path: root/Presence/XMPP.hs

{-# LANGUAGE OverloadedStrings   #-}
{-# LANGUAGE FlexibleContexts    #-}
{-# LANGUAGE CPP                 #-}
{-# LANGUAGE ViewPatterns        #-}
module XMPP 
    ( module XMPPTypes
    , module SocketLike
    , listenForXmppClients
    , listenForRemotePeers
    , newServerConnections
    , seekRemotePeers
    , quitListening
    , OutBoundMessage(..)
    , sendMessage
    )  where

import ServerC
import XMPPTypes
import SocketLike
import ByteStringOperators
import ControlMaybe

import Data.HList
import Network.Socket 
    ( Family
    , connect
    , socketToHandle
    , sClose
    , Socket(..)
    , socket
    , SocketType(..)
    )
import Network.BSD 
    ( PortNumber
    , getHostName
    , hostName
    , hostAliases
    , getProtocolNumber
    )
import System.IO
    ( BufferMode(..)
    , IOMode(..)
    , hSetBuffering
    )
import Control.Concurrent.STM
import Data.Conduit
import qualified Data.Conduit.List as CL
import qualified Data.Conduit.Binary as CB
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as S (pack,putStr,putStrLn,append)
import qualified Data.ByteString.Lazy.Char8 as L
    ( putStrLn
    , fromChunks
    , unlines
    , hPutStrLn
    )
import Control.Concurrent (forkIO,killThread)
import Control.Concurrent.Async
import Control.Exception 
    ( handle
    -- , SomeException(..)
    , finally
    , bracketOnError )
import GHC.IO.Exception (IOException(..))
import Control.Monad.IO.Class
import Control.Monad.Trans.Class
import Control.Monad.Trans.Maybe
import Todo
import Control.Monad as Monad
import Text.XML.Stream.Parse (parseBytes,content)
import Text.XML.Stream.Render
import Data.XML.Types as XML
import Data.Text.Encoding      as S (decodeUtf8,encodeUtf8)
import Data.Text.Lazy.Encoding as L (decodeUtf8,encodeUtf8)
import Data.Text.Lazy (toStrict)
import GetHostByAddr
import Data.Monoid
import qualified Data.Sequence as Seq
import Data.Foldable (toList)
#ifdef RENDERFLUSH
import Data.Conduit.Blaze
#endif
import Data.List (find)
import qualified Text.Show.ByteString as L
import NestingXML
import           Data.Set as Set (Set)
import qualified Data.Set as Set
import qualified Data.Map as Map
import           Data.Map as Map (Map)
import GHC.Conc 
    ( threadStatus
    , ThreadStatus(..)
    , ThreadId
    )

data Commands = Send [XML.Event] | QuitThread
 deriving Prelude.Show

getNamesForPeer :: Peer -> IO [ByteString]
getNamesForPeer LocalHost = fmap ((:[]) . S.pack) getHostName
getNamesForPeer peer@(RemotePeer addr) = do
    ent <- getHostByAddr addr --  AF_UNSPEC addr
    let names = hostName ent : hostAliases ent
    return . map S.pack $ names


xmlifyPresenceForClient :: Presence -> IO [XML.Event]
xmlifyPresenceForClient (Presence jid stat) = do
    let n   = name jid
        rsc = resource jid
    names <- getNamesForPeer (peer jid)
    let tostr p = L.decodeUtf8 $ n <$++> "@" <?++> L.fromChunks [p] <++?>  "/" <++$> rsc
        jidstrs = fmap (toStrict . tostr) names
    return (concatMap presenceEvents jidstrs)
 where
    presenceEvents jidstr =
      [ EventBeginElement "{jabber:client}presence" (("from",[ContentText jidstr]):typ stat)
      , EventBeginElement "{jabber:client}show" []
      , EventContent (ContentText . shw $ stat)
      , EventEndElement "{jabber:client}show"
      , EventEndElement "{jabber:client}presence"
      ]
    typ Offline = [("type",[ContentText "unavailable"])]
    typ _       = []
    shw Available = "chat"
    shw Away      = "away"
    shw Offline   = "away" -- Is this right?

