{-# LANGUAGE MultiParamTypeClasses, ViewPatterns, FlexibleInstances, KindSignatures, DataKinds, GADTs, RankNTypes, PolyKinds #-}
module Internal.Layout where

import GHC.TypeLits

import Data.Proxy (Proxy(..))
import Internal.CornerLayout (Corner(..))
import Control.Arrow (second)
import XMonad.Hooks.ManageDocks
import XMonad.Layout.Circle
import XMonad.Layout.Accordion
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.Dishes
import XMonad.Layout.MosaicAlt
import XMonad.Layout.Fullscreen
import qualified XMonad.Layout.Dwindle as D
import XMonad.Layout
import XMonad.Layout.LayoutModifier
import XMonad
import XMonad.Core
import XMonad.Layout.NoBorders (smartBorders, noBorders)

import Internal.LayoutZipper
import Internal.Windows

import qualified Data.Map as M
import qualified XMonad.StackSet as W

myLayout :: _
myLayout =
  fullscreenFull $
    avoidStruts $
      spacingRaw True (Border 5 5 5 5) True (Border 5 5 5 5) True $
        layoutZipper $
          mods (spiral (6/7)) |:
          mods (modifyMosaic (MosaicAlt M.empty :: MosaicAlt Window)) |:
          mods (Corner (3/4) (3/100)) |:
          mods (ModifyDescription TallDescriptionModifier (Tall 1 (3/100) (1/2))) |:
          mods (ModifyDescription ThreeColDescMod (ThreeCol 1 (3/100) (1/2))) |:
          mods Grid |:
          mods (Dishes 2 (1/6)) |:
          mods (D.Dwindle D.R D.CW 1.5 1.1) |:
          nil

-- This is a type class that defines how to reinterpret a message. One can think
-- of this as a kind of type-level function. It lets one associate a function
-- (reinterpretMessage) with a type construct, which for the case below is a
-- Symbol.
--
-- It would be nice to attach this function to the LayoutModifier directly as a
-- value, however LayoutModifiers must be Show-able and Read-able and functions
-- are not. However encoding in the typesystem itsef which function is to be
-- called is the best alternative I have.
class DoReinterpret (k :: t) where
  reinterpretMessage ::
    Proxy k -> SomeMessage -> X (Maybe SomeMessage)

-- Mosaic doesn't have the concept of a "Master Space", so reinterpret messages
-- intended to modify the master space and instead have those messages expand
-- and shrink the current window.
--
-- "ForMosaic" is an instance of the Symbol kind. This is some neat type-system
-- hacking one can do in Haskell.
instance DoReinterpret "ForMosaic" where
  
  -- IncMaster message
  reinterpretMessage _ (fromMessage -> Just (IncMasterN n)) = do
    (fmap $ SomeMessage .
      (if n > 0
        then expandWindowAlt
        else shrinkWindowAlt)) <$> getFocusedWindow
  
  -- ResizeMaster message
  reinterpretMessage _ (fromMessage -> Just m) = do
    (fmap $ SomeMessage .
      (case m of
        Expand -> expandWindowAlt
        Shrink -> shrinkWindowAlt)) <$> getFocusedWindow

  -- Messages that don't match the above, just leave it unmodified.
  reinterpretMessage _ m = return (Just m)

-- Data construct for association a DoReinterpret function with a concrete
-- construct that can be used in the LayoutModifier instance.
--
-- It wolud be nice to have ReinterpretMessage hold the function as a value
-- rather than delegate to this kind-instance, however, it won't work because
-- LayoutModifiers have to be Read-able and Show-able, and functions are neither
-- of those, so a value-level function may not be a member of a LayoutModifier,
-- thus I have to settle for delegating to a hard-coded instance using
-- type-classes.
data ReinterpretMessage k a = ReinterpretMessage
  deriving (Show, Read)

-- Instance for ReinterpretMessage as a Layout modifier.
instance (DoReinterpret k) =>
      LayoutModifier (ReinterpretMessage k) a where 

  handleMessOrMaybeModifyIt self message = do

    -- Delegates to the reinterpretMessage function associatied with the
    -- type-variable k.
    newMessage <- reinterpretMessage (ofProxy self) message
    case newMessage of
      Just m -> return $ Just $ Right m
      Nothing -> return $ Just $ Left self
    where
      -- ofProxy just provides reifies the phantom type k so the type system can
      -- figure out what instance to go to.
      ofProxy :: ReinterpretMessage k a -> Proxy k
      ofProxy _ = Proxy

modifyMosaic :: l a -> ModifiedLayout (ReinterpretMessage "ForMosaic") l a
modifyMosaic = ModifiedLayout ReinterpretMessage

mods =
  ModifiedLayout (Zoomable False 0.05 0.05) .
    ModifiedLayout (Flippable False) .
    ModifiedLayout (HFlippable False) .
    ModifiedLayout (Rotateable False)


data ModifyDescription m l a = ModifyDescription m (l a)
  deriving (Show, Read)

data TallDescriptionModifier = TallDescriptionModifier
  deriving (Show, Read)

data ThreeColDescMod = ThreeColDescMod
  deriving (Show, Read)

