Check negative on cancellation.

- Like perform operations, cancel_operations can add/remove an account
  from negative accounts system.
- Balances checks are now performed against real_balance instead of
  balance.
  So if someone with a balance_offset go, for real, to positive land (ie even
  without taking into account the balance offset), its account is removed from
  the negative system.
- Fix bug on real_balance when negative exists but balance_offset is
  not set.

Fixes #156.

kfet/models.py

@@ -81,7 +81,7 @@ class Account(models.Model):
     # Propriétés supplémentaires
     @property
     def real_balance(self):
-        if (hasattr(self, 'negative')):
+        if hasattr(self, 'negative') and self.negative.balance_offset:
             return self.balance - self.negative.balance_offset
         return self.balance
 
@@ -210,6 +210,29 @@ class Account(models.Model):
     def delete(self, *args, **kwargs):
         pass
 
+    def check_negative(self):
+        if self.real_balance < 0:
+            if hasattr(self, 'negative') and not self.negative.start:
+                self.negative.start = timezone.now()
+                self.negative.save()
+            elif not hasattr(self, 'negative'):
+                self.negative = (
+                    AccountNegative.objects.create(
+                        account=self, start=timezone.now(),
+                    )
+                )
+        elif hasattr(self, 'negative'):
+            # self.real_balance >= 0
+            balance_offset = self.negative.balance_offset
+            if balance_offset:
+                (
+                    Account.objects
+                    .filter(pk=self.pk)
+                    .update(balance=F('balance')-balance_offset)
+                )
+                self.refresh_from_db()
+            self.negative.delete()
+
     class UserHasAccount(Exception):
         def __init__(self, trigramme):
             self.trigramme = trigramme

kfet/views.py

@@ -1105,22 +1105,15 @@ def kpsul_perform_operations(request):
     with transaction.atomic():
         # If not cash account,
         # saving account's balance and adding to Negative if not in
-        if not operationgroup.on_acc.is_cash:
-            Account.objects.filter(pk=operationgroup.on_acc.pk).update(
-                balance=F('balance') + operationgroup.amount)
-            operationgroup.on_acc.refresh_from_db()
-            if operationgroup.on_acc.balance < 0:
-                if hasattr(operationgroup.on_acc, 'negative'):
-                    if not operationgroup.on_acc.negative.start:
-                        operationgroup.on_acc.negative.start = timezone.now()
-                        operationgroup.on_acc.negative.save()
-                else:
-                    negative = AccountNegative(
-                        account=operationgroup.on_acc, start=timezone.now())
-                    negative.save()
-            elif (hasattr(operationgroup.on_acc, 'negative') and
-                    not operationgroup.on_acc.negative.balance_offset):
-                operationgroup.on_acc.negative.delete()
+        on_acc = operationgroup.on_acc
+        if not on_acc.is_cash:
+            (
+                Account.objects
+                .filter(pk=on_acc.pk)
+                .update(balance=F('balance') + operationgroup.amount)
+            )
+            on_acc.refresh_from_db()
+            on_acc.check_negative()
 
         # Updating checkout's balance
         if to_checkout_balance:
@@ -1311,8 +1304,15 @@ def kpsul_cancel_operations(request):
         (Operation.objects.filter(pk__in=opes)
             .update(canceled_by=canceled_by, canceled_at=canceled_at))
         for account in to_accounts_balances:
-            Account.objects.filter(pk=account.pk).update(
-                balance = F('balance') + to_accounts_balances[account])
+            (
+                Account.objects
+                .filter(pk=account.pk)
+                .update(balance=F('balance') + to_accounts_balances[account])
+            )
+            if not account.is_cash:
+                # Should always be true, but we want to be sure
+                account.refresh_from_db()
+                account.check_negative()
         for checkout in to_checkouts_balances:
             Checkout.objects.filter(pk=checkout.pk).update(
                 balance = F('balance') + to_checkouts_balances[checkout])