refactor: move LocationContext logic out of Stop

lib/screens/stops/stop.ex

@@ -3,14 +3,8 @@ defmodule Screens.Stops.Stop do
 
   require Logger
 
-  alias Screens.LocationContext
-  alias Screens.RoutePatterns.RoutePattern
-  alias Screens.Routes.Route
-  alias Screens.RouteType
   alias Screens.Stops
-  alias Screens.Util
   alias Screens.V3Api
-  alias ScreensConfig.V2.{BusEink, BusShelter, Dup, GlEink, PreFare}
 
   defstruct ~w[id name location_type platform_code platform_name]a
 
@@ -24,8 +18,6 @@ defmodule Screens.Stops.Stop do
           platform_name: String.t() | nil
         }
 
-  @type screen_type :: BusEink | BusShelter | GlEink | PreFare | Dup
-
   def fetch_parent_station_name_map(get_json_fn \\ &V3Api.get_json/2) do
     case get_json_fn.("stops", %{
            "filter[location_type]" => 1
@@ -116,89 +108,4 @@ defmodule Screens.Stops.Stop do
         {:error, error}
     end
   end
-
-  @doc """
-  Fetches all the location context for a screen given its app type, stop id, and time
-  """
-  @spec fetch_location_context(
-          screen_type(),
-          id(),
-          DateTime.t()
-        ) :: {:ok, LocationContext.t()} | :error
-  def fetch_location_context(app, stop_id, now) do
-    Screens.Telemetry.span(
-      ~w[screens stops stop fetch_location_context]a,
-      %{app: app, stop_id: stop_id},
-      fn ->
-        with alert_route_types <- get_route_type_filter(app, stop_id),
-             {:ok, routes_at_stop} <-
-               Route.serving_stop_with_active(stop_id, now, alert_route_types),
-             {:ok, tagged_stop_sequences} <-
-               fetch_tagged_stop_sequences_by_app(app, stop_id, routes_at_stop) do
-          stop_name = fetch_stop_name(stop_id)
-          stop_sequences = RoutePattern.untag_stop_sequences(tagged_stop_sequences)
-
-          {:ok,
-           %LocationContext{
-             home_stop: stop_id,
-             home_stop_name: stop_name,
-             tagged_stop_sequences: tagged_stop_sequences,
-             upstream_stops: upstream_stop_id_set(stop_id, stop_sequences),
-             downstream_stops: downstream_stop_id_set(stop_id, stop_sequences),
-             routes: routes_at_stop,
-             alert_route_types: alert_route_types
-           }}
-        else
-          :error ->
-            Logger.error(
-              "[fetch_location_context fetch error] Failed to get location context for an alert: stop_id=#{stop_id}"
-            )
-
-            :error
-        end
-      end
-    )
-  end
-
-  # Returns the route types we care about for the alerts of this screen type / place
-  @spec get_route_type_filter(screen_type(), String.t()) :: list(RouteType.t())
-  def get_route_type_filter(app, _) when app in [BusEink, BusShelter], do: [:bus]
-  def get_route_type_filter(GlEink, _), do: [:light_rail]
-  # Ashmont should not show Mattapan alerts for PreFare or Dup
-  def get_route_type_filter(app, "place-asmnl") when app in [PreFare, Dup], do: [:subway]
-  def get_route_type_filter(PreFare, _), do: [:light_rail, :subway]
-  # WTC is a special bus-only case
-  def get_route_type_filter(Dup, "place-wtcst"), do: [:bus]
-  def get_route_type_filter(Dup, _), do: [:light_rail, :subway]
-
-  @spec upstream_stop_id_set(String.t(), list(list(id()))) :: MapSet.t(id())
-  def upstream_stop_id_set(stop_id, stop_sequences) do
-    stop_sequences
-    |> Enum.flat_map(fn stop_sequence -> Util.slice_before(stop_sequence, stop_id) end)
-    |> MapSet.new()
-  end
-
-  @spec downstream_stop_id_set(String.t(), list(list(id()))) :: MapSet.t(id())
-  def downstream_stop_id_set(stop_id, stop_sequences) do
-    stop_sequences
-    |> Enum.flat_map(fn stop_sequence -> Util.slice_after(stop_sequence, stop_id) end)
-    |> MapSet.new()
-  end
-
-  defp fetch_tagged_stop_sequences_by_app(app, stop_id, _routes_at_stop)
-       when app in [BusEink, BusShelter, GlEink] do
-    RoutePattern.fetch_tagged_stop_sequences_through_stop(stop_id)
-  end
-
-  defp fetch_tagged_stop_sequences_by_app(Dup, stop_id, routes_at_stop) do
-    route_ids = Route.route_ids(routes_at_stop)
-    RoutePattern.fetch_tagged_parent_station_sequences_through_stop(stop_id, route_ids)
-  end
-
-  defp fetch_tagged_stop_sequences_by_app(PreFare, stop_id, routes_at_stop) do
-    route_ids = Route.route_ids(routes_at_stop)
-
-    # We limit results to canonical route patterns only--no stop sequences for nonstandard patterns.
-    RoutePattern.fetch_tagged_parent_station_sequences_through_stop(stop_id, route_ids, true)
-  end
 end

