{-# OPTIONS -fglasgow-exts #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  XUtil
-- Copyright   :  (C) 2007 Andrea Rossato
-- License     :  BSD3
--
-- Maintainer  :  andrea.rossato@unitn.it
-- Stability   :  unstable
-- Portability :  unportable
--
-----------------------------------------------------------------------------

module XUtil
    ( XFont
    , initFont
    , initCoreFont
    , initUtf8Font
    , releaseFont
    , textExtents
    , textWidth
    , printString
    , initColor
    , newWindow
    , nextEvent'
    , readFileSafe
    , hGetLineSafe
    , io
    , fi
    , withColors
    , DynPixel(..)
    ) where

import Control.Concurrent
import Control.Monad
import Control.Monad.Trans
import Data.IORef
import Foreign
import Graphics.X11.Xlib hiding (textExtents, textWidth)
import qualified Graphics.X11.Xlib as Xlib (textExtents, textWidth)
import Graphics.X11.Xlib.Extras
import System.Posix.Types (Fd(..))
import System.IO
import System.IO.Unsafe (unsafePerformIO)
#if defined XFT || defined UTF8
import Foreign.C
# if __GLASGOW_HASKELL__ < 612
import qualified System.IO.UTF8 as UTF8 (readFile,hGetLine)
# else
import qualified System.IO as UTF8 (readFile,hGetLine)
# endif
#endif
#if defined XFT
import Data.List
import Graphics.X11.Xft
import Graphics.X11.Xrender
#endif

readFileSafe :: FilePath -> IO String
#if defined XFT || defined UTF8
readFileSafe = UTF8.readFile
#else
readFileSafe = readFile
#endif

hGetLineSafe :: Handle -> IO String
#if defined XFT || defined UTF8
hGetLineSafe = UTF8.hGetLine
#else
hGetLineSafe = hGetLine
#endif

-- Hide the Core Font/Xft switching here
data XFont =Core FontStruct
           | Utf8 FontSet
#ifdef XFT
           | Xft  XftFont
#endif

-- | When initFont gets a font name that starts with 'xft:' it switchs to the Xft backend
-- Example: 'xft:Sans-10'
initFont :: Display ->String -> IO XFont
initFont d s =
#ifdef XFT
  if xftPrefix `isPrefixOf` s then
     do setupLocale
        xftdraw <- xftFontOpen d (defaultScreenOfDisplay d) (drop (length xftPrefix) s)
        return (Xft xftdraw)
  else
#endif
#ifdef UTF8
      (setupLocale >> initUtf8Font d s >>= return . Utf8)
#else
      (initCoreFont d s >>= return . Core)
#endif
#ifdef XFT
  where xftPrefix = "xft:"
#endif

releaseFont :: Display -> XFont -> IO ()
#ifdef XFT
releaseFont d (Xft xftfont) = xftFontClose    d xftfont
#endif
releaseFont d (Utf8     fs) = releaseUtf8Font d fs
releaseFont d (Core     fs) = releaseCoreFont d fs

-- | Given a fontname returns the font structure. If the font name is
--  not valid the default font will be loaded and returned.
initCoreFont :: Display -> String -> IO FontStruct
initCoreFont dpy s = catch (getIt dpy) (fallBack dpy)
      where getIt    d = loadQueryFont d s
            fallBack d = const $ loadQueryFont d "-misc-fixed-*-*-*-*-10-*-*-*-*-*-*-*"

releaseCoreFont :: Display -> FontStruct -> IO ()
releaseCoreFont d = freeFont d

-- | Given a fontname returns the font structure. If the font name is
--  not valid the default font will be loaded and returned.
initUtf8Font :: Display -> String -> IO FontSet
initUtf8Font dpy s = do
  (_,_,fs) <- catch (getIt dpy) (fallBack dpy)
  return fs
      where getIt    d = createFontSet d s
            fallBack d = const $ createFontSet d "-misc-fixed-*-*-*-*-10-*-*-*-*-*-*-*"

releaseUtf8Font :: Display -> FontSet -> IO ()
releaseUtf8Font d = freeFontSet d

textWidth :: Display -> XFont -> String -> IO Int
textWidth _   (Utf8 fs) s = return $ fi $ wcTextEscapement fs s
textWidth _   (Core fs) s = return $ fi $ Xlib.textWidth fs s
#ifdef XFT
textWidth dpy (Xft xftdraw) s = do
    gi <- xftTextExtents dpy xftdraw s
    return $ xglyphinfo_xOff gi
#endif

