defmodule Day1 do
  def part1(file_path) do
    file_path
    |> File.read!()
    |> String.split("\n")
    |> Enum.map(&String.split/1)
    |> Enum.filter(fn list -> length(list) == 2 end)
    |> Enum.map(fn [a, b] -> {String.to_integer(a), String.to_integer(b)} end)
    |> Enum.unzip()
    |> Tuple.to_list()
    |> Enum.map(&Enum.sort/1)
    |> Enum.zip()
    |> Enum.map(fn {a, b} -> abs(a - b) end)
    |> Enum.sum()
  end

  def part2(file_path) do
    file_path
    |> File.read!()
    |> String.split("\n")
    |> Enum.map(&String.split/1)
    |> Enum.filter(fn list -> length(list) == 2 end)
    |> Enum.map(fn [a, b] -> {String.to_integer(a), String.to_integer(b)} end)
    |> Enum.unzip()
    |> Tuple.to_list()
    |> Enum.map(&Enum.sort/1)
    |> (fn [list1, list2] -> {list1, Enum.frequencies(list2)} end).()
    |> (fn {list1, freqs} ->
          list1
          |> Enum.map(&{&1, Map.get(freqs, &1, 0)})
          |> Enum.filter(fn {_, count} -> count != 0 end)
          |> Enum.map(fn {value, count} -> value * count end)
        end).()
    |> Enum.sum()
  end
end