Custom subscription delay with prorating. Read comments and description for details.

pmpro-subscription-delays-with-prorated-initial-payment.php

/*
Uses PMPro Subscription Delays Add On to set date of first paymen to the first of next month. So if current date is: 2018-03-21, date
of first subscription payment is 2018-04-01. Initial payment is prorated based on signup date uses total number of weekdays as the base.
For example if the date is 2018-02-02 (February 2nd, 2018). They will be charged (19/20)*$initial_payment.
*/

function my_pmprosd_modify_start_date($start_date, $order, $subscription_delay)
{
	$day_number = date('j');
	$month_number = date('m') ;
	$year_number = date('Y');

	if($month_number == 12)
	{
		$month_number = '01';
		$year_number = $year_number + 1;
	}
	else
		$month_number = $month_number + 1;
	
	$start_date = date("Y-m-d", strtotime($year_number.'-'.$month_number.'-01'));

	return $start_date;
}

add_filter('pmprosd_modify_start_date', 'my_pmprosd_modify_start_date', 10, 3);

function my_pmpro_checkout_level($level)
{
	$day_number = date('j');
	$month_number = date('m') ;
	$year_number = date('Y');
	
	$total_number_of_days_in_month = date('t');
	
	$total_number_of_working_days_in_month = getWorkingDays($year_number.'-'.$month_number.'-01', $year_number.'-'.$month_number.'-'.$total_number_of_days_in_month);
	
	$working_days_remaining = getWorkingDays($year_number.'-'.$month_number.'-'.$day_number, $year_number.'-'.$month_number.'-'.$total_number_of_days_in_month);
	
	$percent_remaining = $working_days_remaining/$total_number_of_working_days_in_month;
	
	$level->initial_payment = $percent_remaining*$level->initial_payment;
	
	return $level;
}
add_filter("pmpro_checkout_level", "my_pmpro_checkout_level");


//Taken from: https://gist.github.com/quawn/8503445
function getWorkingDays($startDate, $endDate, $holidays = array()) {
    // do strtotime calculations just once
    $endDate = strtotime($endDate);
    $startDate = strtotime($startDate);
    //The total number of days between the two dates. We compute the no. of seconds and divide it to 60*60*24
    //We add one to inlude both dates in the interval.
    $days = ($endDate - $startDate) / 86400 + 1;
    $no_full_weeks = floor($days / 7);
    $no_remaining_days = fmod($days, 7);
    //It will return 1 if it's Monday,.. ,7 for Sunday
    $the_first_day_of_week = date("N", $startDate);
    $the_last_day_of_week = date("N", $endDate);
    //---->The two can be equal in leap years when february has 29 days, the equal sign is added here
    //In the first case the whole interval is within a week, in the second case the interval falls in two weeks.
    if ($the_first_day_of_week <= $the_last_day_of_week) {
        if ($the_first_day_of_week <= 6 && 6 <= $the_last_day_of_week) $no_remaining_days--;
        if ($the_first_day_of_week <= 7 && 7 <= $the_last_day_of_week) $no_remaining_days--;
    }
    else {
        // (edit by Tokes to fix an edge case where the start day was a Sunday
        // and the end day was NOT a Saturday)
        // the day of the week for start is later than the day of the week for end
        if ($the_first_day_of_week == 7) {
            // if the start date is a Sunday, then we definitely subtract 1 day
            $no_remaining_days--;
            if ($the_last_day_of_week == 6) {
                // if the end date is a Saturday, then we subtract another day
                $no_remaining_days--;
            }
        }
        else {
            // the start date was a Saturday (or earlier), and the end date was (Mon..Fri)
            // so we skip an entire weekend and subtract 2 days
            $no_remaining_days -= 2;
        }
    }
    //The no. of business days is: (number of weeks between the two dates) * (5 working days) + the remainder
//---->february in none leap years gave a remainder of 0 but still calculated weekends between first and last day, this is one way to fix it
   $workingDays = $no_full_weeks * 5;
    if ($no_remaining_days > 0 )
    {
      $workingDays += $no_remaining_days;
    }
    //We subtract the holidays
    foreach($holidays as $holiday){
        $time_stamp=strtotime($holiday);
        //If the holiday doesn't fall in weekend
        if ($startDate <= $time_stamp && $time_stamp <= $endDate && date("N",$time_stamp) != 6 && date("N",$time_stamp) != 7)
            $workingDays--;
    }
    return $workingDays;
}