textExtents :: XFont -> String -> IO (Int32,Int32)
textExtents (Core fs) s = do
  let (_,a,d,_) = Xlib.textExtents fs s
  return (a,d)
textExtents (Utf8 fs) s = do
  let (_,rl)  = wcTextExtents fs s
      ascent  = fi $ - (rect_y rl)
      descent = fi $ rect_height rl + (fi $ rect_y rl)
  return (ascent, descent)
#ifdef XFT
textExtents (Xft xftfont) _ = do
  ascent  <- fi `fmap` xftfont_ascent  xftfont
  descent <- fi `fmap` xftfont_descent xftfont
  return (ascent, descent)
#endif

printString :: Display -> Drawable -> XFont -> GC -> String -> String
            -> Position -> Position -> String  -> IO ()
printString d p (Core fs) gc fc bc x y s = do
    setFont d gc $ fontFromFontStruct fs
    withColors d [fc, bc] $ \[fc', bc'] -> do
      setForeground d gc fc'
      setBackground d gc bc'
      drawImageString d p gc x y s

printString d p (Utf8 fs) gc fc bc x y s =
    withColors d [fc, bc] $ \[fc', bc'] -> do
      setForeground d gc fc'
      setBackground d gc bc'
      io $ wcDrawImageString d p fs gc x y s

#ifdef XFT
printString dpy drw fs@(Xft font) gc fc bc x y s = do
  let screen   = defaultScreenOfDisplay dpy
      colormap = defaultColormapOfScreen screen
      visual   = defaultVisualOfScreen screen
  withColors dpy [bc] $ \[bcolor] -> do
    (a,d)  <- textExtents fs s
    gi     <- xftTextExtents dpy font s
    setForeground dpy gc bcolor
    fillRectangle dpy drw gc (x - fi (xglyphinfo_x gi))
                             (y - fi a)
                             (fi $ xglyphinfo_xOff gi)
                             (fi $ a + d)
    withXftDraw dpy drw visual colormap $
      \draw -> withXftColorName dpy visual colormap fc $
      \color -> xftDrawString draw color font x y s
#endif

data DynPixel = DynPixel { allocated :: Bool
                         , pixel     :: Pixel
                         }

-- | Get the Pixel value for a named color: if an invalid name is
-- given the black pixel will be returned.
initColor :: Display -> String -> IO DynPixel
initColor dpy c = (initColor' dpy c) `catch`
                  (const . return $ DynPixel False (blackPixel dpy $ defaultScreen dpy))

type ColorCache = [(String, Color)]
{-# NOINLINE colorCache #-}
colorCache :: IORef ColorCache
colorCache = unsafePerformIO $ newIORef []

getCachedColor :: String -> IO (Maybe Color)
getCachedColor color_name = lookup color_name `fmap` readIORef colorCache

putCachedColor :: String -> Color -> IO ()
putCachedColor name c_id = modifyIORef colorCache $ \c -> (name, c_id) : c

initColor' :: Display -> String -> IO DynPixel
initColor' dpy c = do
  let colormap = defaultColormap dpy (defaultScreen dpy)
  cached_color <- getCachedColor c
  c' <- case cached_color of
          Just col -> return col
          _        -> do (c'', _) <- allocNamedColor dpy colormap c
                         putCachedColor c c''
                         return c''
  return $ DynPixel True (color_pixel c')

withColors :: MonadIO m => Display -> [String] -> ([Pixel] -> m a) -> m a
withColors d cs f = do
  ps <- mapM (io . initColor d) cs
  f $ map pixel ps

-- | Creates a window with the attribute override_redirect set to True.
-- Windows Managers should not touch this kind of windows.
newWindow :: Display -> Screen -> Window -> Rectangle -> Bool -> IO Window
newWindow dpy scr rw (Rectangle x y w h) o = do
  let visual   = defaultVisualOfScreen scr
      attrmask = cWOverrideRedirect
  allocaSetWindowAttributes $
         \attributes -> do
           set_override_redirect attributes o
           createWindow dpy rw x y w h 0 (defaultDepthOfScreen scr)
                        inputOutput visual attrmask attributes
-- | A version of nextEvent that does not block in foreign calls.
nextEvent' :: Display -> XEventPtr -> IO ()
nextEvent' d p = do
    pend <- pending d
    if pend /= 0
        then nextEvent d p
        else do
            threadWaitRead (Fd fd)
            nextEvent' d p
 where
    fd = connectionNumber d

io :: MonadIO m => IO a -> m a
io = liftIO

-- | Short-hand for 'fromIntegral'
fi :: (Integral a, Num b) => a -> b
fi = fromIntegral

#if defined XFT || defined UTF8
#include <locale.h>
foreign import ccall unsafe "locale.h setlocale"
    setlocale :: CInt -> CString -> IO CString

setupLocale :: IO CString
setupLocale = withCString "" $ setlocale (#const LC_ALL)
#endif