Date Recurring Scheduler By Month

batch_processor.php

function batch_scheduler($start, $end, $interval) {
    $years = array();
    $recurrings = array($start);

    preg_match('/^[0-9]{4}/', $start, $startYear);
    preg_match('/^[0-9]{4}/', $end, $endYear);

    $diff = $endYear[0] - $startYear[0];

    if ($diff > 5) {
        for ($i = 0; $i <= $diff; $i = $i+5) {
            $years[] = $startYear[0] + $i;
        }

        if ( ! in_array($endYear[0], $years)) {
            $years[] = $endYear[0];
        }

        for ($m = 1; $m < count($years); $m++) {
            $s = preg_replace('/^[0-9]{4}/', $years[$m-1], $start);
            $e = preg_replace('/^[0-9]{4}/', $years[$m], $end);

            $scheduler = new Scheduler($s, $e);
            $recurrings[] = $scheduler->setRecurring($interval)->get();
        }
    } else {
        $scheduler = new Scheduler($start, $end);
        $recurrings[] = $scheduler->setRecurring($interval)->get();
    }

    

    return array_flatten(array_unique(array_flatten($recurrings)));
}

Scheduler.php

<?php

use \Exception;
use Carbon\Carbon;

class Scheduler {

    /**
     * Scheduler starting date
     * 
     * @var string
     */
    protected $startDate;

    /**
     * Scheduler end date
     * 
     * @var string
     */
    protected $endDate;

    /**
     * Recurrings scheduler dates
     * 
     * @var array
     */
    protected $recurrings = array();

    /**
     * Instantiate scheduler
     * 
     * @param string $startDate
     * @param string $endDate
     */
    public function __construct($startDate, $endDate)
    {
        $this->setDates($startDate, $endDate);
    }

    /**
     * Set start and end date for scheduler
     * 
     * @param string $startDate
     * @param string $endDate
     */
    public function setDates($startDate, $endDate)
    {
        $start = $this->toCarbon($startDate);
        $end = $this->toCarbon($endDate);

        if ($end < $start) {
            throw new Exception("End date {$endDate} cannot be lower than start date {$startDate}");
        }

        $this->startDate = $startDate;
        $this->endDate = $end->format('Y-m-d');
    }

    /**
     * Set scheduler recurring by month
     * 
     * @param integer $months
     * @return mixed
     */
    public function setRecurring($months, $startDate = null, $format = 'Y-m-d')
    {
        if ($months > 12) {
            throw new Exception("Scheduler recurring interval cannot be more than 12 months. {$months} given.");
        }

        $start = $this->toCarbon($this->startDate);
        $this->recurrings = $this->getNextRecurringDate($start, $months);

        return $this;
    }

    /**
     * Get recurrings scheduler dates
     * 
     * @return array
     */
    public function get()
    {
        $recurrings = $this->recurrings;

        $end = $this->toCarbon($this->endDate);
        $last = $this->toCarbon(array_pop($recurrings));

        if ($last > $end) {
            array_pop($this->recurrings);
        }

        return $this->recurrings;
    }

    /**
     * Get next recurring dates
     * 
     * @param  Carbon\Carbon $base
     * @param  integer $months [description]
     * @return array
     */
    protected function getNextRecurringDate(Carbon $base, $interval)
    {
        $dates = array();
        list($year, $month, $day) = $this->calculateNextDate($base->format('Y-m-d'), $interval);
        $next = $this->toCarbon("{$year}-{$month}-{$day}");
        $nextTotalDays = $next->format('t');

        $start = $this->toCarbon($this->startDate);
        $end = $this->toCarbon($this->endDate);

        $recurring = $base->addMonths($interval);

        if ($recurring->month > $month) {
            $nextDate = $this->toCarbon("{$year}-{$month}-{$nextTotalDays}");
            $diff = $recurring->diffInDays($nextDate);

            $recurring->subDays($diff);
        }

        if ($recurring->day != $start->day and $recurring->month != 2) {
            $recurring->day = $start->day;
        }

        if ($start->day == $start->lastOfMonth()->day) {
            $recurring->day = $recurring->lastOfMonth()->day;
        }

        $dates[] = $recurring->format('Y-m-d');

        if ($recurring < $end) {
            $dates[] = $this->getNextRecurringDate($recurring, $interval);
        } 

        return array_flatten($dates);
    }

    /**
     * Get next recurring date
     * 
     * @param  string $base
     * @param  integer $interval
     * @return array
     */
    protected function calculateNextDate($base, $interval)
    {
        list($year, $month, $day) = $this->toArray($base);

        $nextMonth = $month + $interval;

        if ($nextMonth > Carbon::MONTHS_PER_YEAR) {
            $nextMonth = $nextMonth - Carbon::MONTHS_PER_YEAR;
            $year = $year+1;
        }

        return array($year, (string) $nextMonth, '1');
    }

    /**
     * Convert MySQL DateTime format to array
     * 
     * @param  string $date
     * @param  string $seperator
     * @return array
     */
    protected function toArray($date, $seperator = '-')
    {
        $dates = explode($seperator, $date);

        return $dates;
    }

    /**
     * Convert date string to Carbon object
     * 
     * @param  string $date
     * @return Carbon\Carbon
     */
    protected function toCarbon($date)
    {
        $carbon = Carbon::createFromTimestamp(strtotime($date));

        return $carbon;
    }

}