InvoiceMap::getIntervalMapCode

protected function getIntervalMapCode()
{
	$intervalCodes = [
		Calculator::SALE_TYPE_DAY_OFFSET => [
			DateType\Day::TYPE_ALTERNATING_DAYS => self::FIELD_DAILY_INTERVAL,
			DateType\Day::TYPE_A_FEW_DAYS_AFTER => self::FIELD_INTERVAL,
		],
		Calculator::SALE_TYPE_WEEK_OFFSET => [
			DateType\Day::TYPE_ALTERNATING_DAYS => self::FIELD_WEEKLY_INTERVAL,
			DateType\Week::TYPE_A_FEW_WEEKS_AFTER => self::FIELD_INTERVAL,
		],
		Calculator::SALE_TYPE_MONTH_OFFSET => [
			DateType\Month::TYPE_DAY_OF_ALTERNATING_MONTHS => self::FIELD_MONTHLY_FIRST_TYPE_INTERVAL,
			DateType\Month::TYPE_WEEKDAY_OF_ALTERNATING_MONTHS => self::FIELD_MONTHLY_SECOND_TYPE_INTERVAL,
			DateType\Month::TYPE_A_FEW_MONTHS_AFTER => self::FIELD_INTERVAL,
		],
		Calculator::SALE_TYPE_YEAR_OFFSET => [
			DateType\Year::TYPE_DAY_OF_CERTAIN_MONTH => self::FIELD_YEARLY_FIRST_TYPE_INTERVAL_MONTH,
			DateType\Year::TYPE_WEEKDAY_OF_CERTAIN_MONTH => self::FIELD_YEARLY_SECOND_TYPE_INTERVAL_MONTH,
			DateType\Year::TYPE_ALTERNATING_YEAR => self::FIELD_INTERVAL,
		],
	];

	return $intervalCodes[$this->mode][$this->unitType];
}