FCM message send service

MessageSend.php

<?php
namespace Core\InfrastructureBundle\Service\Firebase;

use Core\ApplicationBundle\Interfaces\PassengerDeviceNotificationSenderInterface;
use Google\Auth\Credentials\ServiceAccountCredentials;
use GuzzleHttp\Client as HttpClient;
use Psr\Http\Message\StreamInterface;

class MessageSend implements PassengerDeviceNotificationSenderInterface
{
    private const FCM_SCOPE = 'https://www.googleapis.com/auth/firebase.messaging';

    private const FCM_BASE_URL = 'https://fcm.googleapis.com/v1/projects/elpass-intercity/messages:send';

    /**
     * @var HttpClient
     */
    private $httpClient;

    public function __construct()
    {
        $headers = [
            'Content-Type' => 'application/json; UTF-8',
        ];

        $this->httpClient = new HttpClient([
            'http_errors' => false,
            'headers' => $headers,
            'connect_timeout' => 15.0,
            'read_timeout' => 15.0,
            'timeout' => 15.0,
            'curl' => [
                CURLOPT_CONNECTTIMEOUT => 15,
            ]
        ]);
    }

    public function execute(
        string $deviceToken,
        string $messageTitle,
        string $messageText,
        array $data = []
    ): StreamInterface {
        $credentials = new ServiceAccountCredentials(
            self::FCM_SCOPE,
            __DIR__ .  '/../../Resources/config/elpass-intercity-firebase.json'
        );

        $credentials->fetchAuthToken();
        $token = $credentials->getLastReceivedToken()['access_token'];

        $message = [
            'token' => $deviceToken,
            'notification' => [
                'body' => $messageText,
                'title' => $messageTitle,
            ],
        ];

        if ($data) {
            $message['data'] = $data;
        }

        $response = $this->httpClient->post(self::FCM_BASE_URL, [
            'json' => [
                'message' => $message,
            ],
            'headers' => [
                'Authorization' => 'Bearer ' . $token,
            ],
        ]);

        return $response->getBody();
    }
}