module Navigation where

import Affection as A

import Data.Matrix as M
import qualified Data.HashSet as HS
import Data.Graph.AStar
import Data.Maybe (isJust)

import Linear

-- internal imports

import Types.Map
import Types.UserData
import Types.Interior

isReachable :: Matrix (Maybe ImgId) -> [V2 Int] -> [ReachPoint] -> Bool
isReachable imgmat reaches exits =
  let astarAppl ex rc = aStar
        (naviGraph imgmat)
        (\a b -> distance (fmap fromIntegral a) (fmap fromIntegral b))
        (\a -> distance (fmap fromIntegral ex) (fmap fromIntegral a))
        (== ex)
        rc
      result =
        (concatMap
          (\exit -> map (astarAppl exit) reaches)
          (map pointCoord exits))
  in  all isJust result

naviGraph :: Matrix (Maybe ImgId) -> V2 Int -> HS.HashSet (V2 Int)
naviGraph imgmat (V2 r c) =
  let list = foldl
        (\acc (or, oc) -> if null (imgObstacle $ imgmat M.! (r + or, c + oc))
          then if or == 0 && oc == 0 then acc else V2 (r + or) (c + oc): acc
          else acc
          )
        []
        [(0, 1), (0, -1), (1, 0), (-1, 0)]
  in  HS.fromList list