Rename / prepare for merge with uncloud repo

uncloud_django_based/uncloud/uncloud_pay/admin.py

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+from django.contrib import admin
+
+# Register your models here.

uncloud_django_based/uncloud/uncloud_pay/apps.py

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+from django.apps import AppConfig
+
+
+class UncloudPayConfig(AppConfig):
+    name = 'uncloud_pay'

uncloud_django_based/uncloud/uncloud_pay/helpers.py

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+from functools import reduce
+from datetime import datetime
+from rest_framework import mixins
+from rest_framework.viewsets import GenericViewSet
+from django.utils import timezone
+from calendar import monthrange
+
+def beginning_of_month(year, month):
+    tz = timezone.get_current_timezone()
+    return datetime(year=year, month=month, day=1, tzinfo=tz)
+
+def end_of_month(year, month):
+    (_, days) = monthrange(year, month)
+    tz = timezone.get_current_timezone()
+    return datetime(year=year, month=month, day=days,
+            hour=23, minute=59, second=59, tzinfo=tz)
+
+class ProductViewSet(mixins.CreateModelMixin,
+                     mixins.RetrieveModelMixin,
+                     mixins.ListModelMixin,
+                     GenericViewSet):
+    """
+    A customer-facing viewset that provides default `create()`, `retrieve()`
+    and `list()`.
+    """
+    pass

uncloud_django_based/uncloud/uncloud_pay/management/commands/charge-negative-balance.py

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+from django.core.management.base import BaseCommand
+from uncloud_auth.models import User
+from uncloud_pay.models import Order, Bill, PaymentMethod, get_balance_for
+
+from datetime import timedelta
+from django.utils import timezone
+
+class Command(BaseCommand):
+    help = 'Generate bills and charge customers if necessary.'
+
+    def add_arguments(self, parser):
+        pass
+
+    def handle(self, *args, **options):
+        users = User.objects.all()
+        print("Processing {} users.".format(users.count()))
+        for user in users:
+            balance = get_balance_for(user)
+            if balance < 0:
+                print("User {} has negative balance ({}), charging.".format(user.username, balance))
+                payment_method = PaymentMethod.get_primary_for(user)
+                if payment_method != None:
+                    amount_to_be_charged = abs(balance)
+                    charge_ok = payment_method.charge(amount_to_be_charged)
+                    if not charge_ok:
+                        print("ERR: charging {} with method {} failed"
+                                .format(user.username, payment_method.uuid)
+                                )
+                else:
+                    print("ERR: no payment method registered for {}".format(user.username))
+        print("=> Done.")

uncloud_django_based/uncloud/uncloud_pay/management/commands/generate-bills.py

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+import logging
+
+from django.core.management.base import BaseCommand
+from uncloud_auth.models import User
+from uncloud_pay.models import Order, Bill
+from django.core.exceptions import ObjectDoesNotExist
+
+from datetime import timedelta, date
+from django.utils import timezone
+from uncloud_pay.models import Bill
+
+logger = logging.getLogger(__name__)
+
+class Command(BaseCommand):
+    help = 'Generate bills and charge customers if necessary.'
+
+    def add_arguments(self, parser):
+        pass
+
+    # TODO: use logger.*
+    def handle(self, *args, **options):
+        # Iterate over all 'active' users.
+        # TODO: filter out inactive users.
+        users = User.objects.all()
+        print("Processing {} users.".format(users.count()))
+
+        for user in users:
+            now = timezone.now()
+            Bill.generate_for(
+                    year=now.year,
+                    month=now.month,
+                    user=user)
+
+        # We're done for this round :-)
+        print("=> Done.")

uncloud_django_based/uncloud/uncloud_pay/management/commands/handle-overdue-bills.py

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+from django.core.management.base import BaseCommand
+from uncloud_auth.models import User
+from uncloud_pay.models import Bill
+
+from datetime import timedelta
+from django.utils import timezone
+
+class Command(BaseCommand):
+    help = 'Take action on overdue bills.'
+
+    def add_arguments(self, parser):
+        pass
+
+    def handle(self, *args, **options):
+        users = User.objects.all()
+        print("Processing {} users.".format(users.count()))
+        for user in users:
+            for bill in Bill.get_overdue_for(user):
+                print("/!\ Overdue bill for {}, {} with amount {}"
+                        .format(user.username, bill.uuid, bill.amount))
+                # TODO: take action?
+
+        print("=> Done.")

