Move notification states out of the NotificationBadge component

Fixes https://github.com/vector-im/riot-web/issues/14153

src/stores/notifications/ListNotificationState.ts

@@ -0,0 +1,120 @@
+/*
+Copyright 2020 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 { EventEmitter } from "events";
+import { INotificationState, NOTIFICATION_STATE_UPDATE } from "./INotificationState";
+import { NotificationColor } from "./NotificationColor";
+import { IDestroyable } from "../../utils/IDestroyable";
+import { TagID } from "../room-list/models";
+import { Room } from "matrix-js-sdk/src/models/room";
+import { arrayDiff } from "../../utils/arrays";
+import { RoomNotificationState } from "./RoomNotificationState";
+import { TagSpecificNotificationState } from "./TagSpecificNotificationState";
+
+export class ListNotificationState extends EventEmitter implements IDestroyable, INotificationState {
+    private _count: number;
+    private _color: NotificationColor;
+    private rooms: Room[] = [];
+    private states: { [roomId: string]: RoomNotificationState } = {};
+
+    constructor(private byTileCount = false, private tagId: TagID) {
+        super();
+    }
+
+    public get symbol(): string {
+        return null; // This notification state doesn't support symbols
+    }
+
+    public get count(): number {
+        return this._count;
+    }
+
+    public get color(): NotificationColor {
+        return this._color;
+    }
+
+    public setRooms(rooms: Room[]) {
+        // If we're only concerned about the tile count, don't bother setting up listeners.
+        if (this.byTileCount) {
+            this.rooms = rooms;
+            this.calculateTotalState();
+            return;
+        }
+
+        const oldRooms = this.rooms;
+        const diff = arrayDiff(oldRooms, rooms);
+        this.rooms = rooms;
+        for (const oldRoom of diff.removed) {
+            const state = this.states[oldRoom.roomId];
+            if (!state) continue; // We likely just didn't have a badge (race condition)
+            delete this.states[oldRoom.roomId];
+            state.off(NOTIFICATION_STATE_UPDATE, this.onRoomNotificationStateUpdate);
+            state.destroy();
+        }
+        for (const newRoom of diff.added) {
+            const state = new TagSpecificNotificationState(newRoom, this.tagId);
+            state.on(NOTIFICATION_STATE_UPDATE, this.onRoomNotificationStateUpdate);
+            if (this.states[newRoom.roomId]) {
+                // "Should never happen" disclaimer.
+                console.warn("Overwriting notification state for room:", newRoom.roomId);
+                this.states[newRoom.roomId].destroy();
+            }
+            this.states[newRoom.roomId] = state;
+        }
+
+        this.calculateTotalState();
+    }
+
+    public getForRoom(room: Room) {
+        const state = this.states[room.roomId];
+        if (!state) throw new Error("Unknown room for notification state");
+        return state;
+    }
+
+    public destroy() {
+        for (const state of Object.values(this.states)) {
+            state.destroy();
+        }
+        this.states = {};
+    }
+
+    private onRoomNotificationStateUpdate = () => {
+        this.calculateTotalState();
+    };
+
+    private calculateTotalState() {
+        const before = {count: this.count, symbol: this.symbol, color: this.color};
+
+        if (this.byTileCount) {
+            this._color = NotificationColor.Red;
+            this._count = this.rooms.length;
+        } else {
+            this._count = 0;
+            this._color = NotificationColor.None;
+            for (const state of Object.values(this.states)) {
+                this._count += state.count;
+                this._color = Math.max(this.color, state.color);
+            }
+        }
+
+        // finally, publish an update if needed
+        const after = {count: this.count, symbol: this.symbol, color: this.color};
+        if (JSON.stringify(before) !== JSON.stringify(after)) {
+            this.emit(NOTIFICATION_STATE_UPDATE);
+        }
+    }
+}
+