Support open amount and line item refunds

[bhelx]

This pull request is to support both open amount and line item refunds on Invoice.

Approvers: @drewish

Testing

Open Amount:

$invoice = Recurly_Invoice::get('1002');  // get some invoice
$ref = $invoice->refundAmount(100);      // refund some amount in cents
var_dump($ref); // verify the returned refund invoice is correct

Line Item [WIP]:

// get some invoice, preferably with multiple line items
$invoice = Recurly_Invoice::get('1002');

// grab out which ever ones you want to refund
$line_items = $invoice->line_items;

// You probably want to build new adjustment objects
// rather than modifying your existing line items
// and passing those in
$adjustment_map = function($line_item) {
  return $line_item->toRefundAttributes();
};
$refunds = array_map($adjustment_map, $line_items);

$ref = $invoice->refund($refunds); // create a refund invoice from refund attributes
var_dump($ref);   // verify the returned refund invoice is correct

[drewish]

Any objection to naming this $refund or $refund_invoice?

[bhelx]

No, sounds good. That's what I am doing in other branch. Will change.

[drewish]

I like this whole refactoring.

[bhelx]

👍

[drewish]

I think we need to ensure that the adjustment has an invoice. If you try to refund an un-invoiced charge:

Recurly_Adjustment::get('2cca2c8255f0d5582af2aa4eed9c26a9')->refund(2, true);

Fatal error: Call to a member function get() on a non-object in /Users/andrew/projects/recurly-client-php/lib/recurly/adjustment.php on line 38

[bhelx]

Good point

[drewish]

+1