server_deactivate: Show error message for server on active plan.

corporate/lib/stripe.py

@@ -424,6 +424,14 @@ class StripeConnectionError(BillingError):
     pass
 
 
+class ServerDeactivateWithExistingPlanError(BillingError):  # nocoverage
+    def __init__(self) -> None:
+        super().__init__(
+            "server deactivation with existing plan",
+            "",
+        )
+
+
 class UpgradeWithExistingPlanError(BillingError):
     def __init__(self) -> None:
         super().__init__(
@@ -3853,10 +3861,9 @@ def do_change_remote_server_plan_type(remote_server: RemoteZulipServer, plan_typ
 
 
 @transaction.atomic
-def do_deactivate_remote_server(remote_server: RemoteZulipServer) -> None:
-    # TODO: This should also ensure that the server doesn't have an active plan,
-    # and deactivate it otherwise. (Like do_deactivate_realm does.)
-
+def do_deactivate_remote_server(
+    remote_server: RemoteZulipServer, billing_session: RemoteServerBillingSession
+) -> None:
     if remote_server.deactivated:
         billing_logger.warning(
             "Cannot deactivate remote server with ID %d, server has already been deactivated.",
@@ -3864,6 +3871,36 @@ def do_deactivate_remote_server(remote_server: RemoteZulipServer) -> None:
         )
         return
 
+    server_plans_to_consider = CustomerPlan.objects.filter(
+        customer__remote_server=remote_server
+    ).exclude(status=CustomerPlan.ENDED)
+    realm_plans_to_consider = CustomerPlan.objects.filter(
+        customer__remote_realm__server=remote_server
+    ).exclude(status=CustomerPlan.ENDED)
+
+    for possible_plan in list(server_plans_to_consider) + list(realm_plans_to_consider):
+        if possible_plan.tier in [
+            CustomerPlan.TIER_SELF_HOSTED_BASE,
+            CustomerPlan.TIER_SELF_HOSTED_LEGACY,
+            CustomerPlan.TIER_SELF_HOSTED_COMMUNITY,
+        ]:  # nocoverage
+            # No action required for free plans.
+            continue
+
+        if possible_plan.status in [
+            CustomerPlan.DOWNGRADE_AT_END_OF_FREE_TRIAL,
+            CustomerPlan.DOWNGRADE_AT_END_OF_CYCLE,
+        ]:  # nocoverage
+            # No action required for plans scheduled to downgrade
+            # automatically.
+            continue
+
+        # This customer has some sort of paid plan; ask the customer
+        # to downgrade their paid plan so that they get the
+        # communication in that flow, and then they can come back and
+        # deactivate their server.
+        raise ServerDeactivateWithExistingPlanError  # nocoverage
+
     remote_server.deactivated = True
     remote_server.save(update_fields=["deactivated"])
     RemoteZulipServerAuditLog.objects.create(

corporate/tests/test_stripe.py

@@ -4604,7 +4604,8 @@ class BillingHelpersTest(ZulipTestCase):
         )
         self.assertFalse(remote_server.deactivated)
 
-        do_deactivate_remote_server(remote_server)
+        billing_session = RemoteServerBillingSession(remote_server)
+        do_deactivate_remote_server(remote_server, billing_session)
 
         remote_server = RemoteZulipServer.objects.get(uuid=server_uuid)
         remote_realm_audit_log = RemoteZulipServerAuditLog.objects.filter(
@@ -4615,7 +4616,7 @@ class BillingHelpersTest(ZulipTestCase):
 
         # Try to deactivate a remote server that is already deactivated
         with self.assertLogs("corporate.stripe", "WARN") as warning_log:
-            do_deactivate_remote_server(remote_server)
+            do_deactivate_remote_server(remote_server, billing_session)
             self.assertEqual(
                 warning_log.output,
                 [

corporate/views/billing_page.py

@@ -14,6 +14,7 @@ from corporate.lib.stripe import (
     RealmBillingSession,
     RemoteRealmBillingSession,
     RemoteServerBillingSession,
+    ServerDeactivateWithExistingPlanError,
     UpdatePlanRequest,
     do_deactivate_remote_server,
 )
@@ -300,11 +301,11 @@ def remote_server_deactivate_page(
         return HttpResponseNotAllowed(["GET", "POST"])
 
     remote_server = billing_session.remote_server
-    if request.method == "GET":
     context = {
         "server_hostname": remote_server.hostname,
         "action_url": reverse(remote_server_deactivate_page, args=[str(remote_server.uuid)]),
     }
+    if request.method == "GET":
         return render(request, "corporate/remote_billing_server_deactivate.html", context=context)
 
     assert request.method == "POST"
@@ -312,7 +313,12 @@ def remote_server_deactivate_page(
         # Should be impossible if the user is using the UI.
         raise JsonableError(_("Parameter 'confirmed' is required"))
 
-    do_deactivate_remote_server(remote_server)
+    try:
+        do_deactivate_remote_server(remote_server, billing_session)
+    except ServerDeactivateWithExistingPlanError:  # nocoverage
+        context["show_existing_plan_error"] = "true"
+        return render(request, "corporate/remote_billing_server_deactivate.html", context=context)
+
     return render(
         request,
         "corporate/remote_billing_server_deactivated_success.html",

templates/corporate/remote_billing_server_deactivate.html

@@ -15,6 +15,13 @@
         </div>
         <div class="white-box">
             <div id="server-deactivate-details">
+                {% if show_existing_plan_error %}
+                <div id="server-deactivate-error" class="alert alert-danger">
+                    Could not deactivate registration. You must first
+                    <a href="https://zulip.com/help/self-hosted-billing#cancel-paid-plan">cancel</a>
+                    all paid plans associated with this server, including scheduled plan upgrades.
+                </div>
+                {% endif %}
                 <form id="server-deactivate-form" method="post" action="{{ action_url }}">
                     {{ csrf_input }}
                     <div id="server-deactivate-form-top-description" class="input-box server-deactivate-form-field no-validation">

web/styles/portico/billing.css

@@ -669,6 +669,7 @@ input[name="licenses"] {
     text-align: left;
 }
 
+#server-deactivate-error,
 #server-login-error,
 #autopay-error {
     font-weight: 400;
@@ -697,6 +698,7 @@ input[name="licenses"] {
     top: 5px;
 }
 
+#server-deactivate-error,
 #server-login-error {
     text-align: left;
     margin: 0 auto;

web/styles/portico/portico_signin.css

@@ -479,6 +479,7 @@ html {
 
     .alert {
         &:not(
+                #server-deactivate-error,
                 #server-login-error,
                 .alert-info,
                 .billing-page-success,

zilencer/views.py

@@ -92,7 +92,8 @@ def deactivate_remote_server(
     request: HttpRequest,
     remote_server: RemoteZulipServer,
 ) -> HttpResponse:
-    do_deactivate_remote_server(remote_server)
+    billing_session = RemoteServerBillingSession(remote_server)
+    do_deactivate_remote_server(remote_server, billing_session)
     return json_success(request)