[BREAKING] make Order a stand-alone version

I think that while the idea of an Orderrecord is good, we might get
away / have a simpler implementation if we only use orders and
reference them where needed.

I saved the previous Order model for easy rollback, if my assumption
is wrong.

uncloud_django_based/uncloud/uncloud_pay/models.py

@@ -809,6 +809,64 @@ class Order(models.Model):
                               editable=False)
     billing_address = models.ForeignKey(BillingAddress, on_delete=models.CASCADE)
 
+    # TODO: enforce ending_date - starting_date to be larger than recurring_period.
+    creation_date = models.DateTimeField(auto_now_add=True)
+    starting_date = models.DateTimeField(default=timezone.now)
+    ending_date = models.DateTimeField(blank=True,
+                                       null=True)
+
+    bill = models.ManyToManyField(Bill,
+                                  editable=False,
+                                  blank=True)
+
+    recurring_period = models.CharField(max_length=32,
+                              choices = RecurringPeriod.choices,
+                              default = RecurringPeriod.PER_MONTH)
+
+    one_time_price = models.DecimalField(default=0.0,
+            max_digits=AMOUNT_MAX_DIGITS,
+            decimal_places=AMOUNT_DECIMALS,
+            validators=[MinValueValidator(0)])
+
+    recurring_price = models.DecimalField(default=0.0,
+            max_digits=AMOUNT_MAX_DIGITS,
+            decimal_places=AMOUNT_DECIMALS,
+            validators=[MinValueValidator(0)])
+
+    replaced_by = models.ForeignKey('self',
+                                    on_delete=models.PROTECT,
+                                    blank=True,
+                                    null=True)
+
+    # Trigger initial bill generation at order creation.
+    def save(self, *args, **kwargs):
+        if self.ending_date and self.ending_date < self.starting_date:
+            raise ValidationError("End date cannot be before starting date")
+
+        super().save(*args, **kwargs)
+
+        Bill.generate_for(self.starting_date.year, self.starting_date.month, self.owner)
+
+    # Used by uncloud_pay tests.
+    @property
+    def bills(self):
+        return Bill.objects.filter(order=self)
+
+    def __str__(self):
+        return "Order {} created at {}, {}->{}, recurring period {}. Price one time {}, recurring {}".format(
+            self.uuid, self.creation_date,
+            self.starting_date, self.ending_date,
+            self.recurring_period,
+            self.one_time_price,
+            self.recurring_price)
+
+class OrderTimothee(models.Model):
+    uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    owner = models.ForeignKey(get_user_model(),
+                              on_delete=models.CASCADE,
+                              editable=False)
+    billing_address = models.ForeignKey(BillingAddress, on_delete=models.CASCADE)
+
     # TODO: enforce ending_date - starting_date to be larger than recurring_period.
     creation_date = models.DateTimeField(auto_now_add=True)
     starting_date = models.DateTimeField(default=timezone.now)
@@ -856,10 +914,13 @@ class Order(models.Model):
               description=description)
 
     def __str__(self):
-        return "Order {} created at {}, {}->{}, recurring period {}".format(
+        return "Order {} created at {}, {}->{}, recurring period {}. Price one time {}, recurring {}".format(
             self.uuid, self.creation_date,
             self.starting_date, self.ending_date,
-            self.recurring_period)
+            self.recurring_period,
+            self.one_time_price,
+            self.recurring_price)
+
 
 
 class OrderRecord(models.Model):