{-# LANGUAGE MultiParamTypeClasses, FlexibleContexts, ForeignFunctionInterface #-}
----------------------------------------------------------------------------
-- |
-- Module      :  XMonad.Main
-- Copyright   :  (c) Spencer Janssen 2007
-- License     :  BSD3-style (see LICENSE)
--
-- Maintainer  :  spencerjanssen@gmail.com
-- Stability   :  unstable
-- Portability :  not portable, uses mtl, X11, posix
--
-- xmonad, a minimalist, tiling window manager for X11
--
-----------------------------------------------------------------------------

module XMonad.Main (xmonad) where

import Data.Bits
import Data.List ((\\))
import qualified Data.Map as M
import qualified Data.Set as S
import Control.Monad.Reader
import Control.Monad.State
import Data.Maybe (fromMaybe)

import Foreign.C
import Foreign.Ptr

import System.Environment (getArgs)

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

import XMonad.Core
import qualified XMonad.Config as Default
import XMonad.StackSet (new, floating, member)
import qualified XMonad.StackSet as W
import XMonad.Operations

import System.IO

------------------------------------------------------------------------
-- Locale support

#include <locale.h>

foreign import ccall unsafe "locale.h setlocale"
    c_setlocale :: CInt -> Ptr CChar -> IO (Ptr CChar)

------------------------------------------------------------------------

-- |
-- The main entry point
--
xmonad :: (LayoutClass l Window, Read (l Window)) => XConfig l -> IO ()
xmonad initxmc = do
    -- setup locale information from environment
    withCString "" $ c_setlocale (#const LC_ALL)
    -- ignore SIGPIPE and SIGCHLD
    installSignalHandlers
    -- First, wrap the layout in an existential, to keep things pretty:
    let xmc = initxmc { layoutHook = Layout $ layoutHook initxmc }
    dpy   <- openDisplay ""
    let dflt = defaultScreen dpy

    rootw  <- rootWindow dpy dflt

    -- If another WM is running, a BadAccess error will be returned.  The
    -- default error handler will write the exception to stderr and exit with
    -- an error.
    selectInput dpy rootw $  substructureRedirectMask .|. substructureNotifyMask
                         .|. enterWindowMask .|. leaveWindowMask .|. structureNotifyMask
                         .|. buttonPressMask
    sync dpy False -- sync to ensure all outstanding errors are delivered

    -- turn off the default handler in favor of one that ignores all errors
    -- (ugly, I know)
    xSetErrorHandler -- in C, I'm too lazy to write the binding: dons

    xinesc <- getCleanedScreenInfo dpy
    nbc    <- do v            <- initColor dpy $ normalBorderColor  xmc
                 ~(Just nbc_) <- initColor dpy $ normalBorderColor Default.defaultConfig
                 return (fromMaybe nbc_ v)

    fbc    <- do v <- initColor dpy $ focusedBorderColor xmc
                 ~(Just fbc_)  <- initColor dpy $ focusedBorderColor Default.defaultConfig
                 return (fromMaybe fbc_ v)

    hSetBuffering stdout NoBuffering
    args <- getArgs

    let layout = layoutHook xmc
        lreads = readsLayout layout
        initialWinset = new layout (workspaces xmc) $ map SD xinesc

        maybeRead reads' s = case reads' s of
                                [(x, "")] -> Just x
                                _         -> Nothing

        winset = fromMaybe initialWinset $ do
                    ("--resume" : s : _) <- return args
                    ws                   <- maybeRead reads s
                    return . W.ensureTags layout (workspaces xmc)
                           $ W.mapLayout (fromMaybe layout . maybeRead lreads) ws

        cf = XConf
            { display       = dpy
            , config        = xmc
            , theRoot       = rootw
            , normalBorder  = nbc
            , focusedBorder = fbc
            , keyActions    = keys xmc xmc
            , buttonActions = mouseBindings xmc xmc
            , mouseFocused  = False
            , mousePosition = Nothing }
        st = XState
            { windowset     = initialWinset
            , mapped        = S.empty
            , waitingUnmap  = M.empty
            , dragging      = Nothing }

    allocaXEvent $ \e ->
        runX cf st $ do

            grabKeys
            grabButtons

            io $ sync dpy False

            ws <- io $ scan dpy rootw

            -- bootstrap the windowset, Operations.windows will identify all
            -- the windows in winset as new and set initial properties for
            -- those windows.  Remove all windows that are no longer top-level
            -- children of the root, they may have disappeared since
            -- restarting.
            windows . const . foldr W.delete winset $ W.allWindows winset \\ ws

            -- manage the as-yet-unmanaged windows
            mapM_ manage (ws \\ W.allWindows winset)

            userCode $ startupHook initxmc

            -- main loop, for all you HOF/recursion fans out there.
            forever_ $ prehandle =<< io (nextEvent dpy e >> getEvent e)

    return ()
      where
        forever_ a = a >> forever_ a

        -- if the event gives us the position of the pointer, set mousePosition
        prehandle e = let mouse = do guard (ev_event_type e `elem` evs)
                                     return (fromIntegral (ev_x_root e)
                                            ,fromIntegral (ev_y_root e))
                      in local (\c -> c { mousePosition = mouse }) (handle e)
        evs = [ keyPress, keyRelease, enterNotify, leaveNotify
              , buttonPress, buttonRelease]


-- ---------------------------------------------------------------------
-- | 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
        mClean <- cleanMask m
        ks <- asks keyActions
        userCodeDef () $ whenJust (M.lookup (mClean, s) ks) id

