models.py

# -*- coding: utf-8 -*-
from decimal import Decimal
from time import sleep

import simplejson as json
import six
import stripe
from django import dispatch
from django.conf import settings
from django.contrib.contenttypes import fields as generic
from django.contrib.contenttypes.models import ContentType
from django.core.validators import MaxValueValidator, MinValueValidator
from django.db import models
from django.utils import timezone
from django.utils.translation import ugettext_lazy as _
from jsonfield import JSONField

from aa_stripe.exceptions import StripeMethodNotAllowed, StripeWebhookAlreadyParsed
from aa_stripe.settings import stripe_settings
from aa_stripe.utils import timestamp_to_timezone_aware_date

USER_MODEL = getattr(settings, "STRIPE_USER_MODEL", settings.AUTH_USER_MODEL)

# signals
webhook_pre_parse = dispatch.Signal(providing_args=["instance", "event_type", "event_model", "event_action"])


class StripeBasicModel(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    stripe_response = JSONField()

    class Meta:
        abstract = True


class StripeCustomer(StripeBasicModel):
    user = models.ForeignKey(USER_MODEL, on_delete=models.CASCADE, related_name='stripe_customers')
    stripe_js_response = JSONField()
    stripe_customer_id = models.CharField(max_length=255, db_index=True)
    is_active = models.BooleanField(default=True)
    is_created_at_stripe = models.BooleanField(default=False)

    def create_at_stripe(self):
        if self.is_created_at_stripe:
            raise StripeMethodNotAllowed()

        stripe.api_key = stripe_settings.API_KEY
        customer = stripe.Customer.create(
            source=self.stripe_js_response["id"],
            description="{user} id: {user.id}".format(user=self.user)
        )
        self.stripe_customer_id = customer["id"]
        self.stripe_response = customer
        self.is_created_at_stripe = True
        self.save()
        return self

    @classmethod
    def get_latest_active_customer_for_user(cls, user):
        """Returns last active stripe customer for user"""
        customer = cls.objects.filter(user_id=user.id, is_active=True).last()
        return customer

    class Meta:
        ordering = ["id"]


class StripeCouponQuerySet(models.query.QuerySet):
    def delete(self):
        # StripeCoupon.delete must be executed (along with post_save)
        deleted_counter = 0
        for obj in self:
            obj.delete()
            deleted_counter = deleted_counter + 1

        return deleted_counter, {self.model._meta.label: deleted_counter}


class StripeCouponManager(models.Manager):
    def get_queryset(self):
        return StripeCouponQuerySet(self.model, using=self._db)


class StripeCoupon(StripeBasicModel):
    # fields that are fetched from Stripe API
    STRIPE_FIELDS = {
        "amount_off", "currency", "duration", "duration_in_months", "livemode", "max_redemptions",
        "percent_off", "redeem_by", "times_redeemed", "valid", "metadata", "created"
    }

    DURATION_FOREVER = "forever"
    DURATION_ONCE = "once"
    DURATION_REPEATING = "repeating"
    DURATION_CHOICES = (
        (DURATION_FOREVER, DURATION_FOREVER),
        (DURATION_ONCE, DURATION_ONCE),
        (DURATION_REPEATING, DURATION_REPEATING)
    )

