import Data.Set as S
import Data.List (transpose)
import Data.Char (digitToInt)
import Debug.Trace (traceShowId)

type TreeSet = S.Set (Int, Int)

toIndices :: [a] -> [Int]
toIndices = fmap fst . zip [0..]

enumerate = zip [0..]

check :: Ord t1 => [t1] -> Int -> t1 -> [Int]
check [] i max = []
check (t:ts) i req = (if t > req then (i:) else id) $ check ts (i+1) (max t req)

addRow :: (Int -> (Int, Int)) -> [Int] -> TreeSet
addRow f ts = S.fromList (Prelude.map f (left ++ right)) where
    check' ts = check ts 0 (-1)
    left = check' ts
    right = (\x -> length ts - x - 1) <$> check' (reverse ts)

evalOutside :: [[Int]] -> TreeSet
evalOutside xs = Prelude.foldr S.union S.empty (hor ++ ver) where
    hor = (\(i, ts) -> addRow (i,) ts) <$> enumerate xs
    ver = (\(i, ts) -> addRow (,i) ts) <$> enumerate (transpose xs)



scenicScore :: (Int, Int) -> [[Int]] -> Int
scenicScore (x,y) ts = product $ count <$> [reverse left, right, reverse up, down] where
    (left, _:right) = Prelude.splitAt x (ts !! y)
    (up, _:down) = Prelude.splitAt y (transpose ts !! x)
    height = ts !! y !! x
    count t = length t `min` (1 + length (takeWhile (<height) t))

allScenics :: [[Int]] -> [Int]
allScenics ts = Prelude.map (\c -> scenicScore c ts) coords where 
    coords = [(i,j) | i <- [0..length ts-1], j <- [0..length (head ts)-1]]
    


main :: IO ()
main = do
    x <- lines <$> readFile "inputs/day08"
    let ts = fmap (fmap digitToInt) x

    putStr "part 1: "
    print $ S.size $ evalOutside ts

    putStr "part 2: "
    print $ maximum (allScenics ts)