Unify dynamic locale routing

i18n/routing.ts

@@ -1,9 +1,17 @@
 import { defineRouting } from "next-intl/routing";
 
-export const routing = defineRouting({
-  locales: ["de", "en", "ar"],
-  defaultLocale: "de",
+export const appLocales = ["de", "en", "ar"] as const;
+
+export type RoutingLocale = (typeof appLocales)[number];
+
+export function createI18nRouting(defaultLocale: RoutingLocale = "de") {
+  return defineRouting({
+    locales: appLocales,
+    defaultLocale,
     localePrefix: "as-needed",
     localeCookie: false,
     localeDetection: false,
   });
+}
+
+export const routing = createI18nRouting();

middleware.ts

@@ -2,7 +2,7 @@ import createMiddleware from "next-intl/middleware";
 import { NextResponse } from "next/server";
 import type { NextRequest } from "next/server";
 
-import { routing } from "./i18n/routing";
+import { appLocales, createI18nRouting, routing } from "./i18n/routing";
 import {
   fromDevelopmentAdminPath,
   getAdminBaseUrl,
@@ -16,19 +16,18 @@ import {
 } from "./lib/admin-routing";
 import { getLocalizedPathWithDefault, stripLocalePrefix } from "./lib/locale";
 
-const intlMiddleware = createMiddleware(routing);
 const ADMIN_SESSION_COOKIE = "moh_admin_session";
 
 type SiteRuntimeState = {
-  defaultLocale: (typeof routing.locales)[number];
+  defaultLocale: (typeof appLocales)[number];
   maintenanceEnabled: boolean;
 };
 
-function isSupportedLocale(locale: string | undefined): locale is (typeof routing.locales)[number] {
+function isSupportedLocale(locale: string | undefined): locale is (typeof appLocales)[number] {
   return locale === "ar" || locale === "en" || locale === "de";
 }
 
-function getPathLocale(pathname: string, fallbackLocale: (typeof routing.locales)[number]) {
+function getPathLocale(pathname: string, fallbackLocale: (typeof appLocales)[number]) {
   const locale = pathname.split("/")[1];
 
   return isSupportedLocale(locale) ? locale : fallbackLocale;
@@ -71,10 +70,6 @@ async function getSiteRuntimeState(request: NextRequest): Promise<SiteRuntimeSta
   }
 }
 
-function hasLocalePrefix(pathname: string) {
-  return routing.locales.some((locale) => pathname === `/${locale}` || pathname.startsWith(`/${locale}/`));
-}
-
 function getAdminBasicAuthUser(): string {
   return process.env.ADMIN_BASIC_AUTH_USER ?? "";
 }
@@ -173,6 +168,7 @@ export default async function middleware(request: NextRequest) {
 
   const siteRuntimeState = await getSiteRuntimeState(request);
   const configuredDefaultLocale = siteRuntimeState.defaultLocale;
+  const intlMiddleware = createMiddleware(createI18nRouting(configuredDefaultLocale));
 
   if (
     siteRuntimeState.maintenanceEnabled &&
@@ -185,36 +181,6 @@ export default async function middleware(request: NextRequest) {
     return NextResponse.redirect(redirectUrl, 307);
   }
 
-  if (
-    configuredDefaultLocale !== routing.defaultLocale &&
-    (pathname === "/de" || pathname.startsWith("/de/"))
-  ) {
-    return NextResponse.next();
-  }
-
-  if (
-    configuredDefaultLocale !== routing.defaultLocale &&
-    !hasLocalePrefix(pathname)
-  ) {
-    const rewriteUrl = request.nextUrl.clone();
-    rewriteUrl.pathname = getLocalizedPathWithDefault(
-      configuredDefaultLocale,
-      pathname,
-      routing.defaultLocale,
-    );
-    return NextResponse.rewrite(rewriteUrl);
-  }
-
-  if (
-    configuredDefaultLocale === routing.defaultLocale &&
-    (pathname === "/de" || pathname.startsWith("/de/"))
-  ) {
-    const redirectUrl = request.nextUrl.clone();
-    const nextPath = pathname.slice(3) || "/";
-    redirectUrl.pathname = nextPath;
-    return NextResponse.redirect(redirectUrl, 308);
-  }
-
   return intlMiddleware(request);
 }
 

tests/locale.test.ts

@@ -0,0 +1,22 @@
+import { describe, expect, it } from "vitest";
+
+import { getLocalizedPathWithDefault } from "../lib/locale";
+
+describe("locale path helpers", () => {
+  it("keeps the configured default locale on the bare domain", () => {
+    expect(getLocalizedPathWithDefault("ar", "/", "ar")).toBe("/");
+    expect(getLocalizedPathWithDefault("de", "/", "ar")).toBe("/de");
+    expect(getLocalizedPathWithDefault("en", "/", "ar")).toBe("/en");
+  });
+
+  it("builds nested paths against the configured default locale", () => {
+    expect(getLocalizedPathWithDefault("ar", "/coming-soon", "ar")).toBe("/coming-soon");
+    expect(getLocalizedPathWithDefault("de", "/coming-soon", "ar")).toBe("/de/coming-soon");
+    expect(getLocalizedPathWithDefault("en", "/portfolio", "de")).toBe("/en/portfolio");
+  });
+
+  it("strips old locale prefixes before rebuilding the target path", () => {
+    expect(getLocalizedPathWithDefault("en", "/ar/contact", "de")).toBe("/en/contact");
+    expect(getLocalizedPathWithDefault("ar", "/de/about", "ar")).toBe("/about");
+  });
+});