import System.Random

type Grid = [[Char]]

gridWidth :: Int
gridWidth = 20

gridHeight :: Int
gridHeight = 10

-- Initialize the grid with empty spaces
emptyGrid :: Grid
emptyGrid = replicate gridHeight (replicate gridWidth ' ')

-- Define the light source position
lightSource :: (Int, Int)
lightSource = (5, 5)

-- Add obstacles (stones) at random positions
addObstacles :: Grid -> Int -> IO Grid
addObstacles grid 0 = return grid
addObstacles grid n = do
  x <- randomRIO (0, gridWidth - 1)
  y <- randomRIO (0, gridHeight - 1)
  let updatedGrid = replaceElement grid x y '#'
  addObstacles updatedGrid (n - 1)

-- Replace an element at the specified position
replaceElement :: Grid -> Int -> Int -> Char -> Grid
replaceElement grid x y newElem =
  take y grid ++
  [take x (grid !! y) ++ [newElem] ++ drop (x + 1) (grid !! y)] ++
  drop (y + 1) grid

-- Spread light from the source
spreadLight :: Grid -> (Int, Int) -> Int -> Grid
spreadLight grid _ 0 = grid
spreadLight grid (x, y) intensity
  | x < 0 || x >= gridWidth || y < 0 || y >= gridHeight = grid
  | grid !! y !! x /= ' ' && grid !! y !! x /= '#' = grid
  | otherwise =
    let updatedGrid = replaceElement grid x y '*'
    in foldl (\g (dx, dy) -> spreadLight g (x + dx, y + dy) (intensity - 1))
             updatedGrid [(1, 0), (-1, 0), (0, 1), (0, -1)]

main :: IO ()
main = do
  gridWithObstacles <- addObstacles emptyGrid 30
  let finalGrid = spreadLight gridWithObstacles lightSource 5
  mapM_ putStrLn finalGrid