from django.db import models from django.db.models import Q from django.contrib.auth import get_user_model from django.utils.translation import gettext_lazy as _ from django.core.validators import MinValueValidator from django.utils import timezone from django.core.exceptions import ObjectDoesNotExist, ValidationError from django.contrib.contenttypes.fields import GenericForeignKey from django.contrib.contenttypes.models import ContentType import logging from functools import reduce import itertools from math import ceil import datetime from calendar import monthrange from decimal import Decimal import uncloud_pay.stripe from uncloud_pay.helpers import beginning_of_month, end_of_month from uncloud_pay import AMOUNT_DECIMALS, AMOUNT_MAX_DIGITS, COUNTRIES from uncloud.models import UncloudModel, UncloudStatus from decimal import Decimal import decimal # Used to generate bill due dates. 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): """ We don't support months are years, because they vary in length. This is not only complicated, but also unfair to the user, as the user pays the same amount for different durations. """ PER_365D = 365*24*3600, _('Per 365 days') PER_30D = 30*24*3600, _('Per 30 days') PER_WEEK = 7*24*3600, _('Per Week') PER_DAY = 24*3600, _('Per Day') PER_HOUR = 3600, _('Per Hour') PER_MINUTE = 60, _('Per Minute') PER_SECOND = 1, _('Per Second') ONE_TIME = 0, _('Onetime') class CountryField(models.CharField): def __init__(self, *args, **kwargs): kwargs.setdefault('choices', COUNTRIES) kwargs.setdefault('default', 'CH') kwargs.setdefault('max_length', 2) super().__init__(*args, **kwargs) def get_internal_type(self): return "CharField" def get_balance_for_user(user): bills = reduce( lambda acc, entry: acc + entry.total, Bill.objects.filter(owner=user), 0) payments = reduce( lambda acc, entry: acc + entry.amount, Payment.objects.filter(owner=user), 0) return payments - bills class StripeCustomer(models.Model): owner = models.OneToOneField( get_user_model(), primary_key=True, on_delete=models.CASCADE) stripe_id = models.CharField(max_length=32) ### # Payments and Payment Methods. class Payment(models.Model): owner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE) amount = models.DecimalField( default=0.0, max_digits=AMOUNT_MAX_DIGITS, decimal_places=AMOUNT_DECIMALS, validators=[MinValueValidator(0)]) source = models.CharField(max_length=256, choices = ( ('wire', 'Wire Transfer'), ('stripe', 'Stripe'), ('voucher', 'Voucher'), ('referral', 'Referral'), ('unknown', 'Unknown') ), default='unknown') timestamp = models.DateTimeField(editable=False, auto_now_add=True) # We override save() in order to active products awaiting payment. def save(self, *args, **kwargs): # _state.adding is switched to false after super(...) call. being_created = self._state.adding unpaid_bills_before_payment = Bill.get_unpaid_for(self.owner) super(Payment, self).save(*args, **kwargs) # Save payment in DB. unpaid_bills_after_payment = Bill.get_unpaid_for(self.owner) newly_paid_bills = list( set(unpaid_bills_before_payment) - set(unpaid_bills_after_payment)) for bill in newly_paid_bills: bill.activate_products() class PaymentMethod(models.Model): owner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, editable=False) source = models.CharField(max_length=256, choices = ( ('stripe', 'Stripe'), ('unknown', 'Unknown'), ), default='stripe') description = models.TextField() primary = models.BooleanField(default=False, editable=False) # Only used for "Stripe" source stripe_payment_method_id = models.CharField(max_length=32, blank=True, null=True) stripe_setup_intent_id = models.CharField(max_length=32, blank=True, null=True) @property def stripe_card_last4(self): if self.source == 'stripe' and self.active: payment_method = uncloud_pay.stripe.get_payment_method( self.stripe_payment_method_id) return payment_method.card.last4 else: return None @property def active(self): if self.source == 'stripe' and self.stripe_payment_method_id != None: return True else: return False def charge(self, amount): if not self.active: raise Exception('This payment method is inactive.') if amount < 0: # Make sure we don't charge negative amount by errors... raise Exception('Cannot charge negative amount.') if self.source == 'stripe': stripe_customer = StripeCustomer.objects.get(owner=self.owner).stripe_id stripe_payment = uncloud_pay.stripe.charge_customer( amount, stripe_customer, self.stripe_payment_method_id) if 'paid' in stripe_payment and stripe_payment['paid'] == False: raise Exception(stripe_payment['error']) else: payment = Payment.objects.create( owner=self.owner, source=self.source, amount=amount) return payment else: raise Exception('This payment method is unsupported/cannot be charged.') def set_as_primary_for(self, user): methods = PaymentMethod.objects.filter(owner=user, primary=True) for method in methods: print(method) method.primary = False method.save() self.primary = True self.save() def get_primary_for(user): methods = PaymentMethod.objects.filter(owner=user) for method in methods: # Do we want to do something with non-primary method? if method.active and method.primary: return method return None class Meta: # TODO: limit to one primary method per user. # unique_together is no good since it won't allow more than one # non-primary method. pass ### # Bills. class BillingAddress(models.Model): owner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE) organization = models.CharField(max_length=100, blank=True, null=True) name = models.CharField(max_length=100) street = models.CharField(max_length=100) city = models.CharField(max_length=50) postal_code = models.CharField(max_length=50) country = CountryField(blank=True) vat_number = models.CharField(max_length=100, default="", blank=True) active = models.BooleanField(default=False) class Meta: constraints = [ models.UniqueConstraint(fields=['owner'], condition=Q(active=True), name='one_active_billing_address_per_user') ] @staticmethod def get_address_for(user): return BillingAddress.objects.get(owner=user, active=True) def __str__(self): return "{} - {}, {}, {} {}, {}".format( self.owner, self.name, self.street, self.postal_code, self.city, self.country) ### # VAT class VATRate(models.Model): starting_date = models.DateField(blank=True, null=True) ending_date = models.DateField(blank=True, null=True) territory_codes = models.TextField(blank=True, default='') currency_code = models.CharField(max_length=10) rate = models.FloatField() rate_type = models.TextField(blank=True, default='') description = models.TextField(blank=True, default='') @staticmethod def get_for_country(country_code): vat_rate = None try: vat_rate = VATRate.objects.get( territory_codes=country_code, start_date__isnull=False, stop_date=None ) return vat_rate.rate except VATRate.DoesNotExist as dne: logger.debug(str(dne)) logger.debug("Did not find VAT rate for %s, returning 0" % country_code) return 0 ### # Orders. class Order(models.Model): """ Order are assumed IMMUTABLE and used as SOURCE OF TRUST for generating bills. Do **NOT** mutate then! """ owner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, editable=True) billing_address = models.ForeignKey(BillingAddress, on_delete=models.CASCADE) description = models.TextField() # 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) recurring_period = models.IntegerField(choices = RecurringPeriod.choices, default = RecurringPeriod.PER_30D) price = models.DecimalField(default=0.0, max_digits=AMOUNT_MAX_DIGITS, decimal_places=AMOUNT_DECIMALS, validators=[MinValueValidator(0)]) replaces = models.ForeignKey('self', related_name='replaced_by', on_delete=models.CASCADE, blank=True, null=True) depends_on = models.ForeignKey('self', related_name='parent_of', on_delete=models.CASCADE, blank=True, null=True) @property def earliest_ending_date(self): """ Recurring orders cannot end before finishing at least one recurring period. One time orders have a recurring period of 0, so this work universally """ return self.starting_date + timedelta(seconds=self.recurring_period) @property def count_billed(self): """ How many times this order was billed so far. This logic is mainly thought to be for recurring bills, but also works for one time bills """ return sum([ br.quantity for br in self.bill_records.all() ]) @property def is_recurring(self): return not self.recurring_period == RecurringPeriod.ONE_TIME @property def is_one_time(self): return not self.is_recurring 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") 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) def __str__(self): return f"{self.description} (order {self.id})" # def active_before(self, ending_date): # # Was this order started before the specified ending date? # if self.starting_date <= ending_date: # if self.ending_date: # if self.ending_date > ending_date: # pass # Termination needs to be verified, maybe also include checking depending orders # @property # def is_terminated_now(self): # return self.is_terminated_at(timezone.now()) # def is_terminated_at(self, a_date): # return self.ending_date != None and self.ending_date <= a_date # def terminate(self): # if not self.is_terminated: # self.ending_date = timezone.now() # self.save() class Bill(models.Model): """ A bill is a representation of usage at a specific time """ owner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE) creation_date = models.DateTimeField(auto_now_add=True) starting_date = models.DateTimeField(default=start_of_this_month) ending_date = models.DateTimeField() due_date = models.DateField(default=default_payment_delay) is_final = models.BooleanField(default=False) class Meta: constraints = [ models.UniqueConstraint(fields=['owner', 'starting_date', 'ending_date' ], name='one_bill_per_month_per_user') ] def __str__(self): return f"Bill {self.owner}-{self.id}" @property def billing_address(self): pass # if self.order_set.all @property def sum(self): bill_records = BillRecord.objects.filter(bill=self) return