Google auth and work with google speadsheets

/**
 * The first create app to link https://console.developers.google.com
 * Later save json file of created app to own site. Path to the file transmit to GoogleHandler initialize method
 * 
 * composer.json
 * {
 *     "require": {
 *         "asimlqt/php-google-spreadsheet-client": "2.3.*", // https://github.com/asimlqt/php-google-spreadsheet-client
 *         "google/apiclient": "^2.0.0@RC"
 *     }
 * }
 *
 */
 
class GoogleHandler
{
    public function initialize($credentials_file)
    {
        putenv("GOOGLE_APPLICATION_CREDENTIALS=service-account-credentials.json");
        
        $client = new Google_Client();
        $credentials_file = $credentials_file;
        if (file_exists($credentials_file)) {
            $client->setAuthConfig($credentials_file);
        } elseif (getenv('GOOGLE_APPLICATION_CREDENTIALS')) {
            $client->useApplicationDefaultCredentials();
        } else {
            return false;
        }
        $appName = $this->modx->getOption('google_app_name');
        $client->setApplicationName($appName);
        $client->setScopes([
            'https://spreadsheets.google.com/feeds'
        ]);
        $tokenArray = $client->fetchAccessTokenWithAssertion();
        return $tokenArray["access_token"];
    }
}

/**
 * Example work with Google API
 */
 
require_once dirname(dirname(dirname(dirname(__FILE__)))).'/index.php'; // include $modx
require_once(MODX_CORE_PATH . 'vendor/autoload.php');
include_once MODX_CORE_PATH . 'vendor/google/apiclient/examples/templates/base.php';

use Google\Spreadsheet\DefaultServiceRequest;
use Google\Spreadsheet\ServiceRequestFactory;

$google_handler = new GoogleHandler($modx);
    
$accessToken = $google_handler->initialize(MODX_CORE_PATH . your_path_to_file);
if (!$accessToken) {
    return false;
}
$row = array(
    'команда' => !empty($_POST['team']) ? $_POST['team'] : '',
    "учреждение" => !empty($_POST['institution']) ? $_POST['institution'] : '',
    "город" => !empty($_POST['city']) ? $_POST['city'] : '',
    "регион" => !empty($_POST['region']) ? $_POST['region'] : '',
    "фиоруководителя" => !empty($_POST['leader']) ? $_POST['leader'] : '',
    "телефон" => !empty($_POST['phone']) ? $_POST['phone'] : '',
    "e-mail" => !empty($_POST['email']) ? $_POST['email'] : ''
);

$serviceRequest = new DefaultServiceRequest($accessToken);
ServiceRequestFactory::setInstance($serviceRequest);

$spreadsheetService = new Google\Spreadsheet\SpreadsheetService();
$spreadsheetFeed = $spreadsheetService->getSpreadsheets();
if ($type === 'Заявка на регистрацию.') {
    $spreadsheet = $spreadsheetFeed->getByTitle( first_spreadsheet );
} else {
    $spreadsheet = $spreadsheetFeed->getByTitle( second_spreadsheet  );
}
$worksheetFeed = $spreadsheet->getWorksheets();

$subject = $google_handler->getSubject($_POST['subject']);

$worksheet = $worksheetFeed->getByTitle($subject['title']);
if (!$worksheet) {
    $worksheet = $spreadsheet->addWorksheet($subject['title'], 50, count($row));
    $cellFeed = $worksheet->getCellFeed();
    $i = 1;
    foreach ($row as $key => $value) {
        $cellFeed->editCell(1, $i, $key);
        $i++;
    }
}
$listFeed = $worksheet->getListFeed();
$listFeed->insert($row);