{-# LANGUAGE OverloadedStrings #-}
import Control.Monad.Trans.Resource (runResourceT)
import Control.Monad.Trans (lift)
import Control.Monad.IO.Class (liftIO)
import Control.Monad.Fix (fix)
import Control.Monad
import Control.Concurrent (forkIO)
import Control.Concurrent.STM
-- import Control.Concurrent.STM.TChan
import Network.Socket
import XMPPTypes (withPort)
import Text.Printf
import System.Posix.Signals
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as Strict8
-- import qualified Data.ByteString.Lazy.Char8 as Lazy8

import Data.Conduit
import qualified Data.Conduit.List as CL
import qualified Data.Conduit.Binary as CB
import Data.Conduit.Blaze (builderToByteStringFlush)

import qualified Text.XML.Stream.Render as XML
import qualified Text.XML.Stream.Parse as XML
import Data.XML.Types as XML
import Data.Maybe (catMaybes)
import Data.Monoid ( (<>) )
import Data.Text (Text)
import qualified Data.Text as Text (pack)

import qualified Control.Concurrent.STM.UpdateStream as Slotted
import ControlMaybe
import NestingXML
import EventUtil
import Server

addrToText :: SockAddr -> Text
addrToText (addr@(SockAddrInet _ _)) = Text.pack $ stripColon (show addr)
 where stripColon s = pre where (pre,port) = break (==':') s
addrToText (addr@(SockAddrInet6 _ _ _ _)) = Text.pack $ stripColon (show addr)
 where stripColon s = if null bracket then pre else pre ++ "]"
          where
            (pre,bracket) = break (==']') s

wlog s = putStrLn s
 where _ = s :: String
wlogb s = Strict8.putStrLn s

control sv = atomically . putTMVar (serverCommand sv)

xmlStream :: ReadCommand -> WriteCommand -> ( Source IO XML.Event
                                            , Sink (Flush XML.Event) IO () )
xmlStream conread conwrite = (xsrc,xsnk)
 where
    xsrc = src $= XML.parseBytes XML.def
    xsnk = -- XML.renderBytes XML.def =$ snk
        XML.renderBuilderFlush XML.def 
        =$= builderToByteStringFlush 
        =$= discardFlush 
        =$ snk
      where
        discardFlush :: Monad m => ConduitM (Flush a) a m ()
        discardFlush = awaitForever $ \x -> do
            let unchunk (Chunk a) = a
                ischunk (Chunk _) = True
                ischunk _         = False
            when (ischunk x) $ yield (unchunk x)

    src = do
        v <- lift conread
        maybe (return ()) -- lift . wlog $ "conread: Nothing")
              (\v -> yield v >> src)
              v
    snk = awaitForever $ liftIO . conwrite
        

type FlagCommand = STM Bool
type ReadCommand = IO (Maybe ByteString)
type WriteCommand = ByteString -> IO Bool

data Stanza
    = UnrecognizedStanza { stanzaChan :: TChan (Maybe XML.Event) }

prettyPrint prefix xs = 
    liftIO $ 
        CL.sourceList xs
        $= XML.renderBytes (XML.def { XML.rsPretty=True })
        =$= CB.lines 
        $$ CL.mapM_ (wlogb . (prefix <>))

xmppInbound :: ConnectionKey -> FlagCommand 
                -> Source IO XML.Event
                -> TChan Stanza
                -> Sink XML.Event IO ()
xmppInbound k pingflag src stanzas = doNestingXML $ do
    withXML $ \begindoc -> do
    when (begindoc==EventBeginDocument) $ do
    whenJust nextElement $ \xml -> do
    withJust (elementAttrs "stream" xml) $ \stream_attrs -> do
    fix $ \loop -> do
        -- liftIO . wlog $ "waiting for stanza."
        chan <- liftIO $ atomically newTChan
        whenJust nextElement $ \stanza -> do
            stanza_lvl <- nesting
            liftIO . atomically $ writeTChan chan (Just stanza)

            liftIO . atomically $ writeTChan stanzas $
                UnrecognizedStanza chan
            doUntilCloser stanza_lvl $ \xml -> do
                liftIO . atomically $ writeTChan chan (Just xml)
            liftIO . atomically $ writeTChan chan Nothing
            loop
    

chanContents :: TChan x -> IO [x]
chanContents ch = do
        x  <- atomically $ do
            bempty <- isEmptyTChan ch
            if bempty
                then return Nothing
                else fmap Just $ readTChan ch
        maybe (return [])
              (\x -> do
                xs <- chanContents ch
                return (x:xs))
              x

readUntilNothing :: TChan (Maybe x) -> IO [x]
readUntilNothing ch = do
        x  <- atomically $ readTChan ch
        maybe (return [])
              (\x -> do
                xs <- readUntilNothing ch
                return (x:xs))
              x


