ResourceBooking::getAvailableTimeSlots

static function getAvailableTimeSlots($accessibility, $options)
{
	$from = (isset($options['from']) && $options['from'] instanceof Date) ? $options['from'] : new Date();
	$to = (isset($options['to']) && $options['to'] instanceof Date) ? $options['to'] : new Date();
	$to->add('P1D');
	$scale = (int)$options['scale'] > 0 ? (int)$options['scale'] : 60;

	$workTimeStart = (int)COption::getOptionString('calendar', 'work_time_start', 9);
	$workTimeEnd = (int)COption::getOptionString('calendar', 'work_time_end', 19);

	$step = 0;
	$currentDate = new DateTime($from->toString(), Date::convertFormatToPhp(FORMAT_DATETIME));
	$slots = [];

	while ($currentDate->getTimestamp() < $to->getTimestamp())
	{
		$currentDate->setTime($workTimeStart, 0, 0);
		while ((int)$currentDate->format('H') < $workTimeEnd)
		{
			if ($currentDate->getTimestamp() > time())
			{
				$isFree = true;
				$slotStart = $currentDate->getTimestamp();
				$slotEnd = $slotStart + $scale * 60;

				foreach ($accessibility as $i => $item)
				{
					if ($item['toTs'] > $slotStart && $item['fromTs'] < $slotEnd)
					{
						$isFree = false;
						break;
					}
				}

				if ($isFree)
				{
					$slots[] = clone $currentDate;
				}
			}
			$currentDate->add('PT'.$scale.'M');
			$step++;
		}

		if($step > 1000)
		{
			break;
		}
		$currentDate->add('P1D');
	}

	return $slots;
}