Reset grace period if usage drops within the last cycle (#4212)

So that `LockSites` job unlocks the site,
encountering no grace period and no upgrade needed.

lib/workers/check_usage.ex

@@ -43,7 +43,6 @@ defmodule Plausible.Workers.CheckUsage do
           on: s.user_id == u.id,
           left_join: ep in Plausible.Billing.EnterprisePlan,
           on: ep.user_id == u.id,
-          where: is_nil(u.grace_period),
           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.
@@ -55,18 +54,87 @@ defmodule Plausible.Workers.CheckUsage do
       )
 
     for subscriber <- active_subscribers do
-      if subscriber.enterprise_plan do
-        check_enterprise_subscriber(subscriber, quota_mod)
-      else
-        check_regular_subscriber(subscriber, quota_mod)
+      case {subscriber.grace_period, subscriber.enterprise_plan} do
+        {nil, nil} ->
+          check_regular_subscriber(subscriber, quota_mod)
+
+        {nil, _} ->
+          check_enterprise_subscriber(subscriber, quota_mod)
+
+        {_, nil} ->
+          maybe_remove_grace_period(subscriber, quota_mod)
+
+        _ ->
+          :skip
       end
     end
 
     :ok
   end
 
+  @spec exceeds_last_two_usage_cycles?(Quota.monthly_pageview_usage(), non_neg_integer()) ::
+          boolean()
+
+  def exceeds_last_two_usage_cycles?(usage, limit) when is_integer(limit) do
+    limit = ceil(limit * (1 + Quota.pageview_allowance_margin()))
+
+    Enum.all?([usage.last_cycle, usage.penultimate_cycle], fn usage ->
+      not Quota.below_limit?(usage.total, limit)
+    end)
+  end
+
+  @spec last_usage_cycle_below_limit?(Quota.monthly_pageview_usage(), non_neg_integer()) ::
+          boolean()
+
+  def last_usage_cycle_below_limit?(usage, limit) when is_integer(limit) do
+    limit = ceil(limit * (1 + Quota.pageview_allowance_margin()))
+
+    Quota.below_limit?(usage.last_cycle.total, limit)
+  end
+
+  defp check_site_usage_for_enterprise(subscriber) do
+    limit = subscriber.enterprise_plan.site_limit
+    usage = Quota.site_usage(subscriber)
+
+    if Quota.below_limit?(usage, limit) do
+      {:below_limit, {usage, limit}}
+    else
+      {:over_limit, {usage, limit}}
+    end
+  end
+
+  def maybe_remove_grace_period(subscriber, quota_mod) do
+    case check_pageview_usage_last_cycle(subscriber, quota_mod) do
+      {:below_limit, _} ->
+        subscriber
+        |> Plausible.Auth.GracePeriod.remove_changeset()
+        |> Repo.update()
+
+      _ ->
+        :skip
+    end
+  end
+
+  defp check_regular_subscriber(subscriber, quota_mod) do
+    case check_pageview_usage_two_cycles(subscriber, quota_mod) do
+      {:over_limit, pageview_usage} ->
+        suggested_plan =
+          Plausible.Billing.Plans.suggest(subscriber, pageview_usage.last_cycle.total)
+
+        PlausibleWeb.Email.over_limit_email(subscriber, pageview_usage, suggested_plan)
+        |> Plausible.Mailer.send()
+
+        subscriber
+        |> Plausible.Auth.GracePeriod.start_changeset()
+        |> Repo.update()
+
+      _ ->
+        nil
+    end
+  end
+
   def check_enterprise_subscriber(subscriber, quota_mod) do
-    pageview_usage = check_pageview_usage(subscriber, quota_mod)
+    pageview_usage = check_pageview_usage_two_cycles(subscriber, quota_mod)
     site_usage = check_site_usage_for_enterprise(subscriber)
 
     case {pageview_usage, site_usage} do
@@ -88,25 +156,7 @@ defmodule Plausible.Workers.CheckUsage do
     end
   end
 
