----------------------------------------------------------------------------
-- |
-- 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
--
-----------------------------------------------------------------------------

module Main where

import Data.Bits
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 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, floating, member)
import qualified StackSet as W
import Operations

import System.IO

-- |
-- The main entry point
--
main :: IO ()
main = do
    dpy   <- openDisplay ""
    let dflt = defaultScreen dpy

    rootw  <- rootWindow dpy dflt
    xinesc <- getScreenInfo dpy
    nbc    <- initColor dpy normalBorderColor
    fbc    <- initColor dpy focusedBorderColor
    hSetBuffering stdout NoBuffering
    args <- getArgs

    let initialWinset = new layoutHook workspaces $ zipWith SD xinesc gaps

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

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

        gaps = take (length xinesc) $ defaultGaps ++ repeat (0,0,0,0)

        cf = XConf
            { display       = dpy
            , theRoot       = rootw
            , normalBorder  = nbc
            , focusedBorder = fbc }
        st = XState
            { windowset     = initialWinset
            , mapped        = S.empty
            , waitingUnmap  = M.empty
            , dragging      = Nothing }

    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

    allocaXEvent $ \e ->
        runX cf st $ do

            grabKeys
            grabButtons

            io $ sync dpy False

            -- bootstrap the windowset, Operations.windows will identify all
            -- the windows in winset as new and set initial properties for
            -- those windows
            windows (const winset)

            -- scan for all top-level windows, add the unmanaged ones to the
            -- windowset
            ws <- io $ scan dpy rootw
            mapM_ manage ws

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

    return ()
      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 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
    forM_ (M.keys keys) $ \(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
    mapM_ (\(m,b) -> mapM_ (grab b . (m .|.)) extraModifiers) (M.keys mouseBindings)

-- ---------------------------------------------------------------------
-- | 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
        userCode $ whenJust (M.lookup (cleanMask m,s) keys) 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) $ unmanage w

-- 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.adjust pred w (waitingUnmap s) })

-- 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
    if isr then userCode $ whenJust (M.lookup (cleanMask (ev_state e), b) mouseBindings) ($ ev_subwindow e)
           else focus w
    sendMessage e -- Always send button events.

-- 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 {ev_window = w}) = withDisplay $ \dpy -> do
    ws <- gets windowset
    wa <- io $ getWindowAttributes dpy w

    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 borderWidth
                    , 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 = userCode logHook

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