support: Show date for start of next billing cycle for current plan.

Instead of showing the next invoice date for the plan, show the
date for the next billing cycle start (e.g. the next plan renewal
charge date), except for plans currently on a free trial.

For plans on a free trial, the next plan renewal date will be when
the free trial ends, which is stored as the next invoice date on
the plan.

analytics/tests/test_support_views.py

@@ -8,7 +8,12 @@ import time_machine
 from django.utils.timezone import now as timezone_now
 from typing_extensions import override
 
-from corporate.lib.stripe import RealmBillingSession, RemoteRealmBillingSession, add_months
+from corporate.lib.stripe import (
+    RealmBillingSession,
+    RemoteRealmBillingSession,
+    add_months,
+    start_of_next_billing_cycle,
+)
 from corporate.models import (
     Customer,
     CustomerPlan,
@@ -599,7 +604,7 @@ class TestSupportEndpoint(ZulipTestCase):
                     "<b>Licenses</b>: 2/10 (Manual)",
                     "<b>Price per license</b>: $80.00",
                     "<b>Annual recurring revenue</b>: $800.00",
-                    "<b>Next invoice date</b>: 02 January 2017",
+                    "<b>Start of next billing cycle</b>:",
                     '<option value="send_invoice" selected>',
                     '<option value="charge_automatically" >',
                 ],
@@ -934,6 +939,8 @@ class TestSupportEndpoint(ZulipTestCase):
         assert plan is not None
         self.assertEqual(customer.default_discount, Decimal(25))
         self.assertEqual(plan.discount, Decimal(25))
+        start_next_billing_cycle = start_of_next_billing_cycle(plan, timezone_now())
+        biling_cycle_string = start_next_billing_cycle.strftime("%d %B %Y")
 
         result = self.client_get("/activity/support", {"q": "lear"})
         self.assert_in_success_response(
@@ -945,7 +952,7 @@ class TestSupportEndpoint(ZulipTestCase):
                 "<b>Licenses</b>: 2/10 (Manual)",
                 "<b>Price per license</b>: $6.00",
                 "<b>Annual recurring revenue</b>: $720.00",
-                "<b>Next invoice date</b>: 02 February 2016",
+                f"<b>Start of next billing cycle</b>: {biling_cycle_string}",
             ],
             result,
         )

corporate/lib/support.py

@@ -13,6 +13,7 @@ from corporate.lib.stripe import (
     BillingSession,
     RemoteRealmBillingSession,
     RemoteServerBillingSession,
+    start_of_next_billing_cycle,
 )
 from corporate.models import (
     Customer,
@@ -60,6 +61,7 @@ class PlanData:
     next_plan: Optional["CustomerPlan"] = None
     licenses: Optional[int] = None
     licenses_used: Optional[int] = None
+    next_billing_cycle_start: Optional[datetime] = None
     is_legacy_plan: bool = False
     has_fixed_price: bool = False
     warning: Optional[str] = None
@@ -167,7 +169,6 @@ def get_current_plan_data_for_support_view(billing_session: BillingSession) -> P
                 plan_data.warning = (
                     "Recent audit log data missing: No information for used licenses"
                 )
-
         assert plan_data.current_plan is not None  # for mypy
 
         plan_data.next_plan = billing_session.get_next_plan(plan_data.current_plan)
@@ -186,6 +187,17 @@ def get_current_plan_data_for_support_view(billing_session: BillingSession) -> P
             else:
                 plan_data.estimated_next_plan_revenue = 0  # nocoverage
 
+        if plan_data.current_plan.status in (
+            CustomerPlan.FREE_TRIAL,
+            CustomerPlan.DOWNGRADE_AT_END_OF_FREE_TRIAL,
+        ):  # nocoverage
+            assert plan_data.current_plan.next_invoice_date is not None
+            plan_data.next_billing_cycle_start = plan_data.current_plan.next_invoice_date
+        else:
+            plan_data.next_billing_cycle_start = start_of_next_billing_cycle(
+                plan_data.current_plan, timezone_now()
+            )
+
         plan_data.is_legacy_plan = (
             plan_data.current_plan.tier == CustomerPlan.TIER_SELF_HOSTED_LEGACY
         )

templates/analytics/current_plan_details.html

@@ -24,6 +24,6 @@
         <b>Plan has a fixed price.</b>
     {% endif %}
     <b>Annual recurring revenue</b>: ${{ dollar_amount(plan_data.annual_recurring_revenue) }}<br />
-    <b>Next invoice date</b>: {{ plan_data.current_plan.next_invoice_date.strftime('%d %B %Y') }}<br />
+    <b>Start of next billing cycle</b>: {{ plan_data.next_billing_cycle_start.strftime('%d %B %Y') }}<br />
 {% endif %}
 {% endif %}