Fix Logic Flow Bypass in Symfony

class CheckoutController extends AbstractController {
    #[Route('/checkout/complete', name: 'checkout_complete')]
    public function complete(Request $request): Response {
        // VULNERABLE: Relying on a simple session flag that can be manipulated or left over
        if (!$request->getSession()->get('payment_started')) {
            return $this->redirectToRoute('checkout_start');
        }
    // Process order without verifying if the payment was actually successful
    return $this->render('checkout/success.html.twig');
}
}

class CheckoutController extends AbstractController {
    #[Route('/checkout/complete', name: 'checkout_complete')]
    public function complete(Order $order, WorkflowInterface $checkoutWorkflow): Response {
        // SECURE: Use Symfony Workflow to enforce strict state transitions
        if (!$checkoutWorkflow->can($order, 'to_completed')) {
            throw new AccessDeniedException('Illegal state transition attempt.');
        }
    try {
        $checkoutWorkflow->apply($order, 'to_completed');
        $this->entityManager->flush();
    } catch (LogicException $e) {
        throw new BadRequestHttpException('Invalid flow.');
    }

    return $this->render('checkout/success.html.twig');
}
}