prefix ## name = Name name Nothing (Just prefix)

streamP name = Name name (Just "http://etherx.jabber.org/streams") (Just "stream")
    
greet host =
    [ EventBeginDocument
    , EventBeginElement (streamP "stream")
        [("from",[ContentText host])
        ,("id",[ContentText "someid"])
        ,("xmlns",[ContentText "jabber:client"])
        ,("xmlns:stream",[ContentText "http://etherx.jabber.org/streams"])
        ,("version",[ContentText "1.0"])
        ]
    , EventBeginElement (streamP "features") []
    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-bind}bind" []
    , EventEndElement "{urn:ietf:params:xml:ns:xmpp-bind}bind"

    {-
    -- , "  <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>"
    , " <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>"
    -- , " <mechanism>DIGEST-MD5</mechanism>"
    , " <mechanism>PLAIN</mechanism>"
    , " </mechanisms> "
    -}

    , EventEndElement (streamP "features")
    ]


-- type Consumer i m r = forall o. ConduitM i o m r
mawait :: Monad m => MaybeT (ConduitM i o m) i
mawait = MaybeT await

-- Note: This function ignores name space qualification
elementAttrs expected (EventBeginElement name attrs)
    | nameLocalName name==expected 
    = return attrs
elementAttrs _ _ = mzero
     
eventIsBeginElement (EventBeginElement _ _) = True
eventIsBeginElement _                       = False

eventIsEndElement (EventEndElement _) = True
eventIsEndElement _                   = False

filterMapElement::
  (Monad m, MonadPlus mp) =>
  (Event -> mp a) -> Event -> mp a -> MaybeT (ConduitM Event o m) (mp a)
filterMapElement ret opentag empty = loop (empty `mplus` ret opentag) 1 
 where
    loop ts 0 = return ts
    loop ts cnt = do
        tag <- mawait
        let ts' = mplus ts (ret tag)
        case () of
         _ | eventIsEndElement tag   -> loop ts' (cnt-1)
         _ | eventIsBeginElement tag -> loop ts' (cnt+1)
         _                           -> loop ts' cnt

gatherElement ::
  (Monad m, MonadPlus mp) =>
  Event -> mp Event -> NestingXML o m (mp Event)
gatherElement opentag empty = loop (empty `mplus` return opentag) 1 
 where
    loop ts 0 = return ts
    loop ts cnt = do
        maybeXML (return ts) $ \tag -> do
        let ts' = mplus ts (return tag)
        case () of
         _ | eventIsEndElement tag   -> loop ts' (cnt-1)
         _ | eventIsBeginElement tag -> loop ts' (cnt+1)
         _                           -> loop ts' cnt

{-
sourceStanza :: Monad m => Event -> ConduitM Event Event m ()
sourceStanza opentag = yield opentag >> loop 1
 where
    loop 0 = return ()
    loop cnt = do
        e <- await
        let go tag cnt = yield tag >> loop cnt
        case e of
            Just tag | eventIsEndElement tag   -> go tag (cnt-1)
            Just tag | eventIsBeginElement tag -> go tag (cnt+1)
            Just tag                           -> go tag cnt
            Nothing                            -> return ()
-}

voidMaybeT body = (>> return ()) . runMaybeT $ body
fixMaybeT f = (>> return ()) . runMaybeT . fix $ f

iq_bind_reply id jid =
    [ EventBeginElement "{jabber:client}iq" [("type",[ContentText "result"]),("id",[ContentText id])]

    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-bind}bind"
        [("xmlns",[ContentText "urn:ietf:params:xml:ns:xmpp-bind"])]
    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-bind}jid" []
    , EventContent (ContentText jid)
    , EventEndElement "{urn:ietf:params:xml:ns:xmpp-bind}jid"
    , EventEndElement  "{urn:ietf:params:xml:ns:xmpp-bind}bind"
    , EventEndElement "{jabber:client}iq"
    ]

uncontent cs = head $ map getText cs
 where
    getText (ContentText x) = x
    getText (ContentEntity x ) = x

tagAttrs (EventBeginElement _ xs) = xs
tagAttrs _                        = []

tagName (EventBeginElement n _) = n
tagName _                       = ""

