music_library/test/music_library_web/controllers/asset_controller_test.exs

defmodule MusicLibraryWeb.AssetControllerTest do
  use MusicLibraryWeb.ConnCase

  import MusicLibrary.Fixtures.Records

  alias MusicLibrary.Assets
  alias MusicLibrary.Assets.Transform

  defp create_asset(_config) do
    {:ok, asset} = Assets.store(%{content: marbles_cover_data(), format: "image/jpeg"})

    %{asset: asset}
  end

  describe "GET /assets/:payload" do
    setup [:create_asset]

    test "404s when asset doesn't exist", %{conn: conn} do
      transform = %Transform{hash: Ecto.UUID.generate()}
      payload = Transform.encode!(transform)

      conn = get(conn, ~p"/assets/#{payload}")
      assert text_response(conn, 404) == "Not found"
    end

    test "serves the asset when no etag is sent", %{conn: conn, asset: asset} do
      transform = %Transform{hash: asset.hash}
      payload = Transform.encode!(transform)
      conn = get(conn, ~p"/assets/#{payload}")

      assert conn.status == 200
      assert get_resp_header(conn, "content-type") == ["image/jpeg; charset=utf-8"]
      assert get_resp_header(conn, "cache-control") == ["public, max-age=31536000"]
      assert get_resp_header(conn, "etag") == [payload]

      assert conn.resp_body == asset.content
    end

    test "serves the asset when etag doesn't match", %{conn: conn, asset: asset} do
      transform = %Transform{hash: asset.hash}
      payload = Transform.encode!(transform)

      conn =
        conn
        |> put_req_header("if-none-match", "invalid-etag")
        |> get(~p"/assets/#{payload}")

      assert conn.status == 200
      assert get_resp_header(conn, "content-type") == ["image/jpeg; charset=utf-8"]
      assert get_resp_header(conn, "cache-control") == ["public, max-age=31536000"]
      assert get_resp_header(conn, "etag") == [payload]

      assert conn.resp_body == asset.content
    end

    test "serves a 304 when etag matches", %{conn: conn, asset: asset} do
      transform = %Transform{hash: asset.hash}
      payload = Transform.encode!(transform)

      conn =
        conn
        |> put_req_header("if-none-match", payload)
        |> get(~p"/assets/#{payload}")

      assert conn.status == 304
      assert get_resp_header(conn, "content-type") == []
      assert get_resp_header(conn, "cache-control") == ["public, max-age=31536000"]
      assert get_resp_header(conn, "etag") == []

      assert conn.resp_body == <<>>
    end

    test "400s on invalid base64 payload", %{conn: conn} do
      conn = get(conn, ~p"/assets/!!!invalid-base64!!!")
      assert text_response(conn, 400) == "Bad request"
    end

    test "400s on valid base64 but invalid JSON payload", %{conn: conn} do
      payload = Base.url_encode64("not json", padding: false)
      conn = get(conn, ~p"/assets/#{payload}")
      assert text_response(conn, 400) == "Bad request"
    end

    test "404s when payload has null hash", %{conn: conn} do
      payload = Base.url_encode64(JSON.encode!(%{hash: nil, width: nil}), padding: false)
      conn = get(conn, ~p"/assets/#{payload}")
      assert text_response(conn, 404) == "Not found"
    end

    test "400s when payload has string width", %{conn: conn, asset: asset} do
      payload =
        %{hash: asset.hash, width: "300"}
        |> JSON.encode!()
        |> Base.url_encode64(padding: false)

      conn = get(conn, ~p"/assets/#{payload}")
      assert text_response(conn, 400) == "Bad request"
    end

    test "400s when payload has negative width", %{conn: conn, asset: asset} do
      payload =
        %{hash: asset.hash, width: -1}
        |> JSON.encode!()
        |> Base.url_encode64(padding: false)

      conn = get(conn, ~p"/assets/#{payload}")
      assert text_response(conn, 400) == "Bad request"
    end

    test "400s when payload has very large width", %{conn: conn, asset: asset} do
      payload =
        %{hash: asset.hash, width: 99_999}
        |> JSON.encode!()
        |> Base.url_encode64(padding: false)

      conn = get(conn, ~p"/assets/#{payload}")
      assert text_response(conn, 400) == "Bad request"
    end

    test "canonical cache key collapses variant payloads into single ETS entry", %{
      conn: conn,
      asset: asset
    } do
      # Two variant payloads encoding the same (hash, width)
      payload_a =
        %{hash: asset.hash, width: 480}
        |> JSON.encode!()
        |> Base.url_encode64(padding: false)

      # Same hash/width but different JSON key order / whitespace
      payload_b =
        %{width: 480, hash: asset.hash}
        |> JSON.encode!()
        |> Base.url_encode64(padding: false)

      # First request populates the cache
      conn_a = get(conn, ~p"/assets/#{payload_a}")
      assert conn_a.status == 200
      assert get_resp_header(conn_a, "etag") == [payload_a]

      # Second request with different payload but same canonical key
      # should serve from cache (same content, correct ETag for this payload)
      conn_b = get(conn, ~p"/assets/#{payload_b}")
      assert conn_b.status == 200
      assert get_resp_header(conn_b, "etag") == [payload_b]

      # Both should return the same image content
      assert conn_a.resp_body == conn_b.resp_body
    end

    @tag :capture_log
    test "404s when asset content is corrupt", %{conn: conn} do
      {:ok, asset} = Assets.store(%{content: "not an image", format: "image/jpeg"})
      transform = %Transform{hash: asset.hash, width: 480}
      payload = Transform.encode!(transform)

      conn = get(conn, ~p"/assets/#{payload}")
      assert text_response(conn, 404) == "Not found"
    end

    test "handles transforms with width", %{conn: conn, asset: asset} do
      transform = %Transform{hash: asset.hash, width: 480}
      payload = Transform.encode!(transform)

      conn = get(conn, ~p"/assets/#{payload}")

      assert conn.status == 200
      assert get_resp_header(conn, "content-type") == ["image/jpeg; charset=utf-8"]
      assert get_resp_header(conn, "cache-control") == ["public, max-age=31536000"]
      assert get_resp_header(conn, "etag") == [payload]

      assert conn.resp_body == marbles_thumb_data()
    end
  end
end