uncloud/uncloud/uncloud_pay/models.py

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from django.db import models
from django.db.models import Q
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from django.contrib.auth import get_user_model
from django.core.validators import MinValueValidator
from django.utils.translation import gettext_lazy as _
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from django.utils import timezone
from django.dispatch import receiver
from django.core.exceptions import ObjectDoesNotExist
import django.db.models.signals as signals
import uuid
from functools import reduce
from math import ceil
from datetime import timedelta
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 import AMOUNT_DECIMALS, AMOUNT_MAX_DIGITS
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# Used to generate bill due dates.
BILL_PAYMENT_DELAY=timedelta(days=10)
# See https://docs.djangoproject.com/en/dev/ref/models/fields/#field-choices-enum-types
class RecurringPeriod(models.TextChoices):
ONE_TIME = 'ONCE', _('Onetime')
PER_YEAR = 'YEAR', _('Per Year')
PER_MONTH = 'MONTH', _('Per Month')
PER_MINUTE = 'MINUTE', _('Per Minute')
PER_DAY = 'DAY', _('Per Day')
PER_HOUR = 'HOUR', _('Per Hour')
PER_SECOND = 'SECOND', _('Per Second')
# See https://docs.djangoproject.com/en/dev/ref/models/fields/#field-choices-enum-types
class ProductStatus(models.TextChoices):
PENDING = 'PENDING', _('Pending')
AWAITING_PAYMENT = 'AWAITING_PAYMENT', _('Awaiting payment')
BEING_CREATED = 'BEING_CREATED', _('Being created')
ACTIVE = 'ACTIVE', _('Active')
DELETED = 'DELETED', _('Deleted')
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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):
uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
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)
# WIP prepaid and service activation logic by fnux.
## We override save() in order to active products awaiting payment.
#def save(self, *args, **kwargs):
# # TODO: only run activation logic on creation, not on update.
# 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_orders()
class PaymentMethod(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)
source = models.CharField(max_length=256,
choices = (
('stripe', 'Stripe'),
('unknown', 'Unknown'),
),
default='stripe')
description = models.TextField()
primary = models.BooleanField(default=True)
# Only used for "Stripe" source
stripe_card_id = models.CharField(max_length=32, blank=True, null=True)
@property
def stripe_card_last4(self):
if self.source == 'stripe':
card_request = uncloud_pay.stripe.get_card(
StripeCustomer.objects.get(owner=self.owner).stripe_id,
self.stripe_card_id)
if card_request['error'] == None:
return card_request['response_object']['last4']
else:
return None
else:
return None
def charge(self, amount):
if amount > 0: # Make sure we don't charge negative amount by errors...
if self.source == 'stripe':
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stripe_customer = StripeCustomer.objects.get(owner=self.owner).stripe_id
charge_request = uncloud_pay.stripe.charge_customer(amount, stripe_customer, self.stripe_card_id)
if charge_request['error'] == None:
payment = Payment(owner=self.owner, source=self.source, amount=amount)
payment.save() # TODO: Check return status
return payment
else:
raise Exception('Stripe error: {}'.format(charge_request['error']))
else:
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raise Exception('This payment method is unsupported/cannot be charged.')
else:
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raise Exception('Cannot charge negative amount.')
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.primary:
return method
return None
class Meta:
unique_together = [['owner', 'primary']]
###
# Bills & Payments.
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class Bill(models.Model):
uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
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owner = models.ForeignKey(get_user_model(),
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on_delete=models.CASCADE)
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creation_date = models.DateTimeField(auto_now_add=True)
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starting_date = models.DateTimeField()
ending_date = models.DateTimeField()
due_date = models.DateField()
valid = models.BooleanField(default=True)
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@property
def reference(self):
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return "{}-{}".format(
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self.owner.username,
self.creation_date.strftime("%Y-%m-%d-%H%M"))
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@property
def records(self):
bill_records = []
orders = Order.objects.filter(bill=self)
for order in orders:
for order_record in order.records:
bill_record = BillRecord(self, order_record)
bill_records.append(bill_record)
return bill_records
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@property
def total(self):
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return reduce(lambda acc, record: acc + record.amount, self.records, 0)
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@property
def final(self):
# A bill is final when its ending date is passed.
return self.ending_date < timezone.now()
@staticmethod
def generate_for(year, month, user):
# /!\ We exclusively work on the specified year and month.
# Default values for next bill (if any). Only saved at the end of
# this method, if relevant.
next_bill = Bill(owner=user,
starting_date=beginning_of_month(year, month),
ending_date=end_of_month(year, month),
creation_date=timezone.now(),
due_date=timezone.now() + BILL_PAYMENT_DELAY)
# Select all orders active on the request period.
orders = Order.objects.filter(
Q(ending_date__gt=next_bill.starting_date) | Q(ending_date__isnull=True),
owner=user)
# Check if there is already a bill covering the order and period pair:
# * Get latest bill by ending_date: previous_bill.ending_date
# * If previous_bill.ending_date is before next_bill.ending_date, a new
# bill has to be generated.
unpaid_orders = []
for order in orders:
try:
previous_bill = order.bill.latest('ending_date')
except ObjectDoesNotExist:
previous_bill = None
if previous_bill == None or previous_bill.ending_date < next_bill.ending_date:
unpaid_orders.append(order)
# Commit next_bill if it there are 'unpaid' orders.
if len(unpaid_orders) > 0:
next_bill.save()
# It is not possible to register many-to-many relationship before
# the two end-objects are saved in database.
for order in unpaid_orders:
order.bill.add(next_bill)
# TODO: use logger.
print("Generated bill {} (amount: {}) for user {}."