sum([ br.sum for br in bill_records ]) @classmethod def create_next_bill_for_user(cls, owner, ending_date=None): last_bill = cls.objects.filter(owner=owner).order_by('id').last() # it is important to sort orders here, as bill records will be # created (and listed) in this order all_orders = Order.objects.filter(owner=owner).order_by('id') first_order = all_orders.first() bill = None ending_date = None # Get date & bill from previous bill if last_bill: if not last_bill.is_final: bill = last_bill starting_date = last_bill.starting_date ending_date = bill.ending_date else: starting_date = last_bill.end_date + datetime.timedelta(seconds=1) else: if first_order: starting_date = first_order.starting_date else: starting_date = timezone.now() if not ending_date: ending_date = end_of_month(starting_date) if not bill: bill = cls.objects.create( owner=owner, starting_date=starting_date, ending_date=ending_date) for order in all_orders: if order.is_one_time: # this code should be ok, but needs to be double checked if order.billrecord_set.count() == 0: br = BillRecord.objects.create(bill=bill, order=order, starting_date=order.starting_date, ending_date=order.ending_date) else: # Bill all recurring orders bill_record_for_this_bill = BillRecord.objects.filter(bill=bill, order=order).first() # This bill already has a bill record for the order # We potentially need to update the ending_date if the ending_date # of the bill changed. if bill_record_for_this_bill: # we may need to adjust it, but let's do this logic another time # If the order has an ending date set, we might need to adjust the bill_record if order.ending_date: if bill_record_for_this_bill.ending_date != order.ending_date: bill_record_for_this_bill.ending_date = order.ending_date else: # recurring, not terminated, should go until at least end of bill if bill_record_for_this_bill.ending_date < bill.ending_date: bill_record_for_this_bill.ending_date = bill.ending_date bill_record_for_this_bill.save() else: # No bill record in this bill for the order yet # Find out whether it was already billed for the billing period of # this bill last_bill_record = BillRecord.objects.filter(order=order).order_by('id').last() # Default starting date this_starting_date=order.starting_date # Skip billing again, if we have been processed for this bill duration if last_bill_record: if last_bill_record.ending_date >= bill.ending_date: continue # If the order ended and has been fully billed - do not process it # anymore if order.ending_date: if last_bill_record.ending_date == order.ending_date: # FIXME: maybe mark order for not processing anymore? # I imagina a boolean column, once this code is stable and # verified continue # Catch programming bugs if the last bill_record was # created incorrectly - should never be entered! if order.ending_date < last_bill_record.ending_date: raise ValidationError(f"Order {order.id} ends before last bill record {last_bill_record.id}") # Start right after last billing run this_starting_date = last_bill_record.ending_date + datetime.timedelta(seconds=1) # If the order is already terminated, use that date instead of bill date if order.ending_date: this_ending_date = order.ending_date else: if order.earliest_ending_date > bill.ending_date: this_ending_date = order.earliest_ending_date else: # bill at maximum for this billing period this_ending_date = bill.ending_date # And finally create a new billrecord! br = BillRecord.objects.create(bill=bill, order=order, starting_date=this_starting_date, ending_date=this_ending_date) # Filtering ideas: # If order is replaced, it should not be added anymore if it has been billed "last time" # If order has ended and finally charged, do not charge anymore # Find out the last billrecord for the order, if there is none, bill from the starting date return bill @classmethod def create_all_bills(cls): for owner in get_user_model().objects.all(): # mintime = time of first order # maxtime = time of last order # iterate month based through it cls.create_next_bill_for_user(owner) # for order in Order.objects.filter(Q(starting_date__gte=self.starting_date), # Q(starting_date__lte=self.ending_date), #for order in Order.objects.filter(owner=owner, # bill_records=None): # For each recurring order get the usage and bill it class BillRecord(models.Model): """ Entry of a bill, dynamically generated from an order. """ bill = models.ForeignKey(Bill, on_delete=models.CASCADE) order = models.ForeignKey(Order, on_delete=models.CASCADE) creation_date = models.DateTimeField(auto_now_add=True) starting_date = models.DateTimeField() ending_date = models.DateTimeField() @property def quantity(self): """ Determine the quantity by the duration""" if self.order.is_one_time: return 1 record_delta = self.ending_date - self.starting_date return record_delta.total_seconds()/self.order.recurring_period @property def sum(self): return self.order.price * Decimal(self.quantity) def __str__(self): return f"{self.bill}: {self.quantity} x {self.order}" ### # Products class Product(UncloudModel): owner = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, editable=False) description = "Generic Product" order = models.ForeignKey(Order, on_delete=models.CASCADE, editable=True, null=True) # FIXME: editable=True -> is in the admin, but also editable in DRF status = models.CharField(max_length=32, choices=UncloudStatus.choices, default=UncloudStatus.AWAITING_PAYMENT) # Default period for all products default_recurring_period = RecurringPeriod.PER_30D def create_order_at(self, when_to_start=None, recurring_period=None): billing_address = BillingAddress.get_address_for(self.owner) if not billing_address: raise ValidationError("Cannot order without a billing address") if not when_to_start: when_to_start = timezone.now() if not recurring_period: recurring_period = self.default_recurring_period one_time_order = None if self.one_time_price > 0: one_time_order = Order.objects.create(owner=self.owner, billing_address=billing_address, starting_date=when_to_start, price=self.one_time_price, recurring_period=RecurringPeriod.ONE_TIME, description=str(self)) if recurring_period != RecurringPeriod.ONE_TIME: if one_time_order: recurring_order = Order.objects.create(owner=self.owner, billing_address=billing_address, starting_date=when_to_start, price=self.recurring_price, recurring_period=recurring_period, depends_on=one_time_order, description=str(self)) else: recurring_order = Order.objects.create(owner=self.owner, billing_address=billing_address, starting_date=when_to_start, price=self.recurring_price, recurring_period=recurring_period, description=str(self)) def create_or_update_order(self, when_to_start=None, recurring_period=None): if not when_to_start: when_to_start = timezone.now() if not self.order: self.create_order_at(when_to_start, recurring_period) else: previous_order = self.order when_to_end = when_to_start - datetime.timedelta(seconds=1) new_order = Order.objects.create(owner=self.owner, billing_address=self.order.billing_address, starting_date=when_to_start, price=self.recurring_price, recurring_period=recurring_period, description=str(self), replaces=self.order) self.order.end_date = when_to_end self.order.save() self.order = new_order def save(self, *args, **kwargs): # Create order if there is none already if not self.order: self.create_or_update_order() super().save(*args, **kwargs) @property def recurring_price(self): pass # To be implemented in child. @property def one_time_price(self): """ Default is 0 CHF """ return 0 @property def is_recurring(self): return self.recurring_price > 0 # on is_one_time as this should be has_one_time which is the same as > 0 again... @property def billing_address(self): return self.order.billing_address @staticmethod def allowed_recurring_periods(): return RecurringPeriod.choices class Meta: abstract = True def discounted_price_by_period(self, requested_period): """ Each product has a standard recurring period for which we define a pricing. I.e. VPN is usually year, VM is usually monthly. The user can opt-in to use a different period, which influences the price: The longer a user commits, the higher the discount. Products can also be limited in the available periods. For instance a VPN only makes sense to be bought for at least one day. Rules are as follows: given a standard recurring period of ..., changing to ... modifies price ... # One month for free if buying / year, compared to a month: about 8.33% discount per_year -> per_month -> /11 per_month -> per_year -> *11 # Month has 30.42 days on average. About 7.9% discount to go monthly per_month -> per_day -> /28 per_day -> per_month -> *28 # Day has 24h, give one for free per_day -> per_hour -> /23 per_hour -> per_day -> /23 Examples VPN @ 120CHF/y becomes - 10.91 CHF/month (130.91 CHF/year) - 0.39 CHF/day (142.21 CHF/year) VM @ 15 CHF/month becomes - 165 CHF/month (13.75 CHF/month) - 0.54 CHF/day (16.30 CHF/month) """ if self.default_recurring_period == RecurringPeriod.PER_365D: if requested_period == RecurringPeriod.PER_365D: return self.recurring_price if requested_period == RecurringPeriod.PER_30D: return self.recurring_price/11. if requested_period == RecurringPeriod.PER_DAY: return self.recurring_price/11./28. elif self.default_recurring_period == RecurringPeriod.PER_30D: if requested_period == RecurringPeriod.PER_365D: return self.recurring_price*11 if requested_period == RecurringPeriod.PER_30D: return self.recurring_price if requested_period == RecurringPeriod.PER_DAY: return self.recurring_price/28. elif self.default_recurring_period == RecurringPeriod.PER_DAY: if requested_period == RecurringPeriod.PER_365D: return self.recurring_price*11*28 if requested_period == RecurringPeriod.PER_30D: return self.recurring_price*28 if requested_period == RecurringPeriod.PER_DAY: return self.recurring_price else: # FIXME: use the right type of exception here! raise Exception("Did not implement the discounter for this case")