# Pastebin jLoy9DIF
module Day2Gqplox where

data Shape = Rock | Paper | Scissors deriving (Show, Ord, Eq, Enum)

data Outcome = Win | Draw | Lose deriving (Show, Ord, Eq, Enum)

shapeScore :: Shape -> Int
shapeScore = succ . fromEnum

score :: Shape -> Outcome -> Int
score opp Win = 6 + (shapeScore . wrappedSucc) opp
score opp Draw = 3 + shapeScore opp
score opp Lose = 0 + (shapeScore . wrappedPred) opp

wrappedSucc :: Shape -> Shape
wrappedSucc Scissors = Rock
wrappedSucc s = succ s

wrappedPred :: Shape -> Shape
wrappedPred = wrappedSucc . wrappedSucc

parseShape :: Char -> Maybe Shape
parseShape 'A' = Just Rock
parseShape 'B' = Just Paper
parseShape 'C' = Just Scissors
parseShape _ = Nothing

parseOutcome :: Char -> Maybe Outcome
parseOutcome 'X' = Just Lose
parseOutcome 'Y' = Just Draw
parseOutcome 'Z' = Just Win
parseOutcome _ = Nothing

solve :: [(Shape, Outcome)] -> Int
solve = sum . map (uncurry score)

parse :: String -> Maybe (Shape, Outcome)
parse str = case str of
            [s, ' ', o] -> (,) <$> parseShape s <*> parseOutcome o
            _ -> Nothing

part2 :: IO Int
part2 = maybe 0 solve . traverse parse . lines <$> readFile "input/day2"