module Day10 where

import Data.Maybe
import Text.Blaze.Html4.FrameSet (input)
import Data.List (sort)
closing :: Char -> Char
closing '(' = ')'
closing '[' = ']'
closing '{' = '}'
closing '<' = '>'

score :: Char -> Int
score ' ' = 0
score ')' = 3
score ']' = 57
score '}' = 1197
score '>' = 25137

closingScore :: Char -> Int
closingScore ')' = 1
closingScore ']' = 2
closingScore '}' = 3
closingScore '>' = 4

calcScore :: String -> Int
calcScore xs = foldr (\char score -> score*5 + closingScore char) 0 (reverse xs)


getInvalidChar :: [Char] -> String -> Char
getInvalidChar _ [] = ' '
getInvalidChar st (x:xs)
    | x == '(' || x == '[' || x == '{' || x == '<' = getInvalidChar (x:st) xs
    | otherwise = if Just x == fmap closing (listToMaybe st) then getInvalidChar (tail st) xs else x

getCompletionString :: [Char] -> String -> String
getCompletionString st [] = map closing st
getCompletionString st (x:xs)
    | x == '(' || x == '[' || x == '{' || x == '<' = getCompletionString (x:st) xs
    | otherwise = if Just x == fmap closing (listToMaybe st) then getCompletionString (tail st) xs else ""


main :: IO ()
main = do
    input <- lines <$> getContents

    putStr "part 1: "
    let chars = map (score . getInvalidChar []) input
    print $ sum chars

    putStr "part 2: "
    let compls = filter (> 0) $ map (calcScore . getCompletionString []) input
    print $ sort compls !! (length compls `div` 2)