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

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  XMonad.Layout.Tabbed
    -- Copyright   :  (c) 2007 David Roundy, Andrea Rossato
    -- License     :  BSD-style (see xmonad/LICENSE)
    --
    -- Maintainer  :  droundy@darcs.net, andrea.rossato@unibz.it
    -- Stability   :  unstable
    -- Portability :  unportable
    --
    -- A tabbed layout for the Xmonad Window Manager
    --
    -----------------------------------------------------------------------------

    module XMonad.Layout.Tabbed
        ( -- * Usage:
          -- $usage
          simpleTabbed, tabbed, addTabs
        , simpleTabbedAlways, tabbedAlways, addTabsAlways
        , simpleTabbedBottom, tabbedBottom, addTabsBottom
        , simpleTabbedBottomAlways, tabbedBottomAlways, addTabsBottomAlways
        , Theme (..)
        , defaultTheme
        , TabbedDecoration (..)
        , shrinkText, CustomShrink(CustomShrink)
        , Shrinker(..)
        ) where

    import Data.Maybe
    import Data.List

    import XMonad
    import qualified XMonad.StackSet as S
    import XMonad.Layout.Decoration
    import XMonad.Layout.Simplest ( Simplest(Simplest) )

    -- $usage
    -- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
    --
    -- > import XMonad.Layout.Tabbed
    --
    -- Then edit your @layoutHook@ by adding the Tabbed layout:
    --
    -- > myLayouts = simpleTabbed ||| Full ||| etc..
    --
    -- or, if you want a specific theme for you tabbed layout:
    --
    -- > myLayouts = tabbed shrinkText defaultTheme ||| Full ||| etc..
    --
    -- and then:
    --
    -- > main = xmonad defaultConfig { layoutHook = myLayouts }
    --
    -- The default Tabbar behaviour is to hide it when only one window is open
    -- on the workspace.  To have it always shown, use one of the layouts or
    -- modifiers ending in "Always".
    --
    -- For more detailed instructions on editing the layoutHook see:
    --
    -- "XMonad.Doc.Extending#Editing_the_layout_hook"
    --
    -- You can also edit the default configuration options.
    --
    -- > myTabConfig = defaultTheme { inactiveBorderColor = "#FF0000"
    -- >                                   , activeTextColor = "#00FF00"}
    --
    -- and
    --
    -- > mylayout = tabbed shrinkText myTabConfig ||| Full ||| etc..

    -- Layouts

    -- | A tabbed layout with the default xmonad Theme.
    --
    -- This is a minimal working configuration:
    --
    -- > import XMonad
    -- > import XMonad.Layout.DecorationMadness
    -- > main = xmonad defaultConfig { layoutHook = simpleTabbed }
    simpleTabbed :: ModifiedLayout (Decoration TabbedDecoration DefaultShrinker) Simplest Window
    simpleTabbed = tabbed shrinkText defaultTheme

    simpleTabbedAlways :: ModifiedLayout (Decoration TabbedDecoration DefaultShrinker) Simplest Window
    simpleTabbedAlways = tabbedAlways shrinkText defaultTheme

    -- | A bottom-tabbed layout with the default xmonad Theme.
    simpleTabbedBottom :: ModifiedLayout (Decoration TabbedDecoration DefaultShrinker) Simplest Window
    simpleTabbedBottom = tabbedBottom shrinkText defaultTheme

    -- | A bottom-tabbed layout with the default xmonad Theme.
    simpleTabbedBottomAlways :: ModifiedLayout (Decoration TabbedDecoration DefaultShrinker) Simplest Window
    simpleTabbedBottomAlways = tabbedBottomAlways shrinkText defaultTheme

    -- | A layout decorated with tabs and the possibility to set a custom
    -- shrinker and theme.
    tabbed     :: (Eq a, Shrinker s) => s -> Theme
               -> ModifiedLayout (Decoration TabbedDecoration s) Simplest a
    tabbed s c = addTabs s c Simplest

    tabbedAlways     :: (Eq a, Shrinker s) => s -> Theme
                     -> ModifiedLayout (Decoration TabbedDecoration s) Simplest a
    tabbedAlways s c = addTabsAlways s c Simplest

