Support Mollie Orders API for Klarna Pay Later and Klarna Slice It methods

[rvdsteege]

Klarna Pay Later and Klarna Slice It (and vouchers) are currently not supported for Mollie, as these require using the Orders API.

• https://docs.mollie.com/orders/overview

[rvdsteege]

Also required for Klarna Pay now.

Internal Help Scout ticket: https://secure.helpscout.net/conversation/1773692826/23434

[remcotolsma]

Some more details in internal / private Basecamp to-do:
https://basecamp.com/1810084/projects/10966871/todos/384902142

[remcotolsma]

A customer inquired about this again:

Hope you are doing well.
I came back again for 2nd time on the topic that we discussed a few months back.

The two payment Klarna payment methods "Klarna Pay Later" (in German "Klarna Rechnungskauf"?) and "Klarna Slice It" (in German "Klarna Ratenkauf"?) are currently not supported in the Pronamic Pay plugin.

We already went into production last October 2021 without them.

Internal Help Scout ticket: https://secure.helpscout.net/conversation/1915990137/24057/.

ℹ️ This customer is using MemberPress.

[remcotolsma]

I created the following branches for developing this feature:

• https://github.com/pronamic/wp-pronamic-pay-mollie/tree/orders-api-for-klarna
• https://github.com/pronamic/wp-pronamic-pay-memberpress/tree/klarna

In https://github.com/mollie/WooCommerce/blob/4ae543c8fc0ddfbc05acef06a622124c06299293/src/Payment/PaymentService.php#L106-L141 they determine per WooCommerce order whether the Mollie Payments API or Mollie Orders API should be used.

Note
If you are looking to create payments with the Klarna Pay now, Klarna Pay later, Klarna Slice it, or voucher payment methods, please use Create order instead.

https://docs.mollie.com/reference/v2/payments-api/create-payment

\in_array(
	$payment->get_payment_method(),
	[
		PaymentMethods::KLARNA_PAY_LATER,
		PaymentMethods::KLARNA_PAY_NOW,
		PaymentMethods::KLARNA_PAY_OVER_TIME,
	],
	true
)

[remcotolsma]

This is merged in: pronamic/wp-pronamic-pay-mollie#4.