billing: Add command for switching plans from Standard to Plus.

corporate/lib/stripe.py

@@ -376,12 +376,11 @@ def make_end_of_cycle_updates_if_needed(
     assert last_ledger_renewal is not None
     last_renewal = last_ledger_renewal.event_time
 
-    if plan.is_free_trial():
+    if plan.is_free_trial() or plan.status == CustomerPlan.SWITCH_NOW_FROM_STANDARD_TO_PLUS:
         assert plan.next_invoice_date is not None
         next_billing_cycle = plan.next_invoice_date
     else:
         next_billing_cycle = start_of_next_billing_cycle(plan, last_renewal)
-
     if next_billing_cycle <= event_time and last_ledger_entry is not None:
         licenses_at_next_renewal = last_ledger_entry.licenses_at_next_renewal
         assert licenses_at_next_renewal is not None
@@ -457,6 +456,47 @@ def make_end_of_cycle_updates_if_needed(
             )
             return new_plan, new_plan_ledger_entry
 
+        if plan.status == CustomerPlan.SWITCH_NOW_FROM_STANDARD_TO_PLUS:
+            standard_plan = plan
+            standard_plan.end_date = next_billing_cycle
+            standard_plan.status = CustomerPlan.ENDED
+            standard_plan.save(update_fields=["status", "end_date"])
+
+            (_, _, _, plus_plan_price_per_license) = compute_plan_parameters(
+                CustomerPlan.PLUS,
+                standard_plan.automanage_licenses,
+                standard_plan.billing_schedule,
+                standard_plan.customer.default_discount,
+            )
+            plus_plan_billing_cycle_anchor = standard_plan.end_date.replace(microsecond=0)
+
+            plus_plan = CustomerPlan.objects.create(
+                customer=standard_plan.customer,
+                status=CustomerPlan.ACTIVE,
+                automanage_licenses=standard_plan.automanage_licenses,
+                charge_automatically=standard_plan.charge_automatically,
+                price_per_license=plus_plan_price_per_license,
+                discount=standard_plan.customer.default_discount,
+                billing_schedule=standard_plan.billing_schedule,
+                tier=CustomerPlan.PLUS,
+                billing_cycle_anchor=plus_plan_billing_cycle_anchor,
+                invoicing_status=CustomerPlan.INITIAL_INVOICE_TO_BE_SENT,
+                next_invoice_date=plus_plan_billing_cycle_anchor,
+            )
+
+            standard_plan_last_ledger = (
+                LicenseLedger.objects.filter(plan=standard_plan).order_by("id").last()
+            )
+            licenses_for_plus_plan = standard_plan_last_ledger.licenses_at_next_renewal
+            plus_plan_ledger_entry = LicenseLedger.objects.create(
+                plan=plus_plan,
+                is_renewal=True,
+                event_time=plus_plan_billing_cycle_anchor,
+                licenses=licenses_for_plus_plan,
+                licenses_at_next_renewal=licenses_for_plus_plan,
+            )
+            return plus_plan, plus_plan_ledger_entry
+
         if plan.status == CustomerPlan.DOWNGRADE_AT_END_OF_CYCLE:
             process_downgrade(plan)
         return None, None
@@ -743,6 +783,14 @@ def update_license_ledger_if_needed(realm: Realm, event_time: datetime) -> None:
     update_license_ledger_for_automanaged_plan(realm, plan, event_time)
 
