defmodule AOC.Day2 do
  use AOC.Day, day: 2

  def parse_input(lines) do
    Enum.map(lines, fn line ->
      [move1, move2] =
        line
        |> String.split(" ")
        |> Enum.map(fn c ->
          c
          |> String.to_charlist()
          |> hd()
        end)

      {move1, move2}
    end)
  end

  def part1(input) do
    input
    |> Enum.map(fn {move1, move2} ->
      score =
        case move2 do
          ?X -> 1
          ?Y -> 2
          ?Z -> 3
        end

      score +
        case {move1, move2} do
          {?A, ?Y} -> 6
          {?B, ?Z} -> 6
          {?C, ?X} -> 6
          {?A, ?X} -> 3
          {?B, ?Y} -> 3
          {?C, ?Z} -> 3
          _ -> 0
        end
    end)
    |> Enum.sum()
  end

  def part2(input) do
    input
    |> Enum.map(fn {move1, result} ->
      score =
        case result do
          ?X -> 0
          ?Y -> 3
          ?Z -> 6
        end

      score +
        case {move1, result} do
          {?A, ?X} -> 3
          {?A, ?Y} -> 1
          {?A, ?Z} -> 2
          {?B, ?X} -> 1
          {?B, ?Y} -> 2
          {?B, ?Z} -> 3
          {?C, ?X} -> 2
          {?C, ?Y} -> 3
          {?C, ?Z} -> 1
        end
    end)
    |> Enum.sum()
  end
end