data Hand
  = Rock
  | Paper
  | Scissor
  deriving (Eq, Enum, Bounded, Show)

instance Ord Hand where
  compare x y =
    case (fromEnum x - fromEnum y) `mod` 3 of
      0 -> EQ
      1 -> GT
      _ -> LT

(+.) :: Hand -> Int -> Hand
(+.) a b = toEnum $ flip mod 3 $ (+) (fromEnum a) b

main :: IO ()
main = do
  input <- map (concat . words) . lines <$> readFile "input"
  print $ day2 id input
  print $ day2 realStrat input

toHands :: [Char] -> [Hand]
toHands x = map toEnum $ zipWith subtract [65, 88] (map fromEnum x)

realStrat :: [Hand] -> [Hand]
realStrat [a, b] = [a, a +. fromEnum (b +. 2)]

day2 :: ([Hand] -> [Hand]) -> [[Char]] -> Int
day2 f = sum . map (play . f . toHands)

play :: [Hand] -> Int
play [x, y] =
  fromEnum y + 1 +
  if x == y
    then 3
    else fromEnum (x < y) * 6