Basic YNAB API implementation in PHP in Symfony 4

YNAB.php

<?php

namespace App\Services;

use Symfony\Component\Security\Core\Security;
use Doctrine\ORM\EntityManagerInterface;
use App\Entity\User;
use GuzzleHttp\Client;
use GuzzleHttp\RequestOptions;

/**
 * Class to implement the YNAB API
 *
 * @author Brandon Olivares
 */
class YNAB
{

    private $entityManager;

    private $user;

    public function __construct(Security $security, EntityManagerInterface $entityManager)
    {
        $this->entityManager = $entityManager;
        $this->user = $security->getUser();

        if ($this->user instanceof User && $this->user->isAuthorizedWithYNAB() && new \DateTime > $this->user->getTokenExpires()) {
            $this->refreshToken();
        }
    }

    public function call(string $endpoint, array $params = [], \stdClass $body = null, string $method = null): \stdClass
    {
        $client = new Client([
            'base_uri' => 'https://api.youneedabudget.com/v1/',
            'headers' => [
                'Authorization' => 'Bearer ' . ($this->user instanceof User ? $this->user->getAccessToken() : getenv('YNAB_TOKEN')),
                'Accept' => 'application/json',
            ],
        ]);
        $options = [
            RequestOptions::QUERY => $params,
        ];
         if ($body) {
         if (!$method) {
             $method = 'POST';
         }
         $options[RequestOptions::jSON] = $body;
         } else {
             $method = 'GET';
         }
         $response = $client->request($method, $endpoint, $options);
         return json_decode($response->getBody());
    }

    public function authorize(string $code, string $redirect_uri): void
    {
        $client = new Client([
            'base_uri' => 'https://app.youneedabudget.com',
        ]);

        $response = $client->post('oauth/token', [
            RequestOptions::FORM_PARAMS => [
                'client_id' => getenv('YNAB_CLIENT_ID'),
                'client_secret' => getenv('YNAB_CLIENT_SECRET'),
                'redirect_uri' => $redirect_uri,
                'grant_type' => 'authorization_code',
                'code' => $code,
            ]
        ]);

        $data = json_decode($response->getBody());
        $this->setTokens($data);
    }

    public function refreshToken(): void
    {
        $client = new Client([
            'base_uri' => 'https://app.youneedabudget.com',
        ]);
        $response = $client->post('oauth/token', [
            RequestOptions::FORM_PARAMS => [
                'client_id' => getenv('YNAB_CLIENT_ID'),
                'client_secret' => getenv('YNAB_CLIENT_SECRET'),
                'grant_type' => 'refresh_token',
                'refresh_token' => $this->user->getRefreshToken(),
            ]
        ]);

        $data = json_decode($response->getBody());
        $this->setTokens($data);
    }

    protected function setTokens(\stdClass $data): void
    {
        if (!isset($data->access_token) || !isset($data->expires_in) || !isset($data->refresh_token)) {
            throw new \LogicException('Invalid response from YNAB API while trying to fetch access token.');
        }

        $this->user->setAccessToken($data->access_token);
        $this->user->setTokenExpires((new \DateTime)
            ->add(new \DateInterval('PT' . $data->expires_in . 'S')));
        $this->user->setRefreshToken($data->refresh_token);
        $this->entityManager->flush();
    }

    public function formatAmount($amount)
    {
        return '$' . number_format(($amount >= 0 ? $amount / 1000.0 : $amount / -1000.0), 2);
    }
}