WIP: Handle Stripe webhook and add success/cancel pages

.env.example

@@ -6,3 +6,5 @@ DATABASE_URL=postgres://postgres:postgres@postgres:5432/postgres
 # Use something along the the following if you are not using docker
 # DATABASE_URL=postgres://postgres:postgres@localhost:5432/datacoop_membersystem
 DEBUG=True
+STRIPE_API_KEY=sk_test_51Pi1452K58NJXwrP3ayQi0LmGCjiVPUdVFnPOT4didTslRQpmGLSxiuYsmwoTJSLDny5I4uIPcpL2fwpG7GvlTbH00mewgemdz
+STRIPE_ENDPOINT_SECRET=whsec_

src/accounting/templates/accounting/order/cancel.html

@@ -0,0 +1,18 @@
+{% extends "base.html" %}
+{% load i18n %}
+
+{% block head_title %}
+    {% trans "Payment cancelled" %}
+{% endblock %}
+
+{% block content %}
+
+    <div class="content-view">
+        <h2>{% trans "Payment canceled" %}</h2>
+
+        <p>
+            <a href="{% order:detail order_id=order.id %}">{% trans "Return to order page" %}</a>
+        </p>
+
+    </div>
+{% endblock %}

src/accounting/templates/accounting/order/detail.html

@@ -41,7 +41,7 @@
         <h2>{% trans "Total price" %}: {{ order.total_with_vat }}</h2>
 
         <p>
-          <a href="" class="button">{% trans "Pay now" %}</a>
+          <a href="{% url "order:pay" order_id=order.pk %}" class="button">{% trans "Pay now" %}</a>
         </p>
 
     </div>

src/accounting/templates/accounting/order/success.html

@@ -0,0 +1,20 @@
+{% extends "base.html" %}
+{% load i18n %}
+
+{% block head_title %}
+    {% trans "Payment received" %}
+{% endblock %}
+
+{% block content %}
+
+    <div class="content-view">
+        <h2>{% trans "Payment received" %}</h2>
+
+        <p>
+        {% blocktrans trimmed with order.id as order_id %}
+            We received your payment for Order {{ order_id }}.
+        {% endblocktrans %}
+        </p>
+
+    </div>
+{% endblock %}

src/accounting/views.py

@@ -1,21 +1,24 @@
 """Views for the membership app."""
 
-from __future__ import annotations
-
-from typing import TYPE_CHECKING
-
+import stripe
+from django.conf import settings
+from django.contrib.sites.models import Site
+from django.core.mail import send_mail
+from django.db import transaction
+from django.http import HttpRequest
+from django.http import HttpResponse
+from django.shortcuts import redirect
 from django.shortcuts import render
+from django.urls import reverse
+from django.views.decorators.csrf import csrf_exempt
 from django_view_decorator import namespaced_decorator_factory
 
 from . import models
 
-if TYPE_CHECKING:
-    from django.http import HttpRequest
-    from django.http import HttpResponse
-
-
 order_view = namespaced_decorator_factory(namespace="order", base_path="order")
 