uncloud_django_based/uncloud/uncloud_pay/migrations/0001_initial.py

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+# Generated by Django 3.0.3 on 2020-03-05 10:17
+
+from django.conf import settings
+import django.core.validators
+from django.db import migrations, models
+import django.db.models.deletion
+import uuid
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('uncloud_auth', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Bill',
+            fields=[
+                ('uuid', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('creation_date', models.DateTimeField(auto_now_add=True)),
+                ('starting_date', models.DateTimeField()),
+                ('ending_date', models.DateTimeField()),
+                ('due_date', models.DateField()),
+                ('valid', models.BooleanField(default=True)),
+                ('owner', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Order',
+            fields=[
+                ('uuid', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('creation_date', models.DateTimeField(auto_now_add=True)),
+                ('starting_date', models.DateTimeField(auto_now_add=True)),
+                ('ending_date', models.DateTimeField(blank=True, null=True)),
+                ('recurring_period', models.CharField(choices=[('ONCE', 'Onetime'), ('YEAR', 'Per Year'), ('MONTH', 'Per Month'), ('MINUTE', 'Per Minute'), ('DAY', 'Per Day'), ('HOUR', 'Per Hour'), ('SECOND', 'Per Second')], default='MONTH', max_length=32)),
+                ('bill', models.ManyToManyField(blank=True, editable=False, to='uncloud_pay.Bill')),
+                ('owner', models.ForeignKey(editable=False, on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='StripeCustomer',
+            fields=[
+                ('owner', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, primary_key=True, serialize=False, to=settings.AUTH_USER_MODEL)),
+                ('stripe_id', models.CharField(max_length=32)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='Payment',
+            fields=[
+                ('uuid', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('amount', models.DecimalField(decimal_places=2, default=0.0, max_digits=10, validators=[django.core.validators.MinValueValidator(0)])),
+                ('source', models.CharField(choices=[('wire', 'Wire Transfer'), ('stripe', 'Stripe'), ('voucher', 'Voucher'), ('referral', 'Referral'), ('unknown', 'Unknown')], default='unknown', max_length=256)),
+                ('timestamp', models.DateTimeField(auto_now_add=True)),
+                ('owner', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+        migrations.CreateModel(
+            name='OrderRecord',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('one_time_price', models.DecimalField(decimal_places=2, default=0.0, max_digits=10, validators=[django.core.validators.MinValueValidator(0)])),
+                ('recurring_price', models.DecimalField(decimal_places=2, default=0.0, max_digits=10, validators=[django.core.validators.MinValueValidator(0)])),
+                ('description', models.TextField()),
+                ('order', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='uncloud_pay.Order')),
+            ],
+        ),
+        migrations.CreateModel(
+            name='PaymentMethod',
+            fields=[
+                ('uuid', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('source', models.CharField(choices=[('stripe', 'Stripe'), ('unknown', 'Unknown')], default='stripe', max_length=256)),
+                ('description', models.TextField()),
+                ('primary', models.BooleanField(default=True)),
+                ('stripe_card_id', models.CharField(blank=True, max_length=32, null=True)),
+                ('owner', models.ForeignKey(editable=False, on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+            ],
+            options={
+                'unique_together': {('owner', 'primary')},
+            },
+        ),
+    ]