-  defp check_regular_subscriber(subscriber, quota_mod) do
-    case check_pageview_usage(subscriber, quota_mod) do
-      {:over_limit, pageview_usage} ->
-        suggested_plan =
-          Plausible.Billing.Plans.suggest(subscriber, pageview_usage.last_cycle.total)
-
-        PlausibleWeb.Email.over_limit_email(subscriber, pageview_usage, suggested_plan)
-        |> Plausible.Mailer.send()
-
-        subscriber
-        |> Plausible.Auth.GracePeriod.start_changeset()
-        |> Repo.update()
-
-      _ ->
-        nil
-    end
-  end
-
-  defp check_pageview_usage(subscriber, quota_mod) do
+  defp check_pageview_usage_two_cycles(subscriber, quota_mod) do
     usage = quota_mod.monthly_pageview_usage(subscriber)
     limit = Quota.monthly_pageview_limit(subscriber)
 
@@ -117,25 +167,14 @@ defmodule Plausible.Workers.CheckUsage do
     end
   end
 
-  @spec exceeds_last_two_usage_cycles?(Quota.monthly_pageview_usage(), non_neg_integer()) ::
-          boolean()
+  defp check_pageview_usage_last_cycle(subscriber, quota_mod) do
+    usage = quota_mod.monthly_pageview_usage(subscriber)
+    limit = Quota.monthly_pageview_limit(subscriber)
 
-  def exceeds_last_two_usage_cycles?(usage, limit) when is_integer(limit) do
-    limit = ceil(limit * (1 + Quota.pageview_allowance_margin()))
-
-    Enum.all?([usage.last_cycle, usage.penultimate_cycle], fn usage ->
-      not Quota.below_limit?(usage.total, limit)
-    end)
-  end
-
-  defp check_site_usage_for_enterprise(subscriber) do
-    limit = subscriber.enterprise_plan.site_limit
-    usage = Quota.site_usage(subscriber)
-
-    if Quota.below_limit?(usage, limit) do
-      {:below_limit, {usage, limit}}
+    if last_usage_cycle_below_limit?(usage, limit) do
+      {:below_limit, usage}
     else
-      {:over_limit, {usage, limit}}
+      {:over_limit, usage}
     end
   end
 end

test/workers/check_usage_test.exs

@@ -184,7 +184,68 @@ defmodule Plausible.Workers.CheckUsageTest do
     assert html_body =~ "We recommend you upgrade to the 100k/mo plan"
   end
 
+  test "clears grace period when plan is applicable again", %{user: user} do
+    quota_stub =
+      Plausible.Billing.Quota
+      |> stub(:monthly_pageview_usage, fn _user ->
+        %{
+          penultimate_cycle: %{date_range: @date_range, total: 11_000},
+          last_cycle: %{date_range: @date_range, total: 11_000}
+        }
+      end)
+
+    insert(:subscription,
+      user: user,
+      paddle_plan_id: @paddle_id_10k,
+      last_bill_date: Timex.shift(Timex.today(), days: -1)
+    )
+
+    CheckUsage.perform(nil, quota_stub)
+    assert user |> Repo.reload() |> Plausible.Auth.GracePeriod.active?()
+
+    quota_stub =
+      Plausible.Billing.Quota
+      |> stub(:monthly_pageview_usage, fn _user ->
+        %{
+          penultimate_cycle: %{date_range: @date_range, total: 11_000},
+          last_cycle: %{date_range: @date_range, total: 9_000}
+        }
+      end)
+
+    CheckUsage.perform(nil, quota_stub)
+    refute user |> Repo.reload() |> Plausible.Auth.GracePeriod.active?()
+  end
+
   describe "enterprise customers" do
+    test "skips checking enterprise users who already have a grace period", %{user: user} do
+      %{grace_period: existing_grace_period} =
+        user
+        |> Plausible.Auth.GracePeriod.start_manual_lock_changeset()
+        |> Repo.update!()
+
+      quota_stub =
+        Plausible.Billing.Quota
+        |> stub(:monthly_pageview_usage, fn _user ->
+          %{
+            penultimate_cycle: %{date_range: @date_range, total: 1_100_000},
+            last_cycle: %{date_range: @date_range, total: 1_100_000}
+          }
+        end)
+
+      enterprise_plan = insert(:enterprise_plan, user: user, monthly_pageview_limit: 1_000_000)
+
+      insert(:subscription,
+        user: user,
+        paddle_plan_id: enterprise_plan.paddle_plan_id,
+        last_bill_date: Timex.shift(Timex.today(), days: -1)
+      )
+
+      CheckUsage.perform(nil, quota_stub)
+
+      assert_no_emails_delivered()
+      assert Repo.reload(user).grace_period.id == existing_grace_period.id
+    end
+
     test "checks billable pageview usage for enterprise customer, sends usage information to enterprise@plausible.io",
          %{
            user: user