perf: only loads selected locales (#3152)

assets/modules/i18n.ts

@@ -1,22 +1,45 @@
 import { type App } from "vue";
 import { createI18n } from "vue-i18n";
 import { locale } from "@/stores/settings";
+import type { Locale } from "vue-i18n";
 
-import messages from "@intlify/unplugin-vue-i18n/messages";
+const localesMap = Object.fromEntries(
+  Object.entries(import.meta.glob("../../locales/*.yml")).map(([path, loadLocale]) => [
+    path.match(/([\w-]*)\.yml$/)?.[1],
+    loadLocale,
+  ]),
+) as Record<Locale, () => Promise<{ default: Record<string, string> }>>;
 
-const defaultLocale = messages?.hasOwnProperty(navigator.language)
-  ? navigator.language
-  : navigator.language.slice(0, 2);
+export const availableLocales = Object.keys(localesMap);
+
+function setI18nLanguage(lang: Locale) {
+  i18n.global.locale.value = lang;
+  return lang;
+}
+
+const loadedLanguages: string[] = [];
+async function loadLanguage(lang: string): Promise<Locale> {
+  if (i18n.global.locale.value === lang) return setI18nLanguage(lang);
+  if (loadedLanguages.includes(lang)) return setI18nLanguage(lang);
+
+  const messages = await localesMap[lang]();
+  i18n.global.setLocaleMessage(lang, messages.default);
+  loadedLanguages.push(lang);
+  return setI18nLanguage(lang);
+}
 
 const i18n = createI18n({
   legacy: false,
-  locale: locale.value || defaultLocale,
-  fallbackLocale: "en",
-  messages,
+  locale: "",
+  messages: {},
 });
 
-watch(locale, (value) => {
-  i18n.global.locale.value = value || defaultLocale;
+watchEffect(() => {
+  loadLanguage(
+    locale.value ||
+      [navigator.language, navigator.language.slice(0, 2)].find((l) => availableLocales.includes(l)) ||
+      "en",
+  );
 });
 
 export const install = (app: App) => app.use(i18n);

assets/pages/settings.vue

@@ -156,7 +156,9 @@ import {
   locale,
 } from "@/stores/settings";
 
-const { t, availableLocales } = useI18n();
+import { availableLocales } from "@/modules/i18n";
+
+const { t } = useI18n();
 
 setTitle(t("title.settings"));
 const { latest, hasUpdate } = useReleases();