Register custom themes after the monaco theme init (#1257)

Signed-off-by: Akos Kitta <a.kitta@arduino.cc>

Co-authored-by: Akos Kitta <a.kitta@arduino.cc>

electron-app/patch/frontend/index.js

@@ -0,0 +1,100 @@
+// Patch for the startup theme. Customizes the `ThemeService.get().defaultTheme();` to dispatch the default IDE2 theme based on the OS' theme.
+// For all subsequent starts of the IDE the theme applied will be the last one set by the user.
+
+// With the current version of Theia adopted (1.25) it is not possible to extend the `ThemeService`, it will be possible starting from Theia 1.27.
+// Once the version of Theia is updated, this patch will be removed and this functionality will be implemented via dependency injection.
+// Ideally, we should open a PR in Theia and add support for `light` and `dark` default themes in the app config.
+
+const {
+  ThemeService,
+  ThemeServiceSymbol,
+  BuiltinThemeProvider,
+} = require('@theia/core/lib/browser/theming');
+const {
+  ApplicationProps,
+} = require('@theia/application-package/lib/application-props');
+const {
+  FrontendApplicationConfigProvider,
+} = require('@theia/core/lib/browser/frontend-application-config-provider');
+
+// It is a mighty hack to support theme updates in the bundled IDE2.
+// If the custom theme registration happens before the restoration of the existing monaco themes, then any custom theme changes will be ignored.
+// This patch introduces a static deferred promise in the monaco-theming service that will be resolved when the restoration is ready.
+// IDE2 cannot require the monaco theme service on the outer module level, as it requires the application config provider to be initialized,
+// but the initialization happens only in the generated `index.js`.
+// This patch customizes the monaco theme service behavior before loading the DI containers via the preload.
+// The preload is called only once before the app loads. The Theia extensions are not loaded at that point, but the app config provider is ready.
+const preloader = require('@theia/core/lib/browser/preloader');
+const originalPreload = preloader.preload;
+preloader.preload = async function () {
+  const { MonacoThemingService } = require('@theia/monaco/lib/browser/monaco-theming-service');
+  const { MonacoThemeServiceIsReady } = require('arduino-ide-extension/lib/browser/utils/window');
+  const { Deferred } = require('@theia/core/lib/common/promise-util');
+  const ready = new Deferred();
+  if (!window[MonacoThemeServiceIsReady]) {
+    window[MonacoThemeServiceIsReady] = ready;
+    console.log('Registered a custom monaco-theme service initialization signal on the window object.');
+  }
+  // Here, it is safe to patch the theme service, app config provider is ready.
+  MonacoThemingService.init = async function () {
+    this.updateBodyUiTheme();
+    ThemeService.get().onDidColorThemeChange(() => this.updateBodyUiTheme());
+    await this.restore();
+    ready.resolve();
+  }.bind(MonacoThemingService);
+  return originalPreload();
+}.bind(preloader);
+
+const lightTheme = 'arduino-theme';
+const darkTheme = 'arduino-theme-dark';
+const defaultTheme =
+  window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches
+    ? darkTheme
+    : lightTheme;
+
+const originalGet = FrontendApplicationConfigProvider.get;
+FrontendApplicationConfigProvider.get = function () {
+  const originalProps = originalGet.bind(FrontendApplicationConfigProvider)();
+  return { ...originalProps, defaultTheme };
+}.bind(FrontendApplicationConfigProvider);
+
+const arduinoDarkTheme = {
+  id: 'arduino-theme-dark',
+  type: 'dark',
+  label: 'Dark (Arduino)',
+  editorTheme: 'arduino-theme-dark',
+  activate() {},
+  deactivate() {},
+};
+
+const arduinoLightTheme = {
+  id: 'arduino-theme',
+  type: 'light',
+  label: 'Light (Arduino)',
+  editorTheme: 'arduino-theme',
+  activate() {},
+  deactivate() {},
+};
+
+if (!window[ThemeServiceSymbol]) {
+  const themeService = new ThemeService();
+  Object.defineProperty(themeService, 'defaultTheme', {
+    get: function () {
+      return (
+        this.themes[defaultTheme] ||
+        this.themes[ApplicationProps.DEFAULT.frontend.config.defaultTheme]
+      );
+    },
+  });
+  themeService.register(
+    ...BuiltinThemeProvider.themes,
+    arduinoDarkTheme,
+    arduinoLightTheme
+  );
+  themeService.startupTheme();
+  themeService.setCurrentTheme(defaultTheme);
+  window[ThemeServiceSymbol] = themeService;
+}
+
+// Require the original, generated `index.js` for `webpack` as the next entry for the `bundle.js`.
+require('../../src-gen/frontend/index');