CalendarFilter::getSectionsForFilter

static function getSectionsForFilter(string $type, ?string $preset, ?int $ownerId, ?int $userId): array
{
	$result = [];

	$sectionList = CCalendar::getSectionList([
		'CAL_TYPE' => $type,
		'OWNER_ID' => $ownerId,
		'checkPermissions' => true,
		'getPermissions' => true,
	]);
	$isPersonalCalendarContext = ($type === 'user' && $userId === $ownerId);

	$hiddenSections = [];
	if ($preset !== self::PRESET_INVITED)
	{
		$hiddenSections = UserSettings::getHiddenSections(
			$userId,
			[
				'type' => $type,
				'ownerId' => $ownerId,
				'isPersonalCalendarContext' => $isPersonalCalendarContext,
			]
		);
		$hiddenSections = array_map(static function($sectionId) {
			return (int)$sectionId;
		}, $hiddenSections);
	}

	foreach ($sectionList as $section)
	{
		if (in_array((int)$section['ID'], $hiddenSections, true))
		{
			continue;
		}

		$result[] = (int)$section['ID'];
	}

	return $result;
}