defmodule FIXME do
  defmacro fixme(
    {:-, _, [{:-, _, [year, month]}, day]},
    message,
    opts \\ []
  ) do
    {opts, _} = Code.eval_quoted(opts)

    # Injectable "today" for tests.
    current_date = opts[:today] || (:calendar.local_time |> elem(0))

    warn = case opts[:warn] do
      nil ->  Application.get_env(:fixme, :warn, false)
      warn -> warn
    end

    fixme_date = {year, month, day}

    message = "Fix by #{year}-#{zeropad month}-#{zeropad day}: #{message}"

    if current_date >= fixme_date do
      raise message
    end

    if warn do
      %{file: file, line: line} = __CALLER__
      :elixir_errors.warn line, file, message
    end
  end

  defp zeropad(number) do
    number |> Integer.to_string |> String.rjust(2, ?0)
  end
end