-----------------------------------------------------------------------------
-- |
-- Module      :  Main.hs
-- Copyright   :  (c) Spencer Janssen 2007
-- License     :  BSD3-style (see LICENSE)
--
-- Maintainer  :  sjanssen@cse.unl.edu
-- Stability   :  unstable
-- Portability :  not portable, uses mtl, X11, posix
--
-----------------------------------------------------------------------------
--
-- xmonad, a minimalist, tiling window manager for X11
--

import Data.Bits
import qualified Data.Map as M
import Control.Monad.Reader

import System.Environment (getArgs)

import Graphics.X11.Xlib hiding (refreshKeyboardMapping)
import Graphics.X11.Xlib.Extras
import Graphics.X11.Xinerama    (getScreenInfo)

import XMonad
import Config
import StackSet (new)
import Operations   (manage, unmanage, focus, setFocusX, full, isClient, rescreen)

--
-- The main entry point
--
main :: IO ()
main = do
    dpy   <- openDisplay ""
    let dflt = defaultScreen dpy
        initcolor c = fst `liftM` allocNamedColor dpy (defaultColormap dpy dflt) c

    rootw  <- rootWindow dpy dflt
    wmdelt <- internAtom dpy "WM_DELETE_WINDOW" False
    wmprot <- internAtom dpy "WM_PROTOCOLS"     False
    xinesc <- getScreenInfo dpy
    nbc    <- initcolor normalBorderColor
    fbc    <- initcolor focusedBorderColor
    args <- getArgs

    let winset | ("--resume" : s : _) <- args
               , [(x, "")]            <- reads s = x
               | otherwise = new (fromIntegral workspaces) (fromIntegral $ length xinesc)
        safeLayouts = case defaultLayouts of [] -> (full, []); (x:xs) -> (x, xs)
        cf = XConf
            { display       = dpy
            , theRoot       = rootw
            , wmdelete      = wmdelt
            , wmprotocols   = wmprot
            -- fromIntegral needed for X11 versions that use Int instead of CInt.
            , normalBorder  = nbc
            , focusedBorder = fbc
            }
        st = XState
            { windowset     = winset
            , layouts       = M.fromList [(w, safeLayouts) | w <- [0 .. W workspaces - 1]]
            , xineScreens   = xinesc
            , dimensions    = (fromIntegral (displayWidth dpy dflt),
                               fromIntegral (displayHeight dpy dflt)) }

    xSetErrorHandler -- in C, I'm too lazy to write the binding: dons

    -- setup initial X environment
    sync dpy False
    selectInput dpy rootw $  substructureRedirectMask .|. substructureNotifyMask
                         .|. enterWindowMask .|. leaveWindowMask .|. structureNotifyMask
    grabKeys dpy rootw
    sync dpy False

    ws <- scan dpy rootw
    allocaXEvent $ \e ->
        runX cf st $ do
            mapM_ manage ws
            -- main loop, for all you HOF/recursion fans out there.
            forever $ handle =<< io (nextEvent dpy e >> getEvent e)
      where forever a = a >> forever a

-- ---------------------------------------------------------------------
-- IO stuff. Doesn't require any X state
-- Most of these things run only on startup (bar grabkeys)

-- | scan for any initial windows to manage
scan :: Display -> Window -> IO [Window]
scan dpy rootw = do
    (_, _, ws) <- queryTree dpy rootw
    filterM ok ws
  where
    ok w = do wa <- getWindowAttributes dpy w
              return $ not (wa_override_redirect wa)
                     && wa_map_state wa == waIsViewable

-- | Grab the keys back
grabKeys :: Display -> Window -> IO ()
grabKeys dpy rootw = do
    ungrabKey dpy anyKey anyModifier rootw
    flip mapM_ (M.keys keys) $ \(mask,sym) -> do
         kc <- keysymToKeycode dpy sym
         -- "If the specified KeySym is not defined for any KeyCode,
         -- XKeysymToKeycode() returns zero."
         when (kc /= '\0') $ mapM_ (grab kc . (mask .|.)) $
            [0, numlockMask, lockMask, numlockMask .|. lockMask]
  where
    grab kc m = grabKey dpy kc m rootw True grabModeAsync grabModeAsync

-- ---------------------------------------------------------------------
-- | Event handler. Map X events onto calls into Operations.hs, which
-- modify our internal model of the window manager state.
--
-- Events dwm handles that we don't:
--
--    [ButtonPress]    = buttonpress,
--    [Expose]         = expose,
--    [PropertyNotify] = propertynotify,
--

handle :: Event -> X ()

-- run window manager command
handle (KeyEvent {ev_event_type = t, ev_state = m, ev_keycode = code})
    | t == keyPress = withDisplay $ \dpy -> do
        s  <- io $ keycodeToKeysym dpy code 0
        whenJust (M.lookup (complement (numlockMask .|. lockMask) .&. m,s) keys) id

-- manage a new window
handle (MapRequestEvent    {ev_window = w}) = withDisplay $ \dpy -> do
    wa <- io $ getWindowAttributes dpy w -- ignore override windows
    when (not (wa_override_redirect wa)) $ manage w

-- window destroyed, unmanage it
-- window gone,      unmanage it
handle (DestroyWindowEvent {ev_window = w}) = whenX (isClient w) $ unmanage w
handle (UnmapEvent         {ev_window = w}) = whenX (isClient w) $ unmanage w

-- set keyboard mapping
handle e@(MappingNotifyEvent {ev_window = w}) = do
    io $ refreshKeyboardMapping e
    when (ev_request e == mappingKeyboard) $ withDisplay $ io . flip grabKeys w

-- click on an unfocused window, makes it focused on this workspace
handle (ButtonEvent {ev_window = w, ev_event_type = t}) | t == buttonPress = focus w

-- entered a normal window, makes this focused.
handle e@(CrossingEvent {ev_window = w, ev_event_type = t})
    | t == enterNotify && ev_mode   e == notifyNormal
                       && ev_detail e /= notifyInferior = focus w

-- left a window, check if we need to focus root
handle e@(CrossingEvent {ev_event_type = t})
    | t == leaveNotify
    = do rootw <- asks theRoot
         when (ev_window e == rootw && not (ev_same_screen e)) $ setFocusX rootw

-- configure a window
handle e@(ConfigureRequestEvent {}) = withDisplay $ \dpy -> do
    io $ configureWindow dpy (ev_window e) (ev_value_mask e) $ WindowChanges
        { wc_x            = ev_x e
        , wc_y            = ev_y e
        , wc_width        = ev_width e
        , wc_height       = ev_height e
        , wc_border_width = ev_border_width e
        , wc_sibling      = ev_above e
        -- this fromIntegral is only necessary with the old X11 version that uses
        -- Int instead of CInt.  TODO delete it when there is a new release of X11
        , wc_stack_mode   = fromIntegral $ ev_detail e }
    io $ sync dpy False

-- the root may have configured
handle e@(ConfigureEvent {ev_window = w}) = do
    r <- asks theRoot
    when (r == w) rescreen

handle _ = return () -- trace (eventName e) -- ignoring