corporate: Move attach_realm_discount to BillingSession class.

This moves the logic for `attach_realm_discount`, which is used in
the support view, to be in the BillingSession class.

Updates the function name to be `attach_discount_to_customer` so
that the context is generalized vs realm specific.

Updates RealmBillingSession implementation to account for actions
that are initiated by a support admin user.

Also moves the helper function `get_discount_for_realm` that is
only used in support views to `corporate/lib/support.py`.

analytics/views/support.py

@@ -54,10 +54,8 @@ if settings.ZILENCER_ENABLED:
 if settings.BILLING_ENABLED:
     from corporate.lib.stripe import approve_sponsorship as do_approve_sponsorship
     from corporate.lib.stripe import (
-        attach_discount_to_realm,
         downgrade_at_the_end_of_billing_cycle,
         downgrade_now_without_creating_additional_invoices,
-        get_discount_for_realm,
         get_latest_seat_count,
         make_end_of_cycle_updates_if_needed,
         switch_realm_from_standard_to_plus_plan,
@@ -65,6 +63,7 @@ if settings.BILLING_ENABLED:
         update_sponsorship_status,
         void_all_open_invoices,
     )
+    from corporate.lib.support import attach_discount_to_realm, get_discount_for_realm
     from corporate.models import (
         Customer,
         CustomerPlan,

corporate/lib/stripe.py

@@ -340,7 +340,9 @@ class BillingSession(ABC):
         pass
 
     @abstractmethod
-    def update_or_create_customer(self, stripe_customer_id: str) -> Customer:
+    def update_or_create_customer(
+        self, stripe_customer_id: Optional[str] = None, *, defaults: Optional[Dict[str, Any]] = None
+    ) -> Customer:
         pass
 
     @catch_stripe_errors
@@ -399,11 +401,39 @@ class BillingSession(ABC):
             self.replace_payment_method(customer.stripe_customer_id, payment_method, True)
         return customer
 
+    def attach_discount_to_customer(self, discount: Decimal) -> None:
+        customer = self.get_customer()
+        old_discount: Optional[Decimal] = None
+        if customer is not None:
+            old_discount = customer.default_discount
+            customer.default_discount = discount
+            customer.save(update_fields=["default_discount"])
+        else:
+            customer = self.update_or_create_customer(defaults={"default_discount": discount})
+        plan = get_current_plan_by_customer(customer)
+        if plan is not None:
+            plan.price_per_license = get_price_per_license(
+                plan.tier, plan.billing_schedule, discount
+            )
+            plan.discount = discount
+            plan.save(update_fields=["price_per_license", "discount"])
+        self.write_to_audit_log(
+            event_type=AbstractRealmAuditLog.REALM_DISCOUNT_CHANGED,
+            event_time=timezone_now(),
+            extra_data={"old_discount": old_discount, "new_discount": discount},
+        )
+
 
 class RealmBillingSession(BillingSession):
-    def __init__(self, user: UserProfile) -> None:
+    def __init__(self, user: UserProfile, realm: Optional[Realm] = None) -> None:
         self.user = user
+        if realm is not None:
+            assert user.is_staff
+            self.realm = realm
+            self.support_session = True
+        else:
             self.realm = user.realm
+            self.support_session = False
 
     @override
     def get_customer(self) -> Optional[Customer]:
@@ -431,6 +461,8 @@ class RealmBillingSession(BillingSession):
 
     @override
     def get_data_for_stripe_customer(self) -> StripeCustomerData:
+        # Support requests do not set any stripe billing information.
+        assert self.support_session is False
         metadata: Dict[str, Any] = {}
         metadata["realm_id"] = self.realm.id
         metadata["realm_str"] = self.realm.string_id
@@ -442,7 +474,12 @@ class RealmBillingSession(BillingSession):
         return realm_stripe_customer_data
 
     @override
-    def update_or_create_customer(self, stripe_customer_id: str) -> Customer:
+    def update_or_create_customer(
+        self, stripe_customer_id: Optional[str] = None, *, defaults: Optional[Dict[str, Any]] = None
+    ) -> Customer:
+        if stripe_customer_id is not None:
+            # Support requests do not set any stripe billing information.
+            assert self.support_session is False
             customer, created = Customer.objects.update_or_create(
                 realm=self.realm, defaults={"stripe_customer_id": stripe_customer_id}
             )
@@ -450,6 +487,11 @@ class RealmBillingSession(BillingSession):
 
             do_make_user_billing_admin(self.user)
             return customer
+        else:
+            customer, created = Customer.objects.update_or_create(
+                realm=self.realm, defaults=defaults
+            )
+            return customer
 
 
 def stripe_customer_has_credit_card_as_default_payment_method(
@@ -1002,31 +1044,6 @@ def is_realm_on_free_trial(realm: Realm) -> bool:
     return plan is not None and plan.is_free_trial()
 