    # choices must be lowercase, because that is how Stripe API returns currency
    CURRENCY_CHOICES = (
        ('usd', 'USD'), ('aed', 'AED'), ('afn', 'AFN'), ('all', 'ALL'), ('amd', 'AMD'), ('ang', 'ANG'), ('aoa', 'AOA'),
        ('ars', 'ARS'), ('aud', 'AUD'), ('awg', 'AWG'), ('azn', 'AZN'), ('bam', 'BAM'), ('bbd', 'BBD'), ('bdt', 'BDT'),
        ('bgn', 'BGN'), ('bif', 'BIF'), ('bmd', 'BMD'), ('bnd', 'BND'), ('bob', 'BOB'), ('brl', 'BRL'), ('bsd', 'BSD'),
        ('bwp', 'BWP'), ('bzd', 'BZD'), ('cad', 'CAD'), ('cdf', 'CDF'), ('chf', 'CHF'), ('clp', 'CLP'), ('cny', 'CNY'),
        ('cop', 'COP'), ('crc', 'CRC'), ('cve', 'CVE'), ('czk', 'CZK'), ('djf', 'DJF'), ('dkk', 'DKK'), ('dop', 'DOP'),
        ('dzd', 'DZD'), ('egp', 'EGP'), ('etb', 'ETB'), ('eur', 'EUR'), ('fjd', 'FJD'), ('fkp', 'FKP'), ('gbp', 'GBP'),
        ('gel', 'GEL'), ('gip', 'GIP'), ('gmd', 'GMD'), ('gnf', 'GNF'), ('gtq', 'GTQ'), ('gyd', 'GYD'), ('hkd', 'HKD'),
        ('hnl', 'HNL'), ('hrk', 'HRK'), ('htg', 'HTG'), ('huf', 'HUF'), ('idr', 'IDR'), ('ils', 'ILS'), ('inr', 'INR'),
        ('isk', 'ISK'), ('jmd', 'JMD'), ('jpy', 'JPY'), ('kes', 'KES'), ('kgs', 'KGS'), ('khr', 'KHR'), ('kmf', 'KMF'),
        ('krw', 'KRW'), ('kyd', 'KYD'), ('kzt', 'KZT'), ('lak', 'LAK'), ('lbp', 'LBP'), ('lkr', 'LKR'), ('lrd', 'LRD'),
        ('lsl', 'LSL'), ('mad', 'MAD'), ('mdl', 'MDL'), ('mga', 'MGA'), ('mkd', 'MKD'), ('mmk', 'MMK'), ('mnt', 'MNT'),
        ('mop', 'MOP'), ('mro', 'MRO'), ('mur', 'MUR'), ('mvr', 'MVR'), ('mwk', 'MWK'), ('mxn', 'MXN'), ('myr', 'MYR'),
        ('mzn', 'MZN'), ('nad', 'NAD'), ('ngn', 'NGN'), ('nio', 'NIO'), ('nok', 'NOK'), ('npr', 'NPR'), ('nzd', 'NZD'),
        ('pab', 'PAB'), ('pen', 'PEN'), ('pgk', 'PGK'), ('php', 'PHP'), ('pkr', 'PKR'), ('pln', 'PLN'), ('pyg', 'PYG'),
        ('qar', 'QAR'), ('ron', 'RON'), ('rsd', 'RSD'), ('rub', 'RUB'), ('rwf', 'RWF'), ('sar', 'SAR'), ('sbd', 'SBD'),
        ('scr', 'SCR'), ('sek', 'SEK'), ('sgd', 'SGD'), ('shp', 'SHP'), ('sll', 'SLL'), ('sos', 'SOS'), ('srd', 'SRD'),
        ('std', 'STD'), ('svc', 'SVC'), ('szl', 'SZL'), ('thb', 'THB'), ('tjs', 'TJS'), ('top', 'TOP'), ('try', 'TRY'),
        ('ttd', 'TTD'), ('twd', 'TWD'), ('tzs', 'TZS'), ('uah', 'UAH'), ('ugx', 'UGX'), ('uyu', 'UYU'), ('uzs', 'UZS'),
        ('vnd', 'VND'), ('vuv', 'VUV'), ('wst', 'WST'), ('xaf', 'XAF'), ('xcd', 'XCD'), ('xof', 'XOF'), ('xpf', 'XPF'),
        ('yer', 'YER'), ('zar', 'ZAR'), ('zmw', 'ZMW')
    )

