defmodule Mix.Tasks.Analytics3i.Top do
  use Mix.Task

  require Logger

  @shortdoc "Top"

  def run(_) do
    {:ok, _} = Application.ensure_all_started(:analytics_3i)

    Logger.add_backend {LoggerFileBackend, :debug}

    Logger.configure_backend {LoggerFileBackend, :debug},
                             path: Path.expand("../../../log/debug.log", __DIR__),
                             format: "$time $metadata[$level] $message\n"

    otrasl_list = load_yaml("data/otrasl.yml")
    st_list = load_yaml("data/st.yml")

    result =
      Path.wildcard("output/*.csv")
      |> Enum.reduce([], fn (file_name, acc) ->
        {otrasl, st} = otrasl_st(file_name)

        list = File.stream!(file_name)
                     |> Stream.take(11)
                     |> CSV.decode!(headers: true)
                     |> Enum.to_list()
                     |> Enum.map(fn m ->
                          Map.merge(%{otrasl: otrasl_list[otrasl]["name"], tech: st_list[st]["name"]}, m)
                        end)

        acc ++ list
      end)

    write_csv!(Map.keys(List.first(result)), result)
  end

  defp otrasl_st(file_name) do
    info = String.split(Path.basename(file_name), ~r{[_.]})

    otrasl_name_size = Enum.count(info) - 3
    otrasl_name_size = if Enum.at(info, otrasl_name_size) == "new", do: otrasl_name_size - 1, else: otrasl_name_size
    otrasl_name = (1..otrasl_name_size) |> Enum.map(fn x -> Enum.at(info, x) end) |> Enum.join("_")

    st_name_size = Enum.count(info) - otrasl_name_size - 2
    st_name = (otrasl_name_size + 1..otrasl_name_size + st_name_size) |> Enum.map(fn x -> Enum.at(info, x) end) |> Enum.join("_")

    {otrasl_name, st_name}
  end

  defp load_yaml(path) do
    path = File.cwd! |> Path.join(path)
    {:ok, data} = YamlElixir.read_from_file path

    data
  end

  defp write_csv!(keys, values) do
    File.open("data/top_ten.csv", [:write, :utf8], fn(file) ->
      values
      |> CSV.encode(headers: keys)
      |> Enum.each(&IO.write(file, &1))
    end)
  end
end