{-# LANGUAGE FlexibleContexts, ScopedTypeVariables #-}
module Main where
import qualified Graphics.UI.FLTK.LowLevel.FL as FL
import Graphics.UI.FLTK.LowLevel.Fl_Enumerations
import Graphics.UI.FLTK.LowLevel.Fl_Types
import Graphics.UI.FLTK.LowLevel.FLTKHS
import Control.Monad
import Data.IORef

star :: Int -> Int -> Double -> IO ()
star w h n = do
  flcPushMatrix
  flcTranslate (ByXY (ByX (fromIntegral w / 2)) (ByY (fromIntegral h /2)))
  flcScaleWithY (ByXY (ByX (fromIntegral w / 2)) (ByY (fromIntegral h /2)))
  forM_ [0..n] $ \i -> do
    forM_ [(i+1)..n] $ \j -> do
      let i_vertex :: Double =  2 * pi * i/n + 0.1
          j_vertex :: Double =  2 * pi * j/n + 0.1
      flcBeginLine
      flcVertex (ByXY (ByX $ cos i_vertex) (ByY $ sin i_vertex))
      flcVertex (ByXY (ByX $ cos j_vertex) (ByY $ sin j_vertex))
      flcEndLine
  flcPopMatrix

sliderCb :: IORef (Double,Double) -> (Double -> (Double,Double) -> (Double,Double))-> Ref HorSlider -> IO ()
sliderCb sides' sidesf' slider' = do
  v' <- getValue slider'
  modifyIORef sides' (sidesf' v')
  (Just p') <- getParent slider'
  redraw p'

badDraw :: IORef (Double,Double) -> Int -> Int -> ((Double,Double) -> Double) -> IO ()
badDraw sides w h which = do
  flcSetColor blackColor >> flcRectf (toRectangle (0,0,w,h))
  flcSetColor whiteColor >> readIORef sides >>= star w h . which


drawWindow :: forall a r1 r2 r3 r4.
              (
               FindOp a (DrawChild ())(Match r1),
               FindOp a (GetChild ()) (Match r2),
               FindOp a (GetH ())     (Match r3),
               FindOp a (GetW ())     (Match r4),
               Op (DrawChild ())  r1 a (Ref Widget -> IO ()),
               Op (GetChild ())   r2 a (Int -> IO (Ref Widget)),
               Op (GetH ())       r3 a (IO Int),
               Op (GetW ())       r4 a (IO Int)
              ) =>
              IORef (Double, Double) ->
              ((Double, Double) -> Double) ->
              Ref a ->
              IO ()
drawWindow sides' whichf' w' = do
  ww' <- getW w'
  wh' <- getH w'
  badDraw sides' ww' wh' whichf'
  c' <- getChild w' (0 :: Int)
  drawChild w' (c' :: Ref Widget)

main :: IO ()
main = do
  visual' <- FL.visual ModeDouble
  if (not visual') then print "Xdbe not supported, faking double buffer with pixmaps.\n" else return ()
  sides' <- newIORef (20,20)
  w01 <- windowNew (toSize (420,420)) Nothing (Just "Fl_Single_Window")
  setBox w01 FlatBox
  begin w01
  w1 <- singleWindowCustom
          (Size (Width 400) (Height 400))
          (Just (Position (X 10) (Y 10)))
          (Just "Single Window")
          defaultCustomWidgetFuncs {
            drawCustom = (Just $ drawWindow sides' fst)
          }
          defaultCustomWindowFuncs
  setBox w1 FlatBox
  setColor w1 blackColor
  setResizable w1 w1
  begin w1
  slider0 <- horSliderNew (toRectangle (20,370,360,25)) Nothing
  range slider0 2 30
  setStep slider0 1
  _ <- readIORef sides' >>= setValue slider0 . fst
  setCallback slider0 (sliderCb sides' (\v (_,s2) -> (v, s2)))
  end w1
  end w01
  w02 <- windowNew (Size (Width 420) (Height 420)) Nothing (Just "Fl_Double_Window")
  setBox w02 FlatBox
  begin w02
  w2 <- doubleWindowCustom
          (Size (Width 400) (Height 400))
          (Just $ Position (X 10) (Y 10))
          (Just "Fl_Double_Window")
          defaultCustomWidgetFuncs {
                drawCustom = Just (drawWindow sides' snd)
              }
          defaultCustomWindowFuncs
  setBox w2 FlatBox
  setColor w2 blackColor
  setResizable w2 w2
  begin w2
  slider1 <- horSliderNew (toRectangle $ (20,370,360,25)) Nothing
  range slider1 2 30
  setStep slider1 1
  _ <- readIORef sides' >>= setValue slider1 . fst
  setCallback slider1 (sliderCb sides' (\v (s1,_) -> (s1,v)))
  end w2
  end w02
  showWidget w01
  showWidget w1
  showWidget w02
  showWidget w2
  _ <- FL.run
  return ()