Live beacons: track users live beacons

src/stores/OwnBeaconStore.ts

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+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import {
+    Beacon,
+    BeaconEvent,
+    MatrixEvent,
+    Room,
+} from "matrix-js-sdk/src/matrix";
+
+import defaultDispatcher from "../dispatcher/dispatcher";
+import { ActionPayload } from "../dispatcher/payloads";
+import { AsyncStoreWithClient } from "./AsyncStoreWithClient";
+
+const isOwnBeacon = (beacon: Beacon, userId: string): boolean => beacon.beaconInfoOwner === userId;
+
+export enum OwnBeaconStoreEvent {
+    LivenessChange = 'OwnBeaconStore.LivenessChange'
+}
+
+type OwnBeaconStoreState = {
+    beacons: Map<string, Beacon>;
+    beaconsByRoomId: Map<Room['roomId'], Set<string>>;
+    liveBeaconIds: string[];
+};
+export class OwnBeaconStore extends AsyncStoreWithClient<OwnBeaconStoreState> {
+    private static internalInstance = new OwnBeaconStore();
+    public readonly beacons = new Map<string, Beacon>();
+    public readonly beaconsByRoomId = new Map<Room['roomId'], Set<string>>();
+    private liveBeaconIds = [];
+
+    public constructor() {
+        super(defaultDispatcher);
+    }
+
+    public static get instance(): OwnBeaconStore {
+        return OwnBeaconStore.internalInstance;
+    }
+
+    protected async onNotReady() {
+        this.matrixClient.removeListener(BeaconEvent.LivenessChange, this.onBeaconLiveness);
+        this.matrixClient.removeListener(BeaconEvent.New, this.onNewBeacon);
+
+        this.beacons.forEach(beacon => beacon.destroy());
+
+        this.beacons.clear();
+        this.beaconsByRoomId.clear();
+        this.liveBeaconIds = [];
+    }
+
+    protected async onReady(): Promise<void> {
+        this.matrixClient.on(BeaconEvent.LivenessChange, this.onBeaconLiveness);
+        this.matrixClient.on(BeaconEvent.New, this.onNewBeacon);
+
+        this.initialiseBeaconState();
+    }
+
+    protected async onAction(payload: ActionPayload): Promise<void> {
+        // we don't actually do anything here
+    }
+
+    public hasLiveBeacons(roomId?: string): boolean {
+        return !!this.getLiveBeaconIds(roomId).length;
+    }
+
+    public getLiveBeaconIds(roomId?: string): string[] {
+        if (!roomId) {
+            return this.liveBeaconIds;
+        }
+        return this.liveBeaconIds.filter(beaconId => this.beaconsByRoomId.get(roomId)?.has(beaconId));
+    }
+
+    private onNewBeacon = (_event: MatrixEvent, beacon: Beacon): void => {
+        if (!isOwnBeacon(beacon, this.matrixClient.getUserId())) {
+            return;
+        }
+        this.addBeacon(beacon);
+        this.checkLiveness();
+    };
+
+    private onBeaconLiveness = (isLive: boolean, beacon: Beacon): void => {
+        // check if we care about this beacon
+        if (!this.beacons.has(beacon.beaconInfoId)) {
+            return;
+        }
+
+        if (!isLive && this.liveBeaconIds.includes(beacon.beaconInfoId)) {
+            this.liveBeaconIds =
+                this.liveBeaconIds.filter(beaconId => beaconId !== beacon.beaconInfoId);
+        }
+
+        if (isLive && !this.liveBeaconIds.includes(beacon.beaconInfoId)) {
+            this.liveBeaconIds.push(beacon.beaconInfoId);
+        }
+
+        this.emit(OwnBeaconStoreEvent.LivenessChange, this.hasLiveBeacons());
+        // TODO stop or start polling here
+        // if not content is live but beacon is not, update state event with live: false
+    };
+
+    private initialiseBeaconState = () => {
+        const userId = this.matrixClient.getUserId();
+        const visibleRooms = this.matrixClient.getVisibleRooms();
+
+        visibleRooms
+            .forEach(room => {
+                const roomState = room.currentState;
+                const beacons = roomState.beacons;
+                const ownBeaconsArray = [...beacons.values()].filter(beacon => isOwnBeacon(beacon, userId));
+                ownBeaconsArray.forEach(beacon => this.addBeacon(beacon));
+            });
+
+        this.checkLiveness();
+    };
+
+    private addBeacon = (beacon: Beacon): void => {
+        this.beacons.set(beacon.beaconInfoId, beacon);
+
+        if (!this.beaconsByRoomId.has(beacon.roomId)) {
+            this.beaconsByRoomId.set(beacon.roomId, new Set<string>());
+        }
+
+        this.beaconsByRoomId.get(beacon.roomId).add(beacon.beaconInfoId);
+        beacon.monitorLiveness();
+    };
+
+    private checkLiveness = (): void => {
+        const prevLiveness = this.hasLiveBeacons();
+        this.liveBeaconIds = [...this.beacons.values()]
+            .filter(beacon => beacon.isLive)
+            .map(beacon => beacon.beaconInfoId);
+
+        const newLiveness = this.hasLiveBeacons();
+
+        if (prevLiveness !== newLiveness) {
+            this.emit(OwnBeaconStoreEvent.LivenessChange, newLiveness);
+        }
+    };
+}