🐛 Fix lang detection (#1281)

Co-authored-by: Benjamin Arias <12382534+bjlaa@users.noreply.github.com>

Author: bjlaa

src/i18nConfig.ts

@@ -1,4 +1,5 @@
 import type { Config } from 'next-i18n-router/dist/types'
+import type { NextRequest } from 'next/server'
 
 export const LOCALE_EN_KEY = 'en'
 export const LOCALE_ES_KEY = 'es'
@@ -17,6 +18,25 @@ const i18nConfig: Config = {
     maxAge: 31536000,
     secure: true, // Required when using SameSite=None
   },
+  localeDetector: (request: NextRequest, config: Config): string => {
+    // Check for NEXT_LOCALE cookie
+    const nextLocale = request.cookies.get(NEXT_LOCALE_COOKIE_NAME)?.value
+    if (nextLocale && config.locales.includes(nextLocale)) {
+      return nextLocale
+    }
+
+    // Check browser language
+    const acceptLanguage = request.headers.get('accept-language')
+    if (acceptLanguage) {
+      const browserLang = acceptLanguage.split(',')[0].split('-')[0]
+      if (config.locales.includes(browserLang)) {
+        return browserLang
+      }
+    }
+
+    // Return default locale
+    return config.defaultLocale
+  },
 }
 
 export default i18nConfig