 
+def get_plan_renewal_or_end_date(plan: CustomerPlan, event_time: datetime) -> datetime:
+    billing_period_end = start_of_next_billing_cycle(plan, event_time)
+
+    if plan.end_date is not None and plan.end_date < billing_period_end:
+        return plan.end_date
+    return billing_period_end
+
+
 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.")
@@ -777,7 +825,7 @@ def invoice_plan(plan: CustomerPlan, event_time: datetime) -> None:
                 }
             description = f"{plan.name} - renewal"
         elif licenses_base is not None and ledger_entry.licenses != licenses_base:
-            assert plan.price_per_license and ledger_entry is not None
+            assert plan.price_per_license
             last_ledger_entry_renewal = (
                 LicenseLedger.objects.filter(
                     plan=plan, is_renewal=True, event_time__lte=ledger_entry.event_time
@@ -787,16 +835,18 @@ def invoice_plan(plan: CustomerPlan, event_time: datetime) -> None:
             )
             assert last_ledger_entry_renewal is not None
             last_renewal = last_ledger_entry_renewal.event_time
-            period_end = start_of_next_billing_cycle(plan, ledger_entry.event_time)
-            proration_fraction = (period_end - ledger_entry.event_time) / (
-                period_end - last_renewal
+            billing_period_end = start_of_next_billing_cycle(plan, ledger_entry.event_time)
+            plan_renewal_or_end_date = get_plan_renewal_or_end_date(plan, ledger_entry.event_time)
+            proration_fraction = (plan_renewal_or_end_date - ledger_entry.event_time) / (
+                billing_period_end - last_renewal
             )
             price_args = {
                 "unit_amount": int(plan.price_per_license * proration_fraction + 0.5),
                 "quantity": ledger_entry.licenses - licenses_base,
             }
             description = "Additional license ({} - {})".format(
-                ledger_entry.event_time.strftime("%b %-d, %Y"), period_end.strftime("%b %-d, %Y")
+                ledger_entry.event_time.strftime("%b %-d, %Y"),
+                plan_renewal_or_end_date.strftime("%b %-d, %Y"),
             )
 
         if price_args:
@@ -811,7 +861,7 @@ def invoice_plan(plan: CustomerPlan, event_time: datetime) -> None:
                 period={
                     "start": datetime_to_timestamp(ledger_entry.event_time),
                     "end": datetime_to_timestamp(
-                        start_of_next_billing_cycle(plan, ledger_entry.event_time)
+                        get_plan_renewal_or_end_date(plan, ledger_entry.event_time)
                     ),
                 },
                 idempotency_key=get_idempotency_key(ledger_entry),
@@ -1071,6 +1121,52 @@ def downgrade_small_realms_behind_on_payments_as_needed() -> None:
                 void_all_open_invoices(realm)
 
 
+def switch_realm_from_standard_to_plus_plan(realm: Realm) -> None:
+    standard_plan = get_current_plan_by_realm(realm)
+
+    if (
+        not standard_plan
+        or standard_plan.status != CustomerPlan.ACTIVE
+        or standard_plan.tier != CustomerPlan.STANDARD
+    ):
+        raise BillingError("Organization does not have an active Standard plan")
+
+    if not standard_plan.customer.stripe_customer_id:
+        raise BillingError("Organization missing Stripe customer.")
+
+    plan_switch_time = timezone_now()
+
+    standard_plan.status = CustomerPlan.SWITCH_NOW_FROM_STANDARD_TO_PLUS
+    standard_plan.next_invoice_date = plan_switch_time
+    standard_plan.save(update_fields=["status", "next_invoice_date"])
+
+    standard_plan_next_renewal_date = start_of_next_billing_cycle(standard_plan, plan_switch_time)
+
+    standard_plan_last_renewal_ledger = (
+        LicenseLedger.objects.filter(is_renewal=True, plan=standard_plan).order_by("id").last()
+    )
+    standard_plan_last_renewal_amount = (
+        standard_plan_last_renewal_ledger.licenses * standard_plan.price_per_license
+    )
+    standard_plan_last_renewal_date = standard_plan_last_renewal_ledger.event_time
+    unused_proration_fraction = 1 - (plan_switch_time - standard_plan_last_renewal_date) / (
+        standard_plan_next_renewal_date - standard_plan_last_renewal_date
+    )
+    amount_to_credit_back_to_realm = math.ceil(
+        standard_plan_last_renewal_amount * unused_proration_fraction
+    )
+    stripe.Customer.create_balance_transaction(
+        standard_plan.customer.stripe_customer_id,
+        amount=-1 * amount_to_credit_back_to_realm,
+        currency="usd",
+        description="Credit from early termination of Standard plan",
+    )
+    invoice_plan(standard_plan, plan_switch_time)
+    plus_plan = get_current_plan_by_realm(realm)
+    assert plus_plan is not None  # for mypy
+    invoice_plan(plus_plan, plan_switch_time)
+
+
 def update_billing_method_of_current_plan(
     realm: Realm, charge_automatically: bool, *, acting_user: Optional[UserProfile]
 ) -> None:

