/**
* Fetch access token with a grant_type of client_credentials
*
* @access public
* @return array
*
* throws \InvalidArgumentException
* @throws HttpResponseException
*/
protected function getAccessToken()
{
$response = $this->httpClient->post(self::ENDPOINT_ACCESS_TOKEN, array('grant_type' => 'client_credentials', 'client_id' => self::$config['client_id'], 'client_secret' => self::$config['client_secret'], 'scope' => implode(',', self::$config['scopes'])));
$data = json_decode($response->getContent(), true);
if (json_last_error() !== JSON_ERROR_NONE) {
$ex = new HttpResponseException('[access_token] Invalid JSON: ' . json_last_error_msg());
$ex->setResponse($this->httpClient->getLastResponse())->setRequest($this->httpClient->getLastRequest());
throw $ex;
}
if (false === array_key_exists('access_token', $data)) {
throw new HttpResponseException('access_token is missing from response. ' . $response->getContent());
}
return $data;
}
