{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, TypeSynonymInstances #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  XMonadContrib.Accordion
-- Copyright   :  (c) glasser@mit.edu
-- License     :  BSD
--
-- Maintainer  :  glasser@mit.edu
-- Stability   :  unstable
-- Portability :  unportable
--
-- LayoutClass that puts non-focused windows in ribbons at the top and bottom
-- of the screen.
-----------------------------------------------------------------------------

module XMonadContrib.Accordion (
    -- * Usage
    -- $usage
    Accordion(Accordion)) where

import XMonad
import XMonad.Layouts
import qualified XMonad.StackSet as W
import Graphics.X11.Xlib
import Data.Ratio

-- $usage
-- > import XMonadContrib.Accordion
-- > layouts = [ Layout Accordion ]

-- %import XMonadContrib.Accordion
-- %layout , Layout Accordion

data Accordion a = Accordion deriving ( Read, Show )

instance LayoutClass Accordion Window where
    pureLayout _ sc ws = zip ups tops ++ [(W.focus ws, mainPane)] ++ zip dns bottoms
     where
       ups    = W.up ws
       dns    = W.down ws
       (top,  allButTop) = splitVerticallyBy (1%8 :: Ratio Int) sc
       (center,  bottom) = splitVerticallyBy (6%7 :: Ratio Int) allButTop
       (allButBottom, _) = splitVerticallyBy (7%8 :: Ratio Int) sc
       mainPane | ups /= [] && dns /= [] = center
                | ups /= []              = allButTop
                | dns /= []              = allButBottom
                | otherwise              = sc
       tops    = if ups /= [] then splitVertically (length ups) top    else []
       bottoms = if dns /= [] then splitVertically (length dns) bottom else []