uncloud_django_based/uncloud/uncloud_pay/models.py

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+from django.db import models
+from django.db.models import Q
+from django.contrib.auth import get_user_model
+from django.core.validators import MinValueValidator
+from django.utils.translation import gettext_lazy as _
+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
+from uncloud.models import UncloudModel, UncloudStatus
+
+
+# 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')
+
+
+
+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':
+                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:
+                raise Exception('This payment method is unsupported/cannot be charged.')
+        else:
+            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.
+
+class Bill(models.Model):
+    uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    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()
+
+    valid = models.BooleanField(default=True)
+
+    @property
+    def reference(self):
+        return "{}-{}".format(
+                self.owner.username,
+                self.creation_date.strftime("%Y-%m-%d-%H%M"))
+
+    @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
+
+    @property
+    def total(self):
+        return reduce(lambda acc, record: acc + record.amount, self.records, 0)
+
+    @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
+        self.recurring_price = order_record.recurring_price
+        self.recurring_period = order_record.recurring_period
+        self.description = order_record.description
+
+        if self.order.starting_date > self.bill.starting_date:
+            self.one_time_price = order_record.one_time_price
+        else:
+            self.one_time_price = 0
+
+    @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)
+            return Decimal(days / days_in_month)
+        elif self.recurring_period == RecurringPeriod.PER_DAY:
+            days = ceil(billed_delta / timedelta(days=1))
+            return Decimal(days)
+        elif self.recurring_period == RecurringPeriod.PER_HOUR:
+            hours = ceil(billed_delta / timedelta(hours=1))
+            return Decimal(hours)
+        elif self.recurring_period == RecurringPeriod.PER_SECOND:
+            seconds = ceil(billed_delta / timedelta(seconds=1))
+            return Decimal(seconds)
+        elif self.recurring_period == RecurringPeriod.ONE_TIME:
+            return Decimal(0)
+        else:
+            raise Exception('Unsupported recurring period: {}.'.
+                    format(record.recurring_period))
+
+    @property
+    def amount(self):
+        return self.recurring_price * self.recurring_count + self.one_time_price
+
+###
+# Orders.
+
+# Order are assumed IMMUTABLE and used as SOURCE OF TRUST for generating
+# bills. Do **NOT** mutate then!
+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(auto_now_add=True)
+    ending_date = models.DateTimeField(blank=True,
+                                       null=True)
+
+    bill = models.ManyToManyField(Bill,
+                                  editable=False,
+                                  blank=True)
+
+    recurring_period = models.CharField(max_length=32,
+                              choices = RecurringPeriod.choices,
+                              default = RecurringPeriod.PER_MONTH)
+
+    @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)
+
+    @property
+    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):
+        OrderRecord.objects.create(order=self,
+                one_time_price=one_time_price,
+                recurring_price=recurring_price,
+                description=description)
+
+
+class OrderRecord(models.Model):
+    """
+    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.
+    """
+
+    order = models.ForeignKey(Order, on_delete=models.CASCADE)
+    one_time_price = models.DecimalField(default=0.0,
+            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()
+
+
+    @property
+    def recurring_period(self):
+        return self.order.recurring_period
+
+    @property
+    def starting_date(self):
+        return self.order.starting_date
+
+    @property
+    def ending_date(self):
+        return self.order.ending_date
+
+
+###
+# Products
+
+# Abstract (= no database representation) class used as parent for products
+# (e.g.  uncloud_vm.models.VMProduct).
+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,
+            choices=UncloudStatus.choices,
+            default=UncloudStatus.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
+
+    @staticmethod
+    def allowed_recurring_periods():
+        return RecurringPeriod.choices
+
+    class Meta:
+        abstract = True

uncloud_django_based/uncloud/uncloud_pay/serializers.py

@@ -0,0 +1,73 @@
+from django.contrib.auth import get_user_model
+from rest_framework import serializers
+from .models import *
+
+###
+# Payments and Payment Methods.
+
+class PaymentSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Payment
+        fields = ['owner', 'amount', 'source', 'timestamp']
+
+class PaymentMethodSerializer(serializers.ModelSerializer):
+    stripe_card_last4 = serializers.IntegerField()
+
+    class Meta:
+        model = PaymentMethod
+        fields = ['uuid', 'source', 'description', 'primary', 'stripe_card_last4']
+
+class ChargePaymentMethodSerializer(serializers.Serializer):
+    amount = serializers.DecimalField(max_digits=10, decimal_places=2)
+
+class CreditCardSerializer(serializers.Serializer):
+    number = serializers.IntegerField()
+    exp_month = serializers.IntegerField()
+    exp_year = serializers.IntegerField()
+    cvc = serializers.IntegerField()
+
+class CreatePaymentMethodSerializer(serializers.ModelSerializer):
+    credit_card = CreditCardSerializer()
+
+    class Meta:
+        model = PaymentMethod
+        fields = ['source', 'description', 'primary', 'credit_card']
+
+###
+# Orders & Products.
+
+class OrderRecordSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = OrderRecord
+        fields  = ['one_time_price', 'recurring_price', 'description']
+
+
+class OrderSerializer(serializers.ModelSerializer):
+    records = OrderRecordSerializer(many=True, read_only=True)
+    class Meta:
+        model = Order
+        fields = ['uuid', 'creation_date', 'starting_date', 'ending_date',
+                'bill', 'recurring_period', 'records', 'recurring_price', 'one_time_price']
+
+
+###
+# Bills
+
+# TODO: remove magic numbers for decimal fields
+class BillRecordSerializer(serializers.Serializer):
+    order = serializers.HyperlinkedRelatedField(
+            view_name='order-detail',
+            read_only=True)
+    description = serializers.CharField()
+    recurring_period = serializers.CharField()
+    recurring_price = serializers.DecimalField(max_digits=10, decimal_places=2)
+    recurring_count = serializers.DecimalField(max_digits=10, decimal_places=2)
+    one_time_price = serializers.DecimalField(max_digits=10, decimal_places=2)
+    amount = serializers.DecimalField(max_digits=10, decimal_places=2)
+
+class BillSerializer(serializers.ModelSerializer):
+    records = BillRecordSerializer(many=True, read_only=True)
+    class Meta:
+        model = Bill
+        fields = ['reference', 'owner', 'total', 'due_date', 'creation_date',
+                'starting_date', 'ending_date', 'records', 'final']

