Calculator.php

<?php

namespace BusinessDays;


/**
 * Class Calculator
 *
 * @package BusinessDays
 */
class Calculator
{
    const MONDAY    = 1;
    const TUESDAY   = 2;
    const WEDNESDAY = 3;
    const THURSDAY  = 4;
    const FRIDAY    = 5;
    const SATURDAY  = 6;
    const SUNDAY    = 7;

    const WEEK_DAY_FORMAT = 'N';
    const HOLIDAY_FORMAT  = 'm-d';
    const FREE_DAY_FORMAT = 'Y-m-d';

    /** @var \DateTime */
    private $date;

    /** @var \DateTime[] */
    private $holidays = array();

    /** @var \DateTime[] */
    private $freeDays = array();

    /** @var int[] */
    private $freeWeekDays = array();

    /**
     * @param \DateTime $startDate Date to start calculations from
     *
     * @return $this
     */
    public function setStartDate(\DateTime $startDate)
    {
        // Use clone so parameter is not passed as a reference.
        // If not, it can brake caller method by changing $startDate parameter while changing it here.

        $this->date = clone $startDate;

        return $this;
    }

    /**
     * @param \DateTime[] $holidays Array of holidays that repeats each year. (Only month and date is used to match).
     *
     * @return $this
     */
    public function setHolidays(array $holidays)
    {
        $this->holidays = $holidays;

        return $this;
    }

    /**
     * @return \DateTime[]
     */
    private function getHolidays()
    {
        return $this->holidays;
    }

    /**
     * @param \DateTime[] $freeDays Array of free days that dose not repeat.
     *
     * @return $this
     */
    public function setFreeDays(array $freeDays)
    {
        $this->freeDays = $freeDays;

        return $this;
    }

    /**
     * @return \DateTime[]
     */
    private function getFreeDays()
    {
        return $this->freeDays;
    }

    /**
     * @param int[] $freeWeekDays Array of days of the week which are not business days.
     *
     * @return $this
     */
    public function setFreeWeekDays(array $freeWeekDays)
    {
        $this->freeWeekDays = $freeWeekDays;

        return $this;
    }

    /**
     * @return int[]
     */
    private function getFreeWeekDays()
    {
        if (count($this->freeWeekDays) >= 7) {
            throw new \InvalidArgumentException('Too many non business days provided');
        }

        return $this->freeWeekDays;
    }

    /**
     * @param int $howManyDays
     *
     * @return $this
     */
    public function addBusinessDays($howManyDays)
    {
        if ($howManyDays < 1) {
            throw new \InvalidArgumentException('The parameter $howManyDays must be greater than 0');
        }

        $iterator = 0;
        while ($iterator < $howManyDays) {
            $this->getDate()->modify('+1 day');
            if ($this->isBusinessDay($this->getDate())) {
                $iterator++;
            }
        }

        return $this;
    }

    /**
     * @param int $howManyDays
     *
     * @return $this
     */
    public function subBusinessDays($howManyDays)
    {
        if ($howManyDays < 1) {
            throw new \InvalidArgumentException('The parameter $howManyDays must be greater than 0');
        }

        $iterator = 0;
        while ($iterator < $howManyDays) {
            if ($this->isBusinessDay($this->getDate())) {
                $iterator++;
            }
            if ($iterator < $howManyDays) { //Don`t modify the date if we are on the last iteration
                $this->getDate()->modify('-1 day');
            }
        }
        return $this;
    }

    /**
     * @return \DateTime
     */
    public function getDate()
    {
        if ($this->date === null) {
            $this->date = new \DateTime();
        }

        return $this->date;
    }

    /**
     * @param \DateTime $date
     *
     * @return bool
     */
    public function isBusinessDay(\DateTime $date)
    {
        if ($this->isFreeWeekDayDay($date)) {
            return false;
        }

        if ($this->isHoliday($date)) {
            return false;
        }

        if ($this->isFreeDay($date)) {
            return false;
        }

        return true;
    }

    /**
     * @param \DateTime $date
     *
     * @return bool
     */
    public function isFreeWeekDayDay(\DateTime $date)
    {
        $currentWeekDay = (int)$date->format(self::WEEK_DAY_FORMAT);

        if (in_array($currentWeekDay, $this->getFreeWeekDays())) {
            return true;
        }

        return false;
    }

    /**
     * @param \DateTime $date
     *
     * @return bool
     */
    public function isHoliday(\DateTime $date)
    {
        $holidayFormatValue = $date->format(self::HOLIDAY_FORMAT);
        foreach ($this->getHolidays() as $holiday) {
            if ($holidayFormatValue == $holiday->format(self::HOLIDAY_FORMAT)) {
                return true;
            }
        }

        return false;
    }

    /**
     * @param \DateTime $date
     *
     * @return bool
     */
    public function isFreeDay(\DateTime $date)
    {
        $freeDayFormatValue = $date->format(self::FREE_DAY_FORMAT);
        foreach ($this->getFreeDays() as $freeDay) {
            if ($freeDayFormatValue == $freeDay->format(self::FREE_DAY_FORMAT)) {
                return true;
            }
        }

        return false;
    }
}