defmodule Tesourex.CSV do
  import Tesourex.Helper

  def parse(tesouro_csv) do
    tesouro_csv
    |> String.splitter("\n")
    |> Stream.filter(&(String.starts_with?(&1, "Tesouro")))
    |> Stream.map(&parse_line/1)
    |> Enum.reduce(%{}, &group_by_name_and_most_recent/2)
  end

  defp group_by_name_and_most_recent(row, acc) do
    Map.update(acc, row[:name], row, &(most_recent(&1, row)))
  end

  defp parse_line(line) do
    line
    |> String.trim()
    |> String.split(";")
    |> parts_to_map
  end

  defp parts_to_map([name,mature_at,last_updated_at,buy_rate,sell_rate,buy_price,sell_price,_]) do
    %{
      name: name_with_year(name, mature_at),
      mature_at: mature_at,
      last_updated_at: last_updated_at,
      buy_rate: parse_value(buy_rate),
      buy_price: parse_value(buy_price),
      sell_rate: parse_value(sell_rate),
      sell_price: parse_value(sell_price)
    }
  end

  defp name_with_year(name, date) do
    year = date
           |> String.split("/")
           |> Enum.at(2)

    "#{name} #{year}"
  end
end