 
-def attach_discount_to_realm(
-    realm: Realm, discount: Decimal, *, acting_user: Optional[UserProfile]
-) -> None:
-    customer = get_customer_by_realm(realm)
-    old_discount: Optional[Decimal] = None
-    if customer is not None:
-        old_discount = customer.default_discount
-        customer.default_discount = discount
-        customer.save(update_fields=["default_discount"])
-    else:
-        Customer.objects.create(realm=realm, default_discount=discount)
-    plan = get_current_plan_by_realm(realm)
-    if plan is not None:
-        plan.price_per_license = get_price_per_license(plan.tier, plan.billing_schedule, discount)
-        plan.discount = discount
-        plan.save(update_fields=["price_per_license", "discount"])
-    RealmAuditLog.objects.create(
-        realm=realm,
-        acting_user=acting_user,
-        event_type=RealmAuditLog.REALM_DISCOUNT_CHANGED,
-        event_time=timezone_now(),
-        extra_data={"old_discount": old_discount, "new_discount": discount},
-    )
-
-
 def update_sponsorship_status(
     realm: Realm, sponsorship_pending: bool, *, acting_user: Optional[UserProfile]
 ) -> None:
@@ -1079,13 +1096,6 @@ def is_sponsored_realm(realm: Realm) -> bool:
     return realm.plan_type == Realm.PLAN_TYPE_STANDARD_FREE
 
 
-def get_discount_for_realm(realm: Realm) -> Optional[Decimal]:
-    customer = get_customer_by_realm(realm)
-    if customer is not None:
-        return customer.default_discount
-    return None
-
-
 def do_change_plan_status(plan: CustomerPlan, status: int) -> None:
     plan.status = status
     plan.save(update_fields=["status"])

corporate/lib/support.py

@@ -1,9 +1,13 @@
+from decimal import Decimal
+from typing import Optional
 from urllib.parse import urlencode, urljoin, urlunsplit
 
 from django.conf import settings
 from django.urls import reverse
 
-from zerver.models import Realm, get_realm
+from corporate.lib.stripe import RealmBillingSession
+from corporate.models import get_customer_by_realm
+from zerver.models import Realm, UserProfile, get_realm
 
 
 def get_support_url(realm: Realm) -> str:
@@ -13,3 +17,15 @@ def get_support_url(realm: Realm) -> str:
         urlunsplit(("", "", reverse("support"), urlencode({"q": realm.string_id}), "")),
     )
     return support_url
+
+
+def get_discount_for_realm(realm: Realm) -> Optional[Decimal]:
+    customer = get_customer_by_realm(realm)
+    if customer is not None:
+        return customer.default_discount
+    return None
+
+
+def attach_discount_to_realm(realm: Realm, discount: Decimal, *, acting_user: UserProfile) -> None:
+    billing_session = RealmBillingSession(acting_user, realm)
+    billing_session.attach_discount_to_customer(discount)

corporate/tests/test_stripe.py

@@ -48,14 +48,12 @@ from corporate.lib.stripe import (
     StripeCardError,
     add_months,
     approve_sponsorship,
-    attach_discount_to_realm,
     catch_stripe_errors,
     compute_plan_parameters,
     customer_has_credit_card_as_default_payment_method,
     do_change_remote_server_plan_type,
     do_deactivate_remote_server,
     downgrade_small_realms_behind_on_payments_as_needed,
-    get_discount_for_realm,
     get_latest_seat_count,
     get_plan_renewal_or_end_date,
     get_price_per_license,
@@ -79,6 +77,7 @@ from corporate.lib.stripe import (
     update_sponsorship_status,
     void_all_open_invoices,
 )
+from corporate.lib.support import attach_discount_to_realm, get_discount_for_realm
 from corporate.models import (
     Customer,
     CustomerPlan,
@@ -2470,75 +2469,6 @@ class StripeTest(StripeTestCase):
         # card on file, and should show it
         # TODO
 