lib/screens/telemetry.ex

@@ -16,7 +16,8 @@ defmodule Screens.Telemetry do
       log_span(~w[screens v3_api get_json]a, metadata: ~w[url cached]a),
       # Stops
       log_span(~w[screens stops stop fetch_stop_name]a, metadata: ~w[stop_id]),
-      log_span(~w[screens stops stop fetch_location_context]a, metadata: ~w[app stop_id]),
+      # Location Context
+      log_span(~w[screens location_context fetch]a, metadata: ~w[app stop_id]),
       # Alerts
       log_span(~w[screens alerts alert fetch]a),
       # Routes

lib/screens/v2/candidate_generator/dup/alerts.ex

@@ -24,7 +24,7 @@ defmodule Screens.V2.CandidateGenerator.Dup.Alerts do
         now \\ DateTime.utc_now(),
         fetch_stop_name_fn \\ &Stop.fetch_stop_name/1,
         fetch_alerts_fn \\ &Alert.fetch/1,
-        fetch_location_context_fn \\ &Stop.fetch_location_context/3
+        fetch_location_context_fn \\ &LocationContext.fetch/3
       ) do
     # In this function:
     # - Fetch relevant alerts for all SUBWAY/LIGHT RAIL routes serving this stop

lib/screens/v2/candidate_generator/widgets/alerts.ex

@@ -4,7 +4,6 @@ defmodule Screens.V2.CandidateGenerator.Widgets.Alerts do
   alias Screens.Alerts.Alert
   alias Screens.LocationContext
   alias Screens.Routes.Route
-  alias Screens.Stops.Stop
   alias Screens.Util
   alias Screens.V2.WidgetInstance.Alert, as: AlertWidget
   alias ScreensConfig.Screen
@@ -21,7 +20,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.Alerts do
         %Screen{app_params: %app{alerts: %Alerts{stop_id: stop_id}}} = config,
         now \\ DateTime.utc_now(),
         fetch_alerts_by_stop_and_route_fn \\ &Alert.fetch_by_stop_and_route/2,
-        fetch_location_context_fn \\ &Stop.fetch_location_context/3
+        fetch_location_context_fn \\ &LocationContext.fetch/3
       )
       when app in @alert_supporting_screen_types do
     with {:ok, location_context} <- fetch_location_context_fn.(app, stop_id, now),

lib/screens/v2/candidate_generator/widgets/elevator_closures.ex

@@ -2,6 +2,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ElevatorClosures do
   @moduledoc false
 
