Updates order status after shipping and payment

A signal was emitted to set the status to CONFIRMED after the shipping
stage, but no one listens to it. Now the status is directly modified.

Similarly, status is directly set to COMPLETED after payment. The cart
is also emptied at this stage. It was already there, but only when the
backend payment is done, and the user redirected to the "Thank you"
page. Now that logic has been copied to the confirm_payment API
function, so that the order is COMPLETED as soon as payment is made.
This is important when using tha PayPal IPN backend, since the user is
redirected back the site later than - if at all, the IPN is sent. 

Not tested!
was
already there,

shop/payment/api.py

@@ -1,15 +1,17 @@
 # -*- coding: utf-8 -*-
 
 """
-This file defines the interafces one should implement when either creating a
+This file defines the interfaces one should implement when either creating a
 new payment module or willing to use modules with another shop system.
 """
 from decimal import Decimal
 from shop.models.ordermodel import OrderPayment
+from shop.models.ordermodel import Order
+from shop.models.cartmodel import Cart
 from shop.shop_api import ShopAPI
+from shop.order_signals import completed
 from django.core.urlresolvers import reverse
 
-
 class PaymentAPI(ShopAPI):
     """
     This object's purpose is to expose an API to the shop system.
@@ -41,7 +43,18 @@ def confirm_payment(self, order, amount, transaction_id, payment_method,
             amount=Decimal(amount),
             transaction_id=transaction_id,
             payment_method=payment_method)
-        # Save is not used in the particular case.
+
+        if save and self.is_order_payed(order):
+            # Set the order status:
+            order.status = Order.COMPLETED
+            order.save()
+            completed.send(sender=self, order=order)
+
+            # Empty the customers basket, to reflect that the purchase was
+            # completed
+            cart_object = Cart.objects.get(user=order.user)
+            cart_object.empty()
+
 
     #==========================================================================
     # URLS
@@ -52,6 +65,11 @@ def get_finished_url(self):
         A helper for backends, so that they can call this when their job
         is finished i.e. The payment has been processed from a user perspective
         This will redirect to the "Thanks for your order" page.
+        
+        To confirm the payment, call confirm_payment before this function. 
+        For example, for PayPal IPN, the payment is confirmed upon receipt 
+        of an Instant Payment Notification, and later this function is called 
+        when the user is directed back from PayPal.
         """
         return reverse('thank_you_for_your_order')
 

shop/shipping/api.py

@@ -2,6 +2,7 @@
 from shop.shop_api import ShopAPI
 from shop.order_signals import payment_selection
 from shop.models.ordermodel import ExtraOrderPriceField
+from shop.models.ordermodel import Order
 from django.shortcuts import redirect
 
 
@@ -58,6 +59,8 @@ def finished(self, order):
         is finished i.e. shipping costs are added to the order.
         This will redirect to the "select a payment method" page.
         """
+        order.status = Order.CONFIRMED
+        order.save()
         # Emit the signal to say we're now selecting payment
         payment_selection.send(self, order=order)
         return redirect('checkout_payment')