Implement MSC3869: Read event relations with the Widget API

package.json

@@ -94,7 +94,7 @@
     "matrix-encrypt-attachment": "^1.0.3",
     "matrix-events-sdk": "^0.0.1-beta.7",
     "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#develop",
-    "matrix-widget-api": "^1.0.0",
+    "matrix-widget-api": "^1.1.0",
     "minimist": "^1.2.5",
     "opus-recorder": "^8.0.3",
     "pako": "^2.0.3",

src/stores/widgets/StopGapWidgetDriver.ts

@@ -21,6 +21,7 @@ import {
     IOpenIDUpdate,
     ISendEventDetails,
     ITurnServer,
+    IReadEventRelationsResult,
     IRoomEvent,
     MatrixCapabilities,
     OpenIDRequestState,
@@ -37,6 +38,7 @@ import { IContent, IEvent, MatrixEvent } from "matrix-js-sdk/src/models/event";
 import { Room } from "matrix-js-sdk/src/models/room";
 import { logger } from "matrix-js-sdk/src/logger";
 import { THREAD_RELATION_TYPE } from "matrix-js-sdk/src/models/thread";
+import { Direction } from "matrix-js-sdk/src/matrix";
 
 import { iterableDiff, iterableIntersection } from "../../utils/iterables";
 import { MatrixClientPeg } from "../../MatrixClientPeg";
@@ -366,4 +368,50 @@ export class StopGapWidgetDriver extends WidgetDriver {
             client.off(ClientEvent.TurnServersError, onTurnServersError);
         }
     }
+
+    public async readEventRelations(
+        eventId: string,
+        roomId?: string,
+        relationType?: string,
+        eventType?: string,
+        from?: string,
+        to?: string,
+        limit?: number,
+        direction?: 'f' | 'b',
+    ): Promise<IReadEventRelationsResult> {
+        const client = MatrixClientPeg.get();
+        const dir =
+            direction && Object.values(Direction as Record<string, string>).includes(direction)
+                ? direction as Direction
+                : undefined;
+        const room = roomId !== undefined ? roomId : RoomViewStore.instance.getRoomId();
+
+        if (typeof room !== "string") {
+            throw new Error('Error while reading the current room');
+        }
+
+        const {
+            originalEvent,
+            events,
+            nextBatch,
+            prevBatch,
+        } = await client.relations(
+            room,
+            eventId,
+            relationType ?? null,
+            eventType ?? null,
+            {
+                from,
+                to,
+                limit,
+                direction: dir,
+            });
+
+        return {
+            originalEvent: originalEvent?.getEffectiveEvent(),
+            chunk: events.map(e => e.getEffectiveEvent()),
+            nextBatch,
+            prevBatch,
+        };
+    }
 }

test/stores/widgets/StopGapWidgetDriver-test.ts

@@ -15,11 +15,13 @@ limitations under the License.
 */
 
 import { mocked, MockedObject } from "jest-mock";
-import { Widget, WidgetKind, WidgetDriver, ITurnServer } from "matrix-widget-api";
-import { MatrixClient, ClientEvent, ITurnServer as IClientTurnServer } from "matrix-js-sdk/src/client";
+import { ClientEvent, ITurnServer as IClientTurnServer, MatrixClient } from "matrix-js-sdk/src/client";
 import { DeviceInfo } from "matrix-js-sdk/src/crypto/deviceinfo";
+import { Direction, MatrixEvent } from "matrix-js-sdk/src/matrix";
+import { ITurnServer, Widget, WidgetDriver, WidgetKind } from "matrix-widget-api";
 
 import { MatrixClientPeg } from "../../../src/MatrixClientPeg";
+import { RoomViewStore } from "../../../src/stores/RoomViewStore";
 import { StopGapWidgetDriver } from "../../../src/stores/widgets/StopGapWidgetDriver";
 import { stubClient } from "../../test-utils";
 