   alias Screens.Alerts.Alert
+  alias Screens.LocationContext
   alias Screens.Routes.Route
   alias Screens.Stops.Stop
   alias Screens.V2.WidgetInstance.ElevatorStatus, as: ElevatorStatusWidget
@@ -15,7 +16,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ElevatorClosures do
           }
         } = config,
         now \\ DateTime.utc_now(),
-        fetch_location_context_fn \\ &Stop.fetch_location_context/3,
+        fetch_location_context_fn \\ &LocationContext.fetch/3,
         fetch_elevator_alerts_with_facilities_fn \\ &Alert.fetch_elevator_alerts_with_facilities/0
       ) do
     with {:ok, location_context} <- fetch_location_context_fn.(PreFare, parent_station_id, now),

lib/screens/v2/candidate_generator/widgets/reconstructed_alert.ex

@@ -2,7 +2,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ReconstructedAlert do
   @moduledoc false
 
   alias Screens.Alerts.Alert
-  alias Screens.LocationContext, as: LC
+  alias Screens.LocationContext
   alias Screens.Routes.Route
   alias Screens.Stops.Stop
   alias Screens.V2.LocalizedAlert
@@ -53,7 +53,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ReconstructedAlert do
         now \\ DateTime.utc_now(),
         fetch_alerts_fn \\ &Alert.fetch/1,
         fetch_stop_name_fn \\ &Stop.fetch_stop_name/1,
-        fetch_location_context_fn \\ &Stop.fetch_location_context/3,
+        fetch_location_context_fn \\ &LocationContext.fetch/3,
         fetch_subway_platforms_for_stop_fn \\ &Stop.fetch_subway_platforms_for_stop/1
       ) do
     %PreFare{
@@ -65,7 +65,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ReconstructedAlert do
          route_ids <- Route.route_ids(location_context.routes),
          {:ok, alerts} <- fetch_alerts_fn.(route_ids: route_ids) do
       relevant_alerts = relevant_alerts(alerts, location_context, now)
-      is_terminal_station = terminal?(stop_id, LC.stop_sequences(location_context))
+      is_terminal_station = terminal?(stop_id, LocationContext.stop_sequences(location_context))
 
       immediate_disruptions = get_immediate_disruptions(relevant_alerts, location_context)
       downstream_disruptions = get_downstream_disruptions(relevant_alerts, location_context)
@@ -95,7 +95,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ReconstructedAlert do
             find_closest_downstream_alerts(
               downstream_disruptions,
               stop_id,
-              LC.stop_sequences(location_context)
+              LocationContext.stop_sequences(location_context)
             )
 
           flex_zone_alerts = downstream_disruptions -- fullscreen_alerts
@@ -300,7 +300,7 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ReconstructedAlert do
   # If the current station's stop_id is the first or last entry in all stop_sequences,
   # it is a terminal station. Delay alerts heading in the direction of the station are not relevant.
   defp relevant_direction?(%{alert: alert, location_context: location_context}) do
-    stop_sequences = LC.stop_sequences(location_context)
+    stop_sequences = LocationContext.stop_sequences(location_context)
     informed_entities = Alert.informed_entities(alert)
 
     direction_id =

lib/screens/v2/location_context.ex

@@ -1,10 +1,15 @@
 defmodule Screens.LocationContext do
   @moduledoc false
 
+  require Logger
+
   alias Screens.RoutePatterns.RoutePattern
   alias Screens.Routes.Route
   alias Screens.RouteType
   alias Screens.Stops.Stop
+  alias Screens.Util
+
+  alias ScreensConfig.V2.{BusEink, BusShelter, Dup, GlEink, PreFare}
 
   @enforce_keys [:home_stop]
   defstruct home_stop: "",
@@ -28,6 +33,74 @@ defmodule Screens.LocationContext do
           alert_route_types: list(RouteType.t())
         }
 
