Adds available_credit tag, and adds a view for refunding an invoice to generate a credit note.

registrasion/templatetags/registrasion_tags.py

@@ -16,6 +16,16 @@ def available_categories(context):
     return CategoryController.available_categories(context.request.user)
 
 
+@register.assignment_tag(takes_context=True)
+def available_credit(context):
+    ''' Returns the amount of unclaimed credit available for this user. '''
+    notes = rego.CreditNote.unclaimed().filter(
+        invoice__user=context.request.user,
+    )
+    ret = notes.values("amount").aggregate(Sum("amount"))["amount__sum"] or 0
+    return 0 - ret
+
+
 @register.assignment_tag(takes_context=True)
 def invoices(context):
     ''' Returns all of the invoices that this user has. '''

registrasion/urls.py

@@ -10,6 +10,8 @@ urlpatterns = patterns(
     url(r"^invoice/([0-9]+)/([A-Z0-9]+)$", views.invoice, name="invoice"),
     url(r"^invoice/([0-9]+)/manual_payment$",
         views.manual_payment, name="manual_payment"),
+    url(r"^invoice/([0-9]+)/refund$",
+        views.refund, name="refund"),
     url(r"^invoice_access/([A-Z0-9]+)$", views.invoice_access,
         name="invoice_access"),
     url(r"^profile$", "edit_profile", name="attendee_edit"),

registrasion/views.py

@@ -524,3 +524,24 @@ def manual_payment(request, invoice_id):
     }
 
     return render(request, "registrasion/manual_payment.html", data)
+
+
+@login_required
+def refund(request, invoice_id):
+    ''' Allows staff to refund payments against an invoice and request a
+    credit note.'''
+
+    if not request.user.is_staff:
+        raise Http404()
+
+    invoice_id = int(invoice_id)
+    inv = get_object_or_404(rego.Invoice, pk=invoice_id)
+    current_invoice = InvoiceController(inv)
+
+    try:
+        current_invoice.refund()
+        messages.success(request, "This invoice has been refunded.")
+    except ValidationError as ve:
+        messages.error(request, ve)
+
+    return redirect("invoice", invoice_id)