module Util where

import Data.Char (isSpace)
import qualified Data.Map as Map
import Data.Map (Map)

splitOn :: (a -> Bool) -> [a] -> [[a]]
splitOn p s = case dropWhile p s of
              [] -> []
              s' -> w : splitOn p s''
                    where (w, s'') = break p s'

split :: (Eq a) => a -> [a] -> [[a]]
split c = splitOn (== c)

enumerate :: [a] -> [(Int,a)]
enumerate l = zip [0..] l

type Point2 = (Int,Int)
type Point3 = (Int,Int,Int)
type Grid = Map Point2 Char

toGrid :: String -> Grid
toGrid s = Map.fromList [((x,y),c) | (y,r) <- enumerate (lines s), (x,c) <- enumerate r]

neighbors8 :: Point2 -> [Point2]
neighbors8 (x,y) =
  [(x-1,y-1),(x,y-1),(x+1,y-1),(x-1,y),(x+1,y),(x-1,y+1),(x,y+1),(x+1,y+1)]

neighbors4 :: Point2 -> [Point2]
neighbors4 (x,y) =
  [(x-1,y), (x+1,y), (x,y-1), (x,y+1)]

trim :: String -> String
trim = f . f
  where f = reverse . dropWhile isSpace