prop/test/microwaveprop/buildings/ms_footprints_test.exs

defmodule Microwaveprop.Buildings.MsFootprintsTest do
  use ExUnit.Case, async: false
  use ExUnitProperties

  alias Microwaveprop.Buildings.MsFootprints

  describe "quadkey/3" do
    test "returns a string of length equal to zoom" do
      assert String.length(MsFootprints.quadkey(33.0, -97.0, 9)) == 9
      assert String.length(MsFootprints.quadkey(33.0, -97.0, 5)) == 5
    end

    test "returns the same quadkey for the same coordinates" do
      assert MsFootprints.quadkey(33.0, -97.0, 9) == MsFootprints.quadkey(33.0, -97.0, 9)
    end

    test "coordinates far apart produce different quadkeys" do
      q1 = MsFootprints.quadkey(33.0, -97.0, 9)
      q2 = MsFootprints.quadkey(40.0, -80.0, 9)
      refute q1 == q2
    end
  end

  describe "quadkeys_for_bbox/2" do
    test "returns a list of quadkey strings" do
      bbox = %{"south" => 32.0, "north" => 34.0, "west" => -98.0, "east" => -96.0}
      keys = MsFootprints.quadkeys_for_bbox(bbox, 9)
      assert keys != []
      assert Enum.all?(keys, &is_binary/1)
    end

    test "each quadkey has the expected length" do
      bbox = %{"south" => 32.0, "north" => 34.0, "west" => -98.0, "east" => -96.0}
      keys = MsFootprints.quadkeys_for_bbox(bbox, 9)
      Enum.each(keys, fn k -> assert String.length(k) == 9 end)
    end

    test "a larger bbox produces more quadkeys" do
      small = %{"south" => 32.5, "north" => 33.0, "west" => -97.5, "east" => -96.5}
      large = %{"south" => 32.0, "north" => 34.0, "west" => -98.0, "east" => -96.0}
      assert length(MsFootprints.quadkeys_for_bbox(large, 9)) > length(MsFootprints.quadkeys_for_bbox(small, 9))
    end
  end

  describe "cache_dir/0" do
    test "returns a string" do
      assert byte_size(MsFootprints.cache_dir()) > 0
    end
  end

  describe "dataset_index/0 with stubbed HTTP" do
    setup do
      Microwaveprop.Cache.invalidate(:ms_footprints_index)
      prev = Application.get_env(:microwaveprop, :ms_footprints_http_get)

      on_exit(fn ->
        if prev,
          do: Application.put_env(:microwaveprop, :ms_footprints_http_get, prev),
          else: Application.delete_env(:microwaveprop, :ms_footprints_http_get)
      end)

      :ok
    end

    test "parses dataset-links CSV into quadkey -> URL map" do
      Application.put_env(:microwaveprop, :ms_footprints_http_get, fn _url, _opts ->
        {:ok,
         %{
           status: 200,
           body:
             "RegionName,QuadKey,Url,Size,DatasetDate\nUnitedStates,023112330,https://example.com/tile1.csv.gz,1234,2026-01-01\nUnitedStates,023112331,https://example.com/tile2.csv.gz,5678,2026-01-01\nCanada,023112332,https://example.com/ca-tile.csv.gz,9999,2026-01-01\n"
         }}
      end)

      index = MsFootprints.dataset_index()
      assert index["023112330"] == "https://example.com/tile1.csv.gz"
      assert index["023112331"] == "https://example.com/tile2.csv.gz"
      refute Map.has_key?(index, "023112332")
      assert map_size(index) == 2
    end

    test "handles empty CSV gracefully" do
      Application.put_env(:microwaveprop, :ms_footprints_http_get, fn _url, _opts ->
        {:ok, %{status: 200, body: "RegionName,QuadKey,Url,Size,DatasetDate\n"}}
      end)

      assert MsFootprints.dataset_index() == %{}
    end

    test "returns cached result on repeated calls" do
      call_count = :counters.new(1, [:atomics])

      Application.put_env(:microwaveprop, :ms_footprints_http_get, fn _url, _opts ->
        :counters.add(call_count, 1, 1)

        {:ok,
         %{
           status: 200,
           body: "RegionName,QuadKey,Url,Size,DatasetDate\nUnitedStates,qk,http://example.com/t,1,2026-01-01\n"
         }}
      end)

      MsFootprints.dataset_index()
      MsFootprints.dataset_index()

      assert :counters.get(call_count, 1) == 1
    end
  end

  describe "download_tile/1 with stubbed HTTP" do
    setup do
      prev = Application.get_env(:microwaveprop, :buildings_cache_dir)
      tmp = Path.join(System.tmp_dir!(), "ms_footprints_#{System.unique_integer([:positive])}")
      Application.put_env(:microwaveprop, :buildings_cache_dir, tmp)
      Microwaveprop.Cache.invalidate(:ms_footprints_index)

      prev_http = Application.get_env(:microwaveprop, :ms_footprints_http_get)

      on_exit(fn ->
        File.rm_rf(tmp)

        if prev,
          do: Application.put_env(:microwaveprop, :buildings_cache_dir, prev),
          else: Application.delete_env(:microwaveprop, :buildings_cache_dir)

        if prev_http,
          do: Application.put_env(:microwaveprop, :ms_footprints_http_get, prev_http),
          else: Application.delete_env(:microwaveprop, :ms_footprints_http_get)
      end)

      :ok
    end

    test "downloads tile when quadkey exists in index" do
      Application.put_env(:microwaveprop, :ms_footprints_http_get, fn url, _opts ->
        if String.contains?(url, "dataset-links.csv") do
          {:ok,
           %{
             status: 200,
             body:
               "RegionName,QuadKey,Url,Size,DatasetDate\nUnitedStates,023112330,http://example.com/tile,1234,2026-01-01\n"
           }}
        else
          {:ok, %{status: 200, body: "fake-gzip-data"}}
        end
      end)

      assert {:ok, path} = MsFootprints.download_tile("023112330")
      assert File.exists?(path)
      assert File.read!(path) == "fake-gzip-data"
    end

    test "returns error for unknown quadkey" do
      Application.put_env(:microwaveprop, :ms_footprints_http_get, fn _url, _opts ->
        {:ok, %{status: 200, body: "RegionName,QuadKey,Url,Size,DatasetDate\n"}}
      end)

      assert {:error, :unknown_quadkey} = MsFootprints.download_tile("nonexistent")
    end

    test "skips download when already cached on disk" do
      tmp = Application.get_env(:microwaveprop, :buildings_cache_dir)
      File.mkdir_p!(tmp)
      File.write!(Path.join(tmp, "023112330.csv.gz"), "existing-data")

      assert {:ok, path} = MsFootprints.download_tile("023112330")
      assert File.read!(path) == "existing-data"
    end
  end
end