{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances #-}
module Internal.Layout where 

import Control.Applicative
import XMonad.Layout.Spacing
import Data.List
import XMonad.Layout.Spiral
import XMonad.Layout.ThreeColumns
import XMonad.Layout.Grid
import XMonad.Layout
import XMonad.Layout.LayoutModifier
import XMonad
import XMonad.Core

import qualified XMonad.StackSet as W

myLayout =
  ModifiedLayout (Zoomable False 0.05 0.05) $
    spacingRaw True (Border 5 5 5 5) True (Border 5 5 5 5) True $
      spiral (6/7) |||
      Tall 1 (3/100) (1/2) |||
      ThreeCol 1 (3/100) (1/2) |||
      Grid

data ResizeZoom = ShrinkZoom | ExpandZoom deriving (Typeable)

instance Message ResizeZoom where

data Zoomable a = Zoomable Bool Float Float -- True if zooming in on the focused window.
  deriving (Show, Read)

data ToggleZoom = ToggleZoom
  deriving (Typeable)

data AlterZoom = AlterZoom Float Float
  deriving (Typeable)

instance Message ToggleZoom where

instance Message AlterZoom where

instance (Eq a) => LayoutModifier Zoomable a where
  redoLayout (Zoomable doit ws hs) (Rectangle x y w h) stack returned =
    if doit
      then
        let focused = W.focus <$> stack
            (zoomed, rest) = partition ((==focused) . Just . fst) returned
         in case zoomed of
              [] -> return (rest, Nothing)
              ((fwin, _):_) ->  return $ ((fwin, Rectangle (x + wp) (y + hp) (w - fromIntegral (wp * 2)) (h - fromIntegral (hp * 2))) : rest, Nothing)

      else return (returned, Nothing)
    where
      wp = floor $ (fromIntegral w) * ws
      hp = floor $ (fromIntegral h) * hs

  handleMessOrMaybeModifyIt self@(Zoomable showing sw sh) mess =
    return $
      (handleResize <$> fromMessage mess)
        <|> ((Left . handleZoom) <$> fromMessage mess)
      where
        handleResize r =
          if showing
            then Left $ Zoomable showing (guard $ sw + d) (guard $ sh + d)
            else Right $ case r of
                   ShrinkZoom -> SomeMessage Shrink
                   ExpandZoom -> SomeMessage Expand

          where d = (case r of
                      ShrinkZoom -> -1
                      ExpandZoom -> 1) * 0.02

        handleZoom ToggleZoom = Zoomable (not showing) sw sh

        guard f | f > 1 = 1
                | f < 0 = 0
                | otherwise = f