handleIQSetBind session cmdChan stanza_id = do
    mchild <- nextElement
    rsc <- case mchild of
             Just child -> do
                let unhandledBind = do
                        liftIO $ putStrLn $ "unhandled-bind: "++show child
                        return ""
                case tagName child of
                    "{urn:ietf:params:xml:ns:xmpp-bind}resource"
                      -> do
                        rsc <- lift content
                        return $ L.fromChunks [S.encodeUtf8 rsc]
                    _ -> unhandledBind
             Nothing -> do
                liftIO $ putStrLn $ "empty bind request!"
                return ""
    liftIO $ do
        L.putStrLn $ "iq-set-bind-resource " <++> rsc
        setResource session rsc
        jid <- getJID session
        atomically $ writeTChan cmdChan (Send $ iq_bind_reply stanza_id (toStrict $ L.decodeUtf8 $ L.show jid) )
        forCachedPresence session $ \presence -> do
            xs <- xmlifyPresenceForClient presence
            atomically . writeTChan cmdChan . Send $ xs


iq_session_reply host stanza_id =
    [ EventBeginElement "{jabber:client}iq" 
        [("id",[ContentText stanza_id])
        ,("from",[ContentText host])
        ,("type",[ContentText "result"])
        ]
    , EventEndElement "{jabber:client}iq"
    ]

handleIQSetSession session cmdChan stanza_id = do
    host <- liftIO $ do
        jid <- getJID session
        names <- getNamesForPeer (peer jid)
        return (S.decodeUtf8 . head $ names)
    liftIO . atomically . writeTChan cmdChan . Send $ iq_session_reply host stanza_id

handleIQSet session cmdChan tag = do
    withJust (lookupAttrib "id" (tagAttrs tag)) $ \stanza_id -> do
    whenJust nextElement $ \child -> do
    let unhandledSet = liftIO $ putStrLn ("iq-set: "++show (stanza_id,child))
    case tagName child of
      "{urn:ietf:params:xml:ns:xmpp-bind}bind" 
        -> handleIQSetBind session cmdChan stanza_id
      "{urn:ietf:params:xml:ns:xmpp-session}session"
        -> handleIQSetSession session cmdChan stanza_id
      _ -> unhandledSet

matchAttrib name value attrs = 
    case find ( (==name) . fst) attrs of
        Just (_,[ContentText x])   | x==value -> True
        Just (_,[ContentEntity x]) | x==value -> True
        _                                     -> False

lookupAttrib name attrs =
    case find ( (==name) . fst) attrs of
        Just (_,[ContentText x])   -> Just x
        Just (_,[ContentEntity x]) -> Just x
        _                          -> Nothing
    
iqTypeSet    = "set"
iqTypeGet    = "get"
iqTypeResult = "result"
iqTypeError  = "error"

isIQOf (EventBeginElement name attrs) testType 
    | name=="{jabber:client}iq" 
    && matchAttrib "type" testType attrs
    = True
isIQOf _ _ = False

iq_service_unavailable host iq_id mjid req =
    [ EventBeginElement "{jabber:client}iq" 
        [("type",[ContentText "error"])
        ,("id",[ContentText iq_id])
        -- , TODO: set "from" if isJust mjid
        ]
    , EventBeginElement req []
    , EventEndElement req
    , EventBeginElement "{jabber:client}error" [("type",[ContentText "cancel"])]
    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-stanzas}service-unavailable" []
    , EventEndElement "{urn:ietf:params:xml:ns:xmpp-stanzas}service-unavailable"
    , EventEndElement "{jabber:client}error"
    , EventEndElement "{jabber:client}iq"
    ]

handleIQGet session cmdChan tag = do
    withJust (lookupAttrib "id" (tagAttrs tag)) $ \stanza_id -> do
    whenJust nextElement $ \child -> do
    host <- liftIO $ do
        jid <- getJID session
        names <- getNamesForPeer (peer jid)
        return (S.decodeUtf8 . head $ names)
    let unhandledGet req = do
            liftIO $ putStrLn ("iq-get: "++show (stanza_id,child))
            liftIO . atomically . writeTChan cmdChan . Send $ iq_service_unavailable host stanza_id Nothing req
    case tagName child of
        -- "{http://jabber.org/protocol/disco#items}query" -> liftIO $ putStrLn "iq-get-query-items"
        "{urn:xmpp:ping}ping" -> liftIO $ do
            let mjid = lookupAttrib "from" (tagAttrs tag)
            let pong = [ EventBeginElement "{jabber:client}iq" 
                         $ (case mjid of
                             Just jid -> (("to",[ContentText jid]):)
                             _        -> id)
                             [("type",[ContentText "result"])
                             ,("id",[ContentText stanza_id])
                             ,("from",[ContentText host])
                             ]
                      , EventEndElement "{jabber:client}iq"
                      ]
            atomically . writeTChan cmdChan . Send $ pong
        req -> unhandledGet req
    

