Add i18n support with Next.js App Router and Dictionaries

proxy.ts

@@ -1,22 +1,52 @@
 import { NextResponse } from "next/server";
 import { auth } from "./auth";
+import { match } from "@formatjs/intl-localematcher";
+import Negotiator from "negotiator";
+
+const locales = ["tr", "en"];
+const defaultLocale = "tr";
+
+function getLocale(request: Request): string {
+  const headers = { "accept-language": request.headers.get("accept-language") || "" };
+  const languages = new Negotiator({ headers }).languages();
+  try {
+    return match(languages, locales, defaultLocale);
+  } catch {
+    return defaultLocale;
+  }
+}
 
 export default auth((req) => {
   const { nextUrl } = req;
   const isLoggedIn = !!req.auth;
-  const isLoginPage = nextUrl.pathname === "/login";
+  const pathname = nextUrl.pathname;
+
+  // Check if there is any supported locale in the pathname
+  const pathnameIsMissingLocale = locales.every(
+    (locale) => !pathname.startsWith(`/${locale}/`) && pathname !== `/${locale}`
+  );
 
-  // Proxy arkasında çalışırken doğru adresi alabilmek için
   const host = req.headers.get("x-forwarded-host") || req.headers.get("host") || "localhost:3000";
   const proto = req.headers.get("x-forwarded-proto") || "http";
   const baseUrl = `${proto}://${host}`;
 
+  // Redirect if there is no locale
+  if (pathnameIsMissingLocale) {
+    const locale = getLocale(req as any);
+    return NextResponse.redirect(
+      new URL(`/${locale}${pathname === '/' ? '' : pathname}`, baseUrl)
+    );
+  }
+
+  const currentLocale = pathname.split('/')[1] || defaultLocale;
+  const isLoginPage = pathname === `/${currentLocale}/login`;
+
   if (!isLoggedIn && !isLoginPage) {
-    return NextResponse.redirect(new URL("/login", baseUrl));
+    return NextResponse.redirect(new URL(`/${currentLocale}/login`, baseUrl));
   }
 
   if (isLoggedIn && isLoginPage) {
-    return NextResponse.redirect(new URL("/dashboard", baseUrl));
+    return NextResponse.redirect(new URL(`/${currentLocale}/dashboard`, baseUrl));
   }
 
   return NextResponse.next();