From 82254a7bf513fc41237d4623b4eaf08ca6f5958c Mon Sep 17 00:00:00 2001
From: Christopher Neugebauer <chrisjrn@gmail.com>
Date: Thu, 15 Sep 2016 10:22:12 +1000
Subject: [PATCH] Credit note is automatically applied if you have a single
 invoice

---
 registrasion/controllers/invoice.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/registrasion/controllers/invoice.py b/registrasion/controllers/invoice.py
index a2adca4e..9fadcd11 100644
--- a/registrasion/controllers/invoice.py
+++ b/registrasion/controllers/invoice.py
@@ -198,10 +198,30 @@ class InvoiceController(ForId, object):
 
         commerce.LineItem.objects.bulk_create(line_items)
 
+        cls._apply_credit_notes(invoice)
         cls.email_on_invoice_creation(invoice)
 
         return invoice
 
+    @classmethod
+    def _apply_credit_notes(cls, invoice):
+        ''' Applies the user's credit notes to the given invoice on creation.
+        '''
+
+        notes = commerce.CreditNote.objects.filter(invoice__user=invoice.user)
+
+        if len(notes) == 0:
+            return
+
+        for note in notes:
+            try:
+                CreditNoteController(note).apply_to_invoice(invoice)
+            except ValidationError:
+                # ValidationError will get raised once we're overpaying.
+                break
+
+        invoice.refresh_from_db()
+
     def can_view(self, user=None, access_code=None):
         ''' Returns true if the accessing user is allowed to view this invoice,
         or if the given access code matches this invoice's user's access code.