Add initial generate-bills and charge-negative-balance uncloud-pay

commands

uncloud/uncloud_pay/models.py

@@ -19,21 +19,26 @@ class RecurringPeriod(models.TextChoices):
     PER_SECOND = 'SECOND', _('Per Second')
 
 class Bill(models.Model):
+    uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
     owner = models.ForeignKey(get_user_model(),
             on_delete=models.CASCADE)
 
-    creation_date = models.DateTimeField()
+    creation_date = models.DateTimeField(auto_now_add=True)
     starting_date = models.DateTimeField()
     ending_date = models.DateTimeField()
     due_date = models.DateField()
 
-    paid = models.BooleanField(default=False)
     valid = models.BooleanField(default=True)
 
     @property
     def amount(self):
-        # iterate over all related orders
-        return 20
+        orders = Order.objects.filter(bill=self)
+        amount = 0
+        for order in orders:
+            amount += order.recurring_price
+
+        return amount
+
 
 
 class Order(models.Model):
@@ -49,8 +54,7 @@ class Order(models.Model):
 
     bill = models.ManyToManyField(Bill,
                                   editable=False,
-                                  blank=True,
-                                  null=True)
+                                  blank=True)
 
 
     recurring_price = models.FloatField(editable=False)