Enable refunds through gateway

[websupporter]

Fixes #30

[mattallan]

I'm not sure if this is worth mentioning but I accidentally started testing refunds where my Woo store set to AUD currency and my PayPal Account set to USD and I had my PP account set up so that I had to accept all payments in a different currency.

This means all AUD orders were appearing in PayPal as "Unclaimed".

When I tried to make a refund on orders that hadn't been "accepted" yet, this resulted in the following notice https://d.pr/i/xfBLou and when I tried making a partial refund I got:

WARNING [UNPROCESSABLE_ENTITY] The requested action could not be performed, semantically incorrect, or failed business validation. https://developer.paypal.com/docs/api/payments/v2/#error-PARTIAL_REFUND_NOT_ALLOWED

I just wanted to check if this is working as expected or whether we have accounted for this case?

---

I haven't done any code review yet, mostly functional testing. Here are some issues that I've found so far:

• When I tried refund that hasn't been captured yet I get the fatal errors below. I'm not sure if we need to implement voiding a payment that haven't been captured instead of trying to refund it. After getting this fatal, when I refreshed the page it said the order was refunded, but it was still on-hold and I was still able to capture the payment: https://d.pr/i/cCuOXr

[29-Sep-2020 07:10:37 UTC] PHP Notice:  Undefined offset: 0 in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-refundprocessor.php on line 71
[29-Sep-2020 07:10:37 UTC] PHP Fatal error:  Uncaught Error: Call to a member function invoice_id() on null in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-refundprocessor.php:74
Stack trace:
#0 /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Gateway/class-creditcardgateway.php(249): WooCommerce\PayPalCommerce\WcGateway\Processor\RefundProcessor->process(Object(Automattic\WooCommerce\Admin\Overrides\Order), 64.95, 'tetst')
#1 /Users/matt/local/store/wp-content/plugins/woocommerce/includes/wc-order-functions.php(666): WooCommerce\PayPalCommerce\WcGateway\Gateway\CreditCardGateway->process_refund(5920, '64.95', 'tetst')
#2 /Users/matt/local/store/wp-content/plugins/woocommerce/includes/wc-order-functions.php(595): wc_refund_payment(Object(Automattic\WooCommerce\Admin\Overrides\Order), '64.95', 'tetst')
#3 /Users/matt/local/store/wp-content/plugins/woocommerce/includes/class-wc-ajax.php(1905): wc_create_refund(Array)
#4 /Users/matt/local/store/wp- in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-refundprocessor.php on line 74

• Refunding without a reason results in:

[29-Sep-2020 07:17:20 UTC] PHP Notice:  Undefined property: stdClass::$status_details in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-api-client/src/Factory/class-capturefactory.php on line 48
[29-Sep-2020 07:17:20 UTC] PHP Notice:  Trying to get property 'reason' of non-object in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-api-client/src/Factory/class-capturefactory.php on line 48

I haven't finished testing everything yet but I wanted to share these things while I continue looking at this PR :)

[websupporter]

The two commits address the notices and fatals thrown. (Codestyle will be ok in next commit again)

[mattallan]

Thanks @websupporter I've confirmed those issues have been resolved.

This is very close now! From my testing, I found one issue:

• ❌ Try refunding an order that is pending payment

[30-Sep-2020 03:21:57 UTC] PHP Fatal error:  Uncaught Error: Call to a member function captures() on null in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-refundprocessor.php:76
Stack trace:
#0 /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Gateway/class-paypalgateway.php(339): WooCommerce\PayPalCommerce\WcGateway\Processor\RefundProcessor->process(Object(Automattic\WooCommerce\Admin\Overrides\Order), 64.95, 'Refunding a pen...')
#1 /Users/matt/local/store/wp-content/plugins/woocommerce/includes/wc-order-functions.php(666): WooCommerce\PayPalCommerce\WcGateway\Gateway\PayPalGateway->process_refund(5948, '64.95', 'Refunding a pen...')
#2 /Users/matt/local/store/wp-content/plugins/woocommerce/includes/wc-order-functions.php(595): wc_refund_payment(Object(Automattic\WooCommerce\Admin\Overrides\Order), '64.95', 'Refunding a pen...')
#3 /Users/matt/local/store/wp-content/plugins/woocommerce/includes/class-wc-ajax.php(1905): wc_create_refund(Array)
# in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-refundprocessor.php on line 76

To reproduce:

1. Enable PayPal Checkout gateway
2. Add a product to the cart
3. Visit the checkout and click on the PayPal button (which will create an order with pending payment status)
4. Close the PayPal pop-up
5. Visit the Edit Order page for this new Pending Payment order
6. Try refund

---

Codestyle will be ok in next commit again

Okay, no worries.

It looks like there's just a small PHPCS issue:

FILE: ...r-woocommerce/modules/ppcp-api-client/src/Factory/class-capturefactory.php
--------------------------------------------------------------------------------
FOUND 1 ERROR AFFECTING 1 LINE
--------------------------------------------------------------------------------
 45 | ERROR | [x] Space before opening parenthesis of function call prohibited

[mattallan]

Thanks for fixing that final thing @websupporter. This looks good to be merged 👍 🚀