-    @mock_stripe()
-    def test_attach_discount_to_realm(self, *mocks: Mock) -> None:
-        # Attach discount before Stripe customer exists
-        user = self.example_user("hamlet")
-        attach_discount_to_realm(user.realm, Decimal(85), acting_user=user)
-        realm_audit_log = RealmAuditLog.objects.filter(
-            event_type=RealmAuditLog.REALM_DISCOUNT_CHANGED
-        ).last()
-        assert realm_audit_log is not None
-        expected_extra_data = {"old_discount": None, "new_discount": str(Decimal("85"))}
-        self.assertEqual(realm_audit_log.extra_data, expected_extra_data)
-        self.login_user(user)
-        # Check that the discount appears in page_params
-        self.assert_in_success_response(["85"], self.client_get("/upgrade/"))
-        # Check that the customer was charged the discounted amount
-        self.upgrade()
-        customer = Customer.objects.first()
-        assert customer is not None
-        [charge] = stripe.Charge.list(customer=customer.stripe_customer_id)
-        self.assertEqual(1200 * self.seat_count, charge.amount)
-        stripe_customer_id = customer.stripe_customer_id
-        assert stripe_customer_id is not None
-        [invoice] = stripe.Invoice.list(customer=stripe_customer_id)
-        self.assertEqual(
-            [1200 * self.seat_count, -1200 * self.seat_count],
-            [item.amount for item in invoice.lines],
-        )
-        # Check CustomerPlan reflects the discount
-        plan = CustomerPlan.objects.get(price_per_license=1200, discount=Decimal(85))
-
-        # Attach discount to existing Stripe customer
-        plan.status = CustomerPlan.ENDED
-        plan.save(update_fields=["status"])
-        attach_discount_to_realm(user.realm, Decimal(25), acting_user=user)
-        with patch("corporate.lib.stripe.timezone_now", return_value=self.now):
-            self.upgrade(license_management="automatic", billing_modality="charge_automatically")
-        [charge, _] = stripe.Charge.list(customer=customer.stripe_customer_id)
-        self.assertEqual(6000 * self.seat_count, charge.amount)
-        stripe_customer_id = customer.stripe_customer_id
-        assert stripe_customer_id is not None
-        [invoice, _] = stripe.Invoice.list(customer=stripe_customer_id)
-        self.assertEqual(
-            [6000 * self.seat_count, -6000 * self.seat_count],
-            [item.amount for item in invoice.lines],
-        )
-        plan = CustomerPlan.objects.get(price_per_license=6000, discount=Decimal(25))
-
-        attach_discount_to_realm(user.realm, Decimal(50), acting_user=user)
-        plan.refresh_from_db()
-        self.assertEqual(plan.price_per_license, 4000)
-        self.assertEqual(plan.discount, 50)
-        customer.refresh_from_db()
-        self.assertEqual(customer.default_discount, 50)
-        invoice_plans_as_needed(self.next_year + timedelta(days=10))
-        stripe_customer_id = customer.stripe_customer_id
-        assert stripe_customer_id is not None
-        [invoice, _, _] = stripe.Invoice.list(customer=stripe_customer_id)
-        self.assertEqual([4000 * self.seat_count], [item.amount for item in invoice.lines])
-        realm_audit_log = RealmAuditLog.objects.filter(
-            event_type=RealmAuditLog.REALM_DISCOUNT_CHANGED
-        ).last()
-        assert realm_audit_log is not None
-        expected_extra_data = {
-            "old_discount": str(Decimal("25.0000")),
-            "new_discount": str(Decimal("50")),
-        }
-        self.assertEqual(realm_audit_log.extra_data, expected_extra_data)
-        self.assertEqual(realm_audit_log.acting_user, user)
-
     def test_approve_sponsorship(self) -> None:
         user = self.example_user("hamlet")
         approve_sponsorship(user.realm, acting_user=user)
@@ -2572,13 +2502,6 @@ class StripeTest(StripeTestCase):
         self.assertEqual(realm_audit_log.extra_data, expected_extra_data)
         self.assertEqual(realm_audit_log.acting_user, iago)
 
-    def test_get_discount_for_realm(self) -> None:
-        user = self.example_user("hamlet")
-        self.assertEqual(get_discount_for_realm(user.realm), None)
-
-        attach_discount_to_realm(user.realm, Decimal(85), acting_user=None)
-        self.assertEqual(get_discount_for_realm(user.realm), 85)
-
     @mock_stripe()
     def test_replace_payment_method(self, *mocks: Mock) -> None:
         user = self.example_user("hamlet")
@@ -3750,7 +3673,7 @@ class StripeTest(StripeTestCase):
             users_to_create=1, create_stripe_customer=False, create_plan=False
         )
         # To create local Customer object but no Stripe customer.
-        attach_discount_to_realm(realm, Decimal(20), acting_user=None)
+        attach_discount_to_realm(realm, Decimal(20), acting_user=self.example_user("iago"))
         rows.append(Row(realm, Realm.PLAN_TYPE_SELF_HOSTED, None, None, False, False))
 
