{-# LANGUAGE LambdaCase #-}
module Main where

import Data.List
import Data.List.Split
import Data.List.Utils
import qualified Data.Map.Strict as M
import Data.Maybe
import Helpers
import Linear.V2

type DungeonMap = M.Map (V2 Int) Char

main :: IO ()
main = do
  map <- updateScreenBuffer M.empty (0, 0) <$> readFile "testinput1"
  putStrLn $ drawMap map
  let spos = findPos '@' map
  let epos = findPos 'e' map
  print $ getNeighbors map spos
  print $ getNeighborsMap map (getNeighbors map spos)
  print $ distanceFromTo map '@' 'd'

updateScreenBuffer :: DungeonMap -> (Int, Int) -> String -> DungeonMap
updateScreenBuffer buf _ [] = buf
updateScreenBuffer buf (x, y) (a:as) = updateScreenBuffer bufNew coord as
  where
    bufNew =
      if a /= '\n'
        then M.insert (V2 x y) a buf
        else buf
    coord =
      if a /= '\n'
        then (x + 1, y)
        else (0, y + 1)

getNeighbors :: DungeonMap -> V2 Int -> DungeonMap
getNeighbors m coord =
  M.fromList
    [ (u + coord, M.findWithDefault '#' (u + coord) m)
    | u <- unitVecs
    , M.findWithDefault '#' (u + coord) m /= '#'
    ]

getNeighborsMap :: DungeonMap -> DungeonMap -> DungeonMap
getNeighborsMap m n = M.unions [getNeighbors m x | (x, _) <- M.toList n]

distanceFromTo :: DungeonMap -> Char -> Char -> Int
distanceFromTo dmap schar echar =
  distanceFromTo' dmap (M.singleton spos schar) spos epos 1
  where
    spos = findPos schar dmap
    epos = findPos echar dmap
    distanceFromTo' mMap nMap start end n =
      if M.member end newNMap
        then n
        else distanceFromTo' mMap newNMap start end (n + 1)
      where
        newNMap = M.union nMap (getNeighborsMap mMap nMap)

findPos :: Char -> DungeonMap -> V2 Int
findPos c = head . M.keys . M.filter (`elem` [c])