defmodule RPNCalculatorInspection do
  def start_reliability_check(calculator, input) do
    %{input: input, pid: spawn_link(fn -> calculator.(input) end)}
  end

  def await_reliability_check_result(%{pid: pid, input: input}, results) do
    receive do
      {:EXIT, ^pid, :normal} -> Map.put(results, input, :ok)
      {:EXIT, ^pid, _reason} -> Map.put(results, input, :error)
    after
      100 -> Map.put(results, input, :timeout)
    end
  end

  def reliability_check(calculator, inputs) do
    trap_exit_state = Process.flag(:trap_exit, true)

    inputs
    |> Enum.map(&start_reliability_check(calculator, &1))
    |> Enum.reduce(%{}, &await_reliability_check_result/2)
    |> tap(fn _ -> Process.flag(:trap_exit, trap_exit_state) end)
  end

  def correctness_check(calculator, inputs) do
    inputs
    |> Enum.map(&Task.async(fn -> calculator.(&1) end))
    |> Enum.map(&Task.await(&1, 100))
  end
end