DBus.hs

-----------------------------------------------------------------------------
-- |
-- Module      :  DBus
-- Copyright   :  (c) Jochen Keil
-- License     :  BSD-style (see LICENSE)
--
-- Maintainer  :  Jochen Keil <jochen dot keil at gmail dot com>
-- Stability   :  unstable
-- Portability :  unportable
--
-- DBus IPC module for Xmobar
--
-----------------------------------------------------------------------------

module IPC.DBus (runIPC) where

import DBus
import DBus.Client
import Control.Monad (when)
import Control.Concurrent.STM
import Control.Exception (handle)
import System.IO (stderr, hPutStrLn)

import Signal

busName :: BusName
busName = busName_ "org.Xmobar.Control"

objectPath :: ObjectPath
objectPath = objectPath_ "/org/Xmobar/Control"

interfaceName :: InterfaceName
interfaceName = interfaceName_ "org.Xmobar.Control"

runIPC :: TMVar SignalType -> IO ()
runIPC mvst = handle printException exportConnection
    where
    printException :: ClientError -> IO ()
    printException = hPutStrLn stderr . clientErrorMessage
    exportConnection = do
        client <- connectSession
        requestName client busName [ nameDoNotQueue ]
        export client objectPath [ sendSignalMethod mvst ]

sendSignalMethod :: TMVar SignalType -> Method
sendSignalMethod mvst = method interfaceName sendSignalName
    (signature_ [variantType $ toVariant (undefined :: SignalType)])
    (signature_ [])
    sendSignalMethodCall
    where
    sendSignalName :: MemberName
    sendSignalName = memberName_ "SendSignal"

    sendSignalMethodCall :: MethodCall -> IO Reply
    sendSignalMethodCall mc = do
        when ( methodCallMember mc == sendSignalName )
             $ mapM_ (sendSignal . fromVariant) (methodCallBody mc)
        return ( replyReturn [] )

    sendSignal :: Maybe SignalType -> IO ()
    sendSignal = maybe (return ()) (atomically . putTMVar mvst)