defmodule MvWeb.Helpers.JoinDescriptionRendererTest do
  @moduledoc """
  Tests for the join-description renderer that auto-links raw URLs and Markdown
  links while escaping all other content.
  """
  use ExUnit.Case, async: true
  use ExUnitProperties

  alias MvWeb.Helpers.JoinDescriptionRenderer

  defp html(value) do
    value
    |> JoinDescriptionRenderer.render()
    |> Phoenix.HTML.safe_to_string()
  end

  describe "render/1" do
    test "converts a raw URL to an anchor tag" do
      result = html("Akzeptiere https://example.com/dsgvo")

      assert result =~ ~s(<a href="https://example.com/dsgvo")
      assert result =~ "https://example.com/dsgvo</a>"
      assert result =~ "Akzeptiere "
    end

    test "converts Markdown [text](url) to an anchor tag with the link text" do
      result = html("[Datenschutzerklärung](https://example.com/dsgvo)")

      assert result =~ ~s(<a href="https://example.com/dsgvo")
      assert result =~ ">Datenschutzerklärung</a>"
    end

    test "returns an empty safe string for nil input" do
      assert JoinDescriptionRenderer.render(nil) == {:safe, ""}
    end

    test "escapes arbitrary HTML in non-link text" do
      result = html("<script>alert(1)</script>")

      refute result =~ "<script>"
      assert result =~ "&lt;script&gt;"
    end

    test "does not double-link a Markdown link whose URL also looks like a raw URL" do
      result = html("[Datenschutz](https://example.com/x)")

      # exactly one anchor, no nested anchor for the inner raw URL
      assert result |> :binary.matches("<a ") |> length() == 1
    end
  end

  describe "property: link-free text" do
    property "preserves non-link text content as HTML-escaped output" do
      check all(text <- link_free_string()) do
        result = html(text)

        # No links emitted, and text content equals the HTML-escaped input.
        refute result =~ "<a "
        assert result == Phoenix.HTML.html_escape(text) |> Phoenix.HTML.safe_to_string()
      end
    end
  end

  describe "property: well-formed Markdown links" do
    property "renders every [text](https://...) as a single anchor with verbatim text and url" do
      check all(
              label <- string(:alphanumeric, min_length: 1),
              path <- string(:alphanumeric)
            ) do
        url = "https://example.com/#{path}"
        result = html("[#{label}](#{url})")

        assert result =~ ~s(<a href="#{url}">#{label}</a>)
        assert result |> :binary.matches("<a ") |> length() == 1
      end
    end
  end

  # Printable strings that contain no bare URLs and no Markdown-link opening bracket.
  defp link_free_string do
    :printable
    |> string()
    |> filter(fn s -> not String.contains?(s, "http") and not String.contains?(s, "[") end)
  end
end