protected function registerMiddleware()
    {
        $router = $this->app['router'];

        $router->aliasMiddleware('currency', SiteCurrencyMiddleware::class);
        $router->aliasMiddleware('admin.api.auth', AdminApiAuth::class);
        $router->aliasMiddleware('admin.auth', AdminAuth::class);
        $router->aliasMiddleware('admin.guest', RedirectIfAdminAuth::class);
        $router->aliasMiddleware('permission', Permission::class);
    }