corporate/migrations/0014_customerplan_end_date.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.6 on 2021-09-17 10:52
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("corporate", "0013_alter_zulipsponsorshiprequest_org_website"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="customerplan",
+            name="end_date",
+            field=models.DateTimeField(null=True),
+        ),
+    ]

corporate/models.py

@@ -85,6 +85,7 @@ class CustomerPlan(models.Model):
     invoiced_through: Optional["LicenseLedger"] = models.ForeignKey(
         "LicenseLedger", null=True, on_delete=CASCADE, related_name="+"
     )
+    end_date: Optional[datetime.datetime] = models.DateTimeField(null=True)
 
     DONE = 1
     STARTED = 2
@@ -103,6 +104,7 @@ class CustomerPlan(models.Model):
     DOWNGRADE_AT_END_OF_CYCLE = 2
     FREE_TRIAL = 3
     SWITCH_TO_ANNUAL_AT_END_OF_CYCLE = 4
+    SWITCH_NOW_FROM_STANDARD_TO_PLUS = 5
     # "Live" plans should have a value < LIVE_STATUS_THRESHOLD.
     # There should be at most one live plan per customer.
     LIVE_STATUS_THRESHOLD = 10

corporate/tests/test_stripe.py

@@ -50,6 +50,7 @@ from corporate.lib.stripe import (
     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,
     get_realms_to_default_discount_dict,
     invoice_plan,
@@ -62,6 +63,7 @@ from corporate.lib.stripe import (
     sign_string,
     stripe_customer_has_credit_card_as_default_source,
     stripe_get_customer,
+    switch_realm_from_standard_to_plus_plan,
     unsign_string,
     update_billing_method_of_current_plan,
     update_license_ledger_for_automanaged_plan,
@@ -297,6 +299,7 @@ MOCKED_STRIPE_FUNCTION_NAMES = [
         "Charge.list",
         "Coupon.create",
         "Customer.create",
+        "Customer.create_balance_transaction",
         "Customer.retrieve",
         "Customer.save",
         "Invoice.create",
@@ -2977,6 +2980,44 @@ class StripeTest(StripeTestCase):
                     email_found = True
             self.assertEqual(row.email_expected_to_be_sent, email_found)
 
