corporate/models: Modify Customer to accommodate self-hosted customers.

This is a part of our efforts to introduce billing for our on-premise
customers.

corporate/lib/stripe.py

@@ -454,8 +454,11 @@ def make_end_of_cycle_updates_if_needed(
                 licenses_at_next_renewal=licenses_at_next_renewal,
             )
 
+            realm = new_plan.customer.realm
+            assert realm is not None
+
             RealmAuditLog.objects.create(
-                realm=new_plan.customer.realm,
+                realm=realm,
                 event_time=event_time,
                 event_type=RealmAuditLog.CUSTOMER_SWITCHED_FROM_MONTHLY_TO_ANNUAL_PLAN,
                 extra_data=orjson.dumps(
@@ -629,6 +632,7 @@ def process_initial_upgrade(
     realm = user.realm
     customer = update_or_create_stripe_customer(user)
     assert customer.stripe_customer_id is not None  # for mypy
+    assert customer.realm is not None
     ensure_realm_does_not_have_active_plan(customer.realm)
     (
         billing_cycle_anchor,
@@ -722,12 +726,14 @@ def update_license_ledger_for_manual_plan(
     licenses_at_next_renewal: Optional[int] = None,
 ) -> None:
     if licenses is not None:
+        assert plan.customer.realm is not None
         assert get_latest_seat_count(plan.customer.realm) <= licenses
         assert licenses > plan.licenses()
         LicenseLedger.objects.create(
             plan=plan, event_time=event_time, licenses=licenses, licenses_at_next_renewal=licenses
         )
     elif licenses_at_next_renewal is not None:
+        assert plan.customer.realm is not None
         assert get_latest_seat_count(plan.customer.realm) <= licenses_at_next_renewal
         LicenseLedger.objects.create(
             plan=plan,
@@ -779,6 +785,7 @@ def invoice_plan(plan: CustomerPlan, event_time: datetime) -> None:
     if plan.invoicing_status == CustomerPlan.STARTED:
         raise NotImplementedError("Plan with invoicing_status==STARTED needs manual resolution.")
     if not plan.customer.stripe_customer_id:
+        assert plan.customer.realm is not None
         raise BillingError(
             f"Realm {plan.customer.realm.string_id} has a paid plan without a Stripe customer."
         )
@@ -981,6 +988,7 @@ def do_change_plan_status(plan: CustomerPlan, status: int) -> None:
 def process_downgrade(plan: CustomerPlan) -> None:
     from zerver.lib.actions import do_change_plan_type
 
+    assert plan.customer.realm is not None
     do_change_plan_type(plan.customer.realm, Realm.PLAN_TYPE_LIMITED, acting_user=None)
     plan.status = CustomerPlan.ENDED
     plan.save(update_fields=["status"])

corporate/lib/stripe_event_handler.py

@@ -71,6 +71,7 @@ def handle_checkout_session_completed_event(
 
     stripe_setup_intent = stripe.SetupIntent.retrieve(stripe_session.setup_intent)
     stripe_customer = stripe.Customer.retrieve(stripe_setup_intent.customer)
+    assert session.customer.realm is not None
     user = get_user_by_delivery_email(stripe_customer.email, session.customer.realm)
     payment_method = stripe_setup_intent.payment_method
 
@@ -116,6 +117,7 @@ def handle_payment_intent_succeeded_event(
     payment_intent.status = PaymentIntent.SUCCEEDED
     payment_intent.save()
     metadata = stripe_payment_intent.metadata
+    assert payment_intent.customer.realm is not None
     user = get_user_by_delivery_email(metadata["user_email"], payment_intent.customer.realm)
 
     description = ""

corporate/migrations/0016_customer_add_remote_server_field.py

@@ -0,0 +1,32 @@
+# Generated by Django 3.2.9 on 2021-11-27 00:08
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("zilencer", "0018_remoterealmauditlog"),
+        ("zerver", "0370_realm_enable_spectator_access"),
+        ("corporate", "0015_event_paymentintent_session"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="customer",
+            name="remote_server",
+            field=models.OneToOneField(
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                to="zilencer.remotezulipserver",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="customer",
+            name="realm",
+            field=models.OneToOneField(
+                null=True, on_delete=django.db.models.deletion.CASCADE, to="zerver.realm"
+            ),
+        ),
+    ]

corporate/models.py

@@ -8,6 +8,7 @@ from django.db import models
 from django.db.models import CASCADE
 
 from zerver.models import Realm, UserProfile
+from zilencer.models import RemoteZulipServer
 
 
 class Customer(models.Model):
@@ -17,7 +18,10 @@ class Customer(models.Model):
     and the active plan, if any.
     """
 
-    realm: Realm = models.OneToOneField(Realm, on_delete=CASCADE)
+    realm: Optional[Realm] = models.OneToOneField(Realm, on_delete=CASCADE, null=True)
+    remote_server: Optional[RemoteZulipServer] = models.OneToOneField(
+        RemoteZulipServer, on_delete=CASCADE, null=True
+    )
     stripe_customer_id: Optional[str] = models.CharField(max_length=255, null=True, unique=True)
     sponsorship_pending: bool = models.BooleanField(default=False)
     # A percentage, like 85.
@@ -30,6 +34,20 @@ class Customer(models.Model):
     # they purchased.
     exempt_from_from_license_number_check: bool = models.BooleanField(default=False)
 
+    @property
+    def is_self_hosted(self) -> bool:
+        is_self_hosted = self.remote_server is not None
+        if is_self_hosted:
+            assert self.realm is None
+        return is_self_hosted
+
+    @property
+    def is_cloud(self) -> bool:
+        is_cloud = self.realm is not None
+        if is_cloud:
+            assert self.remote_server is None
+        return is_cloud
+
     def __str__(self) -> str:
         return f"<Customer {self.realm} {self.stripe_customer_id}>"