    coupon_id = models.CharField(max_length=255, help_text=_("Identifier for the coupon"))
    amount_off = models.DecimalField(
        blank=True, null=True, decimal_places=2, max_digits=10,
        help_text=_("Amount (in the currency specified) that will be taken off the subtotal of any invoices for this"
                    "customer."))
    currency = models.CharField(
        max_length=3, choices=CURRENCY_CHOICES, blank=True, null=True,
        help_text=_("If amount_off has been set, the three-letter ISO code for the currency of the amount to take "
                    "off."))
    duration = models.CharField(
        max_length=255, choices=DURATION_CHOICES,
        help_text=_("Describes how long a customer who applies this coupon will get the discount."))
    duration_in_months = models.PositiveIntegerField(
        blank=True, null=True, help_text=_("If duration is repeating, the number of months the coupon applies. "
                                           "Null if coupon duration is forever or once."))
    livemode = models.BooleanField(
        default=False, help_text=_("Flag indicating whether the object exists in live mode or test mode."))
    max_redemptions = models.PositiveIntegerField(
        blank=True, null=True,
        help_text=_("Maximum number of times this coupon can be redeemed, in total, before it is no longer valid."))
    metadata = JSONField(help_text=_("Set of key/value pairs that you can attach to an object. It can be useful for "
                                     "storing additional information about the object in a structured format."))
    percent_off = models.PositiveIntegerField(
        blank=True, null=True,
        help_text=_("Percent that will be taken off the subtotal of any invoicesfor this customer for the duration of "
                    "the coupon. For example, a coupon with percent_off of 50 will make a $100 invoice $50 instead."))
    redeem_by = models.DateTimeField(
        blank=True, null=True, help_text=_("Date after which the coupon can no longer be redeemed."))
    times_redeemed = models.PositiveIntegerField(
        default=0, help_text=_("Number of times this coupon has been applied to a customer."))
    valid = models.BooleanField(
        default=False,
        help_text=_("Taking account of the above properties, whether this coupon can still be applied to a customer."))
    created = models.DateTimeField()
    is_deleted = models.BooleanField(default=False)
    is_created_at_stripe = models.BooleanField(default=False)

    objects = StripeCouponManager()

    def __init__(self, *args, **kwargs):
        super(StripeCoupon, self).__init__(*args, **kwargs)
        self._previous_is_deleted = self.is_deleted

    def __str__(self):
        return self.coupon_id

    def update_from_stripe_data(self, stripe_coupon, exclude_fields=None, commit=True):
        """
        Update StripeCoupon object with data from stripe.Coupon without calling stripe.Coupon.retrieve.

        To only update the object, set the commit param to False.
        Returns the number of rows altered or None if commit is False.
        """
        fields_to_update = self.STRIPE_FIELDS - set(exclude_fields or [])
        update_data = {key: stripe_coupon[key] for key in fields_to_update}
        if update_data.get("created"):
            update_data["created"] = timestamp_to_timezone_aware_date(update_data["created"])

        if update_data.get("amount_off"):
            update_data["amount_off"] = Decimal(update_data["amount_off"]) / 100

        # also make sure the object is up to date (without the need to call database)
        for key, value in six.iteritems(update_data):
            setattr(self, key, value)

        if commit:
            return StripeCoupon.objects.filter(pk=self.pk).update(**update_data)

    def save(self, force_retrieve=False, *args, **kwargs):
        """
        Use the force_retrieve parameter to create a new StripeCoupon object from an existing coupon created at Stripe

        API or update the local object with data fetched from Stripe.
        """
        stripe.api_key = stripe_settings.API_KEY
        if self._previous_is_deleted != self.is_deleted and self.is_deleted:
            try:
                coupon = stripe.Coupon.retrieve(self.coupon_id)
                coupon.delete()
            except stripe.error.InvalidRequestError:
                # means that the coupon has already been removed from stripe
                pass

            return super(StripeCoupon, self).save(*args, **kwargs)

        if self.pk or force_retrieve:
            try:
                coupon = stripe.Coupon.retrieve(self.coupon_id)
                if not force_retrieve:
                    coupon.metadata = self.metadata
                    coupon.save()