uncloud_django_based/uncloud/uncloud_pay/stripe.py

@@ -0,0 +1,133 @@
+import stripe
+import stripe.error
+import logging
+
+from django.core.exceptions import ObjectDoesNotExist
+import uncloud_pay.models
+
+import uncloud.secrets
+
+# Static stripe configuration used below.
+CURRENCY = 'chf'
+
+stripe.api_key = uncloud.secrets.STRIPE_KEY
+
+# Helper (decorator) used to catch errors raised by stripe logic.
+def handle_stripe_error(f):
+    def handle_problems(*args, **kwargs):
+        response = {
+            'paid': False,
+            'response_object': None,
+            'error': None
+        }
+
+        common_message = "Currently it is not possible to make payments."
+        try:
+            response_object = f(*args, **kwargs)
+            response = {
+                'response_object': response_object,
+                'error': None
+            }
+            return response
+        except stripe.error.CardError as e:
+            # Since it's a decline, stripe.error.CardError will be caught
+            body = e.json_body
+            err = body['error']
+            response.update({'error': err['message']})
+            logging.error(str(e))
+            return response
+        except stripe.error.RateLimitError:
+            response.update(
+                {'error': "Too many requests made to the API too quickly"})
+            return response
+        except stripe.error.InvalidRequestError as e:
+            logging.error(str(e))
+            response.update({'error': "Invalid parameters"})
+            return response
+        except stripe.error.AuthenticationError as e:
+            # Authentication with Stripe's API failed
+            # (maybe you changed API keys recently)
+            logging.error(str(e))
+            response.update({'error': common_message})
+            return response
+        except stripe.error.APIConnectionError as e:
+            logging.error(str(e))
+            response.update({'error': common_message})
+            return response
+        except stripe.error.StripeError as e:
+            # maybe send email
+            logging.error(str(e))
+            response.update({'error': common_message})
+            return response
+        except Exception as e:
+            # maybe send email
+            logging.error(str(e))
+            response.update({'error': common_message})
+            return response
+
+    return handle_problems
+
+# Convenience CC container, also used for serialization.
+class CreditCard():
+    number = None
+    exp_year = None
+    exp_month = None
+    cvc = None
+
+    def __init__(self, number, exp_month, exp_year, cvc):
+        self.number=number
+        self.exp_year = exp_year
+        self.exp_month = exp_month
+        self.cvc = cvc
+
+# Actual Stripe logic.
+
+def get_customer_id_for(user):
+    try:
+        # .get() raise if there is no matching entry.
+        return uncloud_pay.models.StripeCustomer.objects.get(owner=user).stripe_id
+    except ObjectDoesNotExist:
+        # No entry yet - making a new one.
+        customer_request = create_customer(user.username, user.email)
+        if customer_request['error'] == None:
+            mapping = uncloud_pay.models.StripeCustomer.objects.create(
+                    owner=user,
+                    stripe_id=customer_request['response_object']['id']
+                    )
+            return mapping.stripe_id
+        else:
+            return None
+
+@handle_stripe_error
+def create_card(customer_id, credit_card):
+    return stripe.Customer.create_source(
+            customer_id,
+            card={
+                'number': credit_card.number,
+                'exp_month': credit_card.exp_month,
+                'exp_year': credit_card.exp_year,
+                'cvc': credit_card.cvc
+                })
+
+@handle_stripe_error
+def get_card(customer_id, card_id):
+    return stripe.Customer.retrieve_source(customer_id, card_id)
+
+@handle_stripe_error
+def charge_customer(amount, customer_id, card_id):
+    # Amount is in CHF but stripes requires smallest possible unit.
+    # See https://stripe.com/docs/api/charges/create
+    adjusted_amount = int(amount * 100)
+    return stripe.Charge.create(
+            amount=adjusted_amount,
+            currency=CURRENCY,
+            customer=customer_id,
+            source=card_id)
+
+@handle_stripe_error
+def create_customer(name, email):
+    return stripe.Customer.create(name=name, email=email)
+
+@handle_stripe_error
+def get_customer(customer_id):
+    return stripe.Customer.retrieve(customer_id)

uncloud_django_based/uncloud/uncloud_pay/tests.py

@@ -0,0 +1,3 @@
+from django.test import TestCase
+
+# Create your tests here.

