Include BillRecords in the admin

uncloud_pay/models.py

@@ -10,7 +10,7 @@ import logging
 from functools import reduce
 import itertools
 from math import ceil
-from datetime import timedelta
+import datetime
 from calendar import monthrange
 from decimal import Decimal
 
@@ -23,11 +23,36 @@ from decimal import Decimal
 import decimal
 
 # Used to generate bill due dates.
-BILL_PAYMENT_DELAY=timedelta(days=10)
+BILL_PAYMENT_DELAY=datetime.timedelta(days=10)
 
 # Initialize logger.
 logger = logging.getLogger(__name__)
 
+def start_of_month(a_day):
+    """ Returns first of the month of a given datetime object"""
+    return a_day.replace(day=1,hour=0,minute=0,second=0, microsecond=0)
+
+def end_of_month(a_day):
+    """ Returns first of the month of a given datetime object"""
+
+    _, last_day = monthrange(a_day.year, a_day.month)
+    return a_day.replace(day=last_day,hour=23,minute=59,second=59, microsecond=0)
+
+def start_of_this_month():
+    """ Returns first of this month"""
+    a_day = timezone.now()
+    return a_day.replace(day=1,hour=0,minute=0,second=0, microsecond=0)
+
+def end_of_this_month():
+    """ Returns first of this month"""
+    a_day = timezone.now()
+
+    _, last_day = monthrange(a_day.year, a_day.month)
+    return a_day.replace(day=last_day,hour=23,minute=59,second=59, microsecond=0)
+
+def default_payment_delay():
+    return timezone.now() + BILL_PAYMENT_DELAY
+
 # See https://docs.djangoproject.com/en/dev/ref/models/fields/#field-choices-enum-types
 class RecurringPeriod(models.IntegerChoices):
     """
@@ -390,34 +415,41 @@ class Order(models.Model):
               description=description)
 
     def __str__(self):
-        return "{} created at {}, {}->{}, recurring period {}. One time price {}, recurring price {}".format(
-            self.id, self.creation_date,
-            self.starting_date, self.ending_date,
-            self.recurring_period,
-            self.one_time_price,
-            self.recurring_price)
+        return f"Order {self.owner}-{self.id}"
+
+        # return "{} created at {}, {}->{}, recurring period {}. One time price {}, recurring price {}".format(
+        #     self.id, self.creation_date,
+        #     self.starting_date, self.ending_date,
+        #     self.recurring_period,
+        #     self.one_time_price,
+        #     self.recurring_price)
 
 
 class Bill(models.Model):
-    """ FIXME:
-    Bill needs to be unique in the triple (owner, year, month)
-    """
-
     owner = models.ForeignKey(get_user_model(),
             on_delete=models.CASCADE)
 
     creation_date = models.DateTimeField(auto_now_add=True)
-    starting_date = models.DateTimeField()
-    ending_date = models.DateTimeField()
-    due_date = models.DateField()
+    # FIXME: this is a race condition, if ending_date is evaluated
+    # in the next month the bill spawns two months!
+    starting_date = models.DateTimeField(default=start_of_this_month)
+    ending_date = models.DateTimeField(default=end_of_this_month)
+    due_date = models.DateField(default=default_payment_delay)
 
     valid = models.BooleanField(default=True)
 
     # Mapping to BillRecords
     # https://stackoverflow.com/questions/4443190/djangos-manytomany-relationship-with-additional-fields
-
     bill_records = models.ManyToManyField(Order, through="BillRecord")
 
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(fields=['owner',
+                                            'starting_date',
+                                            'ending_date' ],
+                                    name='one_bill_per_month_per_user')
+        ]
+
     # billing address and vat rate is the same for the whole bill
     # @property
     # def vat_rate(self):
@@ -425,7 +457,7 @@ class Bill(models.Model):
 
 
     def __str__(self):
-        return f"uc-{self.id}"
+        return f"Bill {self.owner}-{self.id}"
 
     @classmethod
     def create_all_bills(cls):
@@ -516,7 +548,7 @@ class BillRecord(models.Model):
     ending_date = models.DateTimeField()
 
     def __str__(self):
-        return f"{order.owner}"
+        return f"{self.bill}: {self.usage_count} x {self.order}"
 
 
 class OrderRecord(models.Model):