Code review test

<?php

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use App\Entity\User;
use Doctrine\ORM\EntityManagerInterface;
use Symfony\Component\Routing\Annotation\Route;
use Symfony\Contracts\HttpClient\HttpClientInterface;

class UserController extends AbstractController
{
    private $entityManager;
    private $mailer;

    public function __construct(
        EntityManagerInterface $entityManager,
        \Swift_Mailer $mailer,
        HttpClientInterface $httpClient
    )
    {
        $this->entityManager = $entityManager;
        $this->mailer = $mailer;
        $this->httpClient = $httpClient;
    }

    /**
     * @Route("/user/create", name="create_user", methods={"POST"})
     */
    public function createUser(Request $request): Response
    {
        $username = $request->request->get('username');
        $email = $request->request->get('email');
        $age = $request->request->get('age');

        //get daily limit from CRM
        $response = $this->httpClient->request(
            'GET',
            'https://crm-api.com/api/get_limits',
        );
        $userDailyLimit = $response->toArray()['user_daily_limit'];

        //check if daily limit is not reached
        if($this->entityManager->getRepository(User::class)->count(['createdAt' => new \DateTime('today')]) >= $userDailyLimit) {
            return new Response('Daily limit reached', 500);
        }

        //check age
        if($age < 18) {
            return new Response('User must be at least 18 years old', 404);
        }

        //create a user
        $user = new User();
        $user->setUsername($username);
        $user->setEmail($email);
        $user->setAge($age);

        //save user to DB
        $this->entityManager->persist($user);
        $this->entityManager->flush();

        //send message to user
        $message = (new \Swift_Message('Welcome'))
            ->setFrom('[email protected]')
            ->setTo($user->getEmail())
            ->setBody("Welcome to the site, {$user->getUsername()}");

        $this->mailer->send($message);

        //create a client for the user in CRM
        $this->httpClient->request(
            'POST',
            'https://crm-api.com/api/clients',
            [
                'json' => [
                    'name' => $username,
                    'email' => $email,
                ],
            ]
        );

        return new Response('User created');
    }
}