Fix runtime default locale resolution

lib/locale.ts

@@ -1,21 +1,23 @@
-import { routing } from "../i18n/routing";
+import { appLocales } from "../i18n/routing";
 
-export type AppLocale = (typeof routing.locales)[number];
+export type AppLocale = (typeof appLocales)[number];
 
-export function resolveLocale(locale: string): AppLocale {
-  if (locale === "en" || locale === "ar") {
-    return locale;
-  }
+export const FALLBACK_LOCALE: AppLocale = "de";
 
-  return routing.defaultLocale;
+export function isSupportedLocale(locale: string | undefined | null): locale is AppLocale {
+  return locale === "de" || locale === "en" || locale === "ar";
+}
+
+export function resolveLocale(locale: string | undefined | null, fallbackLocale: AppLocale): AppLocale {
+  return isSupportedLocale(locale) ? locale : fallbackLocale;
 }
 
 export function getDirection(locale: string): "ltr" | "rtl" {
-  return resolveLocale(locale) === "ar" ? "rtl" : "ltr";
+  return locale === "ar" ? "rtl" : "ltr";
 }
 
 export function stripLocalePrefix(pathname: string): string {
-  for (const locale of routing.locales) {
+  for (const locale of appLocales) {
     if (pathname === `/${locale}`) {
       return "/";
     }
@@ -31,7 +33,7 @@ export function stripLocalePrefix(pathname: string): string {
 export function getLocalizedPath(
   locale: string,
   pathname = "/",
-  defaultLocale: AppLocale = routing.defaultLocale,
+  defaultLocale: AppLocale,
 ): string {
   return getLocalizedPathWithDefault(locale, pathname, defaultLocale);
 }
@@ -39,9 +41,9 @@ export function getLocalizedPath(
 export function getLocalizedPathWithDefault(
   locale: string,
   pathname = "/",
-  defaultLocale: AppLocale = routing.defaultLocale,
+  defaultLocale: AppLocale,
 ): string {
-  const localeKey = resolveLocale(locale);
+  const localeKey = resolveLocale(locale, defaultLocale);
   const normalizedPath = pathname === "" ? "/" : pathname;
   const strippedPath = stripLocalePrefix(normalizedPath);
 

lib/metadata.ts

@@ -1,6 +1,6 @@
 import type { Metadata } from "next";
 
-import { routing } from "../i18n/routing";
+import { appLocales } from "../i18n/routing";
 import {
   PAGE_TITLE_TOKEN,
   SITE_NAME_TOKEN,
@@ -22,9 +22,9 @@ function toAbsoluteUrl(pathname: string): string {
   return new URL(pathname, getSiteUrl()).toString();
 }
 
-export function buildLocaleAlternates(pathname: string, defaultLocale = routing.defaultLocale) {
+export function buildLocaleAlternates(pathname: string, defaultLocale: AppLocale) {
   const languages = Object.fromEntries(
-    routing.locales.map((locale) => [locale, toAbsoluteUrl(getLocalizedPathWithDefault(locale, pathname, defaultLocale))]),
+    appLocales.map((locale) => [locale, toAbsoluteUrl(getLocalizedPathWithDefault(locale, pathname, defaultLocale))]),
   ) as Record<AppLocale, string>;
 
   return {
@@ -120,8 +120,8 @@ export async function buildLocalizedMetadata({
   description,
   applyTitleTemplate,
 }: LocalizedMetadataInput): Promise<Metadata> {
-  const localeKey = resolveLocale(locale);
   const [settings, bindings] = await Promise.all([getSiteSettings(), getSiteSettingsMediaBindings()]);
+  const localeKey = resolveLocale(locale, settings.defaultLocale);
 
   return buildLocalizedMetadataFromConfig({
     settings,
@@ -152,7 +152,7 @@ export function buildLocalizedMetadataFromConfig(input: {
     description,
     applyTitleTemplate = true,
   } = input;
-  const localeKey = resolveLocale(locale);
+  const localeKey = resolveLocale(locale, settings.defaultLocale);
   const localeSettings = settings.locales[localeKey];
   const resolvedDescription = description?.trim() || localeSettings.siteDescription;
   const resolvedTitle = applyTitleTemplate
@@ -167,7 +167,7 @@ export function buildLocalizedMetadataFromConfig(input: {
     openGraph: {
       title: resolvedTitle,
       description: resolvedDescription,
-      url: toAbsoluteUrl(getLocalizedPath(localeKey, pathname)),
+      url: toAbsoluteUrl(getLocalizedPath(localeKey, pathname, settings.defaultLocale)),
       siteName: localeSettings.siteName,
       locale: localeKey,
       type: "website",

lib/toast.tsx

@@ -6,7 +6,7 @@ import {
   type ToastPosition,
 } from "react-hot-toast";
 
-import { resolveLocale } from "@/lib/locale";
+import { FALLBACK_LOCALE, resolveLocale } from "@/lib/locale";
 
 type ToastVariant = "default" | "success" | "error" | "loading";
 
@@ -14,13 +14,13 @@ type ToastMessage = string;
 
 function getCurrentLocale() {
   if (typeof window === "undefined") {
-    return "de" as const;
+    return FALLBACK_LOCALE;
   }
 
   const pathname = window.location.pathname;
-  const maybeLocale = pathname.split("/")[1] || "de";
+  const maybeLocale = pathname.split("/")[1] || FALLBACK_LOCALE;
 
-  return resolveLocale(maybeLocale);
+  return resolveLocale(maybeLocale, FALLBACK_LOCALE);
 }
 
 function getToastPosition(isArabic: boolean): ToastPosition {