<?php
declare(strict_types=1);

/**
 * [base64url_encode base64 url encode data.]
 *
 * @param  string       $data Data to encode
 *
 * @return string|bool       Encoded Data. False, if data couldn't be encoded.
 */
function base64url_encode(string $data) {
  $b64 = base64_encode($data);
  if ($b64 === false) return false;
  $url = strtr($b64, '+/', '-_');
  return rtrim($url, '=');
}