use new headway periods (#839)

lib/engine/config/headway.ex

@@ -3,7 +3,7 @@ defmodule Engine.Config.Headway do
   defstruct @enforce_keys
 
   @type headway_group :: String.t()
-  @type time_period :: :peak | :off_peak
+  @type time_period :: :peak | :off_peak | :saturday | :sunday
   @type headway_id :: {headway_group(), time_period()}
 
   @type t :: %__MODULE__{
@@ -33,19 +33,25 @@ defmodule Engine.Config.Headway do
 
   @spec current_time_period(DateTime.t()) :: time_period()
   def current_time_period(dt) do
-    day_of_week = dt |> DateTime.to_date() |> Date.day_of_week()
-
-    weekday? = day_of_week in 1..5
+    # Subtract 3 hours, since the service day ends at 3 AM
+    day_of_week = DateTime.add(dt, -3, :hour) |> Date.day_of_week()
 
     rush_hour? =
       (dt.hour >= 7 and dt.hour < 9) or (dt.hour >= 16 and dt.hour < 18) or
         (dt.hour == 18 and dt.minute <= 30)
 
-    if(weekday? and rush_hour?, do: :peak, else: :off_peak)
+    case {day_of_week, rush_hour?} do
+      {6, _} -> :saturday
+      {7, _} -> :sunday
+      {_, true} -> :peak
+      {_, false} -> :off_peak
+    end
   end
 
   @spec parse_time_period(String.t()) :: {:ok, time_period()} | :error
   defp parse_time_period("peak"), do: {:ok, :peak}
   defp parse_time_period("off_peak"), do: {:ok, :off_peak}
+  defp parse_time_period("saturday"), do: {:ok, :saturday}
+  defp parse_time_period("sunday"), do: {:ok, :sunday}
   defp parse_time_period(_), do: :error
 end

test/engine/config/headway_test.exs

@@ -19,31 +19,17 @@ defmodule Engine.Config.HeadwayTest do
 
   describe "current_time_period/1" do
     test "correctly determines peak and offpeak" do
-      dt1 = DateTime.from_naive!(~N[2020-03-20 06:00:00], "America/New_York")
-      dt2 = DateTime.from_naive!(~N[2020-03-20 07:00:00], "America/New_York")
-      dt3 = DateTime.from_naive!(~N[2020-03-20 07:45:00], "America/New_York")
-      dt4 = DateTime.from_naive!(~N[2020-03-20 09:00:01], "America/New_York")
-      dt5 = DateTime.from_naive!(~N[2020-03-20 12:00:00], "America/New_York")
-      dt6 = DateTime.from_naive!(~N[2020-03-20 15:00:00], "America/New_York")
-      dt7 = DateTime.from_naive!(~N[2020-03-20 16:00:00], "America/New_York")
-      dt8 = DateTime.from_naive!(~N[2020-03-20 18:00:00], "America/New_York")
-      dt9 = DateTime.from_naive!(~N[2020-03-20 18:20:00], "America/New_York")
-      dt10 = DateTime.from_naive!(~N[2020-03-20 18:40:00], "America/New_York")
-      dt11 = DateTime.from_naive!(~N[2020-03-21 06:00:00], "America/New_York")
-      dt12 = DateTime.from_naive!(~N[2020-03-21 08:00:00], "America/New_York")
+      assert DateTime.new!(~D[2020-03-20], ~T[18:00:00], "America/New_York")
+             |> Headway.current_time_period() == :peak
 
-      assert Headway.current_time_period(dt1) == :off_peak
-      assert Headway.current_time_period(dt2) == :peak
-      assert Headway.current_time_period(dt3) == :peak
-      assert Headway.current_time_period(dt4) == :off_peak
-      assert Headway.current_time_period(dt5) == :off_peak
-      assert Headway.current_time_period(dt6) == :off_peak
-      assert Headway.current_time_period(dt7) == :peak
-      assert Headway.current_time_period(dt8) == :peak
-      assert Headway.current_time_period(dt9) == :peak
-      assert Headway.current_time_period(dt10) == :off_peak
-      assert Headway.current_time_period(dt11) == :off_peak
-      assert Headway.current_time_period(dt12) == :off_peak
+      assert DateTime.new!(~D[2020-03-21], ~T[02:00:00], "America/New_York")
+             |> Headway.current_time_period() == :off_peak
+
+      assert DateTime.new!(~D[2020-03-21], ~T[08:00:00], "America/New_York")
+             |> Headway.current_time_period() == :saturday
+
+      assert DateTime.new!(~D[2020-03-22], ~T[12:00:00], "America/New_York")
+             |> Headway.current_time_period() == :sunday
     end
   end
 end