fromClient :: (MonadThrow m,MonadIO m, JabberClientSession session) => 
    session -> TChan Commands -> Sink XML.Event m ()
fromClient session cmdChan = doNestingXML $ do
    let log  = liftIO . L.putStrLn . ("(C) " <++>)
        send = liftIO . atomically . writeTChan cmdChan . Send
    withXML $ \begindoc -> do
    when (begindoc==EventBeginDocument) $ do
    log "begin-doc"
    withXML $ \xml -> do
    withJust (elementAttrs "stream" xml) $ \stream_attrs -> do
    log $ "stream atributes: " <++> bshow stream_attrs
    host <- liftIO $ do
        jid <- getJID session
        names <- getNamesForPeer (peer jid)
        return (S.decodeUtf8 . head $ names)
    send $ greet host
    
    fix $ \loop -> do
        log "waiting for stanza."
        whenJust nextElement $ \stanza -> do
            stanza_lvl <- nesting

            let unhandledStanza = do
                    xs <- gatherElement stanza Seq.empty
                    prettyPrint "unhandled-C: " (toList xs)
            case () of
             _ | stanza `isIQOf` iqTypeSet -> handleIQSet session cmdChan stanza
             _ | stanza `isIQOf` iqTypeGet -> handleIQGet session cmdChan stanza
             _ | otherwise                 -> unhandledStanza

            awaitCloser stanza_lvl
            loop

    log $ "end of stream"
    withXML $ \xml -> do
    log $ "end-of-document: " <++> bshow xml

prettyPrint prefix xs = 
    liftIO $ do
        CL.sourceList xs $= renderBytes (def { rsPretty=True }) =$= CB.lines $$ CL.mapM_ (S.putStrLn . (prefix `S.append`))

toClient :: MonadIO m => TChan Presence -> TChan Commands -> Source m [XML.Event]
toClient pchan cmdChan = fix $ \loop -> do
    let send xs = yield xs >> prettyPrint ">C: " xs
    event <- liftIO . atomically $ 
              orElse (fmap Left  $ readTChan pchan)
                     (fmap Right $ readTChan cmdChan)
    case event of
      Right QuitThread -> return ()
      Right (Send xs)  -> send xs >> loop
      Left  presence   -> do 
        xs <- liftIO $ xmlifyPresenceForClient presence
        send xs
        loop

handleClient
  :: (SocketLike sock, HHead l (XMPPClass session),
      JabberClientSession session) =>
     HCons sock (HCons t l) -> Source IO ByteString -> Sink ByteString IO () -> IO ()
handleClient st src snk = do
    let HCons sock (HCons _ st') = st
        session_factory = hHead st'
    pname <- getPeerName sock
    session <- newSession session_factory sock
    Prelude.putStrLn $ "PEER NAME: "++Prelude.show pname
    pchan <- subscribe session Nothing
    cmdChan <- atomically newTChan

#ifdef RENDERFLUSH
    writer <- async (   toClient pchan cmdChan 
                    $$  flushList
                    =$= renderBuilderFlush def 
                    =$= builderToByteStringFlush 
                    =$= discardFlush 
                     =$ snk )
#else
    writer <- async ( toClient pchan cmdChan $$ renderChunks =$ snk )
#endif
    finally         ( src $= parseBytes def $$ fromClient session cmdChan )
        $ do
            atomically $ writeTChan cmdChan QuitThread
            wait writer
            closeSession session

listenForXmppClients ::
  (HList l, HHead l (XMPPClass session), HExtend e1 l2 l1,
   HExtend e l1 (HCons PortNumber l), JabberClientSession session) =>
  Family -> e1 -> e -> l2 -> IO ServerHandle
listenForXmppClients addr_family session_factory port st = do
    doServer (addr_family .*. port .*. session_factory .*. st) handleClient

