feat: add modular i18n foundation

src/i18n/index.ts

@@ -0,0 +1,60 @@
+import { createI18n } from "vue-i18n";
+import { isSupportedLocale, resolveInitialLocale } from "./locales.ts";
+import { messages } from "./messages.ts";
+import { readStoredLocale, writeStoredLocale } from "./storage.ts";
+import { defaultLocale } from "./types.ts";
+import type { SupportedLocale } from "./types.ts";
+import { syncVantLocale } from "./vant.ts";
+
+function getNavigatorLanguages(): string[] {
+  if (typeof navigator === "undefined") {
+    return [];
+  }
+
+  const languages = navigator.languages ? [...navigator.languages] : [];
+
+  if (languages.length > 0) {
+    return languages;
+  }
+
+  return navigator.language ? [navigator.language] : [];
+}
+
+function setDocumentLanguage(locale: SupportedLocale): void {
+  if (typeof document === "undefined") {
+    return;
+  }
+
+  document.documentElement.lang = locale;
+}
+
+const initialLocale = resolveInitialLocale({
+  storedLocale: readStoredLocale(),
+  navigatorLanguages: getNavigatorLanguages(),
+});
+
+syncVantLocale(initialLocale);
+setDocumentLanguage(initialLocale);
+
+export const i18n = createI18n({
+  legacy: false,
+  locale: initialLocale,
+  fallbackLocale: defaultLocale,
+  messages,
+});
+
+export function getCurrentLocale(): SupportedLocale {
+  const locale = i18n.global.locale.value;
+  return isSupportedLocale(locale) ? locale : defaultLocale;
+}
+
+export function setLocale(locale: string): void {
+  if (!isSupportedLocale(locale)) {
+    return;
+  }
+
+  i18n.global.locale.value = locale;
+  writeStoredLocale(locale);
+  syncVantLocale(locale);
+  setDocumentLanguage(locale);
+}