module Graphics.UI.GLUT.Turtle.GLUTools (
	initialize,
	createWindow,
	printLines,
	keyboardCallback,
	displayAction,
	loop,

	module Graphics.UI.GLUT
) where

import Graphics.UI.GLUT hiding (initialize, createWindow)
import qualified Graphics.UI.GLUT as G
import System.Environment
import Control.Monad
import Data.IORef
import Data.IORef.Tools

initialize :: IO [String]
initialize = do
	prgName <- getProgName
	rawArgs <- getArgs
	args <- G.initialize prgName rawArgs
	initialDisplayMode $= [RGBMode, DoubleBuffered]
	return args

createWindow :: String -> Int -> Int -> IO Window
createWindow name w h = do
	initialWindowSize $= Size (fromIntegral w) (fromIntegral h)
	G.createWindow name

printLines :: G.Window -> Double -> [String] -> IO ()
printLines win w strs = do
	G.currentWindow $= Just win
	G.clearColor $= G.Color4 0 0 0 0
	G.clear [G.ColorBuffer]
	G.lineWidth $= (fromRational $ toRational w)
	zipWithM_ (printString (-2.8)) [-1800, -1600 .. 1800] strs
	G.swapBuffers

printString :: G.GLfloat -> G.GLfloat -> String -> IO ()
printString x y str =
	G.preservingMatrix $ do
		G.scale (0.0005 :: G.GLfloat)  0.0005 0.0005
		G.clearColor $= G.Color4 0 0 0 0
		G.color (G.Color4 0 1 0 0 :: G.Color4 G.GLfloat)
		w <- G.stringWidth G.Roman "Stroke font"
		G.translate (G.Vector3 (x * fromIntegral w)
			y 0 :: G.Vector3 G.GLfloat)
		G.renderString G.Roman str

keyboardCallback ::
	(Char -> G.KeyState -> G.Modifiers -> G.Position -> IO ()) -> IO ()
keyboardCallback f = G.keyboardMouseCallback $= Just (\k ks m p -> case k of
	G.Char chr -> do
		f chr ks m p
	_ -> return ())

displayAction :: IORef Int -> IO () -> IO ()
displayAction changed act = loop changed act >> G.displayCallback $= act

loop :: IORef Int -> IO a -> IO ()
loop changed act = G.addTimerCallback 10 $ timerAction changed act

timerAction :: IORef Int -> IO a -> IO ()
timerAction changed act = do
	c <- readIORef changed
	when (c > 0) $ do
		_ <- act
		atomicModifyIORef_ changed (subtract 1)
	G.addTimerCallback 10 $ timerAction changed act