zulip-desktop/app/renderer/js/utils/reconnect-util.ts

import {ipcRenderer} from 'electron';

import type WebView from '../components/webview';
import backoff from 'backoff';
import Logger from './logger-util';

const logger = new Logger({
	file: 'domain-util.log',
	timestamp: true
});

export default class ReconnectUtil {
	webview: WebView;
	url: string;
	alreadyReloaded: boolean;
	fibonacciBackoff: backoff.Backoff;

	constructor(webview: WebView) {
		this.webview = webview;
		this.url = webview.props.url;
		this.alreadyReloaded = false;
		this.clearState();
	}

	clearState(): void {
		this.fibonacciBackoff = backoff.fibonacci({
			initialDelay: 5000,
			maxDelay: 300000
		});
	}

	async isOnline(): Promise<boolean> {
		return ipcRenderer.invoke('is-online', this.url);
	}

	pollInternetAndReload(): void {
		this.fibonacciBackoff.backoff();
		this.fibonacciBackoff.on('ready', async () => {
			if (await this._checkAndReload()) {
				this.fibonacciBackoff.reset();
			} else {
				this.fibonacciBackoff.backoff();
			}
		});
	}

	async _checkAndReload(): Promise<boolean> {
		if (this.alreadyReloaded) {
			return true;
		}

		if (await this.isOnline()) {
			ipcRenderer.send('forward-message', 'reload-viewer');
			logger.log('You\'re back online.');
			return true;
		}

		logger.log('There is no internet connection, try checking network cables, modem and router.');
		const errorMessageHolder = document.querySelector('#description');
		if (errorMessageHolder) {
			errorMessageHolder.innerHTML = `
						<div>Your internet connection doesn't seem to work properly!</div>
						<div>Verify that it works and then click try again.</div>`;
		}

		return false;
	}
}