Category::extractDelayBasisId

private function extractDelayBasisId(string $basis): string
{
	$startString = '{=Document:';
	$endString = '}';
	$startPos = strpos($basis, $startString);
	$endPos = strpos($basis, $endString, $startPos + strlen($startString));

	if ($startPos !== false && $endPos !== false) {
		return substr($basis, $startPos + strlen($startString), $endPos - $startPos - strlen($startString));
	}

	return '';
}