uncloud-mravi/uncloud_django_based/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.core.exceptions import ObjectDoesNotExist
import uuid
import logging
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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from uncloud.models import UncloudModel, UncloudStatus
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from decimal import Decimal
import decimal
# Define DecimalField properties, used to represent amounts of money.
AMOUNT_MAX_DIGITS=10
AMOUNT_DECIMALS=2
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# FIXME: check why we need +1 here.
decimal.getcontext().prec = AMOUNT_DECIMALS + 1
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# Used to generate bill due dates.
BILL_PAYMENT_DELAY=timedelta(days=10)
# Initialize logger.
logger = logging.getLogger(__name__)
# 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_WEEK = 'WEEK', _('Per Week')
PER_DAY = 'DAY', _('Per Day')
PER_HOUR = 'HOUR', _('Per Hour')
PER_MINUTE = 'MINUTE', _('Per Minute')
PER_SECOND = 'SECOND', _('Per Second')
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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=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):
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if not self.active:
raise Exception('This payment method is inactive.')
if amount < 0: # Make sure we don't charge negative amount by errors...
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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)
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return payment
else:
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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?
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if method.active and method.primary:
return method
return None
class Meta:
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# 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
###
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# Bills.
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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.
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generated_bills = []
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# Default values for next bill (if any).
starting_date=beginning_of_month(year, month)
ending_date=end_of_month(year, month)
creation_date=timezone.now()
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# Select all orders active on the request period (i.e. starting on or after starting_date).
orders = Order.objects.filter(
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Q(ending_date__gte=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
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# * For monthly bills: if previous_bill.ending_date is before
# (next_bill) ending_date, a new bill has to be generated.
# * For yearly bill: if previous_bill.ending_date is on working
# month, generate new bill.
unpaid_orders = { 'monthly_or_less': [], 'yearly': {}}
for order in orders:
try:
previous_bill = order.bill.latest('ending_date')
except ObjectDoesNotExist:
previous_bill = None
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# FIXME: control flow is confusing in this block.
if order.recurring_period == RecurringPeriod.PER_YEAR:
# We ignore anything smaller than a day in here.
next_yearly_bill_start_on = None
if previous_bill == None:
next_yearly_bill_start_on = order.starting_date
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elif previous_bill.ending_date <= ending_date:
next_yearly_bill_start_on = (previous_bill.ending_date + timedelta(days=1))
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# Store for bill generation. One bucket per day of month with a starting bill.
# bucket is a reference here, no need to reassign.
if next_yearly_bill_start_on:
# We want to group orders by date but keep using datetimes.
next_yearly_bill_start_on = next_yearly_bill_start_on.replace(
minute=0, hour=0, second=0, microsecond=0)
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bucket = unpaid_orders['yearly'].get(next_yearly_bill_start_on)
if bucket == None:
unpaid_orders['yearly'][next_yearly_bill_start_on] = [order]
else:
unpaid_orders['yearly'][next_yearly_bill_start_on] = bucket + [order]
else:
if previous_bill == None or previous_bill.ending_date <= ending_date:
unpaid_orders['monthly_or_less'].append(order)
# Handle working month's billing.
if len(unpaid_orders['monthly_or_less']) > 0:
# TODO: PREPAID billing is not supported yet.
prepaid_due_date = min(creation_date, starting_date) + BILL_PAYMENT_DELAY
postpaid_due_date = max(creation_date, ending_date) + BILL_PAYMENT_DELAY
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next_monthly_bill = Bill.objects.create(owner=user,
creation_date=creation_date,
starting_date=starting_date, # FIXME: this is a hack!
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ending_date=ending_date,
due_date=postpaid_due_date)
# It is not possible to register many-to-many relationship before
# the two end-objects are saved in database.
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for order in unpaid_orders['monthly_or_less']:
order.bill.add(next_monthly_bill)
logger.info("Generated monthly bill {} (amount: {}) for user {}."
