{-# LANGUAGE ForeignFunctionInterface #-}
{-# LANGUAGE ScopedTypeVariables #-}
module FGConsole where

import Data.Word
import System.Posix.IO
import System.Posix.Types
import Control.Concurrent
-- import GHC.IO.Handle
import Unsafe.Coerce
import Control.Exception as E
-- import Prelude as E
import Control.Monad
import Foreign.C

import Logging
import System.Posix.Signals

-- c_monitorTTY fd = trace "c_monitorTTY" (return ()) -- (trace "WTF" todo)

foreign import ccall "monitorTTY" c_monitorTTY :: Fd -> IO CInt
foreign import ccall "closeTTY" c_closeTTY :: IO ()

forkTTYMonitor :: (Word8 -> IO ()) -> IO (Maybe (Fd,ThreadId))
forkTTYMonitor handler =  do
    (rfd,wfd) <- createPipe
    retvar <- newEmptyMVar
    thread <- forkIO $ do
        let cleanup = do
                trace "quitting monitorTTY thread." (return ())
                closeFd wfd `E.catch` \(e::IOException) -> return ()
                closeFd rfd `E.catch` \(e::IOException) -> return ()
                c_closeTTY
        -- rh <- fdToHandle rfd
        didfork <- c_monitorTTY wfd
        putMVar retvar didfork
        when (didfork == 0) $ do
        let monitor =
                (do
                    threadWaitRead rfd
                    (cs,cnt) <- fdRead rfd 1
                    forM_ cs (handler . unsafeCoerce {- . trace "read byte" -})
                    monitor)
                `E.catch`
                      \(e :: IOException) -> do
                        err <- getErrno
                        case () of
                         _ | err==eAGAIN -> monitor
                         _ | otherwise   -> cleanup
                `E.catch`
                      \(e ::  AsyncException) -> cleanup
        monitor
    didfork <- takeMVar retvar
    if didfork == 0
        then return $! Just (rfd,thread)
        else return $! Nothing

killTTYMonitor :: (Fd, ThreadId) -> IO ()
killTTYMonitor (rfd,thread) = do
    closeFd rfd
    yield
    killThread thread
    raiseSignal sigUSR1
    -- threadDelay 1000000


-- vim:ft=haskell: