/thread';
+import { logger } from 'matrix-js-sdk/src/logger';
 
 /**
  * Returns whether an event should allow actions like reply, reactions, edit, etc.
@@ -158,3 +161,37 @@ export function isVoiceMessage(mxEvent: MatrixEvent): boolean {
         !!content['org.matrix.msc3245.voice']
     );
 }
+
+export async function fetchInitialEvent(
+    client: MatrixClient,
+    roomId: string,
+    eventId: string): Promise<MatrixEvent | null> {
+    let initialEvent: MatrixEvent;
+
+    try {
+        const eventData = await client.fetchRoomEvent(roomId, eventId);
+        initialEvent = new MatrixEvent(eventData);
+    } catch (e) {
+        logger.warn("Could not find initial event: " + initialEvent.threadRootId);
+        initialEvent = null;
+    }
+
+    if (initialEvent?.isThreadRelation) {
+        try {
+            const rootEventData = await client.fetchRoomEvent(roomId, initialEvent.threadRootId);
+            const rootEvent = new MatrixEvent(rootEventData);
+            const room = client.getRoom(roomId);
+            const thread = new Thread(
+                [rootEvent],
+                room,
+                client,
+            );
+            thread.addEvent(initialEvent);
+            room.threads.set(thread.id, thread);
+        } catch (e) {
+            logger.warn("Could not find root event: " + initialEvent.threadRootId);
+        }
+    }
+
+    return initialEvent;
+}