CCrmDateTimeHelper::getUserTimezoneOffset

static function getUserTimezoneOffset(int $userId = null): int
{
	static $offsets = [];

	$currentUser = Container::getInstance()->getContext()->getUserId();
	if (is_null($userId))
	{
		$userId = $currentUser;
	}

	if (!isset($offsets[$userId]))
	{
		$offsets[$userId] = (int)($userId > 0 ? CTimeZone::GetOffset($currentUser === $userId ? null : $userId) : 0);
	}

	return $offsets[$userId] ?: 0;
}