multi_extract.ex

def multi_extract(path, index \\ nil, timer \\ false) do
    case is_nil(index) do
      true ->
        case Unzip.validate_path_all_indexes(path) do
          {:ok, indexes} ->
            {pids, times} = Enum.reduce(indexes, {[], []}, fn index, {pids, times} -> 
                              case multi_extract(path, index, timer) do
                                {:ok, pid, time} -> {pids ++ [pid], times ++ [time]}
                                {:ok, pid}       -> {pids ++ [pid], times}
                                {:error, reason} -> {pids ++ [{:error, reason}], times}
                              end
                            end)

            if times == [], do: {:ok, pids}, else: {:ok, pids, times}
          {:error, reason} -> {:error, reason}
        end
      false ->
        if timer, do: Timer.start

        case Unzip.validate_path_and_index(path, index) do
          {:ok, file}      -> Unzip.xml_file_list(index)
          |> Unzip.extract_xml_to_file(file)
          |> case do
            {:ok, file_paths} -> do_multi_extract(file_paths, index, timer)
            {:error, reason}  -> {:error, reason}
          end
          {:error, reason} -> {:error, reason}
        end
    end
  end