{-# LANGUAGE ExistentialQuantification #-}

module Phi.Phi ( Phi
               , MessageBus
               , Message
               , fromMessage
               , initPhi
               , runPhi
               , sendMessage
               , getMessageBus
               , receiveMessage
               ) where

import Control.Concurrent.Chan
import Control.Monad
import Data.Typeable

data Phi = Phi (Chan Message)
data MessageBus = MessageBus (Chan Message)

data Message = forall a. (Typeable a, Show a) => Message a

fromMessage :: (Typeable a, Show a) => Message -> Maybe a
fromMessage (Message m) = cast m

initPhi :: IO Phi
initPhi = liftM Phi newChan

runPhi :: Phi -> IO ()
runPhi (Phi chan) = forever $ readChan chan

sendMessage :: (Typeable a, Show a) => Phi -> a -> IO ()
sendMessage (Phi chan) = writeChan chan . Message

getMessageBus :: Phi -> IO MessageBus
getMessageBus (Phi chan) = liftM MessageBus $ dupChan chan

receiveMessage :: MessageBus -> IO Message
receiveMessage (MessageBus chan) = readChan chan