{-# LANGUAGE LambdaCase #-}

import Data.List.Split
import Linear.V3

main = do
    moons <- parseContent <$> readFile "testinput"
    let velocity = replicate 4 $ V3 0 0 0
    print $ energy $ step (moons,velocity) 1000

removeJunk :: String -> String
removeJunk xs = [ x | x <- xs, x `notElem` " <>xyz=" ]

parseContent :: String -> [V3 Int]
parseContent = map ((\[x,y,z]->V3 x y z) . map read . splitOn ",") . lines . removeJunk

gravity :: [V3 Int] -> [V3 Int]
gravity xs = [sum [signum $ x-y | x<-xs, y/=x] | y<-xs]

step :: ([V3 Int],[V3 Int]) -> Int -> ([V3 Int],[V3 Int])
step (moons,vel) 0 = (moons,vel)
step (moons,vel) n = step (zipWith (+) moons newVel,newVel) (n-1)
    where dVel = gravity moons
          newVel = zipWith (+) vel dVel

energy :: ([V3 Int],[V3 Int]) -> Int
energy (x,y) = sum $ zipWith (*) (geten x) (geten y) where
    geten = map (sum . abs)