defmodule MicrowavepropWeb.GridBoundsTest do
  use ExUnit.Case, async: true

  alias MicrowavepropWeb.GridBounds

  describe "clamp/1" do
    test "passes nil through" do
      assert GridBounds.clamp(nil) == {:ok, nil}
    end

    test "passes a small viewport through unchanged" do
      bounds = %{"south" => 30.0, "north" => 35.0, "west" => -100.0, "east" => -90.0}
      assert {:ok, ^bounds} = GridBounds.clamp(bounds)
    end

    test "clamps south/north/west/east to the supported extent" do
      bounds = %{"south" => -50.0, "north" => 90.0, "west" => -200.0, "east" => 50.0}

      assert {:ok, %{"south" => 20.0, "north" => 65.0, "west" => -150.0, "east" => -50.0}} =
               GridBounds.clamp(bounds)
    end

    # The map's own `minZoom: 4` produces a viewport that clamps to the
    # full extent. Rejecting it blanked the overlay whenever a user
    # zoomed all the way out, so the clamped full grid must be served.
    test "serves global bounds by clamping them to the supported extent" do
      global = %{"south" => -90.0, "north" => 90.0, "west" => -180.0, "east" => 180.0}

      assert {:ok, %{"south" => 20.0, "north" => 65.0, "west" => -150.0, "east" => -50.0}} =
               GridBounds.clamp(global)
    end

    # The cap is defense-in-depth against the clamp window being widened
    # later; nothing the clamp can emit today exceeds it.
    test "the clamped extent stays inside the area cap" do
      assert (65.0 - 20.0) * (-50.0 - -150.0) <= GridBounds.max_viewport_area_sq_deg()
    end

    test "rejects inverted bounds" do
      inverted = %{"south" => 40.0, "north" => 30.0, "west" => -90.0, "east" => -100.0}
      assert GridBounds.clamp(inverted) == {:error, :invalid_bounds}
    end

    test "rejects malformed bounds" do
      assert GridBounds.clamp(%{}) == {:error, :invalid_bounds}

      assert GridBounds.clamp(%{"south" => "x", "north" => 1, "west" => 1, "east" => 1}) ==
               {:error, :invalid_bounds}
    end
  end
end