electron-bridge: Move mutable state out of electron_bridge.

Only the initial value of a mutable field is exposed via
exposeInMainWorld, which is why we have a bunch of setter and getter
functions.  It’s better to avoid the possibility for this confusion.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

app/renderer/js/electron-bridge.ts

@@ -1,68 +1,62 @@
 import {ipcRenderer} from 'electron';
 import {EventEmitter} from 'events';
 
+import isDev from 'electron-is-dev';
+
 import {ClipboardDecrypterImpl} from './clipboard-decrypter';
 import {NotificationData, newNotification} from './notification';
 
 type ListenerType = ((...args: any[]) => void);
 
-class ElectronBridgeImpl extends EventEmitter implements ElectronBridge {
+let notificationReplySupported = false;
-	send_notification_reply_message_supported: boolean;
+// Indicates if the user is idle or not
-	idle_on_system: boolean;
+let idle = false;
-	last_active_on_system: number;
+// Indicates the time at which user was last active
+let lastActive = Date.now();
 
-	constructor() {
+export const bridgeEvents = new EventEmitter();
-		super();
-		this.send_notification_reply_message_supported = false;
-		// Indicates if the user is idle or not
-		this.idle_on_system = false;
 
-		// Indicates the time at which user was last active
+const electron_bridge: ElectronBridge = {
-		this.last_active_on_system = Date.now();
+	send_event: (eventName: string | symbol, ...args: unknown[]): void => {
-	}
+		bridgeEvents.emit(eventName, ...args);
+	},
 
-	send_event = (eventName: string | symbol, ...args: unknown[]): void => {
+	on_event: (eventName: string, listener: ListenerType): void => {
-		this.emit(eventName, ...args);
+		bridgeEvents.on(eventName, listener);
-	};
+	},
 
-	on_event = (eventName: string, listener: ListenerType): void => {
+	new_notification: (
-		this.on(eventName, listener);
-	};
-
-	new_notification = (
 		title: string,
 		options: NotificationOptions | undefined,
 		dispatch: (type: string, eventInit: EventInit) => boolean
 	): NotificationData =>
-		newNotification(title, options, dispatch);
+		newNotification(title, options, dispatch),
 
-	get_idle_on_system = (): boolean => this.idle_on_system;
+	get_idle_on_system: (): boolean => idle,
 
-	get_last_active_on_system = (): number => this.last_active_on_system;
+	get_last_active_on_system: (): number => lastActive,
 
-	get_send_notification_reply_message_supported = (): boolean =>
+	get_send_notification_reply_message_supported: (): boolean =>
-		this.send_notification_reply_message_supported;
+		notificationReplySupported,
 
-	set_send_notification_reply_message_supported = (value: boolean): void => {
+	set_send_notification_reply_message_supported: (value: boolean): void => {
-		this.send_notification_reply_message_supported = value;
+		notificationReplySupported = value;
-	};
+	},
 
-	decrypt_clipboard = (version: number): ClipboardDecrypterImpl =>
+	decrypt_clipboard: (version: number): ClipboardDecrypterImpl =>
-		new ClipboardDecrypterImpl(version);
+		new ClipboardDecrypterImpl(version)
-}
+};
 
-const electron_bridge = new ElectronBridgeImpl();
+bridgeEvents.on('total_unread_count', (...args) => {
-
-electron_bridge.on('total_unread_count', (...args) => {
 	ipcRenderer.send('unread-count', ...args);
 });
 
-electron_bridge.on('realm_name', realmName => {
+bridgeEvents.on('realm_name', realmName => {
 	const serverURL = location.origin;
 	ipcRenderer.send('realm-name-changed', serverURL, realmName);
 });
 
-electron_bridge.on('realm_icon_url', (iconURL: unknown) => {
+bridgeEvents.on('realm_icon_url', (iconURL: unknown) => {
 	if (typeof iconURL !== 'string') {
 		throw new TypeError('Expected string for iconURL');
 	}
@@ -72,6 +66,25 @@ electron_bridge.on('realm_icon_url', (iconURL: unknown) => {
 	ipcRenderer.send('realm-icon-changed', serverURL, iconURL);
 });
 
+// Set user as active and update the time of last activity
+ipcRenderer.on('set-active', () => {
+	if (isDev) {
+		console.log('active');
+	}
+
+	idle = false;
+	lastActive = Date.now();
+});
+
+// Set user as idle and time of last activity is left unchanged
+ipcRenderer.on('set-idle', () => {
+	if (isDev) {
+		console.log('idle');
+	}
+
+	idle = true;
+});
+
 // This follows node's idiomatic implementation of event
 // emitters to make event handling more simpler instead of using
 // functions zulip side will emit event using ElectronBrigde.send_event

app/renderer/js/preload.ts

@@ -1,8 +1,6 @@
 import {contextBridge, ipcRenderer, webFrame} from 'electron';
 import fs from 'fs';
 
-import isDev from 'electron-is-dev';
-
 import electron_bridge from './electron-bridge';
 import * as NetworkError from './pages/network';
 
@@ -72,25 +70,6 @@ document.addEventListener('keydown', event => {
 	}
 });
 
-// Set user as active and update the time of last activity
-ipcRenderer.on('set-active', () => {
-	if (isDev) {
-		console.log('active');
-	}
-
-	electron_bridge.idle_on_system = false;
-	electron_bridge.last_active_on_system = Date.now();
-});
-
-// Set user as idle and time of last activity is left unchanged
-ipcRenderer.on('set-idle', () => {
-	if (isDev) {
-		console.log('idle');
-	}
-
-	electron_bridge.idle_on_system = true;
-});
-
 (async () => webFrame.executeJavaScript(
 	fs.readFileSync(require.resolve('./injected'), 'utf8')
 ))();