Check usage for users with active/cancelled/past due subscriptions (p…

…lausible#4607)

* Check usage for users with active/cancelled/past due subscriptions

So that over limit e-mails and grace period is handled
regardless - they're still subscribers.

* Ensure current subscription is fetched, for an ongoing plan

* Add extra test

* Revert "Ensure current subscription is fetched, for an ongoing plan"

This reverts commit 9ddc7bd.

* Fixup test

* Reapply "Ensure current subscription is fetched, for an ongoing plan"

This reverts commit 7ab5379.

* Do a subscription preload and assert ID match

* Use inner lateral join to fetch subscriptions

lib/plausible/billing/billing.ex

@@ -265,7 +265,13 @@ defmodule Plausible.Billing do
     user =
       User
       |> Repo.get!(subscription.user_id)
-      |> Map.put(:subscription, subscription)
+      |> Plausible.Users.with_subscription()
+
+    if subscription.id != user.subscription.id do
+      Sentry.capture_message("Susbscription ID mismatch",
+        extra: %{subscription: inspect(subscription), user_id: user.id}
+      )
+    end
 
     user
     |> Plausible.Users.update_accept_traffic_until()

lib/workers/check_usage.ex

@@ -36,19 +36,34 @@ defmodule Plausible.Workers.CheckUsage do
   def perform(_job, usage_mod \\ Quota.Usage, today \\ Date.utc_today()) do
     yesterday = today |> Date.shift(day: -1)
 
+    last_subscription_query =
+      from(s in Subscription,
+        order_by: [desc: s.inserted_at],
+        where: s.user_id == parent_as(:user).id,
+        where:
+          s.status in [
+            ^Subscription.Status.active(),
+            ^Subscription.Status.past_due(),
+            ^Subscription.Status.deleted()
+          ],
+        where: not is_nil(s.last_bill_date),
+        # Accounts for situations like last_bill_date==2021-01-31 AND today==2021-03-01. Since February never reaches the 31st day, the account is checked on 2021-03-01.
+        where: s.next_bill_date >= ^today,
+        where:
+          least(day_of_month(s.last_bill_date), day_of_month(last_day_of_month(^yesterday))) ==
+            day_of_month(^yesterday),
+        limit: 1
+      )
+
     active_subscribers =
       Repo.all(
         from(u in User,
-          join: s in Plausible.Billing.Subscription,
-          on: s.user_id == u.id,
+          as: :user,
+          inner_lateral_join: s in subquery(last_subscription_query),
+          on: true,
           left_join: ep in Plausible.Billing.EnterprisePlan,
           on: ep.user_id == u.id,
-          where: s.status == ^Subscription.Status.active(),
-          where: not is_nil(s.last_bill_date),
-          # Accounts for situations like last_bill_date==2021-01-31 AND today==2021-03-01. Since February never reaches the 31st day, the account is checked on 2021-03-01.
-          where:
-            least(day_of_month(s.last_bill_date), day_of_month(last_day_of_month(^yesterday))) ==
-              day_of_month(^yesterday),
+          order_by: u.id,
           preload: [subscription: s, enterprise_plan: ep]
         )
       )