+stripe.api_key = settings.STRIPE_API_KEY
+
 
 @order_view(
     paths="<int:order_id>/",
@@ -36,3 +39,128 @@ def order_detail(request: HttpRequest, order_id: int) -> HttpResponse:
         template_name="accounting/order/detail.html",
         context=context,
     )
+
+
+@order_view(
+    paths="<int:order_id>/pay/",
+    name="pay",
+    login_required=True,
+)
+def order_pay(request: HttpRequest, order_id: int) -> HttpResponse:
+    """Create a Stripe session and redirects to Stripe Checkout."""
+    user = request.user  # People just need to login to pay something, not necessarily be a member
+    order = models.Order.objects.get(pk=order_id, member=user)
+    current_site = Site.objects.get_current(request)
+    base_domain = f"https://{current_site.domain}"
+
+    try:
+        line_items = []
+        for item in order.items.all():
+            line_items.append(  # noqa: PERF401
+                {
+                    "price_data": {
+                        "currency": item.total_with_vat.currency,
+                        "unit_amount": int((item.price + item.vat).amount * 100),
+                        "product_data": {
+                            "name": item.product.name,
+                        },
+                    },
+                    "quantity": item.quantity,
+                }
+            )
+        checkout_session = stripe.checkout.Session.create(
+            line_items=line_items,
+            mode="payment",
+            success_url=base_domain
+            + reverse("order:success", kwargs={"order_id": order.id, "stripe_session_id": "{CHECKOUT_SESSION_ID}"}),
+            cancel_url=base_domain + "/cancel",
+        )
+    except Exception as e:
+        send_mail("Error in checkout", str(e), settings.DEFAULT_FROM_EMAIL, settings.ADMINS)
+        raise
+
+    # TODO: Redirect with status=303
+    return redirect(checkout_session.url)
+
+
+@transaction.atomic
+@order_view(
+    paths="<int:order_id>/pay/success/<str:stripe_session_id>/",
+    name="success",
+    login_required=True,
+)
+def success(request: HttpRequest, order_id: int, stripe_session_id: str) -> HttpResponse:
+    """Create a Stripe session and redirects to Stripe Checkout.
+
+    From Stripe docs: When you have a webhook endpoint set up to listen for checkout.session.completed events and
+    you set a success_url, Checkout waits for your server to respond to the webhook event delivery before redirecting
+    your customer. If you use this approach, make sure your server responds to checkout.session.completed events as
+    quickly as possible.
+    """
+    user = request.user  # People just need to login to pay something, not necessarily be a member
+    order = models.Order.objects.get(pk=order_id, member=user)
+
+    bool(stripe_session_id)
+
+    context = {
+        "order": order,
+    }
+
+    return render(
+        request=request,
+        template_name="accounting/order/success.html",
+        context=context,
+    )
+
+
+@transaction.atomic
+@order_view(
+    paths="<int:order_id>/pay/cancel/",
+    name="cancel",
+    login_required=True,
+)
+def cancel(request: HttpRequest, order_id: int) -> HttpResponse:
+    """Page to display when a payment is canceled."""
+    user = request.user  # People just need to login to pay something, not necessarily be a member
+    order = models.Order.objects.get(pk=order_id, member=user)
+
+    context = {
+        "order": order,
+    }
+
+    return render(
+        request=request,
+        template_name="accounting/order/cancel.html",
+        context=context,
+    )
+
+
+@csrf_exempt
+@order_view(
+    paths="stripe/webhook/",
+    name="webhook",
+    login_required=True,
+)
+def stripe_webhook(request: HttpRequest) -> HttpResponse:
+    """Handle Stripe webhook.
+
+    https://docs.stripe.com/metadata/use-cases
+    """
+    payload = request.body
+    sig_header = request.headers["stripe-signature"]
+    event = None
+
+    try:
+        event = stripe.Webhook.construct_event(payload, sig_header, settings.STRIPE_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":
+        # TODO: Implement the payment
+        pass
+
+    return HttpResponse(status=200)

src/project/settings.py

@@ -28,6 +28,8 @@ CSRF_TRUSTED_ORIGINS = env.list(
 
 ADMINS = [tuple(x.split(":")) for x in env.list("DJANGO_ADMINS", default=[])]
 
+DEFAULT_FROM_EMAIL = "server@data.coop"
+
 DEFAULT_AUTO_FIELD = "django.db.models.AutoField"
 
 # Application definition
@@ -178,6 +180,8 @@ LOGGING = {
     },
 }
 
+STRIPE_API_KEY = env.str("STRIPE_API_KEY")
+STRIPE_ENDPOINT_SECRET = env.str("STRIPE_ENDPOINT_SECRET")
 
 if DEBUG:
     INSTALLED_APPS += ["debug_toolbar", "django_browser_reload"]