#ifdef RENDERFLUSH
flushList :: Monad m => ConduitM [a] (Flush a) m ()
flushList = fixMaybeT $ \loop -> do
    xs <- mawait
    lift ( CL.sourceList xs $$ CL.mapM_ (yield . Chunk) )
    lift ( yield Flush )
    loop

discardFlush :: Monad m => ConduitM (Flush a) a m ()
discardFlush = fixMaybeT $ \loop -> do
    x <- mawait
    let unchunk (Chunk a) = a
        ischunk (Chunk _) = True
        ischunk _         = False
    lift . when (ischunk x) $ yield (unchunk x)
    loop
#else
renderChunks :: (MonadUnsafeIO m, MonadIO m) => ConduitM [Event] ByteString m ()
renderChunks = fixMaybeT $  \loop -> do
    xs <- mawait
    lift . when (not . null $ xs) $ ( CL.sourceList xs $= renderBytes def $$ CL.mapM_ yield )
    loop
#endif


listenForRemotePeers
  :: (HList l, HHead l (XMPPPeerClass session),
      HExtend e l1 (HCons PortNumber l), HExtend e1 l2 l1,
      JabberPeerSession session) =>
     Family -> e1 -> e -> l2 -> IO ServerHandle
listenForRemotePeers addrfamily session_factory port st = do
    doServer (addrfamily .*. port .*. session_factory .*. st) handlePeer

handlePeer
  :: (SocketLike sock, HHead l (XMPPPeerClass session),
      JabberPeerSession session) =>
     HCons sock (HCons t1 l) -> Source IO ByteString -> t -> IO ()
handlePeer st src snk = do
    let HCons sock (HCons _ st') = st
        session_factory = hHead st'
    name <- fmap bshow $ getPeerName sock
    L.putStrLn $ "(P) connected " <++> name
    session <- newPeerSession session_factory sock

    finally ( src $= parseBytes def $$ fromPeer session )
        $ do 
            L.putStrLn $ "(P) disconnected " <++> name
            closePeerSession session


handlePeerPresence session stanza False = do
    -- Offline
    withJust (lookupAttrib "from" (tagAttrs stanza)) $ \jid -> do
    peer_jid <- liftIO $ parseAddressJID (L.fromChunks [S.encodeUtf8 jid])
    liftIO $ announcePresence session (Presence peer_jid Offline)
handlePeerPresence session stanza True = do
    -- online (Available or Away)
    let log  = liftIO . L.putStrLn . ("(P) " <++>)
    withJust (lookupAttrib "from" (tagAttrs stanza)) $ \jid -> do
    pjid <- liftIO $ parseAddressJID (L.fromChunks [S.encodeUtf8 jid])
    -- stat <- show element content
    let parseChildren stat = do
            child <- nextElement
            case child of
                Just tag | tagName tag=="{jabber:server}show"
                                      -> fmap toStat (lift content)
                Just tag | otherwise  -> parseChildren stat
                Nothing -> return stat
        toStat "away" = Away
        toStat "xa"   = Away -- TODO: xa
        toStat "dnd"  = Away -- TODO: dnd
        toStat "chat" = Available

    stat' <- parseChildren Available
    liftIO $ announcePresence session (Presence pjid stat')
    log $ bshow (Presence pjid stat')

matchAttribMaybe name (Just value) attrs = 
    case find ( (==name) . fst) attrs of
        Just (_,[ContentText x])   | x==value -> True
        Just (_,[ContentEntity x]) | x==value -> True
        _                                     -> False
matchAttribMaybe name Nothing attrs  
    | find ( (==name) . fst) attrs==Nothing
    = True
matchAttribMaybe name Nothing attrs  
    | otherwise
    = False

presenceTypeOffline = Just "unavailable"
presenceTypeOnline  = Nothing
presenceTypeProbe   = Just "probe"

isPresenceOf (EventBeginElement name attrs) testType
    | name=="{jabber:server}presence"
    && matchAttribMaybe "type" testType attrs
    = True
isPresenceOf _ _ = False

handlePresenceProbe session stanza = do
    withJust (lookupAttrib "to" (tagAttrs stanza)) $ \to -> do
    -- withJust (lookupAttrib "from" (tagAttrs stanza)) $ \from -> do
    jid <- liftIO $ parseAddressJID $ L.fromChunks [S.encodeUtf8 to]
    withJust (name jid) $ \user -> do
    liftIO $ L.putStrLn $ "RECEIVED PROBE "<++>bshow (peerAddress session,to)
    liftIO $ do
        subs <- getSubscribers (peerSessionFactory session) user
        liftIO $ L.putStrLn $ "subscribers for "<++>bshow user<++>": " <++>bshow subs
        forM_ subs $ \jidstr -> do
            handle (\(IOError _ _ _ _ _ _) -> return ()) $ do
            -- handle (\(SomeException _) -> return ()) $ do
                L.putStrLn $ "parsing " <++>jidstr
                sub <- parseHostNameJID jidstr
                putStrLn $ "comparing " ++show (peer sub , peerAddress session)
                when (peer sub == peerAddress session) $ do
                ps <- userStatus session user
                mapM_ (announcePresence session) ps
    return ()

