add change language

src/i18n/index.ts

@@ -0,0 +1,75 @@
+import { createI18n as createVueI18n } from 'vue-i18n';
+import type { SupportedLocale } from './constants';
+import { defaultLocale, supportedLocales } from './constants';
+import en from './messages/en';
+import vi from './messages/vi';
+
+export const i18nMessages = {
+  en,
+  vi,
+} as const;
+
+let activeI18n: ReturnType<typeof createI18n> | null = null;
+
+const normalizeLocaleToken = (locale?: string | null): string | undefined => {
+  if (!locale) return undefined;
+  return locale
+    .trim()
+    .toLowerCase()
+    .replace('_', '-');
+};
+
+export const toSupportedLocale = (locale?: string | null): SupportedLocale | undefined => {
+  const normalized = normalizeLocaleToken(locale);
+  if (!normalized) return undefined;
+
+  const direct = supportedLocales.find(item => item === normalized);
+  if (direct) return direct;
+
+  const base = normalized.split('-')[0];
+  return supportedLocales.find(item => item === base);
+};
+
+export const normalizeLocale = (locale?: string | null): SupportedLocale => {
+  return toSupportedLocale(locale) ?? defaultLocale;
+};
+
+export const resolveLocaleFromAcceptLanguage = (acceptLanguage?: string | null): SupportedLocale | undefined => {
+  if (!acceptLanguage) return undefined;
+
+  const candidates = acceptLanguage
+    .split(',')
+    .map((part) => {
+      const [rawLocale, ...params] = part.trim().split(';');
+      const qParam = params.find(param => param.trim().startsWith('q='));
+      const quality = qParam ? Number.parseFloat(qParam.split('=')[1] ?? '1') : 1;
+      return {
+        locale: rawLocale,
+        quality: Number.isFinite(quality) ? quality : 1,
+      };
+    })
+    .sort((a, b) => b.quality - a.quality);
+
+  for (const candidate of candidates) {
+    const matched = toSupportedLocale(candidate.locale);
+    if (matched) return matched;
+  }
+
+  return undefined;
+};
+
+export const createI18n = (initialLocale?: string | null) => {
+  const locale = normalizeLocale(initialLocale);
+  const i18n = createVueI18n({
+    legacy: false,
+    locale,
+    fallbackLocale: defaultLocale,
+    messages: i18nMessages,
+  });
+  activeI18n = i18n;
+  return i18n;
+};
+
+export const getActiveI18n = () => activeI18n;
+
+export type AppI18n = ReturnType<typeof createI18n>;