Certified/app/Http/Middleware/SetLocale.php

<?php

namespace App\Http\Middleware;

use App\Enums\Locale;
use Closure;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Facades\Auth;
use Symfony\Component\HttpFoundation\Response;

class SetLocale
{
    /**
     * Resolve the locale to use for this request, preferring (in order) the
     * authenticated user's saved preference, a locale switched to earlier in
     * the session, and finally the browser's Accept-Language header.
     */
    public function handle(Request $request, Closure $next): Response
    {
        $locale = Auth::check()
            ? Auth::user()->locale
            : session('locale') ?? $request->getPreferredLanguage(Locale::values());

        if (in_array($locale, Locale::values(), true)) {
            App::setLocale($locale);
        }

        return $next($request);
    }
}