Merge pull request #9366 from wireapp/feat/default-system-language-WPB-21019

feat: Desktop app respect operating system's language setting by default(WPB-21019)

Author: arjita-mitra

electron/src/locale/index.ts

@@ -55,6 +55,13 @@ export type SupportedI18nLanguageObject = Record<SupportedI18nLanguage, i18nStri
 
 const app = Electron.app || require('@electron/remote').app;
 
+const parseLocale = (locale: string): SupportedI18nLanguage => {
+  const languageKeys = Object.keys(SUPPORTED_LANGUAGES) as SupportedI18nLanguage[];
+  return languageKeys.find(languageKey => languageKey === locale) || languageKeys[0];
+};
+
+const getSystemLocale = (): SupportedI18nLanguage => parseLocale(app.getLocale().substring(0, 2));
+
 export const LANGUAGES: SupportedI18nLanguageObject = {
   cs,
   da,
@@ -139,17 +146,24 @@ export const SUPPORTED_LANGUAGES = {
 let current: SupportedI18nLanguage | undefined;
 
 export const getCurrent = (): SupportedI18nLanguage => {
+  const systemLocale = getSystemLocale();
+
   if (!current) {
-    // We care only about the language part and not the country (en_US, de_DE)
-    const defaultLocale = parseLocale(app.getLocale().substring(0, 2));
-    current = settings.restore(SettingsType.LOCALE, defaultLocale);
+    const savedLocale = settings.restore<SupportedI18nLanguage | undefined>(SettingsType.LOCALE);
+    const savedOverride = settings.restore<boolean | undefined>(SettingsType.LOCALE_OVERRIDE);
+    const hasUserOverride =
+      typeof savedOverride === 'boolean' ? savedOverride : Boolean(savedLocale && savedLocale !== systemLocale);
+
+    current = savedLocale && hasUserOverride ? parseLocale(savedLocale) : systemLocale;
+    return current;
   }
-  return current;
-};
 
-const parseLocale = (locale: string): SupportedI18nLanguage => {
-  const languageKeys = Object.keys(SUPPORTED_LANGUAGES) as SupportedI18nLanguage[];
-  return languageKeys.find(languageKey => languageKey === locale) || languageKeys[0];
+  // If there’s no override and the system locale changed, update the cache
+  const hasOverride = settings.restore<boolean | undefined>(SettingsType.LOCALE_OVERRIDE) === true;
+  if (!hasOverride && current !== systemLocale) {
+    current = systemLocale;
+  }
+  return current;
 };
 
 const customReplacements: Record<string, string> = {
@@ -180,5 +194,15 @@ export const getText = (
 
 export const setLocale = (locale: string): void => {
   current = parseLocale(locale);
-  settings.save(SettingsType.LOCALE, current);
+
+  const systemLocale = getSystemLocale();
+  const isOverride = current !== systemLocale;
+
+  if (isOverride) {
+    settings.save(SettingsType.LOCALE_OVERRIDE, true);
+    settings.save(SettingsType.LOCALE, current);
+  } else {
+    settings.delete(SettingsType.LOCALE_OVERRIDE);
+    settings.delete(SettingsType.LOCALE);
+  }
 };

electron/src/settings/SettingsType.ts

@@ -46,6 +46,8 @@ export enum SettingsType {
   FULL_SCREEN = 'fullscreen',
   /** Which language (ISO 639-1) should be used to load our web app (de, en, fr, etc.)? */
   LOCALE = 'locale',
+  /** Whether the locale has been explicitly set by the user instead of using the system default. */
+  LOCALE_OVERRIDE = 'localeOverride',
   /** Defines the proxy server url (e.g. http://127.0.0.1:3128)
    *
    * https://github.com/wireapp/wire-desktop/wiki/Start-Parameters#use-authenticated-proxy-server