-- manage a new window
handle (MapRequestEvent    {ev_window = w}) = withDisplay $ \dpy -> do
    wa <- io $ getWindowAttributes dpy w -- ignore override windows
    -- need to ignore mapping requests by managed windows not on the current workspace
    managed <- isClient w
    when (not (wa_override_redirect wa) && not managed) $ do manage w

-- window destroyed, unmanage it
-- window gone,      unmanage it
handle (DestroyWindowEvent {ev_window = w}) = whenX (isClient w) $ do
    unmanage w
    modify (\s -> s { mapped       = S.delete w (mapped s)
                    , waitingUnmap = M.delete w (waitingUnmap s)})

-- We track expected unmap events in waitingUnmap.  We ignore this event unless
-- it is synthetic or we are not expecting an unmap notification from a window.
handle (UnmapEvent {ev_window = w, ev_send_event = synthetic}) = whenX (isClient w) $ do
    e <- gets (fromMaybe 0 . M.lookup w . waitingUnmap)
    if (synthetic || e == 0)
        then unmanage w
        else modify (\s -> s { waitingUnmap = M.update mpred w (waitingUnmap s) })
 where mpred 1 = Nothing
       mpred n = Just $ pred n

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

-- handle button release, which may finish dragging.
handle e@(ButtonEvent {ev_event_type = t})
    | t == buttonRelease = do
    drag <- gets dragging
    case drag of
        -- we're done dragging and have released the mouse:
        Just (_,f) -> modify (\s -> s { dragging = Nothing }) >> f
        Nothing    -> broadcastMessage e

-- handle motionNotify event, which may mean we are dragging.
handle e@(MotionEvent {ev_event_type = _t, ev_x = x, ev_y = y}) = do
    drag <- gets dragging
    case drag of
        Just (d,_) -> d (fromIntegral x) (fromIntegral y) -- we're dragging
        Nothing -> broadcastMessage e

-- click on an unfocused window, makes it focused on this workspace
handle e@(ButtonEvent {ev_window = w,ev_event_type = t,ev_button = b })
    | t == buttonPress = do
    -- If it's the root window, then it's something we
    -- grabbed in grabButtons. Otherwise, it's click-to-focus.
    isr <- isRoot w
    m <- cleanMask $ ev_state e
    mact <- asks (M.lookup (m, b) . buttonActions)
    case mact of
        (Just act) | isr -> act $ ev_subwindow e
        _                -> focus w
    broadcastMessage e -- Always send button events.

-- entered a normal window: focus it if focusFollowsMouse is set to
-- True in the user's config.
handle e@(CrossingEvent {ev_window = w, ev_event_type = t})
    | t == enterNotify && ev_mode   e == notifyNormal
    = whenX (asks $ focusFollowsMouse . config) (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 {ev_window = w}) = withDisplay $ \dpy -> do
    ws <- gets windowset
    wa <- io $ getWindowAttributes dpy w

    bw <- asks (borderWidth . config)

    if M.member w (floating ws)
        || not (member w ws)
        then do io $ configureWindow dpy w (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 = fromIntegral bw
                    , wc_sibling      = ev_above e
                    , wc_stack_mode   = ev_detail e }
                when (member w ws) (float w)
        else io $ allocaXEvent $ \ev -> do
                 setEventType ev configureNotify
                 setConfigureEvent ev w w
                     (wa_x wa) (wa_y wa) (wa_width wa)
                     (wa_height wa) (ev_border_width e) none (wa_override_redirect wa)
                 sendEvent dpy w False 0 ev
    io $ sync dpy False

-- configuration changes in the root may mean display settings have changed
handle (ConfigureEvent {ev_window = w}) = whenX (isRoot w) rescreen

-- property notify
handle PropertyEvent { ev_event_type = t, ev_atom = a }
    | t == propertyNotify && a == wM_NAME = userCodeDef () =<< asks (logHook . config)

handle e = broadcastMessage e -- trace (eventName e) -- ignoring


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

-- | scan for any new windows to manage. If they're already managed,
-- this should be idempotent.
scan :: Display -> Window -> IO [Window]
scan dpy rootw = do
    (_, _, ws) <- queryTree dpy rootw
    filterM ok ws
  -- TODO: scan for windows that are either 'IsViewable' or where WM_STATE ==
  -- Iconic
  where ok w = do wa <- getWindowAttributes dpy w
                  a  <- internAtom dpy "WM_STATE" False
                  p  <- getWindowProperty32 dpy a w
                  let ic = case p of
                            Just (3:_) -> True -- 3 for iconified
                            _          -> False
                  return $ not (wa_override_redirect wa)
                         && (wa_map_state wa == waIsViewable || ic)

-- | Grab the keys back
grabKeys :: X ()
grabKeys = do
    XConf { display = dpy, theRoot = rootw } <- ask
    let grab kc m = io $ grabKey dpy kc m rootw True grabModeAsync grabModeAsync
    io $ ungrabKey dpy anyKey anyModifier rootw
    ks <- asks keyActions
    forM_ (M.keys ks) $ \(mask,sym) -> do
         kc <- io $ keysymToKeycode dpy sym
         -- "If the specified KeySym is not defined for any KeyCode,
         -- XKeysymToKeycode() returns zero."
         when (kc /= '\0') $ mapM_ (grab kc . (mask .|.)) =<< extraModifiers

-- | XXX comment me
grabButtons :: X ()
grabButtons = do
    XConf { display = dpy, theRoot = rootw } <- ask
    let grab button mask = io $ grabButton dpy button mask rootw False buttonPressMask
                                           grabModeAsync grabModeSync none none
    io $ ungrabButton dpy anyButton anyModifier rootw
    ems <- extraModifiers
    ba <- asks buttonActions
    mapM_ (\(m,b) -> mapM_ (grab b . (m .|.)) ems) (M.keys $ ba)