Never download SRTM tiles during page load, only in Oban workers

- Srtm.lookup no longer auto-downloads by default, requires download: true
- TerrainProfileWorker passes download: true for background tile fetch
- Contact detail page enqueues TerrainProfileWorker if profile missing
- Page load gracefully handles missing tiles via API fallback or nil

lib/microwaveprop/terrain/elevation_client.ex

@@ -7,16 +7,16 @@ defmodule Microwaveprop.Terrain.ElevationClient do
 
   @batch_size 100
 
-  @spec fetch_elevation_profile(float(), float(), float(), float(), pos_integer()) ::
+  @spec fetch_elevation_profile(float(), float(), float(), float(), pos_integer(), keyword()) ::
           {:ok, list(map())} | {:error, String.t()}
-  def fetch_elevation_profile(lat1, lon1, lat2, lon2, n \\ 64) do
+  def fetch_elevation_profile(lat1, lon1, lat2, lon2, n \\ 64, opts \\ []) do
     case srtm_tiles_dir() do
       nil ->
         Logger.debug("SRTM tiles_dir not configured, using API")
         fetch_elevation_profile_api(lat1, lon1, lat2, lon2, n)
 
       tiles_dir ->
-        case Srtm.fetch_elevation_profile(lat1, lon1, lat2, lon2, tiles_dir, n) do
+        case Srtm.fetch_elevation_profile(lat1, lon1, lat2, lon2, tiles_dir, n, opts) do
           {:ok, _profile} = ok ->
             Logger.info("Elevation profile served from SRTM tiles")
             ok

lib/microwaveprop/terrain/srtm.ex

@@ -51,9 +51,9 @@ defmodule Microwaveprop.Terrain.Srtm do
     end
   end
 
-  @spec lookup(float(), float(), String.t()) ::
+  @spec lookup(float(), float(), String.t(), keyword()) ::
           {:ok, integer()} | {:error, :no_tile} | {:error, :void}
-  def lookup(lat, lon, tiles_dir) do
+  def lookup(lat, lon, tiles_dir, opts \\ []) do
     path = Path.join(tiles_dir, tile_filename(lat, lon))
 
     case :file.open(path, [:read, :binary, :raw]) do
@@ -61,9 +61,9 @@ defmodule Microwaveprop.Terrain.Srtm do
         read_elevation(fd, lat, lon)
 
       {:error, :enoent} ->
-        if File.dir?(tiles_dir) do
+        if opts[:download] && File.dir?(tiles_dir) do
           case download_tile(lat, lon, tiles_dir) do
-            {:ok, _path} ->
+            {:ok, _} ->
               case :file.open(path, [:read, :binary, :raw]) do
                 {:ok, fd} -> read_elevation(fd, lat, lon)
                 {:error, _} -> {:error, :no_tile}
@@ -78,15 +78,15 @@ defmodule Microwaveprop.Terrain.Srtm do
     end
   end
 
-  @spec fetch_elevation_profile(float(), float(), float(), float(), String.t(), pos_integer()) ::
+  @spec fetch_elevation_profile(float(), float(), float(), float(), String.t(), pos_integer(), keyword()) ::
           {:ok, list(map())} | {:error, term()}
-  def fetch_elevation_profile(lat1, lon1, lat2, lon2, tiles_dir, n \\ 64) do
+  def fetch_elevation_profile(lat1, lon1, lat2, lon2, tiles_dir, n \\ 64, opts \\ []) do
     pts = sample_path(lat1, lon1, lat2, lon2, n)
     dist_km = haversine_km(lat1, lon1, lat2, lon2)
 
     results =
       Enum.reduce_while(pts, {:ok, []}, fn pt, {:ok, acc} ->
-        case lookup(pt.lat, pt.lon, tiles_dir) do
+        case lookup(pt.lat, pt.lon, tiles_dir, opts) do
           {:ok, elev} ->
             entry = %{
               lat: pt.lat,

lib/microwaveprop/workers/terrain_profile_worker.ex

@@ -29,7 +29,7 @@ defmodule Microwaveprop.Workers.TerrainProfileWorker do
       # Look up HRRR refractivity gradient for dynamic k-factor
       k = lookup_k_factor(contact)
 
-      case ElevationClient.fetch_elevation_profile(lat1, lon1, lat2, lon2) do
+      case ElevationClient.fetch_elevation_profile(lat1, lon1, lat2, lon2, 64, download: true) do
         {:ok, profile} ->
           analysis = TerrainAnalysis.analyse(profile, dist_km, freq_ghz, k_factor: k)
 

lib/microwaveprop_web/live/contact_live/show.ex

@@ -13,6 +13,7 @@ defmodule MicrowavepropWeb.ContactLive.Show do
   alias Microwaveprop.Weather
   # alias Microwaveprop.Weather.HrrrClient
   # alias Microwaveprop.Workers.HrrrFetchWorker
+  alias Microwaveprop.Workers.TerrainProfileWorker
 
   @earth_radius_m 6_371_000.0
 
@@ -26,6 +27,7 @@ defmodule MicrowavepropWeb.ContactLive.Show do
     hrrr = List.first(hrrr_path)
     {hrrr, hrrr_status} = maybe_enqueue_hrrr(hrrr, contact)
     terrain = Terrain.get_terrain_profile(contact.id)
+    maybe_enqueue_terrain(terrain, contact)
     elevation_profile = compute_elevation_profile(contact, hrrr_path, weather.soundings)
     propagation_analysis = build_propagation_analysis(contact, hrrr, terrain, elevation_profile, weather.soundings)
 
@@ -175,6 +177,16 @@ defmodule MicrowavepropWeb.ContactLive.Show do
     end
   end
 
+  defp maybe_enqueue_terrain(terrain, _contact) when not is_nil(terrain), do: :ok
+
+  defp maybe_enqueue_terrain(nil, contact) do
+    if contact.pos1 && contact.pos2 do
+      Oban.insert(TerrainProfileWorker.new(%{"qso_id" => contact.id}))
+    end
+
+    :ok
+  end
+
   defp maybe_enqueue_hrrr(hrrr, _contact) when not is_nil(hrrr), do: {hrrr, :loaded}
 
   # TODO: Re-enable auto HRRR backfill on page view when appropriate

test/microwaveprop/terrain/srtm_test.exs

@@ -98,7 +98,15 @@ defmodule Microwaveprop.Terrain.SrtmTest do
         Plug.Conn.send_resp(conn, 200, gzipped)
       end)
 
-      assert {:ok, @test_elevation} = Srtm.lookup(32.0, -97.0, tmp_dir)
+      assert {:ok, @test_elevation} = Srtm.lookup(32.0, -97.0, tmp_dir, download: true)
+    end
+
+    test "returns {:error, :no_tile} without download opt" do
+      tmp_dir = Path.join(System.tmp_dir!(), "srtm_test_#{System.unique_integer([:positive])}")
+      File.mkdir_p!(tmp_dir)
+      on_exit(fn -> File.rm_rf!(tmp_dir) end)
+
+      assert {:error, :no_tile} = Srtm.lookup(32.0, -97.0, tmp_dir)
     end
 
     test "returns {:error, :no_tile} when download fails" do
@@ -112,7 +120,7 @@ defmodule Microwaveprop.Terrain.SrtmTest do
       end)
 
       capture_log(fn ->
-        assert {:error, :no_tile} = Srtm.lookup(80.0, 0.0, tmp_dir)
+        assert {:error, :no_tile} = Srtm.lookup(80.0, 0.0, tmp_dir, download: true)
       end)
     end
   end