+    @mock_stripe()
+    def test_switch_realm_from_standard_to_plus_plan(self, *mock: Mock) -> None:
+        realm = get_realm("zulip")
+
+        # Test upgrading to Plus when realm has no Standard subscription
+        with self.assertRaises(BillingError) as billing_context:
+            switch_realm_from_standard_to_plus_plan(realm)
+        self.assertEqual(
+            "Organization does not have an active Standard plan",
+            billing_context.exception.error_description,
+        )
+
+        plan, ledger = self.subscribe_realm_to_manual_license_management_plan(
+            realm, 9, 9, CustomerPlan.MONTHLY
+        )
+        # Test upgrading to Plus when realm has no stripe_customer_id
+        with self.assertRaises(BillingError) as billing_context:
+            switch_realm_from_standard_to_plus_plan(realm)
+        self.assertEqual(
+            "Organization missing Stripe customer.", billing_context.exception.error_description
+        )
+
+        plan.customer.stripe_customer_id = "cus_12345"
+        plan.customer.save(update_fields=["stripe_customer_id"])
+        plan.price_per_license = get_price_per_license(CustomerPlan.STANDARD, CustomerPlan.MONTHLY)
+        plan.automanage_licenses = True
+        plan.invoiced_through = ledger
+        plan.save(update_fields=["price_per_license", "automanage_licenses", "invoiced_through"])
+
+        switch_realm_from_standard_to_plus_plan(realm)
+
+        plan.refresh_from_db()
+        self.assertEqual(plan.status, CustomerPlan.ENDED)
+        plus_plan = get_current_plan_by_realm(realm)
+        assert plus_plan is not None
+        self.assertEqual(plus_plan.tier, CustomerPlan.PLUS)
+        self.assertEqual(LicenseLedger.objects.filter(plan=plus_plan).count(), 1)
+
     def test_update_billing_method_of_current_plan(self) -> None:
         realm = get_realm("zulip")
         customer = Customer.objects.create(realm=realm, stripe_customer_id="cus_12345")
@@ -3239,6 +3280,28 @@ class BillingHelpersTest(ZulipTestCase):
         with self.assertRaisesRegex(InvalidTier, "Unknown tier: 10"):
             get_price_per_license(CustomerPlan.ENTERPRISE, CustomerPlan.ANNUAL)
 
+    def test_get_plan_renewal_or_end_date(self) -> None:
+        realm = get_realm("zulip")
+        customer = Customer.objects.create(realm=realm, stripe_customer_id="cus_12345")
+        billing_cycle_anchor = timezone_now()
+        plan = CustomerPlan.objects.create(
+            customer=customer,
+            status=CustomerPlan.ACTIVE,
+            billing_cycle_anchor=billing_cycle_anchor,
+            billing_schedule=CustomerPlan.MONTHLY,
+            tier=CustomerPlan.STANDARD,
+        )
+        renewal_date = get_plan_renewal_or_end_date(plan, billing_cycle_anchor)
+        self.assertEqual(renewal_date, add_months(billing_cycle_anchor, 1))
+
+        # When the plan ends 2 days before the start of the next billing cycle,
+        # the function should return the end_date.
+        plan_end_date = add_months(billing_cycle_anchor, 1) - timedelta(days=2)
+        plan.end_date = plan_end_date
+        plan.save(update_fields=["end_date"])
+        renewal_date = get_plan_renewal_or_end_date(plan, billing_cycle_anchor)
+        self.assertEqual(renewal_date, plan_end_date)
+
     def test_update_or_create_stripe_customer_logic(self) -> None:
         user = self.example_user("hamlet")
         # No existing Customer object

stubs/stripe/__init__.pyi

@@ -39,6 +39,10 @@ class Customer:
     def delete_discount(customer: Customer) -> None: ...
     @staticmethod
     def list(limit: Optional[int] = ...) -> List[Customer]: ...
+    @staticmethod
+    def create_balance_transaction(
+        customer_id: str, amount: int, currency: str, description: str
+    ) -> None: ...
 
 class Invoice:
     id: str

zilencer/management/commands/switch_realm_from_standard_to_plus_plan.py

@@ -0,0 +1,23 @@
+from typing import Any
+
+from django.conf import settings
+from django.core.management.base import CommandError, CommandParser
+
+from zerver.lib.management import ZulipBaseCommand
+
+if settings.BILLING_ENABLED:
+    from corporate.lib.stripe import switch_realm_from_standard_to_plus_plan
+
+
+class Command(ZulipBaseCommand):
+    def add_arguments(self, parser: CommandParser) -> None:
+        self.add_realm_args(parser)
+
+    def handle(self, *args: Any, **options: Any) -> None:
+        realm = self.get_realm(options)
+
+        if not realm:
+            raise CommandError("No realm found.")
+
+        if settings.BILLING_ENABLED:
+            switch_realm_from_standard_to_plus_plan(realm)