support: Get plan data via BillingSession for support views.

corporate/lib/support.py

@@ -1,14 +1,25 @@
+from dataclasses import dataclass
 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 django.utils.timezone import now as timezone_now
 
-from corporate.models import Customer
+from corporate.lib.stripe import BillingSession
+from corporate.models import Customer, CustomerPlan, get_current_plan_by_customer
 from zerver.models import Realm, get_realm
 
 
+@dataclass
+class PlanData:
+    customer: Optional["Customer"] = None
+    current_plan: Optional["CustomerPlan"] = None
+    licenses: Optional[int] = None
+    licenses_used: Optional[int] = None
+
+
 def get_support_url(realm: Realm) -> str:
     support_realm_uri = get_realm(settings.STAFF_SUBDOMAIN).uri
     support_url = urljoin(
@@ -24,3 +35,25 @@ def get_customer_discount_for_support_view(
     if customer is None:
         return None
     return customer.default_discount
+
+
+def get_current_plan_data_for_support_view(billing_session: BillingSession) -> PlanData:
+    customer = billing_session.get_customer()
+    plan = None
+    if customer is not None:
+        plan = get_current_plan_by_customer(customer)
+    plan_data = PlanData(
+        customer=customer,
+        current_plan=plan,
+    )
+    if plan is not None:
+        new_plan, last_ledger_entry = billing_session.make_end_of_cycle_updates_if_needed(
+            plan, timezone_now()
+        )
+        if last_ledger_entry is not None:
+            if new_plan is not None:
+                plan_data.current_plan = new_plan  # nocoverage
+            plan_data.licenses = last_ledger_entry.licenses
+            plan_data.licenses_used = billing_session.current_count_for_billed_licenses()
+
+    return plan_data