defmodule MvWeb.JoinConfirmController do
  @moduledoc """
  Handles GET /confirm_join/:token for the public join flow (double opt-in).

  Renders a full HTML page with public header and hero layout (success, expired,
  or invalid). Calls a configurable callback (default Mv.Membership) so tests can
  stub the dependency. Public route; no authentication required.
  """
  use MvWeb, :controller

  use Gettext, backend: MvWeb.Gettext

  def confirm(conn, %{"token" => token}) when is_binary(token) do
    callback = Application.get_env(:mv, :join_confirm_callback, Mv.Membership)

    case callback.confirm_join_request(token, actor: nil) do
      {:ok, _request} ->
        success_response(conn)

      {:error, :token_expired} ->
        expired_response(conn)

      {:error, _} ->
        invalid_response(conn)
    end
  end

  def confirm(conn, _params), do: invalid_response(conn)

  defp success_response(conn) do
    conn
    |> assign_confirm_assigns(:success)
    |> put_view(MvWeb.JoinConfirmHTML)
    |> render("confirm.html")
  end

  defp expired_response(conn) do
    conn
    |> assign_confirm_assigns(:expired)
    |> put_view(MvWeb.JoinConfirmHTML)
    |> render("confirm.html")
  end

  defp invalid_response(conn) do
    conn
    |> put_status(404)
    |> assign_confirm_assigns(:invalid)
    |> put_view(MvWeb.JoinConfirmHTML)
    |> render("confirm.html")
  end

  defp assign_confirm_assigns(conn, result) do
    page_title = page_title_for_result(result)

    conn
    |> assign(:result, result)
    |> assign(:page_title, page_title)
    |> assign(:flash, conn.assigns[:flash] || conn.flash || %{})
  end

  defp page_title_for_result(:success), do: gettext("Join confirmation")
  defp page_title_for_result(:expired), do: gettext("Link expired")
  defp page_title_for_result(:invalid), do: gettext("Invalid link")
end