website/conservancy/supporters/views.py

from datetime import datetime
import logging

from django.conf import settings
from django.http import HttpResponse
from django.shortcuts import render, redirect
from django.utils import timezone
import stripe

from .. import ParameterValidator
from . import forms, mail
from .models import Supporter, SustainerOrder

logger = logging.getLogger(__name__)


def sustainers(request):
    with ParameterValidator(request.GET, 'upgrade_id') as validator:
        try:
            amount_param = float(request.GET['upgrade'])
        except (KeyError, ValueError):
            validator.fail()
        else:
            validator.validate('{:.2f}'.format(amount_param))
    partial_amount = amount_param if validator.valid else 0
    context = {
        'partial_amount': partial_amount,
        'minimum_amount': 120 - partial_amount,
    }
    return render(request, "supporters/sustainers.html", context)


def sponsors(request):
    """Conservancy Sponsors Page view

    Performs object queries necessary to render the sponsors page.
    """
    supporters = Supporter.objects.all().filter(display_until_date__gte=datetime.now())
    supporters_count = len(supporters)
    anonymous_count = len(supporters.filter(display_name='Anonymous'))
    supporters = supporters.exclude(display_name='Anonymous').order_by('ledger_entity_id')
    c = {
        'supporters': supporters,
        'supporters_count': supporters_count,
        'anonymous_count': anonymous_count,
    }
    return render(request, "supporters/sponsors.html", c)


def create_checkout_session(
    reference_id, email: str, amount: int, recurring: str, base_url: str
):
    # https://docs.stripe.com/payments/accept-a-payment
    # https://docs.stripe.com/api/checkout/sessions
    YOUR_DOMAIN = base_url
    try:
        checkout_session = stripe.checkout.Session.create(
            client_reference_id=str(reference_id),
            line_items=[
                {
                    'price_data': {
                        'currency': 'usd',
                        'product_data': {'name': 'Contribution'},
                        'unit_amount': amount * 100,  # in cents
                        # https://docs.stripe.com/products-prices/pricing-models#variable-pricing
                        'recurring': {'interval': recurring} if recurring else None,
                    },
                    'quantity': 1,
                },
            ],
            customer_email=email,
            mode='subscription' if recurring else 'payment',
            success_url=YOUR_DOMAIN + '/sustainer/success/?session_id={CHECKOUT_SESSION_ID}',
            cancel_url=YOUR_DOMAIN + '/sustainer/stripe/',
        )
    except Exception as e:
        return str(e)
    return checkout_session.url


def sustainers_paypal(request):
    return render(request, 'supporters/sustainers_paypal.html')


def sustainers_stripe(request):
    if request.method == 'POST':
        form = forms.SustainerForm(request.POST)
        if form.is_valid():
            order = form.save()
            base_url = f'{request.scheme}://{request.get_host()}'
            # There are a few options for integrating with Stripe. A common one, and
            # possibly the least intrusive is to use the proprietary
            # https://js.stripe.com/v3/ to embed Stripe form fields into your own
            # form. Another embeds a hosted form in your page. The approach we've used
            # is to redirect to a hosted checkout page. This is far from perfect, but it
            # avoids adding proprietary JS on sfconservancy.org.
            stripe_checkout_url = create_checkout_session(
                order.id, order.email, order.amount, order.recurring, base_url
            )
            return redirect(stripe_checkout_url)
    else:
        form = forms.SustainerForm()
    return render(request, 'supporters/sustainers_stripe.html', {'form': form})


stripe.api_key = settings.STRIPE_API_KEY
if stripe.api_key == '':
    logger.warning('Missing STRIPE_API_KEY')


def fulfill_checkout(session_id):
    print("Fulfilling Checkout Session", session_id)

    # TODO: Make this function safe to run multiple times,
    # even concurrently, with the same session ID

    # TODO: Make sure fulfillment hasn't already been
    # peformed for this Checkout Session

    # Retrieve the Checkout Session from the API with line_items expanded
    checkout_session = stripe.checkout.Session.retrieve(
        session_id,
        expand=['line_items', 'invoice'],
    )

    # Check the Checkout Session's payment_status property
    # to determine if fulfillment should be peformed
    if checkout_session.payment_status != 'unpaid':
        # TODO: Perform fulfillment of the line items

        # TODO: Record/save fulfillment status for this
        # Checkout Session
        logger.info(f'Session ID {session_id} PAID!')
        try:
            order = SustainerOrder.objects.get(
                id=checkout_session['client_reference_id'], paid_time=None
            )
            order.paid_time = timezone.now()
            if checkout_session['payment_intent']:
                # Payments get a payment intent directly
                order.payment_id = checkout_session['payment_intent']
            else:
                # Subscriptions go get a payment intent generated on the invoice
                order.payment_id = checkout_session['invoice']['payment_intent']
            order.save()
            logger.info(f'Marked sustainer order {order.id} (order.email) as paid')
            email = mail.make_stripe_email(order)
            email.send()
        except SustainerOrder.DoesNotExist:
            logger.info('No action')


def success(request):
    fulfill_checkout(request.GET['session_id'])
    return render(request, 'supporters/stripe_success.html', {})


def webhook(request):
    payload = request.body
    sig_header = request.META['HTTP_STRIPE_SIGNATURE']
    event = None

    # From webhook dashboard
    endpoint_secret = settings.STRIPE_ENDPOINT_SECRET
    if endpoint_secret == '':
        logger.warning('Missing STRIPE_ENDPOINT_SECRET')

    try:
        event = stripe.Webhook.construct_event(payload, sig_header, endpoint_secret)
    except ValueError:
        # Invalid payload
        return HttpResponse(status=400)
    except stripe.error.SignatureVerificationError:
        # Invalid signature
        return HttpResponse(status=400)

    if (
        event['type'] == 'checkout.session.completed'
        or event['type'] == 'checkout.session.async_payment_succeeded'
    ):
        fulfill_checkout(event['data']['object']['id'])

    return HttpResponse(status=200)