Fix PlatformSettingsHandler always returning true due to returning a Promise (#8954)

* Fix PlatformSettingsHandler always returning true due to returning a Promise

* Improve typescript

src/PlatformPeg.ts

@@ -16,6 +16,9 @@ limitations under the License.
 */
 
 import BasePlatform from "./BasePlatform";
+import defaultDispatcher from "./dispatcher/dispatcher";
+import { Action } from "./dispatcher/actions";
+import { PlatformSetPayload } from "./dispatcher/payloads/PlatformSetPayload";
 
 /*
  * Holds the current instance of the `Platform` to use across the codebase.
@@ -29,23 +32,26 @@ import BasePlatform from "./BasePlatform";
  * object.
  */
 export class PlatformPeg {
-    platform: BasePlatform = null;
+    private platform: BasePlatform = null;
 
     /**
      * Returns the current Platform object for the application.
      * This should be an instance of a class extending BasePlatform.
      */
-    get() {
+    public get() {
         return this.platform;
     }
 
     /**
-     * Sets the current platform handler object to use for the
-     * application.
-     * This should be an instance of a class extending BasePlatform.
+     * Sets the current platform handler object to use for the application.
+     * @param {BasePlatform} platform an instance of a class extending BasePlatform.
      */
-    set(plaf: BasePlatform) {
-        this.platform = plaf;
+    public set(platform: BasePlatform) {
+        this.platform = platform;
+        defaultDispatcher.dispatch<PlatformSetPayload>({
+            action: Action.PlatformSet,
+            platform,
+        });
     }
 }
 

src/dispatcher/actions.ts

@@ -315,4 +315,10 @@ export enum Action {
      * Fired when the client was logged in. No additional payload information required.
      */
     OnLoggedIn = "on_logged_in",
+
+    /**
+     * Fired when the PlatformPeg gets a new platform set upon it, should only happen once per app load lifecycle.
+     * Fires with the PlatformSetPayload.
+     */
+    PlatformSet = "platform_set",
 }

src/dispatcher/payloads/PlatformSetPayload.ts

@@ -0,0 +1,24 @@
+/*
+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 { Action } from "../actions";
+import { ActionPayload } from "../payloads";
+import BasePlatform from "../../BasePlatform";
+
+export interface PlatformSetPayload extends ActionPayload {
+    action: Action.PlatformSet;
+    platform: BasePlatform;
+}

src/settings/handlers/PlatformSettingsHandler.ts

@@ -16,21 +16,49 @@ limitations under the License.
 
 import SettingsHandler from "./SettingsHandler";
 import PlatformPeg from "../../PlatformPeg";
+import { SETTINGS } from "../Settings";
+import { SettingLevel } from "../SettingLevel";
+import defaultDispatcher from "../../dispatcher/dispatcher";
+import { ActionPayload } from "../../dispatcher/payloads";
+import { Action } from "../../dispatcher/actions";
 
 /**
  * Gets and sets settings at the "platform" level for the current device.
  * This handler does not make use of the roomId parameter.
  */
 export default class PlatformSettingsHandler extends SettingsHandler {
+    private store: { [settingName: string]: any } = {};
+
+    constructor() {
+        super();
+
+        defaultDispatcher.register(this.onAction);
+    }
+
+    private onAction = (payload: ActionPayload) => {
+        if (payload.action === Action.PlatformSet) {
+            this.store = {};
+            // Load setting values as they are async and `getValue` must be synchronous
+            Object.entries(SETTINGS).forEach(([key, setting]) => {
+                if (setting.supportedLevels.includes(SettingLevel.PLATFORM) && payload.platform.supportsSetting(key)) {
+                    payload.platform.getSettingValue(key).then(value => {
+                        this.store[key] = value;
+                    });
+                }
+            });
+        }
+    };
+
     public canSetValue(settingName: string, roomId: string): boolean {
         return PlatformPeg.get().supportsSetting(settingName);
     }
 
     public getValue(settingName: string, roomId: string): any {
-        return PlatformPeg.get().getSettingValue(settingName);
+        return this.store[settingName];
     }
 
     public setValue(settingName: string, roomId: string, newValue: any): Promise<void> {
+        this.store[settingName] = newValue; // keep cache up to date for synchronous access
         return PlatformPeg.get().setSettingValue(settingName, newValue);
     }