billing: Hide license management fields for free trial states.

* For free trial, don't show number of licenses for current billing period.
* For free trial scheduled to downgrade, don't show number of
  licenses for next billing period.

corporate/lib/stripe.py

@@ -1919,6 +1919,10 @@ class BillingSession(ABC):
 
         licenses = update_plan_request.licenses
         if licenses is not None:
+            if plan.is_free_trial():  # nocoverage
+                raise JsonableError(
+                    _("Cannot update licenses in the current billing period for free trial plan.")
+                )
             if plan.automanage_licenses:
                 raise JsonableError(
                     _(
@@ -1952,6 +1956,15 @@ class BillingSession(ABC):
                         "Unable to update licenses manually. Your plan is on automatic license management."
                     )
                 )
+            if plan.status in (
+                CustomerPlan.DOWNGRADE_AT_END_OF_CYCLE,
+                CustomerPlan.DOWNGRADE_AT_END_OF_FREE_TRIAL,
+            ):  # nocoverage
+                raise JsonableError(
+                    _(
+                        "Cannot change the licenses for next billing cycle for a plan that is being downgraded."
+                    )
+                )
             if last_ledger_entry.licenses_at_next_renewal == licenses_at_next_renewal:
                 raise JsonableError(
                     _(

corporate/tests/test_stripe.py

@@ -1331,7 +1331,7 @@ class StripeTest(StripeTestCase):
             for substring in [
                 "Zulip Cloud Standard <i>(free trial)</i>",
                 str(self.seat_count),
-                "Number of licenses for current billing period",
+                "Number of licenses for next billing period",
                 f"{self.seat_count} in use",
                 "Your next invoice is due on",
                 "March 2, 2012",

templates/corporate/billing.html

@@ -104,6 +104,7 @@
                     </div>
                 </div>
                 {% else %}
+                {% if not (free_trial or downgrade_at_end_of_free_trial) %}
                 <div class="input-box billing-page-field no-validation input-box-number">
                     <label for="current-manual-license-count" class="inline-block label-title">
                         Number of licenses for current billing period
@@ -123,7 +124,8 @@
                     </div>
                     <div id="current-license-change-error" class="alert alert-danger billing-page-error"></div>
                 </div>
-                {% if not downgrade_at_end_of_cycle %}
+                {% endif %}
+                {% if not (downgrade_at_end_of_cycle or downgrade_at_end_of_free_trial) %}
                 <div class="input-box billing-page-field no-validation input-box-number">
                     <label for="next-manual-license-count" class="inline-block label-title">
                         Number of licenses for next billing period