@@ -131,4 +133,124 @@ describe("StopGapWidgetDriver", () => {
             await servers.return(undefined);
         });
     });
+
+    describe("readEventRelations", () => {
+        it('reads related events from the current room', async () => {
+            jest.spyOn(RoomViewStore.instance, 'getRoomId').mockReturnValue('!this-room-id');
+
+            client.relations.mockResolvedValue({
+                originalEvent: new MatrixEvent(),
+                events: [],
+            });
+
+            await expect(driver.readEventRelations('$event')).resolves.toEqual({
+                originalEvent: expect.objectContaining({ content: {} }),
+                chunk: [],
+                nextBatch: undefined,
+                prevBatch: undefined,
+            });
+
+            expect(client.relations).toBeCalledWith('!this-room-id', '$event', null, null, {});
+        });
+
+        it('reads related events if the original event is missing', async () => {
+            client.relations.mockResolvedValue({
+                // the relations function can return an undefined event, even
+                // though the typings don't permit an undefined value.
+                originalEvent: undefined as any,
+                events: [],
+            });
+
+            await expect(driver.readEventRelations('$event', '!room-id')).resolves.toEqual({
+                originalEvent: undefined,
+                chunk: [],
+                nextBatch: undefined,
+                prevBatch: undefined,
+            });
+
+            expect(client.relations).toBeCalledWith('!room-id', '$event', null, null, {});
+        });
+
+        it('reads related events from a selected room', async () => {
+            client.relations.mockResolvedValue({
+                originalEvent: new MatrixEvent(),
+                events: [new MatrixEvent(), new MatrixEvent()],
+                nextBatch: 'next-batch-token',
+            });
+
+            await expect(driver.readEventRelations('$event', '!room-id')).resolves.toEqual({
+                originalEvent: expect.objectContaining({ content: {} }),
+                chunk: [
+                    expect.objectContaining({ content: {} }),
+                    expect.objectContaining({ content: {} }),
+                ],
+                nextBatch: 'next-batch-token',
+                prevBatch: undefined,
+            });
+
+            expect(client.relations).toBeCalledWith('!room-id', '$event', null, null, {});
+        });
+
+        it('reads related events with custom parameters', async () => {
+            client.relations.mockResolvedValue({
+                originalEvent: new MatrixEvent(),
+                events: [],
+            });
+
+            await expect(driver.readEventRelations(
+                '$event',
+                '!room-id',
+                'm.reference',
+                'm.room.message',
+                'from-token',
+                'to-token',
+                25,
+                'f',
+            )).resolves.toEqual({
+                originalEvent: expect.objectContaining({ content: {} }),
+                chunk: [],
+                nextBatch: undefined,
+                prevBatch: undefined,
+            });
+
+            expect(client.relations).toBeCalledWith(
+                '!room-id',
+                '$event',
+                'm.reference',
+                'm.room.message',
+                {
+                    limit: 25,
+                    from: 'from-token',
+                    to: 'to-token',
+                    direction: Direction.Forward,
+                },
+            );
+        });
+
+        it('should ignore invalid direction', async () => {
+            client.relations.mockResolvedValue({
+                originalEvent: new MatrixEvent(),
+                events: [],
+            });
+
+            await driver.readEventRelations(
+                '$event',
+                undefined,
+                undefined,
+                undefined,
+                undefined,
+                undefined,
+                undefined,
+                'q' as any,
+            );
+
+            expect(client.relations).toBeCalledWith(
+                '!this-room-id',
+                '$event',
+                null,
+                null,
+                { direction: undefined },
+            );
+        });
+    });
 });

yarn.lock

@@ -6782,10 +6782,10 @@ matrix-web-i18n@^1.3.0:
     "@babel/traverse" "^7.18.5"
     walk "^2.3.15"
 
-matrix-widget-api@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/matrix-widget-api/-/matrix-widget-api-1.0.0.tgz#0cde6839cca66ad817ab12aca3490ccc8bac97d1"
-  integrity sha512-cy8p/8EteRPTFIAw7Q9EgPUJc2jD19ZahMR8bMKf2NkILDcjuPMC0UWnsJyB3fSnlGw+VbGepttRpULM31zX8Q==
+matrix-widget-api@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/matrix-widget-api/-/matrix-widget-api-1.1.0.tgz#d17b6dccf307b0257263efd5259402ae25959853"
+  integrity sha512-c3jpH3gy0JEjhk81zuY2rbLbSA6EKmy733Ngq5uFr0i9xrFI38CFT8UxGOsc8d5RDtmWOQEq8Jpu1I0/DO114g==
   dependencies:
     "@types/events" "^3.0.0"
     events "^3.2.0"