From c35dbfff58c57194aba75299fb0b4de675981bcf Mon Sep 17 00:00:00 2001
From: Josh Larson <jlarson@mbta.com>
Date: Thu, 19 Dec 2024 16:05:25 -0500
Subject: [PATCH] feat(TripPlanner): Show more itineraries (#2278)

---
 lib/dotcom/trip_plan/input_form.ex              |  1 +
 lib/dotcom/trip_plan/itinerary_groups.ex        | 15 +++++++++++++--
 test/dotcom/trip_plan/itinerary_groups_test.exs | 15 +++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/lib/dotcom/trip_plan/input_form.ex b/lib/dotcom/trip_plan/input_form.ex
index b634f2f0ad..8d542444a2 100644
--- a/lib/dotcom/trip_plan/input_form.ex
+++ b/lib/dotcom/trip_plan/input_form.ex
@@ -48,6 +48,7 @@ defmodule Dotcom.TripPlan.InputForm do
       toPlace: PlanParams.to_place_param(to),
       arriveBy: datetime_type == "arrive_by",
       date: PlanParams.to_date_param(datetime),
+      numItineraries: 100,
       time: PlanParams.to_time_param(datetime),
       transportModes: __MODULE__.Modes.selected_mode_keys(modes) |> PlanParams.to_modes_param(),
       wheelchair: wheelchair
diff --git a/lib/dotcom/trip_plan/itinerary_groups.ex b/lib/dotcom/trip_plan/itinerary_groups.ex
index 5d0562fa0f..f59c84b619 100644
--- a/lib/dotcom/trip_plan/itinerary_groups.ex
+++ b/lib/dotcom/trip_plan/itinerary_groups.ex
@@ -12,6 +12,7 @@ defmodule Dotcom.TripPlan.ItineraryGroups do
   alias OpenTripPlannerClient.ItineraryTag
 
   @short_walk_threshold_minutes 5
+  @max_per_group 5
 
   @type summarized_leg :: %{
           routes: [Routes.Route.t()],
@@ -35,8 +36,10 @@ defmodule Dotcom.TripPlan.ItineraryGroups do
   def from_itineraries(itineraries) do
     itineraries
     |> Enum.group_by(&unique_legs_to_hash/1)
+    |> Enum.map(&drop_hash/1)
+    |> Enum.reject(&Enum.empty?/1)
+    |> Enum.map(&limit_itinerary_count/1)
     |> Enum.map(&to_summarized_group/1)
-    |> Enum.reject(&Enum.empty?(&1.itineraries))
     |> Enum.sort_by(fn
       %{itineraries: [%{tag: tag} | _] = _} ->
         Enum.find_index(ItineraryTag.tag_priority_order(), &(&1 == tag))
@@ -61,13 +64,21 @@ defmodule Dotcom.TripPlan.ItineraryGroups do
     {Routes.Route.type_atom(route.type), leg.from.name, leg.to.name}
   end
 
-  defp to_summarized_group({_hash, grouped_itineraries}) do
+  defp drop_hash({_hash, grouped_itineraries}) do
+    grouped_itineraries
+  end
+
+  defp to_summarized_group(grouped_itineraries) do
     %{
       itineraries: ItineraryTag.sort_tagged(grouped_itineraries),
       summary: summary(grouped_itineraries)
     }
   end
 
+  defp limit_itinerary_count(itineraries) do
+    Enum.take(itineraries, @max_per_group)
+  end
+
   defp summary(itineraries) do
     itineraries
     |> Enum.map(&to_map_with_fare/1)
diff --git a/test/dotcom/trip_plan/itinerary_groups_test.exs b/test/dotcom/trip_plan/itinerary_groups_test.exs
index 064ac246b5..d5661419f8 100644
--- a/test/dotcom/trip_plan/itinerary_groups_test.exs
+++ b/test/dotcom/trip_plan/itinerary_groups_test.exs
@@ -34,6 +34,21 @@ defmodule Dotcom.TripPlan.ItineraryGroupsTest do
       assert Kernel.length(grouped_itineraries) == 1
     end
 
+    test "only includes the first five itineraries in a group", %{stops: [a, b, c]} do
+      # SETUP
+      bus_a_b_leg = TripPlanner.build(:bus_leg, from: a, to: b)
+      subway_b_c_leg = TripPlanner.build(:subway_leg, from: b, to: c)
+
+      itineraries =
+        TripPlanner.build_list(10, :itinerary, legs: [bus_a_b_leg, subway_b_c_leg])
+
+      # EXERCISE
+      [group] = ItineraryGroups.from_itineraries(itineraries)
+
+      # VERIFY
+      assert Kernel.length(group.itineraries) == 5
+    end
+
     test "does not group itineraries with different modes", %{stops: [a, b, c]} do
       # SETUP
       bus_a_b_leg = TripPlanner.build(:bus_leg, from: a, to: b)