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

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

data XMPPState
    = PingSlot
 deriving (Eq,Ord)


peerPing :: Maybe Text -> Text -> Text -> [XML.Event]
peerPing mid to from = 
       [ EventBeginElement "{jabber:server}iq"
         $ (case mid of
            Just c -> (("id",[ContentText c]):)
            _      -> id               )
            [ ("type",[ContentText "get"])
            , attr "to"   to
            , attr "from" from
            ]
       , EventBeginElement "{urn:xmpp:ping}ping" []
       , EventEndElement "{urn:xmpp:ping}ping"
       , EventEndElement "{jabber:server}iq" ]


forkConnection :: ConnectionKey
                -> FlagCommand
                -> Source IO XML.Event
                -> Sink (Flush XML.Event) IO ()
                -> TChan Stanza
                ->  IO (TChan Stanza)
forkConnection k pingflag src snk stanzas = do
    rdone <- atomically newEmptyTMVar
    forkIO $ do
        -- src $$ awaitForever (lift . putStrLn . takeWhile (/=' ') . show)
        src $$ xmppInbound k pingflag src stanzas
        atomically $ putTMVar rdone ()
        wlog $ "end reader fork: " ++ show k
    slots <- atomically $ Slotted.new isEventBeginElement isEventEndElement
    needsFlush <- atomically $ newTVar False
    let _ = slots :: Slotted.UpdateStream XMPPState XML.Event
    let greet_src = do
            CL.sourceList greetPeer =$= CL.map Chunk
            yield Flush
        slot_src = do
            what <- lift . atomically $ foldr1 orElse
                [Slotted.pull slots >>= \x -> do
                    writeTVar needsFlush True
                    return $ do
                    yield (Chunk x)
                    slot_src
                ,do Slotted.isEmpty slots >>= check
                    readTVar needsFlush >>= check
                    writeTVar needsFlush False
                    return $ do
                    yield Flush
                    slot_src
                ,readTMVar rdone >> return (return ())
                ]
            what
    forkIO $ do (greet_src >> slot_src) $$ snk
                wlog $ "end post-queue fork: " ++ show k
    output <- atomically newTChan
    forkIO $ do
        -- mapM_ (atomically . Slotted.push slots Nothing) greetPeer
        fix $ \loop -> do
            what <- atomically $ foldr1 orElse
                [readTChan output >>= \stanza -> return $ do
                    let xchan = stanzaChan stanza
                    fix $ \inner -> do
                        what <- atomically $ orElse
                            (readTChan xchan >>= \mxml -> return $ do
                                case mxml of
                                  Just xml -> do
                                    atomically $ Slotted.push slots Nothing xml
                                    inner
                                  Nothing -> loop)
                            (readTMVar rdone >> return (return ()))
                        what
                ,do pingflag >>= check
                    return $ do
                    let to = addrToText (callBackAddress k)
                        from = "todo" -- Look it up from Server object
                                      -- or pass it with Connection event.
                        mid = Just "ping"
                    mapM_ (atomically . Slotted.push slots (Just $ PingSlot))
                          (peerPing mid to from)
                    loop
                ,readTMVar rdone >> return (return ())
                ]
            what
        wlog $ "end pre-queue fork: " ++ show k
    return output

monitor sv params = do
    chan <- return $ serverEvent sv
    stanzas <- atomically newTChan
    fix $ \loop -> do
    action <- atomically $ foldr1 orElse
      [ readTChan chan >>= \(k,e) -> return $ do 
        case e of
            Connection pingflag conread conwrite -> do
                 let (xsrc,xsnk) = xmlStream conread conwrite
                 forkConnection k pingflag xsrc xsnk stanzas
                 wlog $ tomsg k "Connection"
            EOF        -> wlog $ tomsg k "EOF"
            HalfConnection In -> do
                wlog $ tomsg k "ReadOnly"
                control sv (Connect (callBackAddress k) params)
            HalfConnection Out -> wlog $ tomsg k "WriteOnly"
            RequiresPing -> wlog $ tomsg k "RequiresPing"
            _ -> return ()
      , readTChan stanzas >>= \stanza -> return $ do
        xs <- readUntilNothing (stanzaChan stanza)
        wlog ""
        prettyPrint "STANZA: " xs
      ]
    action
    loop
 where
    tomsg k str =  printf "%12s %s" str (show k)
        where
            _ = str :: String

data ConnectionKey
       = PeerKey { callBackAddress :: SockAddr }
       | ClientKey { localAddress :: SockAddr }
 deriving (Show, Ord, Eq)

peerKey (sock,addr) = do
    peer <- getPeerName sock
    return $ PeerKey (peer `withPort` fromIntegral peerport)

clientKey (sock,addr) = return $ ClientKey addr

peerport = 5269
clientport = 5222

main = runResourceT $ do
    sv <- server
    lift $ do
    peer_params <- return (connectionDefaults peerKey)
                          { pingInterval = 10000
                          , timeout = 10000
                          , duplex = False }
    client_params <- return $ connectionDefaults clientKey
    forkIO $ monitor sv peer_params
    control sv (Listen peerport peer_params)
    -- control sv (Listen clientport client_params)

    -- atomically $ newEmptyTMVar >>= readTMVar -- Wait for control-c
    quitVar <- newEmptyTMVarIO
    installHandler sigTERM (CatchOnce (atomically $ putTMVar quitVar True)) Nothing
    installHandler sigINT (CatchOnce (atomically $ putTMVar quitVar True)) Nothing
    quitMessage <- atomically $ takeTMVar quitVar

    wlog "goodbye."
    return ()