优化多语言处理

src/i18n/request.ts

@@ -1,7 +1,13 @@
 import { getRequestConfig } from "next-intl/server"
-import enMessages from "@/i18n/messages/en.json"
+import { getMessagesForLocale } from "@/i18n/messages"
+import { resolveRequestLocale } from "@/i18n/resolve-request-locale"
+import { APP_LOCALE_TO_INTL_LOCALE } from "@/lib/i18n"
 
-export default getRequestConfig(async () => ({
-  locale: "en",
-  messages: enMessages,
-}))
+export default getRequestConfig(async () => {
+  const appLocale = await resolveRequestLocale()
+
+  return {
+    locale: APP_LOCALE_TO_INTL_LOCALE[appLocale],
+    messages: await getMessagesForLocale(appLocale),
+  }
+})

src/i18n/resolve-request-locale.ts

@@ -0,0 +1,51 @@
+import { cookies, headers } from "next/headers"
+import {
+  LANGUAGE_COOKIE_KEY,
+  LANGUAGE_MODE_COOKIE_KEY,
+  parseAcceptLanguageHeader,
+  parseLocaleFromCookieValue,
+  resolveSystemLocale,
+} from "@/lib/i18n"
+import type { AppLocale, LanguageMode } from "@/lib/types"
+
+const FALLBACK_LOCALE: AppLocale = "en"
+
+function parseLanguageModeCookie(value: string | undefined): LanguageMode {
+  return value === "manual" ? "manual" : "system"
+}
+
+export async function resolveRequestLocale(): Promise<AppLocale> {
+  let configuredLocale: AppLocale | null = null
+  let languageMode: LanguageMode = "system"
+
+  try {
+    const cookieStore = await cookies()
+    configuredLocale = parseLocaleFromCookieValue(
+      cookieStore.get(LANGUAGE_COOKIE_KEY)?.value
+    )
+    languageMode = parseLanguageModeCookie(
+      cookieStore.get(LANGUAGE_MODE_COOKIE_KEY)?.value
+    )
+  } catch {
+    // Ignore when request cookies are unavailable (e.g. static export build).
+  }
+
+  if (configuredLocale && languageMode === "manual") {
+    return configuredLocale
+  }
+
+  try {
+    const headerStore = await headers()
+    const candidates = parseAcceptLanguageHeader(
+      headerStore.get("accept-language")
+    )
+    const fromHeader = resolveSystemLocale(candidates)
+    if (fromHeader) {
+      return fromHeader
+    }
+  } catch {
+    // Ignore when request headers are unavailable (e.g. static export build).
+  }
+
+  return configuredLocale ?? FALLBACK_LOCALE
+}