fromPeer :: (MonadThrow m,MonadIO m, JabberPeerSession session) => 
    session -> Sink XML.Event m ()
fromPeer session = doNestingXML $ do
    let log  = liftIO . L.putStrLn . ("(P) " <++>)
    withXML $ \begindoc -> do
    when (begindoc==EventBeginDocument) $ do
    log "begin-doc"
    withXML $ \xml -> do
    withJust (elementAttrs "stream" xml) $ \stream_attrs -> do
    log $ "stream atributes: " <++> bshow stream_attrs

    fix $ \loop -> do
        log "waiting for stanza."
        whenJust nextElement $ \stanza -> do
            stanza_lvl <- nesting

            let unhandledStanza = do
                    xs <- gatherElement stanza Seq.empty
                    prettyPrint "P: " (toList xs)
            case () of
              _ | stanza `isPresenceOf` presenceTypeOnline
                    -> handlePeerPresence session stanza True
              _ | stanza `isPresenceOf` presenceTypeOffline
                    -> handlePeerPresence session stanza False
              _ | stanza `isPresenceOf` presenceTypeProbe
                    -> handlePresenceProbe session stanza
              _ -> unhandledStanza

            awaitCloser stanza_lvl
            loop

    log $ "end of stream"
    withXML $ \xml -> do
    log $ "end-of-document: " <++> bshow xml




data OutBoundMessage = OutBoundPresence Presence | PresenceProbe JID JID
 deriving Prelude.Show

newServerConnections = newTVar Map.empty

data CachedMessages = CachedMessages 
    { presences :: Map JID JabberShow
    , probes :: Map JID (Set JID)
    }

connect_to_server chan peer = (>> return ()) . runMaybeT $ do
    let port = 5269 :: Int
    -- We'll cache Presence notifications until the socket
    -- is ready.
    cached <- liftIO $ newIORef (CachedMessages Map.empty Map.empty)

    let cacheCmd (OutBoundPresence (Presence jid Offline)) cached = do
                    cache <- readIORef cached
                    writeIORef cached (cache { presences=Map.delete jid . presences $ cache })
        cacheCmd (OutBoundPresence p@(Presence jid st)) cached = do
                    cache <- readIORef cached
                    writeIORef cached (cache { presences=Map.insert jid st . presences $ cache })
        cacheCmd (PresenceProbe from to) cached = do
                    cache <- readIORef cached
                    let probes' = Map.adjust (Set.insert from) to $ probes cache
                    writeIORef cached (cache { probes=probes' })

    fix $ \sendmsgs -> do
        connected <- liftIO . async $ connect' (peerAddr peer) port

        sock <- MaybeT . fix $ \loop -> do
            e <- atomically $ orElse
                    (fmap Right $ waitSTM connected)
                    (fmap Left  $ readTChan chan)
            case e of
                Left cmd   -> cacheCmd cmd cached >> loop
                Right sock -> return sock

        retry <- do
            (cache,snk) <- liftIO $ do
                h <- socketToHandle sock ReadWriteMode
                hSetBuffering h NoBuffering
                cache <- readIORef $ cached
                -- hint garbage collector: we're done with this...
                writeIORef cached (CachedMessages Map.empty Map.empty) 
                return (cache,packetSink h)
            MaybeT $ handleOutgoingToPeer (restrictSocket sock) cache chan snk

        liftIO $ cacheCmd retry cached
        liftIO $ putStrLn $ "retrying " ++ show retry
        sendmsgs


greetPeer =
    [ EventBeginDocument
    , EventBeginElement (streamP "stream")
        [("xmlns",[ContentText "jabber:server"])
        ,("version",[ContentText "1.0"])
        ]
    ]

goodbyePeer = 
    [ EventEndElement (streamP "stream")
    , EventEndDocument
    ]

presenceProbe sock fromjid tojid = do
    addr <- getSocketName sock
    let jidstr jid = toStrict . L.decodeUtf8 
                      $ name jid <$++> "@" 
                        <?++> showPeer (RemotePeer addr) 
                        <++?>  "/" <++$> resource jid
        from = jidstr fromjid
        to = toStrict . L.decodeUtf8
              $ name tojid <$++> "@"
                <?++> showPeer (peer tojid)
    return 
      [ EventBeginElement "{jabber:server}presence"
            [("from",[ContentText from])
            ,("to",[ContentText to])
            ,("type",[ContentText "probe"])
            ]
      , EventEndElement "{jabber:server}presence"
      ]

