uncloud-mravi/uncloud_pay/models.py
2020-08-09 14:44:29 +02:00

815 lines
29 KiB
Python

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 end_before(a_date):
""" Return suitable datetimefield for ending just before a_date """
return a_date - datetime.timedelta(seconds=1)
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 + datetime.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 replace_with(self, new_order):
new_order.replaces = self
self.ending_date = new_order.starting_date - datetime.timedelta(seconds=1)
self.save()
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})"
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)
billing_address = models.ForeignKey(BillingAddress,
on_delete=models.CASCADE,
editable=True,
null=False)
# FIXME: editable=True -> is in the admin, but also editable in DRF
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}"
def close(self):
"""
Close/finish a bill
"""
self.is_final = True
self.save()
@property
def sum(self):
bill_records = BillRecord.objects.filter(bill=self)
return sum([ br.sum for br in bill_records ])
@classmethod
def create_bills_for_all_users(cls):
"""
Create bills for all users
"""
for owner in get_user_model().objects.all():
cls.create_next_bills_for_user(owner)
@classmethod
def create_next_bills_for_user(cls, owner, ending_date=None):
"""
Create one bill per billing address, as the VAT rates might be different
for each address
"""
bills = []
for billing_address in BillingAddress.objects.filter(owner=owner):
bills.append(cls.create_next_bill_for_user_address(owner, billing_address, ending_date))
return bills
@classmethod
def create_next_bill_for_user_address(cls, owner, billing_address, ending_date=None):
last_bill = cls.objects.filter(owner=owner, billing_address=billing_address).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, billing_address=billing_address).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.ending_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,
billing_address=billing_address)
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
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}"
def save(self, *args, **kwargs):
if self.ending_date < self.starting_date:
raise ValidationError("End date cannot be before starting date")
super().save(*args, **kwargs)
###
# Products
class Product(UncloudModel):
owner = models.ForeignKey(get_user_model(),
on_delete=models.CASCADE,
editable=False)
description = "Generic Product"
orders = models.ManyToManyField(Order)
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
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))
self.orders.add(one_time_order)
else:
one_time_order = None
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))
self.orders.add(recurring_order)
def create_or_update_order(self, when_to_start=None, recurring_period=None):
if not when_to_start:
when_to_start = timezone.now()
# Update order = create new order
if self.order:
previous_order = self.order
when_to_end = end_before(when_to_start)
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)
print(new_order)
self.order.end_date = when_to_end
self.order.save()
self.order = new_order
else:
return self.create_order_at(when_to_start, recurring_period)
@property
def recurring_price(self):
""" implement correct values in the child class """
return 0
@property
def one_time_price(self):
""" implement correct values in the child class """
return 0
@property
def is_recurring(self):
return self.recurring_price > 0
@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")
# Sample products included into uncloud
class SampleOneTimeProduct(Product):
default_recurring_period = RecurringPeriod.ONE_TIME
@property
def one_time_price(self):
return 5
class SampleRecurringProduct(Product):
default_recurring_period = RecurringPeriod.PER_30D
@property
def recurring_price(self):
return 10
class SampleRecurringProductOneTimeFee(Product):
default_recurring_period = RecurringPeriod.PER_30D
@property
def one_time_price(self):
return 5
@property
def recurring_price(self):
return 1