Electron support

From https://github.com/vector-im/vector-web/pull/2511 but with
just the actual electron changes

electron/src/electron-main.js

@@ -0,0 +1,157 @@
+// @flow
+
+/*
+Copyright 2016 Aviral Dasgupta and OpenMarket Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+const electron = require('electron');
+const url = require('url');
+
+const VectorMenu = require('./vectormenu');
+
+const PERMITTED_URL_SCHEMES = [
+    'http:',
+    'https:',
+    'mailto:',
+];
+
+const UPDATE_POLL_INTERVAL_MS = 60 * 60 * 1000;
+
+let mainWindow = null;
+let appQuitting = false;
+
+function safeOpenURL(target) {
+    // openExternal passes the target to open/start/xdg-open,
+    // so put fairly stringent limits on what can be opened
+    // (for instance, open /bin/sh does indeed open a terminal
+    // with a shell, albeit with no arguments)
+    const parsed_url = url.parse(target);
+    if (PERMITTED_URL_SCHEMES.indexOf(parsed_url.protocol) > -1) {
+        // explicitly use the URL re-assembled by the url library,
+        // so we know the url parser has understood all the parts
+        // of the input string
+        const new_target = url.format(parsed_url);
+        electron.shell.openExternal(new_target);
+    }
+}
+
+function onWindowOrNavigate(ev, target) {
+    // always prevent the default: if something goes wrong,
+    // we don't want to end up opening it in the electron
+    // app, as we could end up opening any sort of random
+    // url in a window that has node scripting access.
+    ev.preventDefault();
+    safeOpenURL(target);
+}
+
+function onLinkContextMenu(ev, params) {
+    const popup_menu = new electron.Menu();
+    popup_menu.append(new electron.MenuItem({
+        label: params.linkURL,
+        click() {
+            safeOpenURL(params.linkURL);
+        },
+    }));
+    popup_menu.popup();
+    ev.preventDefault();
+}
+
+function installUpdate() {
+    // for some reason, quitAndInstall does not fire the
+    // before-quit event, so we need to set the flag here.
+    appQuitting = true;
+    electron.autoUpdater.quitAndInstall();
+}
+
+function pollForUpdates() {
+    try {
+        electron.autoUpdater.checkForUpdates();
+    } catch (e) {
+        console.log("Couldn't check for update", e);
+    }
+}
+
+electron.ipcMain.on('install_update', installUpdate);
+
+electron.app.on('ready', () => {
+    try {
+        // For reasons best known to Squirrel, the way it checks for updates
+        // is completely different between macOS and windows. On macOS, it
+        // hits a URL that either gives it a 200 with some json or
+        // 204 No Content. On windows it takes a base path and looks for
+        // files under that path.
+        if (process.platform == 'darwin') {
+            electron.autoUpdater.setFeedURL("https://riot.im/autoupdate/desktop/");
+        } else if (process.platform == 'win32') {
+            electron.autoUpdater.setFeedURL("https://riot.im/download/desktop/win32/");
+        } else {
+            // Squirrel / electron only supports auto-update on these two platforms.
+            // I'm not even going to try to guess which feed style they'd use if they
+            // implemented it on Linux, or if it would be different again.
+            console.log("Auto update not supported on this platform");
+        }
+        // We check for updates ourselves rather than using 'updater' because we need to
+        // do it in the main process (and we don't really need to check every 10 minutes:
+        // every hour should be just fine for a desktop app)
+        // However, we still let the main window listen for the update events.
+        pollForUpdates();
+        setInterval(pollForUpdates, UPDATE_POLL_INTERVAL_MS);
+    } catch (err) {
+        // will fail if running in debug mode
+        console.log("Couldn't enable update checking", err);
+    }
+
+    mainWindow = new electron.BrowserWindow({
+        icon: `${__dirname}/../../vector/img/logo.png`,
+        width: 1024, height: 768,
+    });
+    mainWindow.loadURL(`file://${__dirname}/../../vector/index.html`);
+    electron.Menu.setApplicationMenu(VectorMenu);
+
+    mainWindow.on('closed', () => {
+        mainWindow = null;
+    });
+    mainWindow.on('close', (e) => {
+        if (process.platform == 'darwin' && !appQuitting) {
+            // On Mac, closing the window just hides it
+            // (this is generally how single-window Mac apps
+            // behave, eg. Mail.app)
+            e.preventDefault();
+            mainWindow.hide();
+            return false;
+        }
+    });
+
+    mainWindow.webContents.on('new-window', onWindowOrNavigate);
+    mainWindow.webContents.on('will-navigate', onWindowOrNavigate);
+
+    mainWindow.webContents.on('context-menu', function(ev, params) {
+        if (params.linkURL) {
+            onLinkContextMenu(ev, params);
+        }
+    });
+});
+
+electron.app.on('window-all-closed', () => {
+    electron.app.quit();
+});
+
+electron.app.on('activate', () => {
+    mainWindow.show();
+});
+
+electron.app.on('before-quit', () => {
+    appQuitting = true;
+});