data Item = Rock | Paper | Scissors deriving (Eq, Show)

readItem :: String -> Item
readItem "A" = Rock
readItem "B" = Paper
readItem "C" = Scissors
readItem "X" = Rock
readItem "Y" = Paper
readItem "Z" = Scissors

wins :: Item -> Item -> Bool
wins Rock Scissors = True
wins Scissors Paper = True
wins Paper Rock = True
wins _ _ = False

scoreItem :: Item -> Int
scoreItem Rock = 1
scoreItem Paper = 2
scoreItem Scissors = 3

scoreWin :: Item -> Item -> Int
scoreWin me you
    | me `wins` you = 6
    | me == you = 3
    | otherwise = 0

score :: Item -> Item -> Int
score me you = scoreWin me you + scoreItem me

scoreLine1 :: String -> Int
scoreLine1 s = score me you where
    [you, me] = map readItem (words s)

whatToPlay :: Item -> Int -> Item
whatToPlay you score = head $ filter f all where
    all = [Rock, Paper, Scissors]
    f me = scoreWin me you == score

neededScore "X" = 0
neededScore "Y" = 3
neededScore "Z" = 6

scoreLine2 :: String -> Int
scoreLine2 s = score me you where
    [you', goal'] = words s
    (you, goal) = (readItem you', neededScore goal')
    me = whatToPlay you goal


main :: IO ()
main = do
    input <- lines <$> getContents
    
    putStr "part 1: "
    print $ sum $ map scoreLine1 input

    putStr "part 2: "
    print $ sum $ map scoreLine2 input