{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE MonoLocalBinds #-}

-- |
-- Module     : Simulation.Aivika.Distributed.Optimistic.Message
-- Copyright  : Copyright (c) 2015-2017, David Sorokin <david.sorokin@gmail.com>
-- License    : BSD3
-- Maintainer : David Sorokin <david.sorokin@gmail.com>
-- Stability  : experimental
-- Tested with: GHC 7.10.3
--
-- This module defines functions for working with messages.
--
module Simulation.Aivika.Distributed.Optimistic.Message
       (sendMessage,
        enqueueMessage,
        messageReceived) where

import Data.Time
import Data.Monoid

import Control.Monad
import Control.Distributed.Process (ProcessId, getSelfPid, wrapMessage, unwrapMessage)
import Control.Distributed.Process.Serializable

import Simulation.Aivika.Trans hiding (ProcessId)
import Simulation.Aivika.Trans.Internal.Types

import Simulation.Aivika.Distributed.Optimistic.Internal.Message
import Simulation.Aivika.Distributed.Optimistic.Internal.IO
import Simulation.Aivika.Distributed.Optimistic.Internal.DIO
import Simulation.Aivika.Distributed.Optimistic.Internal.Event
import qualified Simulation.Aivika.Distributed.Optimistic.Internal.InputMessageQueue as IMQ
import qualified Simulation.Aivika.Distributed.Optimistic.Internal.OutputMessageQueue as OMQ
import Simulation.Aivika.Distributed.Optimistic.DIO
import Simulation.Aivika.Distributed.Optimistic.Ref.Base

-- | Send a message to the specified remote process with the current receive time.
sendMessage :: forall a. Serializable a => ProcessId -> a -> Event DIO ()
sendMessage pid a =
  do t <- liftDynamics time
     enqueueMessage pid t a 

-- | Send a message to the specified remote process with the given receive time.
enqueueMessage :: forall a. Serializable a => ProcessId -> Double -> a -> Event DIO ()
enqueueMessage pid t a =
  Event $ \p ->
  do let queue       = queueOutputMessages $
                       runEventQueue (pointRun p)
         sendTime    = pointTime p
         receiveTime = t
     sequenceNo <- liftIOUnsafe $ OMQ.generateMessageSequenceNo queue
     sender <- messageInboxId
     let receiver = pid
         antiToggle = False
         binaryData = wrapMessage a
         message = Message { messageSequenceNo = sequenceNo,
                             messageSendTime = sendTime,
                             messageReceiveTime = receiveTime,
                             messageSenderId = sender,
                             messageReceiverId = receiver,
                             messageAntiToggle = antiToggle,
                             messageData = binaryData
                           }
     OMQ.sendMessage queue message
          
-- | The signal triggered when the remote message of the specified type has come.
messageReceived :: forall a. Serializable a => Signal DIO a
messageReceived =
  Signal { handleSignal = \h ->
            Event $ \p ->
            let queue = queueInputMessages $
                        runEventQueue (pointRun p)
                signal = IMQ.messageEnqueued queue
            in invokeEvent p $
               handleSignal signal $ \x ->
               do y <- unwrapMessage (messageData x)
                  case y of
                    Nothing -> return ()
                    Just a  -> h a
         }