{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}

-- Wraps ResizableTall, allows setting master count to a number directly
module XMonad.Layout.SetMasterNTall
  ( SetMasterNTall(..)
  , SetMasterN(..)
  ) where

import XMonad
import qualified XMonad.StackSet as W
import XMonad.Layout.ResizableTile

-- Message
data SetMasterN = SetMasterN Int
instance Message SetMasterN

-- Layout
newtype SetMasterNTall a = SetMasterNTall { unSetMasterNTall :: ResizableTall a }
    deriving (Read, Show)

instance LayoutClass SetMasterNTall a where
  runLayout (W.Workspace t l s) =
    let ws' = W.Workspace t (unSetMasterNTall l) s
    in  (fmap . fmap . fmap) SetMasterNTall . runLayout ws'

  handleMessage (SetMasterNTall l@(ResizableTall _n0 d f s)) mess
      | Just (SetMasterN n) <- fromMessage mess = pure $ Just $ SetMasterNTall $ ResizableTall n d f s
      | otherwise = (fmap . fmap) SetMasterNTall . handleMessage l $ mess

  description (SetMasterNTall l) = description l