-----------------------------------------------------------------------------
-- |
-- Module      :  XMonadContrib.Combo
-- Copyright   :  (c) David Roundy <droundy@darcs.net>
-- License     :  BSD-style (see LICENSE)
-- 
-- Maintainer  :  David Roundy <droundy@darcs.net>
-- Stability   :  unstable
-- Portability :  unportable
--
-- A layout that combines multiple layouts.
--
-----------------------------------------------------------------------------

module XMonadContrib.Combo (
                            -- * Usage
                            -- $usage 
                            combo
                           ) where

import XMonad
import StackSet ( integrate, differentiate )

-- $usage
--
-- To use this layout write, in your Config.hs:
-- 
-- > import XMonadContrib.Combo 
-- 
-- and add something like
-- 
-- > combo [(full,1),(tabbed,1)] (twoPane 0.03 0.5)
--
-- to your defaultLayouts.

combo :: [(Layout, Int)] -> Layout -> Layout
combo origls super = Layout { doLayout = \r s -> arrange r (integrate s), modifyLayout = message }
    where arrange _ [] = return []
          arrange r [w] = return [(w,r)]
          arrange rinput origws =
              do rs <- map snd `fmap` runLayout super rinput (differentiate $ take (length origls) origws)
                 let wss [] _ = []
                     wss [_] ws = [ws]
                     wss (n:ns) ws = take len1 ws : wss ns (drop len1 ws)
                         where len1 = min n (length ws - length ns)
                 out <- sequence $ zipWith3 runLayout (map fst origls) rs
                                                      (map differentiate $
                                                       wss (take (length rs) $ map snd origls) origws)
                 return $ concat out
          message m = do msuper' <- modifyLayout super m
                         case msuper' of
                           Nothing -> return Nothing
                           Just super' -> return $ Just $ combo origls super'