                # update all fields in the local object in case someone tried to change them
                self.update_from_stripe_data(coupon, exclude_fields=["metadata"] if not force_retrieve else [])
                self.stripe_response = coupon
            except stripe.error.InvalidRequestError:
                if force_retrieve:
                    raise

                self.is_deleted = True
        else:
            self.stripe_response = stripe.Coupon.create(
                id=self.coupon_id,
                duration=self.duration,
                amount_off=int(self.amount_off * 100) if self.amount_off else None,
                currency=self.currency,
                duration_in_months=self.duration_in_months,
                max_redemptions=self.max_redemptions,
                metadata=self.metadata,
                percent_off=self.percent_off,
                redeem_by=self.redeem_by
            )
            # stripe will generate coupon_id if none was specified in the request
            if not self.coupon_id:
                self.coupon_id = self.stripe_response["id"]

        self.created = timestamp_to_timezone_aware_date(self.stripe_response["created"])
        # for future
        self.is_created_at_stripe = True
        return super(StripeCoupon, self).save(*args, **kwargs)

    def delete(self, *args, **kwargs):
        self.is_deleted = True
        self.save()
        return 0, {self._meta.label: 0}


class StripeCharge(StripeBasicModel):
    user = models.ForeignKey(USER_MODEL, on_delete=models.CASCADE, related_name='stripe_charges')
    customer = models.ForeignKey(StripeCustomer, on_delete=models.SET_NULL, null=True)
    amount = models.IntegerField(null=True, help_text=_("in cents"))
    is_charged = models.BooleanField(default=False)
    stripe_charge_id = models.CharField(max_length=255, blank=True, db_index=True)
    description = models.CharField(max_length=255, help_text=_("Description sent to Stripe"))
    comment = models.CharField(max_length=255, help_text=_("Comment for internal information"))
    content_type = models.ForeignKey(ContentType, null=True, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField(null=True, db_index=True)
    source = generic.GenericForeignKey('content_type', 'object_id')

    def charge(self):
        if self.is_charged:
            raise StripeMethodNotAllowed("Already charged.")

        stripe.api_key = stripe_settings.API_KEY
        customer = StripeCustomer.get_latest_active_customer_for_user(self.user)
        if customer:
            try:
                stripe_charge = stripe.Charge.create(
                    amount=self.amount,
                    currency="usd",
                    customer=customer.stripe_customer_id,
                    description=self.description
                )
            except stripe.error.StripeError:
                self.is_charged = False
                self.save()
                raise

            self.stripe_charge_id = stripe_charge["id"]
            self.stripe_response = stripe_charge
            self.is_charged = True
            self.save()
            return stripe_charge


class StripeSubscriptionPlan(StripeBasicModel):
    INTERVAL_DAY = "day"
    INTERVAL_WEEK = "week"
    INTERVAL_MONTH = "month"
    INTERVAL_YEAR = "year"

    INTERVAL_CHOICES = (
        (INTERVAL_DAY, INTERVAL_DAY),
        (INTERVAL_WEEK, INTERVAL_WEEK),
        (INTERVAL_MONTH, INTERVAL_MONTH),
        (INTERVAL_YEAR, INTERVAL_YEAR),
    )

