menu: Add option to check for updates.

Fixes: #479.

app/main/autoupdater.js

@@ -1,11 +1,11 @@
 'use strict';
-const { app, dialog } = require('electron');
+const { app, dialog, shell } = require('electron');
 const { autoUpdater } = require('electron-updater');
 const isDev = require('electron-is-dev');
 
 const ConfigUtil = require('./../renderer/js/utils/config-util.js');
 
-function appUpdater() {
+function appUpdater(updateFromMenu = false) {
 	// Don't initiate auto-updates in development
 	if (isDev) {
 		return;
@@ -17,6 +17,8 @@ function appUpdater() {
 		return;
 	}
 
+	let updateAvailable = false;
+
 	// Create Logs directory
 	const LogsDir = `${app.getPath('userData')}/Logs`;
 
@@ -30,6 +32,55 @@ function appUpdater() {
 	// Handle auto updates for beta/pre releases
 	autoUpdater.allowPrerelease = ConfigUtil.getConfigItem('betaUpdate') || false;
 
+	const eventsListenerRemove = ['update-available', 'update-not-available'];
+	autoUpdater.on('update-available', info => {
+		if (updateFromMenu) {
+			dialog.showMessageBox({
+				message: `A new version ${info.version}, of Zulip Desktop is available`,
+				detail: 'The update will be downloaded in the background. You will be notified when it is ready to be installed.'
+			});
+
+			updateAvailable = true;
+
+			// This is to prevent removal of 'update-downloaded' and 'error' event listener.
+			eventsListenerRemove.forEach(event => {
+				autoUpdater.removeAllListeners(event);
+			});
+		}
+	});
+
+	autoUpdater.on('update-not-available', () => {
+		if (updateFromMenu) {
+			dialog.showMessageBox({
+				message: 'No updates available',
+				detail: `You are running the latest version of Zulip Desktop.\nVersion: ${app.getVersion()}`
+			});
+			// Remove all autoUpdator listeners so that next time autoUpdator is manually called these
+			// listeners don't trigger multiple times.
+			autoUpdater.removeAllListeners();
+		}
+	});
+
+	autoUpdater.on('error', error => {
+		if (updateFromMenu) {
+			const messageText = (updateAvailable) ? ('Unable to download the updates') : ('Unable to check for updates');
+			dialog.showMessageBox({
+				type: 'error',
+				buttons: ['Manual Download', 'Cancel'],
+				message: messageText,
+				detail: (error).toString() + `\n\nThe latest version of Zulip Desktop is available at -\nhttps://zulipchat.com/apps/.\n
+Current Version: ${app.getVersion()}`
+			}, response => {
+				if (response === 0) {
+					shell.openExternal('https://zulipchat.com/apps/');
+				}
+			});
+			// Remove all autoUpdator listeners so that next time autoUpdator is manually called these
+			// listeners don't trigger multiple times.
+			autoUpdater.removeAllListeners();
+		}
+	});
+
 	// Ask the user if update is available
 	// eslint-disable-next-line no-unused-vars
 	autoUpdater.on('update-downloaded', event => {

app/main/menu.js

@@ -4,6 +4,7 @@ const path = require('path');
 const { app, shell, BrowserWindow, Menu, dialog } = require('electron');
 
 const fs = require('fs-extra');
+const { appUpdater } = require('./autoupdater');
 
 const ConfigUtil = require(__dirname + '/../renderer/js/utils/config-util.js');
 const DNDUtil = require(__dirname + '/../renderer/js/utils/dnd-util.js');
@@ -195,7 +196,12 @@ class AppMenu {
 						AppMenu.sendAction('open-about');
 					}
 				}
-			}, {
+			},	{
+				label: `Check for Update`,
+				click() {
+					AppMenu.checkForUpdate();
+				}
+			},	{
 				type: 'separator'
 			}, {
 				label: 'Desktop App Settings',
@@ -302,7 +308,12 @@ class AppMenu {
 						AppMenu.sendAction('open-about');
 					}
 				}
-			}, {
+			}, 	{
+				label: `Check for Update`,
+				click() {
+					AppMenu.checkForUpdate();
+				}
+			},	{
 				type: 'separator'
 			}, {
 				label: 'Desktop App Settings',
@@ -399,6 +410,9 @@ class AppMenu {
 		win.webContents.send(action, ...params);
 	}
 
+	static checkForUpdate() {
+		appUpdater(true);
+	}
 	static resetAppSettings() {
 		const resetAppSettingsMessage = 'By proceeding you will be removing all connected organizations and preferences from Zulip.';