{-# LANGUAGE TypeFamilies, DeriveDataTypeable #-}

module Phi.Widgets.Taskbar ( TaskbarConfig(..)
                           , defaultTaskbarConfig
                           , taskbar
                           ) where

import Control.Concurrent
import Control.Monad
import Control.Monad.State
import Control.Monad.Trans

import Data.Char
import Data.Maybe
import Data.Typeable
import qualified Data.Map as M

import Foreign.C.Types

import Graphics.Rendering.Cairo
import Graphics.Rendering.Pango.Cairo
import Graphics.Rendering.Pango.Enums (PangoRectangle(..))
import Graphics.Rendering.Pango.Layout

import Graphics.X11.Xlib (Window)
import qualified Graphics.X11.Xlib as Xlib
import qualified Graphics.X11.Xlib.Extras as XExtras

import Codec.Binary.UTF8.String

import Phi.Phi
import Phi.Types
import Phi.Border
import Phi.Widget
import Phi.X11.Atoms


data TaskbarConfig = TaskbarConfig { taskMaxSize  :: !Int
                                   , showDesktops :: !Bool
                                   , taskBorder   :: !BorderConfig
                                   , activeTaskBorder   :: !BorderConfig
                                   } deriving Show

defaultTaskbarConfig :: TaskbarConfig
defaultTaskbarConfig = TaskbarConfig { taskMaxSize = 150
                                     , showDesktops = False
                                     , taskBorder = defaultBorderConfig
                                     , activeTaskBorder = defaultBorderConfig { borderColor = (1, 1, 1, 1) }
                                     }

data Taskbar = Taskbar TaskbarConfig deriving Show

data TaskbarState = TaskbarState { taskbarActiveWindow :: !Window
                                 , taskbarDesktopCount :: !Int
                                 , taskbarWindows      :: ![Window]
                                 , taskbarWindowStates :: !(M.Map Window WindowState)
                                 } deriving Show

data WindowState = WindowState { windowTitle   :: !String
                               , windowDesktop :: !Int
                               , windowVisible :: !Bool
                               } deriving (Show, Eq)

data TaskbarMessage = WindowListUpdate [Xlib.Window] (M.Map Window WindowState)
                    | DesktopCountUpdate Int
                    | ActiveWindowUpdate Window
                    deriving (Show, Typeable)

instance WidgetClass Taskbar where
  type WidgetData Taskbar = TaskbarState
  
  initWidget (Taskbar _) phi dispvar = do
    forkIO $ taskbarRunner phi dispvar
    
    return $ TaskbarState 0 0 [] M.empty

    
  minSize _ = 0
  weight _ = 1
  
  render (Taskbar config) TaskbarState {taskbarActiveWindow = activeWindow, taskbarDesktopCount = desktopCount, taskbarWindows = windows, taskbarWindowStates = windowStates} w h = do
    let desktopWindows = map (\desktop -> (desktop, filter (fromMaybe False . fmap (windowOnDesktop desktop) . flip M.lookup windowStates) windows)) $ take desktopCount [0..]
        windowCount = sum $ map (length . snd) $ desktopWindows
    when (windowCount /= 0) $ do
      let windowWidth = min (taskMaxSize config) (w `div` windowCount)
      
      forM_ (zip [0..] $ join $ map snd desktopWindows) $ \(i, window) -> do
        let border = if window == activeWindow then activeTaskBorder config else taskBorder config
        drawBorder border (i*windowWidth) 0 windowWidth h
  
  handleMessage _ priv m = case (fromMessage m) of
    Just (WindowListUpdate windows windowStates) -> priv {taskbarWindows = windows, taskbarWindowStates = windowStates}
    Just (DesktopCountUpdate count) -> priv {taskbarDesktopCount = count}
    Just (ActiveWindowUpdate window) -> priv {taskbarActiveWindow = window}
    _ -> priv


windowOnDesktop :: Int -> WindowState -> Bool
windowOnDesktop desktop state = (windowVisible state) && (desktop == windowDesktop state)


taskbarRunner :: Phi -> Display -> IO ()
taskbarRunner phi dispvar = do
  (windows, tasks) <- liftIO $ withDisplay dispvar $ \disp -> do
    (windows, tasks) <- getWindowStates disp (getAtoms dispvar) [] M.empty
    desktopCount <- getDesktopCount disp (getAtoms dispvar) 
    activeWindow <- getActiveWindow disp (getAtoms dispvar) 
    sendMessage phi $ WindowListUpdate windows tasks
    sendMessage phi $ DesktopCountUpdate desktopCount
    sendMessage phi $ ActiveWindowUpdate activeWindow
    return (windows, tasks)
  sendMessage phi Repaint
  
  flip evalStateT (windows, tasks) $ forever $ do
    m <- receiveMessage phi
    case (fromMessage m) of
      Just event@XExtras.PropertyEvent {} -> 
        handlePropertyUpdate phi dispvar event
      _ ->
        return ()
            
handlePropertyUpdate :: Phi -> Display -> XExtras.Event -> StateT ([Window], M.Map Window WindowState) IO ()
handlePropertyUpdate phi dispvar XExtras.PropertyEvent {XExtras.ev_atom = atom, XExtras.ev_window = window} = do
  let atoms = getAtoms dispvar
  
