Main.hs

module Main where

  import Snake hiding (replicate, length, any)
  import Data.List (intercalate)
  import Control.Concurrent
  -- import System.Console.ANSI
  import Control.Monad
  import System.IO
  import System.IO.NoBufferingWorkaround
  import System.Random
  import System.CPUTime

  -- The game needs to be turned into a grid will all of the correct elements
  -- in the right place.

  makeGrid :: Game -> Grid
  makeGrid ((snek, _), (fud, _), (w, h)) = [[a | x <- [0..w - 1], let a = if (x, y) == head snek then Head else if (x,y) `elem` snek then Snake else if (x, y) == fud then Food else Blank] | y <- [0..h - 1]]

  pretty :: Grid -> String
  pretty g = ((top++) . (++bottom) . (++"║\n") . ('║':) . concat . intercalate ["║\n║"]  . map (map show)) g
    where
      n = length (head g)
      top = ("╔" ++ (replicate n '═') ++ "╗\n")
      bottom = ("╚" ++ (replicate n '═') ++ "╝\n")

  -- IO Stuff

  clearScreen = putStr "\ESC[2J"

  moveCursor x y = mapM_ putStr ["\ESC[", show x, ";", show y, "H"]

  hideCursor = putStr "\ESC[?25l"

  showCursor = putStr "\ESC[?25h"

  main = do
    c <- newEmptyMVar
    initGetCharNoBuffering
    hideCursor
    clearScreen
    forkIO $ do
      hideCursor
      forever $ do
        a <- getCharNoBuffering
        case a of
          Just x  -> putMVar c x
          Nothing -> threadDelay 100
    gameLoop game c 0
    showCursor

  turnChar 'w' = turn North
  turnChar 'a' = turn West
  turnChar 's' = turn South
  turnChar 'd' = turn East
  turnChar _ = Just

  gameLoop :: Game -> MVar (Char) -> Int -> IO ()
  gameLoop (snake, food, size) c t0 = do
    -- Input
    a <- tryTakeMVar c
    let snake' = case (a >>= flip turnChar snake) of
                   Nothing -> snake
                   Just s  -> s
    -- Fixed Delta Update
    t1 <- fmap fromIntegral getCPUTime
    let diff = fromIntegral (t1 - t0)
    if diff < (fromIntegral delay) then do
      gameLoop (snake', food, size) c t0
    else do
    -- Physics
    let snake'' = (eat food . move) snake'
    food' <- if eatable food snake'' then do
               x <- randomRIO (0, fst size - 1)
               y <- randomRIO (0, snd size - 1)
               return ((x, y), 1)
             else return food
    let game' = (snake'', food', size)
    let grid = (pretty . makeGrid) game'
    -- Render
    if dead snake'' size then
      putStrLn $ "You're dead, You scored: " ++ (show $ score snake'')
    else do
        moveCursor 1 1
        putStrLn ""
        putStrLn ("Current Score: " ++ (show $ score snake''))
        putStrLn grid
        t2 <- fmap fromIntegral getCPUTime
        gameLoop game' c t2