uncloud_django_based/uncloud/uncloud_pay/views.py

@@ -0,0 +1,150 @@
+from django.shortcuts import render
+from django.db import transaction
+from django.contrib.auth import get_user_model
+from rest_framework import viewsets, permissions, status
+from rest_framework.response import Response
+from rest_framework.decorators import action
+
+import json
+
+from .models import *
+from .serializers import *
+from datetime import datetime
+import uncloud_pay.stripe as uncloud_stripe
+
+###
+# Standard user views:
+
+class BalanceViewSet(viewsets.ViewSet):
+    # here we return a number
+    # number = sum(payments) - sum(bills)
+
+    #bills = Bill.objects.filter(owner=self.request.user)
+    #payments = Payment.objects.filter(owner=self.request.user)
+
+    # sum_paid = sum([ amount for amount payments..,.  ]) # you get the picture
+    # sum_to_be_paid = sum([ amount for amount bills..,.  ]) # you get the picture
+    pass
+
+
+class BillViewSet(viewsets.ReadOnlyModelViewSet):
+    serializer_class = BillSerializer
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_queryset(self):
+        return Bill.objects.filter(owner=self.request.user)
+
+class PaymentViewSet(viewsets.ReadOnlyModelViewSet):
+    serializer_class = PaymentSerializer
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_queryset(self):
+        return Payment.objects.filter(owner=self.request.user)
+
+class OrderViewSet(viewsets.ReadOnlyModelViewSet):
+    serializer_class = OrderSerializer
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_queryset(self):
+        return Order.objects.filter(owner=self.request.user)
+
+
+class PaymentMethodViewSet(viewsets.ModelViewSet):
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_serializer_class(self):
+        if self.action == 'create':
+            return CreatePaymentMethodSerializer
+        elif self.action == 'charge':
+            return ChargePaymentMethodSerializer
+        else:
+            return PaymentMethodSerializer
+
+
+    def get_queryset(self):
+        return PaymentMethod.objects.filter(owner=self.request.user)
+
+    # XXX: Handling of errors is far from great down there.
+    @transaction.atomic
+    def create(self, request):
+        serializer = self.get_serializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+
+        # Retrieve Stripe customer ID for user.
+        customer_id  = uncloud_stripe.get_customer_id_for(request.user)
+        if customer_id == None:
+            return Response(
+                    {'error': 'Could not resolve customer stripe ID.'},
+                    status=status.HTTP_500_INTERNAL_SERVER_ERROR)
+
+        # Register card under stripe customer.
+        credit_card = uncloud_stripe.CreditCard(**serializer.validated_data.pop('credit_card'))
+        card_request = uncloud_stripe.create_card(customer_id, credit_card)
+        if card_request['error']:
+            return Response({'stripe_error': card_request['error']}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)
+        card_id = card_request['response_object']['id']
+
+        # Save payment method locally.
+        serializer.validated_data['stripe_card_id'] = card_request['response_object']['id']
+        payment_method = PaymentMethod.objects.create(owner=request.user, **serializer.validated_data)
+
+        # We do not want to return the credit card details sent with the POST
+        # request.
+        output_serializer = PaymentMethodSerializer(payment_method)
+        return Response(output_serializer.data)
+
+    @action(detail=True, methods=['post'])
+    def charge(self, request, pk=None):
+        payment_method = self.get_object()
+        serializer = self.get_serializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        amount = serializer.validated_data['amount']
+        try:
+            payment = payment_method.charge(amount)
+            output_serializer = PaymentSerializer(payment)
+            return Response(output_serializer.data)
+        except Exception as e:
+            return Response({'error': str(e)}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)
+
+###
+# Admin views.
+
+class AdminPaymentViewSet(viewsets.ModelViewSet):
+    serializer_class = PaymentSerializer
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_queryset(self):
+        return Payment.objects.all()
+
+    def create(self, request):
+        serializer = self.get_serializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        serializer.save(timestamp=datetime.now())
+
+        headers = self.get_success_headers(serializer.data)
+        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
+
+class AdminBillViewSet(viewsets.ModelViewSet):
+    serializer_class = BillSerializer
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_queryset(self):
+        return Bill.objects.all()
+
+    def unpaid(self, request):
+        return Bill.objects.filter(owner=self.request.user, paid=False)
+
+    def create(self, request):
+        serializer = self.get_serializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        serializer.save(creation_date=datetime.now())
+
+        headers = self.get_success_headers(serializer.data)
+        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
+
+class AdminOrderViewSet(viewsets.ModelViewSet):
+    serializer_class = OrderSerializer
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_queryset(self):
+        return Order.objects.all()