{-# LANGUAGE GADTs, NoMonomorphismRestriction, ScopedTypeVariables, KindSignatures #-}

-----------------------------------------------------------------------------
-- |
-- Module      : Control.Monad.Trans.Crtn.World
-- Copyright   : (c) 2012 Ian-Woo Kim
--
-- License     : BSD3
-- Maintainer  : Ian-Woo Kim <ianwookim@gmail.com>
-- Stability   : experimental
-- Portability : GHC
--
-- describe world object
--
-----------------------------------------------------------------------------

module Control.Monad.Trans.Crtn.World where 

-- import Control.Monad.Error 
-- import Control.Monad.Trans.Either 
-- 
import Control.Monad.Trans.Crtn
import Control.Monad.Trans.Crtn.Event 
import Control.Monad.Trans.Crtn.Logger 
import Control.Monad.Trans.Crtn.Object
-- 
import Prelude hiding ((.),id)


-- | 
data WorldOp e m i o where 
  GiveEvent :: WorldOp e m e ()
  FlushLog :: WorldOp e m (LogServer m ()) (LogServer m ())
  FlushQueue :: WorldOp e m () [Either (ActionOrder e) e]

-- | 
type World e m r = SObjT (WorldOp e m) m r  


-- | 
giveEvent :: (Monad m) => e -> CObjT (WorldOp e m) m () 
giveEvent ev = request (Arg GiveEvent ev) >> return () 


-- | 
flushLog :: (Monad m) => LogServer m () -> CObjT (WorldOp e m) m (LogServer m ()) 
flushLog logobj = do req <- request (Arg FlushLog logobj) 
                     case req of 
                       Res FlushLog logobj' -> return logobj' 
                       Ign -> return logobj 
                       _ -> error "error in flushLog"  -- allow partiality

-- | 
flushQueue :: (Monad m) => CObjT (WorldOp e m) m [Either (ActionOrder e) e]
flushQueue = do req <- request (Arg FlushQueue ())
                case req of 
                  Res FlushQueue lst -> return lst 
                  Ign -> return [] 
                  _ -> error "error in flushQueue" -- allow partiality