    is_created_at_stripe = models.BooleanField(default=False)
    source = JSONField(blank=True, help_text=_("Source of the plan, ie: {\"prescription\": 1}"))
    amount = models.IntegerField(help_text=_("In cents. More: https://stripe.com/docs/api#create_plan-amount"))
    currency = models.CharField(
        max_length=3, help_text=_("3 letter ISO code, default USD, https://stripe.com/docs/api#create_plan-currency"),
        default="USD")
    name = models.CharField(
        max_length=255, help_text=_("Name of the plan, to be displayed on invoices and in the web interface."))
    interval = models.CharField(
        max_length=10, help_text=_("Specifies billing frequency. Either day, week, month or year."),
        choices=INTERVAL_CHOICES)
    interval_count = models.IntegerField(default=1, validators=[MinValueValidator(1)])
    metadata = JSONField(help_text=_("A set of key/value pairs that you can attach to a plan object. It can be useful"
                         " for storing additional information about the plan in a structured format."))
    statement_descriptor = models.CharField(
        max_length=22, help_text=_("An arbitrary string to be displayed on your customer’s credit card statement."),
        blank=True)
    trial_period_days = models.IntegerField(
        default=0, validators=[MinValueValidator(0)],
        help_text=_("Specifies a trial period in (an integer number of) days. If you include a trial period,"
                    " the customer won’t be billed for the first time until the trial period ends. If the customer "
                    "cancels before the trial period is over, she’ll never be billed at all."))

    def create_at_stripe(self):
        if self.is_created_at_stripe:
            raise StripeMethodNotAllowed()

        stripe.api_key = stripe_settings.API_KEY
        try:
            plan = stripe.Plan.create(
                id=self.id,
                amount=self.amount,
                currency=self.currency,
                interval=self.interval,
                interval_count=self.interval_count,
                name=self.name,
                metadata=self.metadata,
                statement_descriptor=self.statement_descriptor,
                trial_period_days=self.trial_period_days
            )
        except stripe.error.StripeError:
            self.is_created_at_stripe = False
            self.save()
            raise

        self.stripe_response = plan
        self.is_created_at_stripe = True
        self.save()
        return plan


class StripeSubscription(StripeBasicModel):
    STATUS_TRIAL = "trialing"
    STATUS_ACTIVE = "active"
    STATUS_PAST_DUE = "past_due"
    STATUS_CANCELED = "canceled"
    STATUS_UNPAID = "unpaid"

    STATUS_CHOICES = (
        (STATUS_TRIAL, STATUS_TRIAL),
        (STATUS_ACTIVE, STATUS_ACTIVE),
        (STATUS_PAST_DUE, STATUS_PAST_DUE),
        (STATUS_CANCELED, STATUS_CANCELED),
        (STATUS_UNPAID, STATUS_UNPAID),
    )
    stripe_subscription_id = models.CharField(max_length=255, blank=True, db_index=True)
    is_created_at_stripe = models.BooleanField(default=False)
    plan = models.ForeignKey(StripeSubscriptionPlan, on_delete=models.CASCADE)
    user = models.ForeignKey(USER_MODEL, on_delete=models.CASCADE, related_name="stripe_subscriptions")
    customer = models.ForeignKey(StripeCustomer, on_delete=models.SET_NULL, null=True)
    status = models.CharField(
        max_length=255, help_text="https://stripe.com/docs/api/python#subscription_object-status, "
        "empty if not sent created at stripe", blank=True, choices=STATUS_CHOICES)
    metadata = JSONField(help_text="https://stripe.com/docs/api/python#create_subscription-metadata")
    tax_percent = models.DecimalField(
        default=0, validators=[MinValueValidator(0), MaxValueValidator(100)], decimal_places=2, max_digits=3,
        help_text="https://stripe.com/docs/api/python#subscription_object-tax_percent")
    # application_fee_percent = models.DecimalField(
    #     default=0, validators=[MinValueValidator(0), MaxValueValidator(100)], decimal_places=2, max_digits=3,
    #     help_text="https://stripe.com/docs/api/python#create_subscription-application_fee_percent")
    coupon = models.ForeignKey(
        StripeCoupon, blank=True, null=True, on_delete=models.SET_NULL,
        help_text="https://stripe.com/docs/api/python#create_subscription-coupon")
    end_date = models.DateField(null=True, blank=True, db_index=True)
    canceled_at = models.DateTimeField(null=True, blank=True, db_index=True)

