{-# LANGUAGE PatternSignatures #-}

----------------------------------------------------------------------------
-- |
-- Module      :  XMonad.Hooks.PositionStoreHooks
-- Copyright   :  (c) Jan Vornberger 2009
-- License     :  BSD3-style (see LICENSE)
--
-- Maintainer  :  jan.vornberger@informatik.uni-oldenburg.de
-- Stability   :  unstable
-- Portability :  not portable
--
-- This module contains two hooks for the
-- PositionStore (see "XMonad.Util.PositionStore") - a ManageHook and
-- an EventHook.
--
-- The ManageHook can be used to fill the PositionStore with position and size
-- information about new windows. The advantage of using this hook is, that the
-- information is recorded independent of the currently active layout. So the
-- floating shape of the window can later be restored even if it was opened in a
-- tiled layout initially.
--
-- For windows, that do not request a particular position, a random position will
-- be assigned. This prevents windows from piling up exactly on top of each other.
--
-- The EventHook makes sure that windows are deleted from the PositionStore
-- when they are closed.
--
-----------------------------------------------------------------------------

module XMonad.Hooks.PositionStoreHooks (
    -- * Usage
    -- $usage
    positionStoreManageHook,
    positionStoreEventHook
    ) where

import XMonad
import qualified XMonad.StackSet as W
import XMonad.Util.PositionStore

import System.Random(randomRIO)
import Control.Applicative((<$>))
import Control.Monad(when)
import Data.Maybe
import Data.Monoid

-- $usage
-- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
--
-- > import XMonad.Hooks.PositionStoreHooks
--
-- and adding 'positionStoreManageHook' to your 'ManageHook' as well
-- as 'positionStoreEventHook' to your event hooks:
--
-- > myManageHook = positionStoreManageHook <+> manageHook defaultConfig
-- > myHandleEventHook = positionStoreEventHook
-- >
-- > main = xmonad defaultConfig { manageHook = myManageHook
-- >                             , handleEventHook = myHandleEventHook
-- >                             }
--

positionStoreManageHook :: ManageHook
positionStoreManageHook = ask >>= liftX . positionStoreInit >> idHook

positionStoreInit :: Window -> X ()
positionStoreInit w = withDisplay $ \d -> do
        wa <- io $ getWindowAttributes d w
        ws <- gets windowset
        arbitraryOffsetX <- randomIntOffset
        arbitraryOffsetY <- randomIntOffset
        if (wa_x wa == 0) && (wa_y wa == 0)
            then do
                let sr@(Rectangle srX srY _ _) = screenRect . W.screenDetail . W.current $ ws
                modifyPosStore (\ps -> posStoreInsert ps w
                                        (Rectangle (srX + fi arbitraryOffsetX)
                                                   (srY + fi arbitraryOffsetY)
                                                    (fi $ wa_width wa)
                                                    (fi $ wa_height wa)) sr )
            else do
                sc <- fromMaybe (W.current ws) <$> pointScreen (fi $ wa_x wa) (fi $ wa_y wa)
                let sr = screenRect . W.screenDetail $ sc
                modifyPosStore (\ps -> posStoreInsert ps w
                                        (Rectangle (fi $ wa_x wa) (fi $ wa_y wa)
                                            (fi $ wa_width wa) (fi $ wa_height wa)) sr )
    where
        fi :: (Integral a, Num b) => a -> b
        fi = fromIntegral
        randomIntOffset :: X (Int)
        randomIntOffset = io $ randomRIO (42, 242)

positionStoreEventHook :: Event -> X All
positionStoreEventHook (DestroyWindowEvent {ev_window = w, ev_event_type = et}) = do
    when (et == destroyNotify) $ do
        modifyPosStore (\ps -> posStoreRemove ps w)
    return (All True)
positionStoreEventHook _ = return (All True)