    -- | A layout decorated with tabs at the bottom and the possibility to set a custom
    -- shrinker and theme.
    tabbedBottom     :: (Eq a, Shrinker s) => s -> Theme
                     -> ModifiedLayout (Decoration TabbedDecoration s) Simplest a
    tabbedBottom s c = addTabsBottom s c Simplest

    tabbedBottomAlways     :: (Eq a, Shrinker s) => s -> Theme
                           -> ModifiedLayout (Decoration TabbedDecoration s) Simplest a
    tabbedBottomAlways s c = addTabsBottomAlways s c Simplest

    -- Layout Modifiers

    -- | A layout modifier that uses the provided shrinker and theme to add tabs to any layout.
    addTabs :: (Eq a, LayoutClass l a, Shrinker s) => s -> Theme -> l a
            -> ModifiedLayout (Decoration TabbedDecoration s) l a
    addTabs = createTabs WhenPlural Top

    addTabsAlways :: (Eq a, LayoutClass l a, Shrinker s) => s -> Theme -> l a
                  -> ModifiedLayout (Decoration TabbedDecoration s) l a
    addTabsAlways = createTabs Always Top

    -- | A layout modifier that uses the provided shrinker and theme to add tabs to the bottom of any layout.
    addTabsBottom :: (Eq a, LayoutClass l a, Shrinker s) => s -> Theme -> l a
                  -> ModifiedLayout (Decoration TabbedDecoration s) l a
    addTabsBottom = createTabs WhenPlural Bottom

    addTabsBottomAlways :: (Eq a, LayoutClass l a, Shrinker s) => s -> Theme -> l a
                        -> ModifiedLayout (Decoration TabbedDecoration s) l a
    addTabsBottomAlways = createTabs Always Bottom

    -- Tab creation abstractions.  Internal use only.

    -- Create tabbar when required at the given location with the given
    -- shrinker and theme to the supplied layout.
    createTabs                ::(Eq a, LayoutClass l a, Shrinker s) => TabbarShown -> TabbarLocation -> s
                              -> Theme -> l a -> ModifiedLayout (Decoration TabbedDecoration s) l a
    createTabs sh loc tx th l = decoration tx th (Tabbed loc sh) l

    data TabbarLocation = Top | Bottom deriving (Read,Show)

    data TabbarShown = Always | WhenPlural deriving (Read, Show, Eq)

    data TabbedDecoration a = Tabbed TabbarLocation TabbarShown deriving (Read, Show)

    instance Eq a => DecorationStyle TabbedDecoration a where
        describeDeco (Tabbed Top _ ) = "Tabbed"
        describeDeco (Tabbed Bottom _ ) = "Tabbed Bottom"
        decorationMouseDragHook _ _ _ = return ()
        pureDecoration (Tabbed lc sh) _ ht _ s wrs (w,r@(Rectangle x y wh hh))
            = if ((sh == Always && numWindows > 0) || numWindows > 1)
              then Just $ case lc of
                            Top -> upperTab
                            Bottom -> lowerTab
              else Nothing
            where ws = filter (`elem` map fst (filter ((==r) . snd) wrs)) (S.integrate s)
                  loc i = x + fi ((wh * fi i) `div` max 1 (fi $ length ws))
                  wid = fi $ maybe x (\i -> loc (i+1) - loc i) $ w `elemIndex` ws
                  nx  = maybe x loc $ w `elemIndex` ws
                  upperTab = Rectangle nx y wid (fi ht)
                  lowerTab = Rectangle nx (y+fi(hh-ht)) wid (fi ht)
                  numWindows = length ws
        shrink (Tabbed loc _ ) (Rectangle _ _ _ dh) (Rectangle x y w h)
            = case loc of
                Top -> Rectangle x (y + fi dh) w (h - dh)
                Bottom -> Rectangle x y w (h - dh)