+  @type screen_type :: BusEink | BusShelter | Dup | GlEink | PreFare
+
+  @doc """
+  Fetches all the location context for a screen given its app type, stop id, and time
+  """
+  @spec fetch(screen_type(), Stop.id(), DateTime.t()) :: {:ok, t()} | :error
+  def fetch(app, stop_id, now) do
+    Screens.Telemetry.span(
+      ~w[screens location_context fetch]a,
+      %{app: app, stop_id: stop_id},
+      fn ->
+        with alert_route_types <- route_type_filter(app, stop_id),
+             {:ok, routes_at_stop} <-
+               Route.serving_stop_with_active(stop_id, now, alert_route_types),
+             {:ok, tagged_stop_sequences} <-
+               fetch_tagged_stop_sequences_by_app(app, stop_id, routes_at_stop) do
+          stop_name = Stop.fetch_stop_name(stop_id)
+          stop_sequences = RoutePattern.untag_stop_sequences(tagged_stop_sequences)
+
+          {
+            :ok,
+            %__MODULE__{
+              home_stop: stop_id,
+              home_stop_name: stop_name,
+              tagged_stop_sequences: tagged_stop_sequences,
+              upstream_stops: upstream_stop_id_set(stop_id, stop_sequences),
+              downstream_stops: downstream_stop_id_set(stop_id, stop_sequences),
+              routes: routes_at_stop,
+              alert_route_types: alert_route_types
+            }
+          }
+        else
+          :error ->
+            Logger.error(
+              "[location_context fetch error] Failed to get location context for an alert: stop_id=#{stop_id}"
+            )
+
+            :error
+        end
+      end
+    )
+  end
+
+  # Returns the route types we care about for the alerts of this screen type / place
+  @spec route_type_filter(screen_type(), String.t()) :: list(RouteType.t())
+  def route_type_filter(app, _) when app in [BusEink, BusShelter], do: [:bus]
+  def route_type_filter(GlEink, _), do: [:light_rail]
+  # Ashmont should not show Mattapan alerts for PreFare or Dup
+  def route_type_filter(app, "place-asmnl") when app in [PreFare, Dup], do: [:subway]
+  def route_type_filter(PreFare, _), do: [:light_rail, :subway]
+  # WTC is a special bus-only case
+  def route_type_filter(Dup, "place-wtcst"), do: [:bus]
+  def route_type_filter(Dup, _), do: [:light_rail, :subway]
+
+  @spec upstream_stop_id_set(String.t(), list(list(Stop.id()))) :: MapSet.t(Stop.id())
+  def upstream_stop_id_set(stop_id, stop_sequences) do
+    stop_sequences
+    |> Enum.flat_map(fn stop_sequence -> Util.slice_before(stop_sequence, stop_id) end)
+    |> MapSet.new()
+  end
+
+  @spec downstream_stop_id_set(String.t(), list(list(Stop.id()))) :: MapSet.t(Stop.id())
+  def downstream_stop_id_set(stop_id, stop_sequences) do
+    stop_sequences
+    |> Enum.flat_map(fn stop_sequence -> Util.slice_after(stop_sequence, stop_id) end)
+    |> MapSet.new()
+  end
+
   @doc """
   Returns IDs of routes that serve this location.
   """
@@ -45,4 +118,21 @@ defmodule Screens.LocationContext do
   def stop_sequences(%__MODULE__{} = t) do
     RoutePattern.untag_stop_sequences(t.tagged_stop_sequences)
   end
+
+  defp fetch_tagged_stop_sequences_by_app(app, stop_id, _routes_at_stop)
+       when app in [BusEink, BusShelter, GlEink] do
+    RoutePattern.fetch_tagged_stop_sequences_through_stop(stop_id)
+  end
+
+  defp fetch_tagged_stop_sequences_by_app(Dup, stop_id, routes_at_stop) do
+    route_ids = Route.route_ids(routes_at_stop)
+    RoutePattern.fetch_tagged_parent_station_sequences_through_stop(stop_id, route_ids)
+  end
+
+  defp fetch_tagged_stop_sequences_by_app(PreFare, stop_id, routes_at_stop) do
+    route_ids = Route.route_ids(routes_at_stop)
+
+    # We limit results to canonical route patterns only--no stop sequences for nonstandard patterns.
+    RoutePattern.fetch_tagged_parent_station_sequences_through_stop(stop_id, route_ids, true)
+  end
 end