.format(next_bill.uuid, next_bill.total, user))
return next_bill
# Return None if no bill was created.
return None
@staticmethod
def get_unpaid_for(user):
balance = get_balance_for(user)
unpaid_bills = []
# No unpaid bill if balance is positive.
if balance >= 0:
return []
else:
bills = Bill.objects.filter(
owner=user,
due_date__lt=timezone.now()
).order_by('-creation_date')
# Amount to be paid by the customer.
unpaid_balance = abs(balance)
for bill in bills:
if unpaid_balance < 0:
break
unpaid_balance -= bill.amount
unpaid_bills.append(bill)
return unpaid_bills
@staticmethod
def get_overdue_for(user):
unpaid_bills = Bill.get_unpaid_for(user)
return list(filter(lambda bill: bill.due_date > timezone.now(), unpaid_bills))
class BillRecord():
"""
Entry of a bill, dynamically generated from order records.
"""
def __init__(self, bill, order_record):
self.bill = bill
self.order = order_record.order
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self.recurring_price = order_record.recurring_price
self.recurring_period = order_record.recurring_period
self.description = order_record.description
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if self.order.starting_date > self.bill.starting_date:
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self.one_time_price = order_record.one_time_price
else:
self.one_time_price = 0
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@property
def recurring_count(self):
# Compute billing delta.
billed_until = self.bill.ending_date
if self.order.ending_date != None and self.order.ending_date < self.order.ending_date:
billed_until = self.order.ending_date
billed_from = self.bill.starting_date
if self.order.starting_date > self.bill.starting_date:
billed_from = self.order.starting_date
if billed_from > billed_until:
# TODO: think about and check edges cases. This should not be
# possible.
raise Exception('Impossible billing delta!')
billed_delta = billed_until - billed_from
# TODO: refactor this thing?
# TODO: weekly
# TODO: yearly
if self.recurring_period == RecurringPeriod.PER_MONTH:
days = ceil(billed_delta / timedelta(days=1))
# XXX: we assume monthly bills for now.
if (self.bill.starting_date.year != self.bill.starting_date.year or
self.bill.starting_date.month != self.bill.ending_date.month):
raise Exception('Bill {} covers more than one month. Cannot bill PER_MONTH.'.
format(self.bill.uuid))
# XXX: minumal length of monthly order is to be enforced somewhere else.
(_, days_in_month) = monthrange(
self.bill.starting_date.year,
self.bill.starting_date.month)
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return Decimal(days / days_in_month)
elif self.recurring_period == RecurringPeriod.PER_DAY:
days = ceil(billed_delta / timedelta(days=1))
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return Decimal(days)
elif self.recurring_period == RecurringPeriod.PER_HOUR:
hours = ceil(billed_delta / timedelta(hours=1))
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return Decimal(hours)
elif self.recurring_period == RecurringPeriod.PER_SECOND:
seconds = ceil(billed_delta / timedelta(seconds=1))
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return Decimal(seconds)
elif self.recurring_period == RecurringPeriod.ONE_TIME:
return Decimal(0)
else:
raise Exception('Unsupported recurring period: {}.'.
format(record.recurring_period))
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@property
def amount(self):
return self.recurring_price * self.recurring_count + self.one_time_price
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###
# Orders.
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# Order are assumed IMMUTABLE and used as SOURCE OF TRUST for generating
# bills. Do **NOT** mutate then!
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class Order(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)
# TODO: enforce ending_date - starting_date to be larger than recurring_period.
creation_date = models.DateTimeField(auto_now_add=True)
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starting_date = models.DateTimeField(auto_now_add=True)
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ending_date = models.DateTimeField(blank=True,
null=True)
bill = models.ManyToManyField(Bill,
editable=False,
blank=True)
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recurring_period = models.CharField(max_length=32,
choices = RecurringPeriod.choices,
default = RecurringPeriod.PER_MONTH)
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@property
def records(self):
return OrderRecord.objects.filter(order=self)
@property
def one_time_price(self):
return reduce(lambda acc, record: acc + record.one_time_price, self.records, 0)
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@property
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def recurring_price(self):
return reduce(lambda acc, record: acc + record.recurring_price, self.records, 0)
def add_record(self, one_time_price, recurring_price, description):
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OrderRecord.objects.create(order=self,
one_time_price=one_time_price,
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recurring_price=recurring_price,
description=description)
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class OrderRecord(models.Model):
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"""
Order records store billing informations for products: the actual product
might be mutated and/or moved to another order but we do not want to loose
the details of old orders.
Used as source of trust to dynamically generate bill entries.
"""
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order = models.ForeignKey(Order, on_delete=models.CASCADE)
one_time_price = models.DecimalField(default=0.0,
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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)])
description = models.TextField()
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@property
def recurring_period(self):
return self.order.recurring_period
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@property
def starting_date(self):
return self.order.starting_date
@property
def ending_date(self):
return self.order.ending_date
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###
# Products
# Abstract (= no database representation) class used as parent for products
# (e.g. uncloud_vm.models.VMProduct).
class Product(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)
description = ""
status = models.CharField(max_length=32,
choices=ProductStatus.choices,
default=ProductStatus.PENDING)
order = models.ForeignKey(Order,
on_delete=models.CASCADE,
editable=False,
null=True)
@property
def recurring_price(self, recurring_period=RecurringPeriod.PER_MONTH):
pass # To be implemented in child.
@property
def one_time_price(self):
return 0
@property
def recurring_period(self):
return self.order.recurring_period
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@staticmethod
def allowed_recurring_periods():
return RecurringPeriod.choices
class Meta:
abstract = True