private function convertToSnakeCase($input)
{
preg_match_all('!([A-Z][A-Z0-9]*(?=$|[A-Z][a-z0-9])|[A-Za-z][a-z0-9]+)!', $input, $matches);
$ret = $matches[0];
foreach ($ret as &$match) {
$match = $match == strtoupper($match) ? strtolower($match) : lcfirst($match);
}
return implode('_', $ret);
}