Self-service refund form (#1135)

* Auto-refund

* Add missing template

* Notification for requested refund

* Model-level tests

* Add front-end tests

* Default to notify

src/pretix/base/services/orders.py

@@ -31,7 +31,7 @@ from pretix.base.models.orders import (
 )
 from pretix.base.models.organizer import TeamAPIToken
 from pretix.base.models.tax import TaxedPrice
-from pretix.base.payment import BasePaymentProvider
+from pretix.base.payment import BasePaymentProvider, PaymentException
 from pretix.base.services.invoices import (
     generate_cancellation, generate_invoice, invoice_qualified,
 )
@@ -1364,11 +1364,59 @@ def perform_order(self, event: str, payment_provider: str, positions: List[str],
 
 @app.task(base=ProfiledTask, bind=True, max_retries=5, default_retry_delay=1, throws=(OrderError,))
 def cancel_order(self, order: int, user: int=None, send_mail: bool=True, api_token=None, oauth_application=None,
-                 device=None, cancellation_fee=None):
+                 device=None, cancellation_fee=None, try_auto_refund=False):
     try:
         try:
-            return _cancel_order(order, user, send_mail, api_token, device, oauth_application,
-                                 cancellation_fee)
+            ret = _cancel_order(order, user, send_mail, api_token, device, oauth_application,
+                                cancellation_fee)
+            if try_auto_refund:
+                notify_admin = False
+                error = False
+                order = Order.objects.get(pk=order)
+                refund_amount = order.pending_sum * -1
+                proposals = order.propose_auto_refunds(refund_amount)
+                can_auto_refund = sum(proposals.values()) == refund_amount
+                if can_auto_refund:
+                    for p, value in proposals.items():
+                        with transaction.atomic():
+                            r = order.refunds.create(
+                                payment=p,
+                                source=OrderRefund.REFUND_SOURCE_BUYER,
+                                state=OrderRefund.REFUND_STATE_CREATED,
+                                amount=value,
+                                provider=p.provider
+                            )
+                            order.log_action('pretix.event.order.refund.created', {
+                                'local_id': r.local_id,
+                                'provider': r.provider,
+                            })
+
+                        try:
+                            r.payment_provider.execute_refund(r)
+                        except PaymentException as e:
+                            with transaction.atomic():
+                                r.state = OrderRefund.REFUND_STATE_FAILED
+                                r.save()
+                                order.log_action('pretix.event.order.refund.failed', {
+                                    'local_id': r.local_id,
+                                    'provider': r.provider,
+                                    'error': str(e)
+                                })
+                            error = True
+                            notify_admin = True
+                        else:
+                            if r.state != OrderRefund.REFUND_STATE_DONE:
+                                notify_admin = True
+                else:
+                    notify_admin = True
+
+                if notify_admin:
+                    order.log_action('pretix.event.order.refund.requested')
+                if error:
+                    raise OrderError(
+                        _('There was an error while trying to send the money back to you. Please contact the event organizer for further information.')
+                    )
+            return ret
         except LockTimeoutException:
             self.retry()
     except (MaxRetriesExceededError, LockTimeoutException):