refactor: support i18n

web/i18n/config.ts

@@ -0,0 +1,76 @@
+export const SUPPORTED_LOCALES = ["zh-CN", "en-US"] as const
+export type AppLocale = (typeof SUPPORTED_LOCALES)[number]
+
+export const DEFAULT_LOCALE: AppLocale = "zh-CN"
+export const LOCALE_STORAGE_KEY = "cs_ai_agent_locale"
+
+const LOCALE_ALIASES: Record<string, AppLocale> = {
+  zh: "zh-CN",
+  "zh-cn": "zh-CN",
+  zh_cn: "zh-CN",
+  "zh-hans": "zh-CN",
+  en: "en-US",
+  "en-us": "en-US",
+  en_us: "en-US",
+}
+
+export function normalizeLocale(value: string | null | undefined): AppLocale {
+  return normalizeSupportedLocale(value) ?? DEFAULT_LOCALE
+}
+
+function normalizeSupportedLocale(
+  value: string | null | undefined
+): AppLocale | null {
+  if (!value) {
+    return null
+  }
+  const key = value.trim().toLowerCase()
+  return LOCALE_ALIASES[key] ?? null
+}
+
+export function isSupportedLocale(
+  value: string | null | undefined
+): value is AppLocale {
+  if (!value) {
+    return false
+  }
+  return SUPPORTED_LOCALES.includes(value as AppLocale)
+}
+
+export function resolveBrowserLocale({
+  storedLocale,
+  navigatorLanguages,
+}: {
+  storedLocale?: string | null
+  navigatorLanguages?: readonly string[] | null
+}): AppLocale {
+  if (isSupportedLocale(storedLocale)) {
+    return storedLocale
+  }
+
+  for (const locale of navigatorLanguages ?? []) {
+    const normalized = normalizeSupportedLocale(locale)
+    if (normalized) {
+      return normalized
+    }
+  }
+
+  return DEFAULT_LOCALE
+}
+
+export function readStoredLocale(): AppLocale {
+  if (typeof window === "undefined") {
+    return DEFAULT_LOCALE
+  }
+  return resolveBrowserLocale({
+    storedLocale: window.localStorage.getItem(LOCALE_STORAGE_KEY),
+    navigatorLanguages: window.navigator.languages,
+  })
+}
+
+export function writeStoredLocale(locale: AppLocale) {
+  if (typeof window === "undefined") {
+    return
+  }
+  window.localStorage.setItem(LOCALE_STORAGE_KEY, locale)
+}