defmodule Aoc2023.Day7 do
  use Aoc2023

  @ranking_1 %{
    ?A => 13,
    ?K => 12,
    ?Q => 11,
    ?J => 10,
    ?T => 9,
    ?9 => 8,
    ?8 => 7,
    ?7 => 6,
    ?6 => 5,
    ?5 => 4,
    ?4 => 3,
    ?3 => 2,
    ?2 => 1
  }

  @ranking_2 @ranking_1 |> Map.put(?J, 0)

  def hand_type(values) do
    for ty <- values, reduce: %{} do
      m -> Map.update(m, ty, 1, &(&1 + 1))
    end
    |> Enum.map(pipe(elem(1)))
    |> Enum.sort(:desc)
    |> case do
      [5] -> 6
      [4, 1] -> 5
      [3, 2] -> 4
      [3, 1, 1] -> 3
      [2, 2, 1] -> 2
      [2, 1, 1, 1] -> 1
      [1, 1, 1, 1, 1] -> 0
    end
  end

  def parse(input) do
    fn rankings, hand_rank ->
      input
      |> lines
      |> Enum.map(&String.split/1)
      |> Enum.map(fn [hand, bid] ->
        {
          hand |> String.to_charlist() |> Enum.map(&Map.get(rankings, &1)),
          bid |> String.to_integer()
        }
      end)
      |> Enum.sort_by(elem(0) |> hand_rank.() &&& elem(0), :asc)
      |> Enum.with_index(1)
      |> Enum.map(fn {{_, bid}, index} -> bid * index end)
      |> Enum.sum()
    end
  end

  def part1(input) do
    input.(@ranking_1, &hand_type/1)
  end

  def part2(input) do
    input.(
      @ranking_2,
      fn hand ->
        @ranking_2
        |> Enum.map(pipe(elem(1)))
        |> Enum.map(fn j -> hand |> Enum.map(&if &1 == 0, do: j, else: &1) end)
        |> Enum.map(&hand_type/1)
        |> Enum.max()
      end
    )
  end
end