defmodule AOC.Day4 do
  use AOC.Day, day: 4

  def parse_input(lines) do
    Enum.map(lines, fn line ->
      [assign1, assign2] =
        line
        |> String.split(",")
        |> Enum.map(fn assign ->
          [from, to] =
            assign
            |> String.split("-")
            |> Enum.map(&String.to_integer/1)

          MapSet.new(from..to)
        end)

      {assign1, assign2}
    end)
  end

  def part1(input) do
    input
    |> Enum.map(fn {set1, set2} ->
      MapSet.subset?(set1, set2) or MapSet.subset?(set2, set1)
    end)
    |> Enum.count(& &1)
  end

  def part2(input) do
    input
    |> Enum.map(fn {set1, set2} ->
      MapSet.intersection(set1, set2)
      |> Enum.any?()
    end)
    |> Enum.count(& &1)
  end
end