simple WordPress rewrite rule

class SimpleEndpoint {
    public function hooks() {
        add_action( 'init', array( $this, 'add_endpoint' ) );
        add_action( 'template_redirect', array( $this, 'handle_request' ) );
    }

    public function add_endpoint() {
        add_rewrite_tag( '%foobar%', '([^&]+)' );
        add_rewrite_rule( '^(foobar)/?$', 'index.php?$matches[1]=1', 'top' );
    }

    public function handle_request() {
        if ( get_query_var('foobar') === '1' ) {
            wp_send_json( 'foo' => 'bar' );
        }
    }
}

$simple_endpoint = new SimpleEndpoint;
$simple_endpoint->hooks();