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.format(next_monthly_bill.uuid, next_monthly_bill.total, user))
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# Add to output.
generated_bills.append(next_monthly_bill)
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# Handle yearly bills starting on working month.
if len(unpaid_orders['yearly']) > 0:
# For every starting date, generate new bill.
for next_yearly_bill_start_on in unpaid_orders['yearly']:
# No postpaid for yearly payments.
prepaid_due_date = min(creation_date, next_yearly_bill_start_on) + BILL_PAYMENT_DELAY
# Bump by one year, remove one day.
ending_date = next_yearly_bill_start_on.replace(
year=next_yearly_bill_start_on.year+1) - timedelta(days=1)
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next_yearly_bill = Bill.objects.create(owner=user,
creation_date=creation_date,
starting_date=next_yearly_bill_start_on,
ending_date=ending_date,
due_date=prepaid_due_date)
# It is not possible to register many-to-many relationship before
# the two end-objects are saved in database.
for order in unpaid_orders['yearly'][next_yearly_bill_start_on]:
order.bill.add(next_yearly_bill)
logger.info("Generated yearly bill {} (amount: {}) for user {}."
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.format(next_yearly_bill.uuid, next_yearly_bill.total, user))
# Add to output.
generated_bills.append(next_yearly_bill)
# Return generated (monthly + yearly) bills.
return generated_bills
@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.bill.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:
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# TODO: think about and check edge cases. This should not be
# possible.
raise Exception('Impossible billing delta!')
billed_delta = billed_until - billed_from
# TODO: refactor this thing?
# TODO: weekly
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if self.recurring_period == RecurringPeriod.PER_YEAR:
# XXX: Should always be one => we do not bill for more than one year.
# TODO: check billed_delta is ~365 days.
return 1
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elif self.recurring_period == RecurringPeriod.PER_MONTH:
days = ceil(billed_delta / timedelta(days=1))
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# Monthly bills always cover one single month.
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)
return days / days_in_month
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elif self.recurring_period == RecurringPeriod.PER_WEEK:
weeks = ceil(billed_delta / timedelta(week=1))
return weeks
elif self.recurring_period == RecurringPeriod.PER_DAY:
days = ceil(billed_delta / timedelta(days=1))
return days
elif self.recurring_period == RecurringPeriod.PER_HOUR:
hours = ceil(billed_delta / timedelta(hours=1))
return hours
elif self.recurring_period == RecurringPeriod.PER_SECOND:
seconds = ceil(billed_delta / timedelta(seconds=1))
return seconds
elif self.recurring_period == RecurringPeriod.ONE_TIME:
return 0
else:
raise Exception('Unsupported recurring period: {}.'.
format(record.recurring_period))
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@property
def amount(self):
return Decimal(float(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)
starting_date = models.DateTimeField()
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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)
# Used by uncloud_pay tests.
def add_record(self, one_time_price, recurring_price, description):
OrderRecord.objects.create(order=self,
one_time_price=one_time_price,
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).
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class Product(UncloudModel):
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,
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choices=UncloudStatus.choices,
default=UncloudStatus.PENDING)
order = models.ForeignKey(Order,
on_delete=models.CASCADE,
editable=False,
null=True)
# Default period for all products
default_recurring_period = RecurringPeriod.PER_MONTH
# Used to save records.
def save(self, *args, **kwargs):
# _state.adding is switched to false after super(...) call.
being_created = self._state.adding
super(Product, self).save(*args, **kwargs)
# Make sure we only create records on creation.
if being_created:
record = OrderRecord(
one_time_price=self.one_time_price,
recurring_price=self.recurring_price(self.recurring_period),
description=self.description)
self.order.orderrecord_set.add(record, bulk=False)
@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
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_YEAR:
if requested_period == RecurringPeriod.PER_YEAR:
return self.recurring_price
if requested_period == RecurringPeriod.PER_MONTH:
return self.recurring_price/11.
if requested_period == RecurringPeriod.PER_DAY:
return self.recurring_price/11./28.
elif self.default_recurring_period == RecurringPeriod.PER_MONTH:
if requested_period == RecurringPeriod.PER_YEAR:
return self.recurring_price*11
if requested_period == RecurringPeriod.PER_MONTH:
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_YEAR:
return self.recurring_price*11*28
if requested_period == RecurringPeriod.PER_MONTH:
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")