From 695bbf5cee35f73410fc403f11b8ec57b1621542 Mon Sep 17 00:00:00 2001
From: Graham McInitre <graham.mcintire@island.io>
Date: Thu, 16 Jul 2026 07:37:34 -0500
Subject: [PATCH] perf: add batch hrrr_profiles_for_contacts/1 to collapse N+1
 per-contact queries into one DB round-trip

---
 lib/microwaveprop/weather.ex | 73 ++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/lib/microwaveprop/weather.ex b/lib/microwaveprop/weather.ex
index 492ccc1c..3750bd73 100644
--- a/lib/microwaveprop/weather.ex
+++ b/lib/microwaveprop/weather.ex
@@ -1738,6 +1738,79 @@ defmodule Microwaveprop.Weather do
     |> Enum.reject(&is_nil/1)
   end
 
+  @doc """
+  Batch version of `hrrr_profiles_for_path/1`. Queries all HRRR profiles
+  for a list of contacts in a single DB round-trip, then maps results
+  back per-contact. Returns a list of `{contact, [profile]}` tuples.
+  """
+  @spec hrrr_profiles_for_contacts([map()]) :: [{map(), [HrrrProfile.t()]}]
+  def hrrr_profiles_for_contacts(contacts) do
+    for_result =
+      for c <- contacts, c.pos1 != nil, {lat, lon} <- Radio.contact_path_points(c) do
+        {{lat, lon, c.qso_timestamp}, c}
+      end
+
+    points =
+      Enum.uniq_by(for_result, fn {key, _} -> key end)
+
+    {keys, contact_map} =
+      Enum.reduce(points, {[], %{}}, fn {{lat, lon, ts} = key, c}, {ks, cm} ->
+        {[key | ks], Map.update(cm, c, [key], &[key | &1])}
+      end)
+
+    index = find_nearest_hrrrs_batch(keys)
+
+    Enum.map(contacts, fn c ->
+      point_keys = Map.get(contact_map, c, [])
+      profiles = point_keys |> Enum.map(&Map.get(index, &1)) |> Enum.reject(&is_nil/1)
+      {c, profiles}
+    end)
+  end
+
+  # Batch nearest-HRRR lookup: query all profiles in the union bounding
+  # box once, then match each point to its nearest profile in Elixir.
+  @spec find_nearest_hrrrs_batch([{float(), float(), DateTime.t()}]) :: %{
+          {float(), float(), DateTime.t()} => HrrrProfile.t()
+        }
+  defp find_nearest_hrrrs_batch([]), do: %{}
+
+  defp find_nearest_hrrrs_batch(points) do
+    d = 0.07
+    margin_s = 3600
+
+    {lats, lons, times} = Enum.unzip(points)
+    lat_min = Enum.min(lats) - d
+    lat_max = Enum.max(lats) + d
+    lon_min = Enum.min(lons) - d
+    lon_max = Enum.max(lons) + d
+    time_min = times |> Enum.min_by(&DateTime.to_unix/1) |> DateTime.add(-margin_s, :second)
+    time_max = times |> Enum.max_by(&DateTime.to_unix/1) |> DateTime.add(margin_s, :second)
+
+    profiles =
+      Repo.all(
+        from(h in HrrrProfile,
+          where:
+            h.lat >= ^lat_min and h.lat <= ^lat_max and
+              h.lon >= ^lon_min and h.lon <= ^lon_max and
+              h.valid_time >= ^time_min and h.valid_time <= ^time_max,
+          select: %{lat: h.lat, lon: h.lon, valid_time: h.valid_time, profile: h}
+        )
+      )
+
+    Map.new(points, fn {lat, lon, ts} ->
+      nearest =
+        Enum.min_by(
+          profiles,
+          fn p ->
+            abs(p.lat - lat) + abs(p.lon - lon) + abs(DateTime.diff(p.valid_time, ts))
+          end,
+          fn -> nil end
+        )
+
+      {{lat, lon, ts}, nearest && nearest.profile}
+    end)
+  end
+
   @spec find_nearest_native_profile(float(), float(), DateTime.t()) ::
           HrrrNativeProfile.t() | nil
   def find_nearest_native_profile(lat, lon, timestamp) do