gistfile1.php

<?php

/**
 * Class Holidays
 */
class Holidays
{
    /**
     * @var array
     */
    protected $days = [];

    /**
     * @param $day
     */
    public function addDay($day)
    {
        $this->days[] = $day;
    }

    /**
     * @param array $days
     */
    public function addDays(array $days)
    {
        $this->days = array_merge($this->days, $days);
    }

    /**
     * @return array
     */
    public function getDays()
    {
        return $this->days;
    }
}

/**
 * Class Workingdays
 */
class Workingdays
{
    /**
     * @var array
     */
    protected $days = [];

    /**
     * @param $day
     */
    public function addDay($day)
    {
        $this->days[] = $day;
    }

    /**
     * @param array $days
     */
    public function addDays(array $days)
    {
        $this->days = array_merge($this->days, $days);
    }

    /**
     * @return array
     */
    public function getDays()
    {
        return $this->days;
    }
}

/**
 * Class HolidayManager
 */
class HolidayManager
{
    /**
     * @var DateTime
     */
    protected $startDate;

    /**
     * @var Holidays
     */
    protected $holidays;

    /**
     * @var Workingdays
     */
    protected $workingdays;

    /**
     * @var
     */
    protected $endDate;

    /**
     * @param DateTime $startDate
     * @param Holidays $holidays
     * @param Workingdays $workingdays
     */
    public function __construct(\DateTime $startDate, Holidays $holidays,  Workingdays $workingdays)
    {
        $this->startDate   = $startDate;
        $this->holidays    = $holidays;
        $this->workingdays = $workingdays;
    }

    /**
     * @param $delay
     * @return DateTime
     */
    public function findNextWorkingDay($delay)
    {
        $day = 1;

        while($delay >= $day) {

            $currentDate = $this->addDay($this->startDate);

            while ($currentDate == $this->startDate) {
                $currentDate = $this->addDay($this->startDate->add(new \DateInterval('P1D')));
            }

            $day++;
        }

        return $this->startDate;
    }

    /**
     * @param $currentDate
     * @return mixed
     */
    protected function addDay($currentDate)
    {
        if (in_array($currentDate->format('Y-m-d'), $this->holidays->getDays())) {
            $this->startDate->add(new \DateInterval('P1D'));
        }

        if (in_array($currentDate->format('*-m-d'), $this->holidays->getDays())) {

            $this->startDate->add(new \DateInterval('P1D'));
        }

        if (!in_array($currentDate->format('N'), $this->workingdays->getDays())) {
            return $currentDate;
        }

        $this->startDate->add(new \DateInterval('P1D'));
    }
}

$holidays = new Holidays;
$holidays->addDays(['2015-12-24', '*-12-25']);
$holidays->addDay('*-01-01');

$workingdays = new Workingdays;
$workingdays->addDays(['1', '2']);
$workingdays->addDay('3');
$workingdays->addDay('4');
$workingdays->addDay('5');

$holidayManager = new HolidayManager(new \DateTime('2015-12-01'), $holidays, $workingdays);
$nextBusinessDay = $holidayManager->findNextWorkingDay(45);

var_dump($nextBusinessDay);