         realm, _, _, _ = create_realm(
@@ -5040,3 +4963,83 @@ class TestTestClasses(ZulipTestCase):
 
         realm.refresh_from_db()
         self.assertEqual(realm.plan_type, Realm.PLAN_TYPE_STANDARD)
+
+
+class TestSupportBillingHelpers(StripeTestCase):
+    def test_get_discount_for_realm(self) -> None:
+        iago = self.example_user("iago")
+        user = self.example_user("hamlet")
+        self.assertEqual(get_discount_for_realm(user.realm), None)
+
+        attach_discount_to_realm(user.realm, Decimal(85), acting_user=iago)
+        self.assertEqual(get_discount_for_realm(user.realm), 85)
+
+    @mock_stripe()
+    def test_attach_discount_to_realm(self, *mocks: Mock) -> None:
+        # Attach discount before Stripe customer exists
+        support_admin = self.example_user("iago")
+        user = self.example_user("hamlet")
+        attach_discount_to_realm(user.realm, Decimal(85), acting_user=support_admin)
+        realm_audit_log = RealmAuditLog.objects.filter(
+            event_type=RealmAuditLog.REALM_DISCOUNT_CHANGED
+        ).last()
+        assert realm_audit_log is not None
+        expected_extra_data = {"old_discount": None, "new_discount": str(Decimal("85"))}
+        self.assertEqual(realm_audit_log.extra_data, expected_extra_data)
+        self.login_user(user)
+        # Check that the discount appears in page_params
+        self.assert_in_success_response(["85"], self.client_get("/upgrade/"))
+        # Check that the customer was charged the discounted amount
+        self.upgrade()
+        customer = Customer.objects.first()
+        assert customer is not None
+        [charge] = stripe.Charge.list(customer=customer.stripe_customer_id)
+        self.assertEqual(1200 * self.seat_count, charge.amount)
+        stripe_customer_id = customer.stripe_customer_id
+        assert stripe_customer_id is not None
+        [invoice] = stripe.Invoice.list(customer=stripe_customer_id)
+        self.assertEqual(
+            [1200 * self.seat_count, -1200 * self.seat_count],
+            [item.amount for item in invoice.lines],
+        )
+        # Check CustomerPlan reflects the discount
+        plan = CustomerPlan.objects.get(price_per_license=1200, discount=Decimal(85))
+
+        # Attach discount to existing Stripe customer
+        plan.status = CustomerPlan.ENDED
+        plan.save(update_fields=["status"])
+        attach_discount_to_realm(user.realm, Decimal(25), acting_user=support_admin)
+        with patch("corporate.lib.stripe.timezone_now", return_value=self.now):
+            self.upgrade(license_management="automatic", billing_modality="charge_automatically")
+        [charge, _] = stripe.Charge.list(customer=customer.stripe_customer_id)
+        self.assertEqual(6000 * self.seat_count, charge.amount)
+        stripe_customer_id = customer.stripe_customer_id
+        assert stripe_customer_id is not None
+        [invoice, _] = stripe.Invoice.list(customer=stripe_customer_id)
+        self.assertEqual(
+            [6000 * self.seat_count, -6000 * self.seat_count],
+            [item.amount for item in invoice.lines],
+        )
+        plan = CustomerPlan.objects.get(price_per_license=6000, discount=Decimal(25))
+
+        attach_discount_to_realm(user.realm, Decimal(50), acting_user=support_admin)
+        plan.refresh_from_db()
+        self.assertEqual(plan.price_per_license, 4000)
+        self.assertEqual(plan.discount, 50)
+        customer.refresh_from_db()
+        self.assertEqual(customer.default_discount, 50)
+        invoice_plans_as_needed(self.next_year + timedelta(days=10))
+        stripe_customer_id = customer.stripe_customer_id
+        assert stripe_customer_id is not None
+        [invoice, _, _] = stripe.Invoice.list(customer=stripe_customer_id)
+        self.assertEqual([4000 * self.seat_count], [item.amount for item in invoice.lines])
+        realm_audit_log = RealmAuditLog.objects.filter(
+            event_type=RealmAuditLog.REALM_DISCOUNT_CHANGED
+        ).last()
+        assert realm_audit_log is not None
+        expected_extra_data = {
+            "old_discount": str(Decimal("25.0000")),
+            "new_discount": str(Decimal("50")),
+        }
+        self.assertEqual(realm_audit_log.extra_data, expected_extra_data)
+        self.assertEqual(realm_audit_log.acting_user, support_admin)