zulip-desktop/app/renderer/js/electron-bridge.ts

import { ipcRenderer } from 'electron';

import { EventEmitter } from 'events';

type ListenerType = ((...args: any[]) => void);

class ElectronBridge extends EventEmitter {
	send_notification_reply_message_supported: boolean;
	idle_on_system: boolean;
	last_active_on_system: number;

	constructor() {
		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
		this.last_active_on_system = Date.now();
	}

	send_event(eventName: string | symbol, ...args: any[]): void {
		this.emit(eventName, ...args);
	}

	on_event(eventName: string, listener: ListenerType): void {
		this.on(eventName, listener);
	}
}

const electron_bridge = new ElectronBridge();

electron_bridge.on('total_unread_count', (...args) => {
	ipcRenderer.send('unread-count', ...args);
});

electron_bridge.on('realm_name', realmName => {
	const serverURL = location.origin;
	ipcRenderer.send('realm-name-changed', serverURL, realmName);
});

electron_bridge.on('realm_icon_url', iconURL => {
	const serverURL = location.origin;
	iconURL = iconURL.includes('http') ? iconURL : `${serverURL}${iconURL}`;
	ipcRenderer.send('realm-icon-changed', serverURL, iconURL);
});

// 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
// which is alias of .emit and on this side we can handle the data by adding
// a listener for the event.
export default electron_bridge;