BaseManager::getSiteIdByDomain

static function getSiteIdByDomain($domain)
{
	$site = array_filter(static::getSiteList(), function($site) use ($domain) {
		return $domain === $site["SERVER_NAME"];
	});

	if (!$site)
	{
		return null;
	}

	$site = current($site);
	if ($site["ID"])
	{
		return $site["ID"];
	}

	return null;
}