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-}

module OutputServer (
  createOutputServer
  ) where

import Control.Concurrent 
import Control.Concurrent.STM
import Control.Concurrent.STM.TChan

import Control.Concurrent.MVar

--------------------------------------------------------------------------------

import TupleType
import NetworkTuple
import TupleStore

------------------------------------------------------------------------------

data OutputSeverMsg = OutOutputServerMsg Tuple
                    | AddOutputServerMsg (Tuple -> IO ())

createOutputServer :: (Tuple -> IO ()) -> 
                        IO (Tuple -> IO (), (Tuple -> IO ()) -> IO ())
createOutputServer localServer = 
  do chan <- atomically $ newTChan
     forkIO $ server chan [localServer]
     return ((\tuple -> atomically $ writeTChan chan (OutOutputServerMsg tuple)),
             (\f -> atomically $ writeTChan chan (AddOutputServerMsg f)))
  where
    server chan tupleServers = loop tupleServers
      where loop []        = loop tupleServers
            loop (next:xs) = 
              do r <- atomically $ readTChan chan  
                 case r of
                   OutOutputServerMsg tuple -> next tuple >> loop xs
                   AddOutputServerMsg f     -> server chan (f:tupleServers)
