<?php
class BusinessCalendar
{

    private $debugMessage;
    private $debug = false;

    public function __construct($debug = false)
    {
        $this->debug = $debug;
    }

    public function setDebug($debug = true)
    {
        $this->debug = $debug;
    }

    public function getNextBusinessDays($date, $workingDays, $holidays, $numDays)
    {
        $days = $this->getBusinessDays($date, $workingDays, $holidays, true, $numDays);

        $this->debugMessage = sprintf(
            'The next %d business after %s are %s',
            $numDays,
            $this->formatDate($date),
            implode(', ', $this->formatDate($days, true))
        );
        $this->printDebugMessage();

        return $days;
    }

    public function getPriorBusinessDays($date, $workingDays, $holidays, $numDays)
    {
        return $this->getBusinessDays($date, $workingDays, $holidays, false, $numDays);
    }

    public function getBusinessDaysForAPeriod($startDate, $endDate, $workingDays, $holidays)
    {
        $days = [];
        $day = $startDate;
        while ($day < $endDate) {
            $day = $this->getTradingDate($day, $workingDays, $holidays, true);
            $days[] = $day;
        }

        $this->debugMessage = sprintf(
            'There are %d business day(s) between %s and %s which are %s',
            count($days),
            $this->formatDate($startDate),
            $this->formatDate($endDate),
            implode(', ', $this->formatDate($days, true))
        );
        $this->printDebugMessage();
        return $days;
    }

    private function printDebugMessage()
    {
        if (!$this->debug) {
            return;
        }
        echo $this->debugMessage.PHP_EOL.PHP_EOL;
    }

    public function getNextBusinessDay($date, $workingDays, $holidays)
    {
        $day = $this->getTradingDate($date, $workingDays, $holidays, true);
        // \033[1;32m
        $this->debugMessage = sprintf(
            "The next business day after %s is %s",
            $this->formatDate($date),
            $this->formatDate($day, true)
        );
        $this->printDebugMessage();

        return $day;
    }

    public function getPriorBusinessDay($date, $workingDays, $holidays)
    {
        $day = $this->getTradingDate($date, $workingDays, $holidays, false);

        $this->debugMessage = sprintf(
            'The business day before %s was %s',
            $this->formatDate($date),
            $this->formatDate($day, true)
        );
        $this->printDebugMessage();
        return $day;
    }

    private function formatDate($dates, $highlight = false)
    {
        $ret = [];
        if (is_array($dates)) {
            array_walk(
                $dates,
                function ($date) use (&$ret, $highlight) {
                    $ret[] = $this->formatDate($date, $highlight);
                }
            );
        } else {
            // return sprintf("\033[40;1m%s\033[0m", (new \DateTime($dates))->format('D d M y'));
            $format = $highlight ? "\033[30;47m%s\033[0m" : "%s";
            return sprintf($format, (new \DateTime($dates))->format('D, j M y'));
        }
        return $ret;
    }

    private function getBusinessDays($date, $workingDays, $holidays, $next, $numDays)
    {
        $days = [];
        $day = $date;
        for ($i = 0; $i < $numDays; $i++) {
            $day = $this->getTradingDate($day, $workingDays, $holidays, $next);
            $days[] = $day;
        }
        return $days;
    }

    private function getTradingDate($date, $weekdays, $holidays, $next = true)
    {
        $date = new \DateTime($date);

        $IsAWeekday = function (\DateTime $date) use ($weekdays) {
            return in_array($date->format('N'), $weekdays);
        };

        $IsAHoliday = function (\DateTime $date) use ($holidays) {
            return  $holidays ?
            in_array($date->format('Y-m-d'), $holidays) : false;
        };

        do {
            if ($next) {
                $date->add(new \DateInterval('P1D'));
            } else {
                $date->sub(new \DateInterval('P1D'));
            }
        } while (!($IsAWeekday($date) && ! $IsAHoliday($date)));

        return $date->format('Y-m-d');
    }
}

$calendar = new BusinessCalendar(true);
$weekdays = [1,2,3,4,5];

$day = '2018-12-11';
$nextDay = $calendar->getNextBusinessDay($day, $weekdays, []);
$nextDay = $calendar->getPriorBusinessDay($day, $weekdays, []);

$nextDay = $calendar->getNextBusinessDay($day, $weekdays, ['2018-08-06', '2018-08-07']);
$nextDays = $calendar->getNextBusinessDays($day, $weekdays, ['2018-08-06', '2018-08-07'], 2);
$nextDays = $calendar->getBusinessDaysForAPeriod(
    $day,
    '2018-12-18',
    $weekdays,
    ['2018-12-12', '2018-12-15']
);