test/screens/v2/candidate_generator/widgets/alerts_test.exs

@@ -8,7 +8,6 @@ defmodule Screens.V2.CandidateGenerator.Widgets.AlertsTest do
   alias ScreensConfig.V2.{Alerts, BusShelter, Busway}
   alias Screens.LocationContext
   alias Screens.RoutePatterns.RoutePattern
-  alias Screens.Stops.Stop
   alias Screens.V2.WidgetInstance.Alert, as: AlertWidget
 
   defp ie(opts \\ []) do
@@ -70,10 +69,10 @@ defmodule Screens.V2.CandidateGenerator.Widgets.AlertsTest do
       location_context = %LocationContext{
         home_stop: stop_id,
         tagged_stop_sequences: tagged_stop_sequences,
-        upstream_stops: Stop.upstream_stop_id_set(stop_id, stop_sequences),
-        downstream_stops: Stop.downstream_stop_id_set(stop_id, stop_sequences),
+        upstream_stops: LocationContext.upstream_stop_id_set(stop_id, stop_sequences),
+        downstream_stops: LocationContext.downstream_stop_id_set(stop_id, stop_sequences),
         routes: routes_at_stop,
-        alert_route_types: Stop.get_route_type_filter(app, stop_id)
+        alert_route_types: LocationContext.route_type_filter(app, stop_id)
       }
 
       %{

test/screens/v2/candidate_generator/widgets/reconstructed_alert_test.exs

@@ -9,7 +9,6 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ReconstructedAlertTest do
   alias ScreensConfig.V2.{Busway, PreFare}
   alias Screens.LocationContext
   alias Screens.RoutePatterns.RoutePattern
-  alias Screens.Stops.Stop
   alias Screens.V2.WidgetInstance.ReconstructedAlert, as: ReconstructedAlertWidget
 
   defp ie(opts) do
@@ -109,10 +108,10 @@ defmodule Screens.V2.CandidateGenerator.Widgets.ReconstructedAlertTest do
       location_context = %LocationContext{
         home_stop: stop_id,
         tagged_stop_sequences: tagged_stop_sequences,
-        upstream_stops: Stop.upstream_stop_id_set(stop_id, stop_sequences),
-        downstream_stops: Stop.downstream_stop_id_set(stop_id, stop_sequences),
+        upstream_stops: LocationContext.upstream_stop_id_set(stop_id, stop_sequences),
+        downstream_stops: LocationContext.downstream_stop_id_set(stop_id, stop_sequences),
         routes: routes_at_stop,
-        alert_route_types: Stop.get_route_type_filter(app, stop_id)
+        alert_route_types: LocationContext.route_type_filter(app, stop_id)
       }
 
       %{

test/screens/v2/localized_alert_test.exs

@@ -7,7 +7,6 @@ defmodule Screens.V2.LocalizedAlertTest do
   alias Screens.LocationContext
   alias Screens.RoutePatterns.RoutePattern
   alias Screens.RouteType
-  alias Screens.Stops.Stop
   alias Screens.V2.LocalizedAlert, as: LocalizedAlert
   alias Screens.V2.WidgetInstance.Alert, as: AlertWidget
 
@@ -35,7 +34,7 @@ defmodule Screens.V2.LocalizedAlertTest do
       widget
       | location_context: %{
           widget.location_context
-          | alert_route_types: Stop.get_route_type_filter(app_config_module, stop_id),
+          | alert_route_types: LocationContext.route_type_filter(app_config_module, stop_id),
             home_stop: stop_id
         }
     }
@@ -54,9 +53,9 @@ defmodule Screens.V2.LocalizedAlertTest do
           widget.location_context
           | tagged_stop_sequences: tagged_sequences,
             upstream_stops:
-              Stop.upstream_stop_id_set(widget.location_context.home_stop, sequences),
+              LocationContext.upstream_stop_id_set(widget.location_context.home_stop, sequences),
             downstream_stops:
-              Stop.downstream_stop_id_set(widget.location_context.home_stop, sequences)
+              LocationContext.downstream_stop_id_set(widget.location_context.home_stop, sequences)
         }
     }
   end