class DescriptionModifier m l where
  newDescription :: m -> l a -> String -> String

instance (Typeable m, Show m, DescriptionModifier m l, LayoutClass l a) => LayoutClass (ModifyDescription m l) a where
  runLayout (W.Workspace t (ModifyDescription m l) a) rect = do
    (rects, maybeNewLayout) <- runLayout (W.Workspace t l a) rect
    return (rects, fmap (ModifyDescription m) maybeNewLayout)

  doLayout (ModifyDescription m l) a s = do
    (rects, maybeNewLayout) <- doLayout l a s
    return (rects, fmap (ModifyDescription m) maybeNewLayout)

  pureLayout (ModifyDescription m l) a s = pureLayout l a s

  emptyLayout (ModifyDescription m l) a = do
    (rects, maybeNewLayout) <- emptyLayout l a
    return (rects, fmap (ModifyDescription m) maybeNewLayout)

  handleMessage (ModifyDescription m l) a = do
    maybeNewLayout <- handleMessage l a
    return (ModifyDescription m <$> maybeNewLayout)

  pureMessage (ModifyDescription m l) a =
    let maybeNewLayout = pureMessage l a in
      ModifyDescription m <$> maybeNewLayout

  description (ModifyDescription m l) = newDescription m l (description l)

instance DescriptionModifier TallDescriptionModifier Tall where
  newDescription _ (Tall mast _ _) _ = "Tall(" ++ show mast ++ ")"

instance DescriptionModifier ThreeColDescMod ThreeCol where
  newDescription _ (ThreeCol mast _ _) _ = "ThreeCol(" ++ show mast ++ ")"
  newDescription _ (ThreeColMid mast _ _) _ = "ThreeColMid(" ++ show mast ++ ")"

data ResizeZoom = ShrinkZoom | ExpandZoom deriving (Typeable)

instance Message ResizeZoom where

newtype Flippable a = Flippable Bool -- True if flipped
  deriving (Show, Read)

newtype HFlippable a = HFlippable Bool -- True if flipped
  deriving (Show, Read)

newtype Rotateable a = Rotateable Bool -- True if rotated
  deriving (Show, Read)

data FlipLayout = FlipLayout deriving (Typeable)

data HFlipLayout = HFlipLayout deriving (Typeable)

data DoRotate = DoRotate deriving (Typeable)

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

-- Toggles if the current window should be zoomed or not. Set the boolean
-- to set the zoom.mhar
data ZoomModifier =
       ToggleZoom |
       Zoom |
       Unzoom
  deriving (Typeable)

instance Message FlipLayout where

instance Message HFlipLayout where

instance Message ZoomModifier where

instance Message DoRotate where

instance (Eq a) => LayoutModifier Rotateable a where
  pureModifier (Rotateable rotate) (Rectangle x' y' sw sh) _ returned =
    if rotate
      then (map (second (unzero . scaleRect . mirrorRect . zero)) returned, Nothing)
      else (returned, Nothing)
    where
      zero (Rectangle x y w h) = Rectangle (x - x') (y - y') w h
      unzero (Rectangle x y w h) = Rectangle (x + x') (y + y') w h

      scaleRect (Rectangle x y w h) =
        Rectangle (x * fi sw `div` fi sh)
                  (y * fi sh `div` fi sw)
                  (w * sw `div` sh)
                  (h * sh `div` sw)

      fi = fromIntegral


  pureMess (Rotateable rot) mess =
    fmap (\DoRotate -> Rotateable (not rot)) (fromMessage mess)

  modifyDescription (Rotateable rot) underlying =
    let descr = description underlying in
      if rot
        then descr ++ " Rotated"
        else descr

instance (Eq a) => LayoutModifier Flippable a where
  pureModifier (Flippable flip) (Rectangle sx _ sw _) stack returned =
    if flip
      then (map (second doFlip) returned, Nothing)
      else (returned, Nothing)
    where
      doFlip (Rectangle x y w h) =
        Rectangle ((sx + fromIntegral sw) - x - fromIntegral w + sx) y w h

  pureMess (Flippable flip) message =
    case fromMessage message of
      Just FlipLayout -> Just (Flippable (not flip))
      Nothing -> Nothing

  modifyDescription (Flippable flipped) underlying =
    let descr = description underlying in
      if flipped
        then descr ++ " Flipped"
        else descr

instance (Eq a) => LayoutModifier HFlippable a where
  pureModifier (HFlippable flip) (Rectangle _ sy _ sh) stack returned =
    if flip
      then (map (second doFlip) returned, Nothing)
      else (returned, Nothing)
    where
      doFlip (Rectangle x y w h) =
        Rectangle x ((sy + fromIntegral sh) - y - fromIntegral h + sy) w h

  pureMess (HFlippable flip) message =
    case fromMessage message of
      Just HFlipLayout -> Just (HFlippable (not flip))
      Nothing -> Nothing

  modifyDescription (HFlippable flipped) underlying =
    let descr = description underlying in
      if flipped
        then descr ++ " HFlipped"
        else descr


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
        handleZoom Zoom = Zoomable True sw sh
        handleZoom Unzoom = Zoomable False sw sh

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