feat: use stop to route cache in alerts filter expansion

config/test.exs

@@ -26,7 +26,8 @@ config :screens,
   blue_bikes_station_information_url: [:no_api_requests_allowed_during_testing],
   blue_bikes_station_status_url: [:no_api_requests_allowed_during_testing],
   blue_bikes_api_client: Screens.BlueBikes.FakeClient,
-  alerts_cache_filter_routes_mod: Screens.Routes.Route.Mock,
+  stops_to_routes_enabled: false,
+  stops_to_routes_route_mod: Screens.Routes.Route.Mock,
   dup_headsign_replacements: %{
     "Test 1" => "T1"
   },

lib/screens/alerts/cache/filter.ex

@@ -2,6 +2,7 @@ defmodule Screens.Alerts.Cache.Filter do
   @moduledoc """
   Logic to apply filters to a list of `Screens.Alerts.Alert` structs.
   """
+  alias Screens.Stops.StopsToRoutes
 
   @default_activities ~w[BOARD EXIT RIDE]
 
@@ -86,17 +87,10 @@ defmodule Screens.Alerts.Cache.Filter do
   end
 
   defp build_matcher({:stops, values}, acc) when is_list(values) do
-    route_mod = route_mod()
-
-    routes =
-      values
-      |> Enum.flat_map(fn stop_id ->
-        {:ok, routes} = route_mod.serving_stop(stop_id)
-        routes
-      end)
+    route_ids = StopsToRoutes.stops_to_routes(values)
 
     route_matchers =
-      for %{id: route_id} <- routes,
+      for route_id <- route_ids,
           stop_id <- [nil | values] do
         %{route: route_id, stop: stop_id}
       end
@@ -132,8 +126,4 @@ defmodule Screens.Alerts.Cache.Filter do
   defp matches?(alert, {key, value}) do
     Enum.any?(alert.informed_entities, &(Map.get(&1, key) == value))
   end
-
-  defp route_mod do
-    Application.get_env(:screens, :alerts_cache_filter_routes_mod, Route)
-  end
 end

lib/screens/stops/stops_to_routes.ex

@@ -11,7 +11,7 @@ defmodule Screens.Stops.StopsToRoutes do
 
   @spec stops_to_routes([stop_id :: String.t()]) :: [route_id :: String.t()]
   def stops_to_routes(stop_ids) do
-    from_cache = get_all(stop_ids)
+    from_cache = if enabled?(), do: get_all(stop_ids), else: %{}
     missing_stop_ids = stop_ids -- Map.keys(from_cache)
 
     from_api =
@@ -20,7 +20,7 @@ defmodule Screens.Stops.StopsToRoutes do
       else
         from_api =
           for stop_id <- missing_stop_ids, into: %{} do
-            {:ok, routes} = fetch_routes_for_stops(stop_id)
+            {:ok, routes} = fetch_routes_for_stop(stop_id)
             route_ids = Enum.map(routes, & &1.id)
 
             {stop_id, route_ids}
@@ -37,9 +37,9 @@ defmodule Screens.Stops.StopsToRoutes do
     |> Enum.uniq()
   end
 
-  defp fetch_routes_for_stops(stop_ids) do
-    stop_impl = Application.get_env(:screens, :stops_to_routes_stop_mod, Screens.Stops.Stop)
-    stop_impl.fetch_routes_for_stops(stop_ids)
+  defp fetch_routes_for_stop(stop_id) do
+    route_impl = Application.get_env(:screens, :stops_to_routes_route_mod, Screens.Routes.Route)
+    route_impl.serving_stop(stop_id)
   end
 
   defp ungroup_values(map) do
@@ -54,4 +54,8 @@ defmodule Screens.Stops.StopsToRoutes do
     additional_minutes = :rand.uniform(30)
     @base_ttl + :timer.minutes(additional_minutes)
   end
+
+  defp enabled? do
+    Application.get_env(:screens, :stops_to_routes_enabled, true)
+  end
 end