remove big mistake: orders from product

Signed-off-by: Nico Schottelius <nico@nico-notebook.schottelius.org>

uncloud_pay/models.py

@@ -354,17 +354,18 @@ class Order(models.Model):
         return self.starting_date + datetime.timedelta(seconds=self.recurring_period)
 
     @property
-    def next_ending_date(self):
+    def next_cancel_or_downgrade_date(self):
         """
         Return the next proper ending date after n times the
-        recurring_period, where n is an integer.
+        recurring_period, where n is an integer that applies for downgrading
+        or cancelling.
         """
 
         if self.recurring_period > 0:
             now = timezone.now()
             delta = now - self.starting_date
 
-            num_times = math.ceil(delta.total_seconds() / self.recurring_period)
+            num_times = ceil(delta.total_seconds() / self.recurring_period)
 
             next_date = self.starting_date + datetime.timedelta(seconds= num_times * self.recurring_period)
         else:
@@ -452,8 +453,9 @@ class Order(models.Model):
         if self.ending_date and self.ending_date < self.starting_date:
             raise ValidationError("End date cannot be before starting date")
 
-        if self.ending_date and self.ending_date < self.earliest_ending_date:
-            raise ValidationError("Ending date is before minimum duration (starting_date + recurring period)")
+        # do not check this if we upgrade
+        # if self.ending_date and self.ending_date < self.earliest_ending_date:
+        #     raise ValidationError("Ending date is before minimum duration (starting_date + recurring period)")
 
         super().save(*args, **kwargs)
 
@@ -853,11 +855,9 @@ class BillRecord(models.Model):
 
 class Product(UncloudModel):
     """
-    A product is something a user orders. To record the pricing, we
+    A product is something a user can order. To record the pricing, we
     create order that define a state in time.
 
-    A product can *depend* on other products.
-
     A product can have *one* one_time_order and/or *one*
     recurring_order.
 
@@ -872,12 +872,12 @@ class Product(UncloudModel):
 
     description = "Generic Product"
 
-    orders = models.ManyToManyField(Order)
-
     status = models.CharField(max_length=32,
             choices=UncloudStatus.choices,
             default=UncloudStatus.AWAITING_PAYMENT)
 
+#    config = models.JSONField()
+
     # Default period for all products
     default_recurring_period = RecurringPeriod.PER_30D
 
@@ -941,6 +941,7 @@ class Product(UncloudModel):
             self.orders.add(recurring_order)
 
 
+    # FIXME: this could/should be part of Order (?)
     def create_or_update_recurring_order(self, when_to_start=None, recurring_period=None):
         if not self.recurring_price:
             return
@@ -954,8 +955,8 @@ class Product(UncloudModel):
         if self.last_recurring_order:
             if self.recurring_price < self.last_recurring_order.price:
 
-                if when_to_start < self.last_recurring_order.next_ending_date:
-                    when_to_start = start_after(self.last_recurring_order.next_ending_date)
+                if when_to_start < self.last_recurring_order.next_cancel_or_downgrade_date:
+                    when_to_start = start_after(self.last_recurring_order.next_cancel_or_downgrade_date)
 
             when_to_end = end_before(when_to_start)
 
@@ -967,10 +968,9 @@ class Product(UncloudModel):
                                              description=str(self),
                                              replaces=self.last_recurring_order)
 
-            self.last_recurring_order.end_date = when_to_end
+            self.last_recurring_order.replace_with(new_order)
             self.orders.add(new_order)
         else:
-            # This might be a bug as it might (re-)create the one time order
             self.create_order(when_to_start, recurring_period)
 
     @property