stripe: Add cron-based plan invoicing to remote realm billing system.

corporate/lib/stripe.py

@@ -2478,7 +2478,8 @@ class BillingSession(ABC):
             stripe.Invoice.finalize_invoice(stripe_invoice)
 
         plan.next_invoice_date = next_invoice_date(plan)
-        plan.save(update_fields=["next_invoice_date"])
+        plan.invoice_overdue_email_sent = False
+        plan.save(update_fields=["next_invoice_date", "invoice_overdue_email_sent"])
 
     def do_change_plan_to_new_tier(self, new_plan_tier: int) -> str:
         customer = self.get_customer()
@@ -4341,10 +4342,40 @@ def get_plan_renewal_or_end_date(plan: CustomerPlan, event_time: datetime) -> da
 def invoice_plans_as_needed(event_time: Optional[datetime] = None) -> None:
     if event_time is None:  # nocoverage
         event_time = timezone_now()
-    # TODO: Add RemoteRealmBillingSession and RemoteServerBillingSession cases.
+    # TODO: Add RemoteServerBillingSession cases.
     for plan in CustomerPlan.objects.filter(next_invoice_date__lte=event_time):
         if plan.customer.realm is not None:
             RealmBillingSession(realm=plan.customer.realm).invoice_plan(plan, event_time)
+        elif plan.customer.remote_realm is not None:
+            remote_realm = plan.customer.remote_realm
+            remote_server = remote_realm.server
+            billing_session = RemoteRealmBillingSession(remote_realm=remote_realm)
+
+            assert remote_server.last_audit_log_update is not None
+            assert plan.next_invoice_date is not None
+            if plan.next_invoice_date > remote_server.last_audit_log_update:
+                if (
+                    plan.next_invoice_date - remote_server.last_audit_log_update
+                    >= timedelta(days=1)
+                    and not plan.invoice_overdue_email_sent
+                ):
+                    context = {
+                        "support_url": billing_session.support_url(),
+                        "last_audit_log_update": remote_server.last_audit_log_update.strftime(
+                            "%Y-%m-%d"
+                        ),
+                    }
+                    send_email(
+                        "zerver/emails/invoice_overdue",
+                        to_emails=[BILLING_SUPPORT_EMAIL],
+                        from_address=FromAddress.tokenized_no_reply_address(),
+                        context=context,
+                    )
+                    plan.invoice_overdue_email_sent = True
+                    plan.save(update_fields=["invoice_overdue_email_sent"])
+                continue
+
+            billing_session.invoice_plan(plan, event_time)
         # TODO: Assert that we never invoice legacy plans.
 
 

corporate/migrations/0033_customerplan_invoice_overdue_email_sent.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.2.8 on 2024-01-10 07:34
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("corporate", "0032_customer_minimum_licenses"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="customerplan",
+            name="invoice_overdue_email_sent",
+            field=models.BooleanField(default=False),
+        ),
+    ]

corporate/models.py

@@ -249,6 +249,11 @@ class CustomerPlan(models.Model):
     # next_invoice_date.
     next_invoice_date = models.DateTimeField(db_index=True, null=True)
 
+    # Flag to track if an email has been sent to Zulip team for
+    # invoice overdue by >= one day. Helps to send an email only once
+    # and not every time when cron run.
+    invoice_overdue_email_sent = models.BooleanField(default=False)
+
     # On next_invoice_date, we go through ledger entries that were
     # created after invoiced_through and process them by generating
     # invoices for any additional users and/or plan renewal. Once the

corporate/tests/test_stripe.py

@@ -6378,6 +6378,105 @@ class TestRemoteRealmBillingFlow(StripeTestCase, RemoteRealmBillingTestCase):
         for key, value in invoice_item_params.items():
             self.assertEqual(invoice_item2[key], value)
 
