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import Data.List.Split (splitOn)
split3Ways :: [Int] -> Int -> Int -> ([Int], [Int], [Int])
split3Ways xs from to
| to >= from = (take from xs, take (to - from) (drop from xs), drop to xs)
| otherwise = split3Ways xs to from
permute :: [Int] -> Int -> Int -> [Int]
permute xs from to
| to >= from = xs1 ++ reverse xs2 ++ xs3
| otherwise = xs1' ++ xs2 ++ xs3'
where (xs1, xs2, xs3) = split3Ways xs from to
xs4 = reverse (xs3 ++ xs1)
(xs3', xs1') = splitAt (length xs3) xs4
step :: ([Int], Int, Int) -> Int -> ([Int], Int, Int)
step (xs, skip, from) n = let m = length xs in
(permute xs from ((from + n) `mod` m), skip + 1, (from + n + skip) `mod` m)
solve1' :: [Int] -> Int
solve1' xs = let (ys, _, _) = foldl step ([0 .. 255], 0, 0) xs in
--solve1' xs = let (ys, _, _) = foldl step ([0 .. 4], 0, 0) xs in
(head ys) * (head $ tail ys)
parseInput :: [Char] -> [Int]
parseInput = (fmap read) . (splitOn ",")
solve1 :: [Char] -> Int
solve1 = solve1' . parseInput
input = "120,93,0,90,5,80,129,74,1,165,204,255,254,2,50,113"
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