{-
toPeerChain
  :: SocketLike sock =>
     sock
     -> CachedMessages
     -> TChan OutBoundMessage
     -> Sink ByteString IO b
     -> IO b
toPeerChain sock cache chan snk = toPeer sock cache chan $$ renderChunks =$ snk
-}

toPeer
  :: SocketLike sock =>
     sock
     -> CachedMessages
     -> TChan OutBoundMessage
     -> (Maybe OutBoundMessage -> IO ())
     -> ConduitM i [Event] IO ()
toPeer sock cache chan fail = do
    let -- log     = liftIO . L.putStrLn . ("(>P) " <++>)
        send xs = yield xs >> prettyPrint ">P: " xs -- >> return (3::Int)
        checkConnection cmd = do
            liftIO $ catch (getPeerName sock >> return ())
                           (\_ -> fail . Just $ cmd)
        sendPresence presence = do
            r <- lift $ xmlifyPresenceForPeer sock presence
            {-
            liftIO $ do
                p' <- catch (fmap (Just . RemotePeer) $ getPeerName sock)
                            (\_ -> (fail . Just . OutBoundPresence $ presence) >> return Nothing)
                L.putStrLn $ "sending Presence to " <++?> fmap showPeer p'
            -}
            let cmd = OutBoundPresence presence
            checkConnection cmd
            yieldOr r (fail . Just $ cmd)
            prettyPrint ">P: " r
        sendProbe from to = do
            r <- liftIO $ presenceProbe sock from to
            let cmd = PresenceProbe from to
            checkConnection cmd
            yieldOr r (fail . Just $ cmd)
            prettyPrint ">P: " r

    send greetPeer
    forM_ (Map.assocs . presences $ cache) $ \(jid,st) -> do
        sendPresence (Presence jid st)
    forM_ (Map.assocs . probes $ cache) $ \(to,froms) -> do
        forM_ (Set.toList froms) $ \from -> do
            liftIO $ L.putStrLn "sending cached probe..."
            sendProbe from to
    fix $ \loop -> do
        event <- lift . atomically $ readTChan chan
        case event of
          OutBoundPresence p    -> sendPresence p
          PresenceProbe from to -> do
            liftIO $ L.putStrLn "sending live probe..."
            sendProbe from to
        loop
    send goodbyePeer

handleOutgoingToPeer
  :: SocketLike sock =>
     sock
     -> CachedMessages
     -> TChan OutBoundMessage
     -> Sink ByteString IO ()
     -> IO (Maybe OutBoundMessage)
handleOutgoingToPeer sock cache chan snk = do
    p <- getPeerName sock
    L.putStrLn $ "(>P) connected " <++> showPeer (RemotePeer p)
    failed <- newIORef Nothing
    let failure cmd = do
            writeIORef failed cmd
            putStrLn $ "Failed: " ++ show cmd
    finally (
#ifdef RENDERFLUSH
        handle (\(IOError _ _ _ _ _ _) -> return ()) $ 
            toPeer sock cache chan failure
                $$  flushList
                =$= renderBuilderFlush def
                =$= builderToByteStringFlush
                =$= discardFlush
                 =$ snk
#else
        handle (\(IOError _ _ _ _ _ _) -> return ()) $ toPeer sock cache chan failure $$ renderChunks =$ snk
#endif
        ) $ L.putStrLn $ "(>P) disconnected " <++> showPeer (RemotePeer p)
    readIORef failed

