refactor(i18n): migrate locale configuration to generated types

- Replace hardcoded locale strings with generated Locale enum from client
- Update cookie key name to be more specific (LOCALE_COOKIE_NAME -> JUDGE4C_LOCALE_KEY)
- Rename defaultLocale to DEFAULT_LOCALE for consistency
- Add 'server-only' imports to ensure server-side usage
- Simplify locale validation using Object.values(Locale)
- Clean up accept-language header parsing logic

src/config/i18n.ts

@@ -1,9 +1,5 @@
-// Supported locales
-export const locales = ["en", "zh"] as const;
-export type Locale = (typeof locales)[number];
+import { Locale } from "@/generated/client";
 
-// Default locale
-export const defaultLocale: Locale = "en";
+export const DEFAULT_LOCALE: Locale = Locale.en;
 
-// Cookie key for storing selected locale
-export const LOCALE_COOKIE_NAME = "LOCALE";
+export const LOCALE_COOKIE_KEY = "judge4c_locale";

src/i18n/locale.ts

@@ -1,31 +1,30 @@
-"use server";
+import "server-only";
 
-import {
-  defaultLocale,
-  Locale,
-  LOCALE_COOKIE_NAME,
-  locales
-} from "@/config/i18n";
+import { Locale } from "@/generated/client";
 import { cookies, headers } from "next/headers";
+import { DEFAULT_LOCALE, LOCALE_COOKIE_KEY } from "@/config/i18n";
 
-export async function getUserLocale() {
-  const cookieLocale = (await cookies()).get(LOCALE_COOKIE_NAME)?.value;
+const validLocales = Object.values(Locale);
 
-  if (cookieLocale && locales.includes(cookieLocale as Locale)) {
+export const getUserLocale = async () => {
+  const cookieLocale = (await cookies()).get(LOCALE_COOKIE_KEY)?.value;
+  if (validLocales.includes(cookieLocale as Locale)) {
     return cookieLocale as Locale;
   }
 
-  const acceptLanguage = (await headers()).get("accept-language") || "";
-  const firstLang = acceptLanguage.split(",")[0]?.trim().toLowerCase();
-  const langPrefix = firstLang?.slice(0, 2);
-
-  if (locales.includes(langPrefix as Locale)) {
+  const acceptLanguage = (await headers())
+    .get("accept-language")
+    ?.split(",")[0]
+    ?.trim()
+    .toLowerCase();
+  const langPrefix = acceptLanguage?.slice(0, 2);
+  if (validLocales.includes(langPrefix as Locale)) {
     return langPrefix as Locale;
   }
 
-  return defaultLocale;
-}
+  return DEFAULT_LOCALE;
+};
 
-export async function setUserLocale(locale: Locale) {
-  (await cookies()).set(LOCALE_COOKIE_NAME, locale);
-}
+export const setUserLocale = async (locale: Locale) => {
+  (await cookies()).set(LOCALE_COOKIE_KEY, locale);
+};

src/i18n/request.ts

@@ -1,11 +1,13 @@
-import { getUserLocale } from '@/i18n/locale';
-import { getRequestConfig } from 'next-intl/server';
+import "server-only";
+
+import { getUserLocale } from "@/i18n/locale";
+import { getRequestConfig } from "next-intl/server";
 
 export default getRequestConfig(async () => {
   const locale = await getUserLocale();
 
   return {
     locale,
-    messages: (await import(`../../messages/${locale}.json`)).default
+    messages: (await import(`../../messages/${locale}.json`)).default,
   };
 });