+    @responses.activate
+    @mock_stripe()
+    def test_invoice_plans_as_needed(self, *mocks: Mock) -> None:
+        self.login("hamlet")
+        hamlet = self.example_user("hamlet")
+
+        self.add_mock_response()
+        with time_machine.travel(self.now, tick=False):
+            send_server_data_to_push_bouncer(consider_usage_statistics=False)
+
+        self.execute_remote_billing_authentication_flow(hamlet)
+        with time_machine.travel(self.now, tick=False):
+            stripe_customer = self.add_card_and_upgrade(
+                tier=CustomerPlan.TIER_SELF_HOSTED_BASIC, schedule="monthly"
+            )
+
+        customer = Customer.objects.get(stripe_customer_id=stripe_customer.id)
+        plan = CustomerPlan.objects.get(customer=customer)
+        assert plan.customer.remote_realm is not None
+        self.assertEqual(plan.next_invoice_date, self.next_month)
+
+        with time_machine.travel(self.now + timedelta(days=2), tick=False):
+            for count in range(5):
+                do_create_user(
+                    f"email - {count}",
+                    f"password {count}",
+                    hamlet.realm,
+                    "name",
+                    role=UserProfile.ROLE_MEMBER,
+                    acting_user=None,
+                )
+
+        # Data upload was 25 days before the invoice date.
+        last_audit_log_update = self.now + timedelta(days=5)
+        with time_machine.travel(last_audit_log_update, tick=False):
+            send_server_data_to_push_bouncer(consider_usage_statistics=False)
+        invoice_plans_as_needed(self.next_month)
+        plan.refresh_from_db()
+        self.assertEqual(plan.next_invoice_date, self.next_month)
+        self.assertTrue(plan.invoice_overdue_email_sent)
+
+        from django.core.mail import outbox
+
+        messages_count = len(outbox)
+        message = outbox[-1]
+        self.assert_length(message.to, 1)
+        self.assertEqual(message.to[0], "sales@zulip.com")
+        self.assertEqual(message.subject, "Invoice overdue due to stale data")
+        self.assertIn(
+            f"Support URL: {self.billing_session.support_url()}",
+            message.body,
+        )
+        self.assertIn(
+            f"Last data upload: {last_audit_log_update.strftime('%Y-%m-%d')}", message.body
+        )
+
+        # Cron runs again, don't send another email to Zulip team.
+        invoice_plans_as_needed(self.next_month + timedelta(days=1))
+        self.assert_length(outbox, messages_count)
+
+        # Ledger is up-to-date. Plan invoiced.
+        with time_machine.travel(self.next_month, tick=False):
+            send_server_data_to_push_bouncer(consider_usage_statistics=False)
+        invoice_plans_as_needed(self.next_month)
+        plan.refresh_from_db()
+        self.assertEqual(plan.next_invoice_date, add_months(self.next_month, 1))
+        self.assertFalse(plan.invoice_overdue_email_sent)
+
+        assert customer.stripe_customer_id
+        [invoice0, invoice1] = iter(stripe.Invoice.list(customer=customer.stripe_customer_id))
+
+        [invoice_item0, invoice_item1, invoice_item2] = iter(invoice0.lines)
+        invoice_item_params = {
+            "amount": 16 * 3.5 * 100,
+            "description": "Zulip Basic - renewal",
+            "quantity": 16,
+            "period": {
+                "start": datetime_to_timestamp(self.next_month),
+                "end": datetime_to_timestamp(add_months(self.next_month, 1)),
+            },
+        }
+        for key, value in invoice_item_params.items():
+            self.assertEqual(invoice_item1[key], value)
+
+        invoice_item_params = {
+            "description": "Additional license (Jan 4, 2012 - Feb 2, 2012)",
+            "quantity": 5,
+            "period": {
+                "start": datetime_to_timestamp(self.now + timedelta(days=2)),
+                "end": datetime_to_timestamp(self.next_month),
+            },
+        }
+        for key, value in invoice_item_params.items():
+            self.assertEqual(invoice_item2[key], value)
+
+        # Verify Zulip team receives mail for the next cycle.
+        invoice_plans_as_needed(add_months(self.next_month, 1))
+        self.assert_length(outbox, messages_count + 1)
+
 
 @override_settings(PUSH_NOTIFICATION_BOUNCER_URL="https://push.zulip.org.example.com")
 class TestRemoteServerBillingFlow(StripeTestCase, RemoteServerTestCase):

templates/zerver/emails/invoice_overdue.html

@@ -0,0 +1,10 @@
+{% extends "zerver/emails/email_base_default.html" %}
+
+{% block content %}
+<b>Support URL</b>: <a href="{{ support_url }}">{{ support_url }}</a>
+
+<br /><br />
+
+<b>Last data upload</b>: {{ last_audit_log_update }}
+
+{% endblock %}

templates/zerver/emails/invoice_overdue.subject.txt

@@ -0,0 +1 @@
+Invoice overdue due to stale data

templates/zerver/emails/invoice_overdue.txt

@@ -0,0 +1,3 @@
+Support URL: {{ support_url }}
+
+Last data upload: {{ last_audit_log_update }}