connect' :: SockAddr -> Int -> IO (Maybe Socket)
connect' addr port = do
    proto <- getProtocolNumber "tcp"
    {-
    -- Given (host :: HostName) ...
    let hints = defaultHints { addrFlags = [AI_ADDRCONFIG]
                             , addrProtocol = proto
                             , addrSocketType = Stream }
    addrs <- getAddrInfo (Just hints) (Just host) (Just serv)
    firstSuccessful $ map tryToConnect addrs
    -}
    let getport (SockAddrInet port _) = port
        getport (SockAddrInet6 port _ _ _) = port
    let doException e@(IOError _ _ _ _ _ _) = do
    -- let doException (SomeException e) = do
            L.putStrLn $  "\nFailed to reach "<++> showPeer (RemotePeer addr) <++> " on port "<++>bshow port<++>": " <++> bshow e
            return Nothing
    handle doException
         $ tryToConnect proto (addr `withPort` port)
  where
  tryToConnect proto addr =
    bracketOnError
        (socket (socketFamily addr) Stream proto)
        (sClose )  -- only done if there's an error
        (\sock -> do
          connect sock addr
          return (Just sock) -- socketToHandle sock ReadWriteMode
        )


sendMessage  :: TVar (Map Peer (TChan OutBoundMessage, ThreadId)) -> OutBoundMessage -> Peer -> IO ()
sendMessage cons msg peer = do
    found <- atomically $ do
        consmap <- readTVar cons
        return (Map.lookup peer consmap)
    let newEntry = do
          chan <- atomically newTChan
          t <- forkIO $ connect_to_server chan peer
          -- L.putStrLn $ "remote-map new: " <++> showPeer peer
          return (True,(chan,t))
    (is_new,entry) <- maybe newEntry
          ( \(chan,t) -> do 
                        st <- threadStatus t
                        let running = do
                                -- L.putStrLn $ "remote-map, thread running: " <++> showPeer peer
                                return (False,(chan,t))
                            died = do
                                -- L.putStrLn $ "remote-map, thread died("<++>bshow st<++>"): " <++> showPeer peer
                                newEntry 
                        case st of 
                          ThreadRunning   -> running
                          ThreadBlocked _ -> running
                          ThreadDied      -> died
                          ThreadFinished  -> died
                        )
          found
    -- L.putStrLn $ "sendMessage ->"<++>showPeer peer<++>": "<++>bshow msg
    atomically $ writeTChan (fst entry) msg
    when is_new . atomically $
        readTVar cons >>= writeTVar cons . Map.insert peer entry



seekRemotePeers :: JabberPeerSession config =>
     XMPPPeerClass config -> TChan Presence -> TVar (Map Peer (TChan OutBoundMessage, ThreadId)) -> IO b0
seekRemotePeers config chan server_connections = do
    fix $ \loop -> do
        event <- atomically $ readTChan chan
        case event of
            p@(Presence jid stat) | not (is_remote (peer jid)) -> do
              -- L.putStrLn $ "seekRemotePeers: " <++> L.show jid <++> " " <++> bshow stat
              runMaybeT $ do
                  u <- MaybeT . return $ name jid
                  subscribers <- liftIO $ do
                    subs <- getSubscribers config u
                    mapM parseHostNameJID subs
                  -- liftIO . L.putStrLn $ "subscribers: " <++> bshow subscribers
                  let peers = Set.map peer (Set.fromList subscribers)
                  forM_ (Set.toList peers) $ \peer -> do
                    when (is_remote peer) $
                        liftIO $ sendMessage server_connections (OutBoundPresence p) peer
                  -- TODO: send presence probes for buddies
                  -- TODO: cache remote presences for clients
            _ -> return (Just ())
        loop 

xmlifyPresenceForPeer sock (Presence jid stat) = do
    -- TODO: accept socket argument and determine local ip address
    --       connected to this peer.
    addr <- getSocketName sock
    let n = name jid
        rsc = resource jid
        jidstr = toStrict . L.decodeUtf8 
                  $ n <$++> "@" <?++> showPeer (RemotePeer addr) <++?>  "/" <++$> rsc 
    return 
      [ EventBeginElement "{jabber:server}presence" 
            (("from",[ContentText jidstr]):typ stat)
      , EventBeginElement "{jabber:server}show" []
      , EventContent (ContentText . shw $ stat)
      , EventEndElement "{jabber:server}show"
      , EventEndElement "{jabber:server}presence"
      ]
 where
    typ Offline = [("type",[ContentText "unavailable"])]
    typ _       = []
    shw Available = "chat"
    shw Away      = "away"
    shw Offline   = "away" -- Is this right?