defmodule AprsmeWeb.InfoLive.ShowHelpersTest do
  use ExUnit.Case, async: true

  alias AprsmeWeb.InfoLive.Show

  describe "format_distance/2 with English locale (imperial)" do
    test "uses feet for distances under a mile" do
      # 0.5 km → ~0.31 miles → ~1641 ft
      result = Show.format_distance(0.5, "en")
      assert result =~ "ft"
      refute result =~ "mi"
    end

    test "uses miles for distances >= 1 mile" do
      # 10 km → ~6.21 miles
      result = Show.format_distance(10.0, "en")
      assert result =~ "mi"
      refute result =~ "ft"
    end

    test "default locale is English" do
      assert Show.format_distance(10.0) =~ "mi"
    end
  end

  describe "format_distance/2 with non-English locale (metric)" do
    test "uses meters for distances under 1 km" do
      result = Show.format_distance(0.5, "de")
      assert result =~ "m"
      refute result =~ "km"
    end

    test "uses km for longer distances" do
      result = Show.format_distance(5.0, "fr")
      assert result =~ "km"
    end

    test "handles multiple metric locales" do
      for loc <- ["es", "de", "fr", "ja"] do
        assert Show.format_distance(10.0, loc) =~ "km"
      end
    end
  end

  describe "calculate_course/4" do
    test "returns 0 (or 360) for due north" do
      # From (0,0) to (1,0) — moving north.
      bearing = Show.calculate_course(0.0, 0.0, 1.0, 0.0)
      assert bearing == 0.0 or bearing == 360.0
    end

    test "returns ~90 for due east" do
      # From (0,0) to (0,1) — moving east.
      bearing = Show.calculate_course(0.0, 0.0, 0.0, 1.0)
      assert_in_delta bearing, 90.0, 0.5
    end

    test "returns ~180 for due south" do
      bearing = Show.calculate_course(1.0, 0.0, 0.0, 0.0)
      assert_in_delta bearing, 180.0, 0.5
    end

    test "returns ~270 for due west" do
      bearing = Show.calculate_course(0.0, 1.0, 0.0, 0.0)
      assert_in_delta bearing, 270.0, 0.5
    end

    test "always returns a value in 0..360" do
      for {lat1, lon1, lat2, lon2} <- [
            {0.0, 0.0, 45.0, 45.0},
            {10.0, 20.0, -10.0, -20.0},
            {0.0, 0.0, 0.0, -1.0}
          ] do
        b = Show.calculate_course(lat1, lon1, lat2, lon2)
        assert b >= 0
        assert b <= 360
      end
    end

    test "accepts Decimal inputs" do
      result = Show.calculate_course(Decimal.new("0.0"), Decimal.new("0.0"), Decimal.new("1.0"), Decimal.new("0.0"))
      assert is_float(result)
    end
  end

  describe "haversine/4" do
    test "returns 0 for identical points" do
      assert Show.haversine(40.0, -100.0, 40.0, -100.0) == 0.0
    end

    test "is symmetric" do
      a = Show.haversine(40.0, -100.0, 41.0, -99.0)
      b = Show.haversine(41.0, -99.0, 40.0, -100.0)
      assert_in_delta a, b, 0.001
    end

    test "returns positive distance for distinct points" do
      d = Show.haversine(40.0, -100.0, 41.0, -99.0)
      assert d > 0
    end
  end
end