Add / remove listeners and timeouts when the sceensaver setting changes

Change-type: patch
Changelog-entry: Add / remove listeners and timeouts when the sceensaver setting changes

lib/gui/app/models/settings.ts

@@ -15,6 +15,7 @@
  */
 
 import * as debug_ from 'debug';
+import { EventEmitter } from 'events';
 import { cloneDeep } from 'lodash';
 
 import { createError } from '../modules/errors';
@@ -41,9 +42,11 @@ const DEFAULT_SETTINGS = {
 
 let settings: Dict<any> = cloneDeep(DEFAULT_SETTINGS);
 
+export const events = new EventEmitter();
+
+// Exported for tests only, don't use that
 export async function reset(): Promise<void> {
 	debug('reset');
-	// TODO: Remove default settings from config file (?)
 	settings = cloneDeep(DEFAULT_SETTINGS);
 	await writeAll(settings);
 }
@@ -51,7 +54,14 @@ export async function reset(): Promise<void> {
 export async function load(): Promise<any> {
 	debug('load');
 	const loadedSettings = await readAll();
+	const oldSettings = cloneDeep(settings);
 	settings = { ...settings, ...loadedSettings };
+	for (const key of Object.keys(settings)) {
+		const value = settings[key];
+		if (!oldSettings.hasOwnProperty(key) || value !== oldSettings[key]) {
+			events.emit(key, value);
+		}
+	}
 	return settings;
 }
 
@@ -69,6 +79,9 @@ export async function set(key: string, value: any): Promise<void> {
 		settings[key] = previousValue;
 		throw error;
 	}
+	if (value !== previousValue) {
+		events.emit(key, value);
+	}
 }
 
 export function get(key: string): any {

lib/gui/app/modules/screensaver.ts

@@ -17,6 +17,8 @@
 import { execFile } from 'child_process';
 import { promisify } from 'util';
 
+import * as settings from '../models/settings';
+
 const execFileAsync = promisify(execFile);
 const EVENT_TYPES = [
 	'focus',
@@ -51,13 +53,47 @@ async function off() {
 	await Promise.all([ledsOff(), screenOff()]);
 }
 
-export function init(): void {
-	let timeout = setTimeout(screenOff, SCREENSAVER_DELAY);
-	for (const eventType of EVENT_TYPES) {
-		addEventListener(eventType, async () => {
+let timeout: NodeJS.Timeout;
+let delay: number | null = null;
+
+async function listener() {
+	if (timeout !== undefined) {
 		clearTimeout(timeout);
-			timeout = setTimeout(off, SCREENSAVER_DELAY);
+	}
+	if (delay !== null) {
+		timeout = setTimeout(off, delay);
+	}
 	await ledsOn();
-		});
+}
+
+async function setDelay($delay: number | null) {
+	const listenersSetUp = delay === null;
+	delay = $delay;
+	if (timeout !== undefined) {
+		clearTimeout(timeout);
+	}
+	if (delay === null) {
+		for (const eventType of EVENT_TYPES) {
+			removeEventListener(eventType, listener);
+		}
+	} else {
+		timeout = setTimeout(screenOff, delay);
+		if (!listenersSetUp) {
+			for (const eventType of EVENT_TYPES) {
+				addEventListener(eventType, listener);
+			}
+		}
 	}
 }
+
+async function getDelay() {
+	const enabled = await settings.get('enableScreensaver');
+	return enabled ? SCREENSAVER_DELAY : null;
+}
+
+export async function init(): Promise<void> {
+	setDelay(await getDelay());
+	settings.events.on('enableScreensaver', enabled => {
+		setDelay(enabled ? SCREENSAVER_DELAY : null);
+	});
+}