import XMonad
import XMonad.Hooks.ManageHelpers
import qualified XMonad.StackSet as W
import Monad
import Data.Monoid (All (All))

main = xmonad $ defaultConfig {handleEventHook = evHook}

-- Helper functions to fullscreen the window
fullFloat, tileWin :: Window -> X ()
fullFloat w = windows $ W.float w r
    where r = W.RationalRect 0 0 1 1
tileWin w = windows $ W.sink w

evHook :: Event -> X All
evHook (ClientMessageEvent _ _ _ dpy win typ dat) = do
  state <- getAtom "_NET_WM_STATE"
  fullsc <- getAtom "_NET_WM_STATE_FULLSCREEN"
  isFull <- runQuery isFullscreen win

  -- Constants for the _NET_WM_STATE protocol
  let remove = 0
      add = 1
      toggle = 2

      -- The ATOM property type for changeProperty
      ptype = 4 

      action = head dat

  when (typ == state && (fromIntegral fullsc) `elem` tail dat) $ do
    when (action == add || (action == toggle && not isFull)) $ do
         io $ changeProperty32 dpy win state ptype propModeReplace [fromIntegral fullsc]
         fullFloat win
    when (head dat == remove || (action == toggle && isFull)) $ do
         io $ changeProperty32 dpy win state ptype propModeReplace []
         tileWin win

  -- It shouldn't be necessary for xmonad to do anything more with this event
  return $ All False

evHook _ = return $ All True