defmodule Remix.Worker do
  use GenServer

  def init(_args) do
    Process.send_after(__MODULE__, :poll_and_reload, 10000)
    GenServer.start_link(__MODULE__, %{}, name: Remix.Worker)
  end

  def handle_info(:poll_and_reload, state) do
    paths = Application.get_all_env(:updated_remix)[:paths]

    new_state =
      Map.new(paths, fn path ->
        current_mtime = get_current_mtime(path)

        last_mtime =
          case Map.fetch(state, path) do
            {:ok, val} -> val
            :error -> nil
          end

        handle_path(path, current_mtime, last_mtime)
      end)

    Process.send_after(__MODULE__, :poll_and_reload, 1000)
    {:noreply, new_state}
  end

  def handle_path(path, current_mtime, current_mtime), do: {path, current_mtime}

  def handle_path(path, current_mtime, _) do
    comp_elixir = fn -> Mix.Tasks.Compile.Elixir.run(["--ignore-module-conflict"]) end
    comp_escript = fn -> Mix.Tasks.Escript.Build.run([]) end

    case Application.get_all_env(:remix)[:silent] do
      true ->
        ExUnit.CaptureIO.capture_io(comp_elixir)

        if Application.get_all_env(:remix)[:escript] == true do
          ExUnit.CaptureIO.capture_io(comp_escript)
        end

      _ ->
        comp_elixir.()

        if Application.get_all_env(:remix)[:escript] == true do
          comp_escript.()
        end
    end

    {path, current_mtime}
  end

  def get_current_mtime(dir) do
    case File.ls(dir) do
      {:ok, files} -> get_current_mtime(files, [], dir)
      _ -> nil
    end
  end

  def get_current_mtime([], mtimes, _cwd) do
    mtimes
    |> Enum.sort()
    |> Enum.reverse()
    |> List.first()
  end

  def get_current_mtime([h | tail], mtimes, cwd) do
    mtime =
      case File.dir?("#{cwd}/#{h}") do
        true -> get_current_mtime("#{cwd}/#{h}")
        false -> File.stat!("#{cwd}/#{h}").mtime
      end

    get_current_mtime(tail, [mtime | mtimes], cwd)
  end
end