import           Parsing (splitByString)

main :: IO ()
main = do
  input <- getContents
  let
    fish = parseFish input
  (putStrLn . show . solution1) fish

solution1 :: [Int] -> Int
solution1 = length . (simulateDays 80)

parseFish :: String -> [Int]
parseFish = (map read) . (splitByString ",")

simulateDays :: Int -> [Int] -> [Int]
simulateDays days fish = foldr (\f acc -> f acc) fish (replicate days tickDay)

tickDay :: [Int] -> [Int]
tickDay [] = []
tickDay (fish:otherFish)
  | fish == 0 = 6:8:(tickDay otherFish)
  | otherwise = (fish - 1):(tickDay otherFish)

-- Tests

testInput = "3,4,3,1,2"
testParsed = parseFish testInput

test1 = solution1 (parseFish testInput)

testTick = (tickDay . tickDay) testParsed
testSimulate = length (simulateDays 80 testParsed)