ESEB-137: Fix 'Next Contribution Date' for webform fixed memberships

[omarabuhussein]

Before

If you configure a webform with a payment plan and a fixed 1 year membership that starts at 1st of January and ends at 31th of December:

then the created recurring contribution "Next Scheduled Contribution Date" will be:

• The first instalment receive date + 1 year (in case of single instalment payment plans)

Or

• The last instalment receive date + 1 month (in case of monthly payment plan).

This shouldn't be the case, and instead the "Next Scheduled Contribution Date" should be:

• The membership end date + 1 day

After

The "Next Scheduled Contribution Date" is : The membership end date + 1 day

Technical Details

The PaymentPlanNextContributionDateUpdater Webform API passes the word "Creation" as 2nd argument to the PaymentPlanNextContributionDate Service that is responsible for calculating the "Next Scheduled Contribution Date"
instead of "creation" (all letters should be lower case), so this part of the code that is responsible for calculating the date for fixed memberships did not run:

uk.co.compucorp.membershipextras/CRM/MembershipExtras/Service/PaymentPlanNextContributionDate.php

Lines 74 to 82 in feaf575

	if ($atLeastOneFixedMembershipExist && strtolower($this->operation) == 'creation') {
	$nextScheduledDate = date('Y-m-d', strtotime($calculationMembership['end_date'] . '00:00:00 +1 day'));
	$nextScheduledDateCycleDay = CRM_MembershipExtras_Service_CycleDayCalculator::calculate($nextScheduledDate, 'month');
	$paymentPlanCycleDay = $this->recurContribution['cycle_day'];
	$adjustmentDaysAmount = $paymentPlanCycleDay - $nextScheduledDateCycleDay;
	$nextScheduledDate = new DateTime($nextScheduledDate);
	$nextScheduledDate->modify("$adjustmentDaysAmount day");
	return $nextScheduledDate->format('Y-m-d 00:00:00');

So I fixed this by passing the right operation name which is "creation" instead of "Creation", and as fail-safe I also change the $operation parameter letters to be lower case before using it.