module Day13 where
import System.IO (openFile)
import Data.Text (unpack, splitOn, pack)
import Prelude hiding (splitAt)
import Data.Char (digitToInt)
import Data.List (nub)

splitAt :: String -> String -> [String]
splitAt delimiter str = map unpack $ splitOn (pack delimiter) $ pack str

fold :: (Int, Int) -> String -> (Int, Int)
fold (x, y) str
    | head str == 'x' = (fold' x, y)
    | head str == 'y' = (x, fold' y)
    where coord = read . last $ splitAt "=" str
          fold' num
            | num > coord = coord - (num - coord)
            | otherwise = num

main :: IO ()
main = do
    input <- readFile "inputs/13.txt"

    let (coords', folds') = (\[a,b] -> (lines a, lines b)) $ splitAt "\n\n" input
    --
    let coords = (\[a,b] -> (read a, read b) :: (Int, Int)) <$> map (splitAt ",") coords'
        folds  = map (last . splitAt " ") folds'

    print . length . nub $ [fold pos (head folds) | pos <- coords ]