  when (elem atom $ map ($ atoms) [ atom_NET_ACTIVE_WINDOW
                                  , atom_NET_NUMBER_OF_DESKTOPS
                                  , atom_NET_CLIENT_LIST
                                  , atom_NET_WM_NAME
                                  , atomWM_NAME
                                  , atom_NET_WM_DESKTOP
                                  , atom_NET_WM_STATE
                                  ]) $ withDisplay dispvar $ \disp -> do
    let rootwin = Xlib.defaultRootWindow disp
    if (window == rootwin)
      then do
      when (atom == atom_NET_ACTIVE_WINDOW atoms) $ do
        activeWindow <- liftIO $ getActiveWindow disp atoms
        sendMessage phi $ ActiveWindowUpdate activeWindow
        sendMessage phi Repaint
      when (atom == atom_NET_NUMBER_OF_DESKTOPS atoms) $ do
        desktopCount <- liftIO $ getDesktopCount disp atoms
        sendMessage phi $ DesktopCountUpdate desktopCount
        sendMessage phi Repaint
      when (atom == atom_NET_CLIENT_LIST atoms) $ do
        (windows, windowStates) <- get
        (windows', windowStates') <- liftIO $ getWindowStates disp atoms windows windowStates
        
        when (windows /= windows' || windowStates /= windowStates') $ do
          sendMessage phi $ WindowListUpdate windows' windowStates'
          sendMessage phi Repaint
          put (windows', windowStates')
    
      else do
      (windows, windowStates) <- get
      when (elem window windows) $ do
        let windowState = M.lookup window windowStates
        windowState' <- liftIO $ getWindowState disp atoms window
        
        when (windowState /= (Just windowState')) $ do
          let windowStates' = M.insert window windowState' windowStates
          sendMessage phi $ WindowListUpdate windows windowStates'
          sendMessage phi Repaint
          put (windows, windowStates')

getDesktopCount :: Xlib.Display -> Atoms -> IO Int
getDesktopCount disp atoms =
  liftM (fromIntegral . fromMaybe 0 . join . fmap listToMaybe) $ XExtras.getWindowProperty32 disp (atom_NET_NUMBER_OF_DESKTOPS atoms) $ Xlib.defaultRootWindow disp

getActiveWindow :: Xlib.Display -> Atoms -> IO Window
getActiveWindow disp atoms =
  liftM (fromIntegral . fromMaybe 0 . join . fmap listToMaybe) $ XExtras.getWindowProperty32 disp (atom_NET_ACTIVE_WINDOW atoms) $ Xlib.defaultRootWindow disp

getWindowStates :: Xlib.Display -> Atoms -> [Window] -> M.Map Window WindowState -> IO ([Window], M.Map Window WindowState)
getWindowStates disp atoms oldWindows windowStates = do
  windows <- getWindowList disp atoms oldWindows
  
  let windowStates' = map (\w -> (w, M.lookup w windowStates)) windows
  
  newWindowStates <- mapM getWindowState' windowStates'
  
  return (windows, M.fromList newWindowStates)
    where
      rootwin = Xlib.defaultRootWindow disp
      
      getWindowState' (window, Just windowState) = return (window, windowState) 
      getWindowState' (window, Nothing) = do
        windowState <- getWindowState disp atoms window
        return (window, windowState)

getWindowState :: Xlib.Display -> Atoms -> Window -> IO  WindowState
getWindowState disp atoms window = do
  Xlib.selectInput disp window Xlib.propertyChangeMask
  netwmname <- liftM (fmap (decode . map fromIntegral)) $ XExtras.getWindowProperty8 disp (atom_NET_WM_NAME atoms) window
  wmname <- case netwmname of
    Just name -> return name
    Nothing -> liftM (map unsignedChr . fromMaybe []) $ XExtras.getWindowProperty8 disp (atomWM_NAME atoms) window
  
  workspace <- liftM (fromIntegral . fromMaybe 0xFFFFFFFF . join . fmap listToMaybe) $ XExtras.getWindowProperty32 disp (atom_NET_WM_DESKTOP atoms) window
  
  visible <- showWindow disp atoms window
  
  return $ WindowState wmname workspace visible
    where
      unsignedChr = chr . fromIntegral . (fromIntegral :: (CChar -> CUChar))

showWindow :: Xlib.Display -> Atoms -> Window -> IO Bool
showWindow disp atoms window = do
  states <- liftM (map fromIntegral . fromMaybe []) $ XExtras.getWindowProperty32 disp (atom_NET_WM_STATE atoms) window
  transientForHint <- XExtras.getTransientForHint disp window
  windowType <- liftM (fromMaybe (atom_NET_WM_WINDOW_TYPE_NORMAL atoms) . fmap fromIntegral . join . fmap listToMaybe) $ XExtras.getWindowProperty32 disp (atom_NET_WM_STATE atoms) window
  
  return $ not $ or [ elem (atom_NET_WM_STATE_SKIP_TASKBAR atoms) states 
                    , transientForHint /= Nothing
                    , elem windowType $ map ($ atoms) [ atom_NET_WM_WINDOW_TYPE_DOCK 
                                                      , atom_NET_WM_WINDOW_TYPE_DESKTOP 
                                                      , atom_NET_WM_WINDOW_TYPE_TOOLBAR 
                                                      , atom_NET_WM_WINDOW_TYPE_MENU 
                                                      , atom_NET_WM_WINDOW_TYPE_SPLASH
                                                      ]
                    ]
  

getWindowList :: Xlib.Display -> Atoms -> [Window] -> IO [Window]
getWindowList disp atoms windows = do
  newWindows <- liftM (map fromIntegral . join . maybeToList) $ XExtras.getWindowProperty32 disp (atom_NET_CLIENT_LIST atoms) $ Xlib.defaultRootWindow disp
  return $ (filter (flip elem newWindows) windows) ++ (filter (not . flip elem windows) newWindows)


taskbar :: TaskbarConfig -> Widget
taskbar config = do
  Widget $ Taskbar config