support getting the room status for a room: invited, joined or archived

src/matrix/Session.js

@@ -16,6 +16,7 @@ limitations under the License.
 */
 
 import {Room} from "./room/Room.js";
+import {RoomStatus} from "./room/RoomStatus.js";
 import {Invite} from "./room/Invite.js";
 import {Pusher} from "./push/Pusher.js";
 import { ObservableMap } from "../observable/index.js";
@@ -597,6 +598,31 @@ export class Session {
         const serverPushers = (serverPushersData?.pushers || []).map(data => new Pusher(data));
         return serverPushers.some(p => p.equals(myPusher));
     }
+
+    async getRoomStatus(roomId) {
+        const isJoined = !!this._rooms.get(roomId);
+        if (isJoined) {
+            return RoomStatus.joined;
+        } else {
+            const isInvited = !!this._invites.get(roomId);
+            let isArchived; 
+            if (this._archivedRooms) {
+                isArchived = !!this._archivedRooms.get(roomId);
+            } else {
+                const txn = await this._storage.readTxn([this._storage.storeNames.archivedRoomSummary]);
+                isArchived = await txn.archivedRoomSummary.has(roomId);
+            }
+            if (isInvited && isArchived) {
+                return RoomStatus.invitedAndArchived;
+            } else if (isInvited) {
+                return RoomStatus.invited;
+            } else if (isArchived) {
+                return RoomStatus.archived;
+            } else {
+                return RoomStatus.none;
+            }
+        }
+    }
 }
 
 export function tests() {

src/matrix/room/RoomStatus.js

@@ -0,0 +1,51 @@
+/*
+Copyright 2021 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.
+*/
+
+export class RoomStatus {
+    constructor(joined, invited, archived) {
+        this.joined = joined;
+        this.invited = invited;
+        this.archived = archived;
+    }
+
+    withInvited() {
+        if (this.invited) {
+            return this;
+        } else if (this.archived) {
+            return RoomStatus.invitedAndArchived;
+        } else {
+            return RoomStatus.invited;
+        }
+    }
+
+    withoutInvited() {
+        if (!this.invited) {
+            return this;
+        } else if (this.joined) {
+            return RoomStatus.joined;
+        } else if (this.archived) {
+            return RoomStatus.archived;
+        } else {
+            return RoomStatus.none;
+        }
+    }
+}
+
+RoomStatus.joined = new RoomStatus(true, false, false);
+RoomStatus.archived = new RoomStatus(false, false, true);
+RoomStatus.invited = new RoomStatus(false, true, false);
+RoomStatus.invitedAndArchived = new RoomStatus(false, true, true);
+RoomStatus.none = new RoomStatus(false, false, false);

src/matrix/storage/idb/stores/RoomSummaryStore.js

@@ -42,6 +42,11 @@ export class RoomSummaryStore {
 		return this._summaryStore.put(summary);
 	}
 
+	async has(roomId) {
+        const fetchedKey = await this._summaryStore.getKey(roomId);
+        return roomId === fetchedKey;
+	}
+
 	remove(roomId) {
 		return this._summaryStore.delete(roomId);
 	}