    def create_at_stripe(self):
        if self.is_created_at_stripe:
            raise StripeMethodNotAllowed()

        stripe.api_key = stripe_settings.API_KEY
        customer = StripeCustomer.get_latest_active_customer_for_user(self.user)
        if customer:
            data = {
                "customer": customer.stripe_customer_id,
                "plan": self.plan.id,
                "metadata": self.metadata,
                "tax_percent": self.tax_percent,
            }
            if self.coupon:
                data["coupon"] = self.coupon.coupon_id

            try:
                subscription = stripe.Subscription.create(**data)
            except stripe.error.StripeError:
                self.is_created_at_stripe = False
                self.save()
                raise

            self.set_stripe_data(subscription)
            return subscription

    def set_stripe_data(self, subscription):
        self.stripe_subscription_id = subscription["id"]
        # for some reason it doesnt work with subscription only
        self.stripe_response = json.loads(str(subscription))
        self.is_created_at_stripe = True
        self.status = subscription["status"]
        self.save()

    def refresh_from_stripe(self):
        stripe.api_key = stripe_settings.API_KEY
        subscription = stripe.Subscription.retrieve(self.stripe_subscription_id)
        self.set_stripe_data(subscription)
        return subscription

    def _stripe_cancel(self):
        subscription = self.refresh_from_stripe()
        if subscription["status"] != "canceled":
            return stripe.Subscription.delete(subscription)

    def cancel(self):
        sub = self._stripe_cancel()
        if sub and sub["status"] == "canceled":
            self.canceled_at = timezone.now()
            self.status = self.STATUS_CANCELED
            self.save()

    @classmethod
    def get_subcriptions_for_cancel(cls):
        today = timezone.localtime(timezone.now()).date()
        return cls.objects.filter(
            end_date__lte=today, status=cls.STATUS_ACTIVE)

    @classmethod
    def end_subscriptions(cls):
        # do not use in cron - one broken subscription will kill all.
        # instead please use end_subscriptions.py script.
        for subscription in cls.get_subcriptions_for_cancel():
            subscription.cancel()
            sleep(0.25)  # 4 requests per second tops


class StripeWebhook(models.Model):
    id = models.CharField(primary_key=True, max_length=255)  # id from stripe. This will prevent subsequent calls.
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    is_parsed = models.BooleanField(default=False)
    raw_data = JSONField()

    def _parse_coupon_notification(self, action):
        coupon_id = self.raw_data["data"]["object"]["id"]
        if action == "created":
            try:
                StripeCoupon(coupon_id=coupon_id).save(force_retrieve=True)
            except stripe.error.InvalidRequestError:
                # do not fail in case the coupon has already been removed from Stripe before we received the webhook
                pass
        elif action == "updated":
            StripeCoupon.objects.filter(coupon_id=coupon_id, is_deleted=False).update(
                metadata=self.raw_data["data"]["object"]["metadata"])
        elif action == "deleted":
            StripeCoupon.objects.filter(coupon_id=coupon_id).update(is_deleted=True)

    def parse(self, save=False):
        if self.is_parsed:
            raise StripeWebhookAlreadyParsed

        event_type = self.raw_data.get("type")
        try:
            event_model, event_action = event_type.rsplit(".", 1)
        except ValueError:
            event_model, event_action = None, None

        webhook_pre_parse.send(
            sender=self.__class__, instance=self, event_type=event_type, event_model=event_model,
            event_action=event_action)

        # parse
        if event_model:
            if event_model == "coupon":
                self._parse_coupon_notification(event_action)

        self.is_parsed = True
        if save:
            self.save()

    def save(self, *args, **kwargs):
        if not self.is_parsed:
            self.parse()

        return super(StripeWebhook, self).save(*args, **kwargs)

    class Meta:
        ordering = ["-created"]