{-# LANGUAGE CPP                       #-}
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE FlexibleContexts          #-}
{-# LANGUAGE FlexibleInstances         #-}
{-# LANGUAGE LambdaCase                #-}
{-# LANGUAGE MultiParamTypeClasses     #-}
{-# LANGUAGE NamedFieldPuns            #-}
{-# LANGUAGE NondecreasingIndentation  #-}
{-# LANGUAGE OverloadedStrings         #-}
{-# LANGUAGE PartialTypeSignatures     #-}
{-# LANGUAGE RankNTypes                #-}
{-# LANGUAGE RecordWildCards           #-}
{-# LANGUAGE ScopedTypeVariables       #-}
{-# LANGUAGE TupleSections             #-}
{-# LANGUAGE TypeFamilies              #-}

import Control.Arrow
import Control.Concurrent.STM
import Control.DeepSeq
import Control.Exception
import Control.Monad
import Data.Char
import Data.List
import qualified Data.Map     as Map
import Data.Time.Clock
import GHC.Stats
import Network.Socket
import System.Environment
import System.IO
import System.Mem
import System.Posix.Process
import Text.PrettyPrint.HughesPJClass
import Text.Printf
import Text.Read
#ifdef THREAD_DEBUG
import Control.Concurrent.Lifted.Instrument
#else
import Control.Concurrent.Lifted
import GHC.Conc                  (labelThread)
#endif

import Network.Address hiding (NodeId, NodeInfo(..))
import Network.BitTorrent.DHT.Search
import Network.QueryResponse
import Network.StreamServer
import Kademlia
import qualified Mainline
import Network.DHT.Routing as R
import Data.Aeson as J (ToJSON, FromJSON)
import qualified Data.Aeson as J
import qualified Data.ByteString.Lazy as L
import Control.Concurrent.Async.Pool
import System.IO.Error
import qualified Data.Serialize as S
import Network.BitTorrent.DHT.ContactInfo as Peers

showReport :: [(String,String)] -> String
showReport kvs = do
    let colwidth = maximum $ map (length . fst) kvs
    (k,v) <- kvs
    concat [ printf "  %-*s" (colwidth+1) k, v, "\n" ]


marshalForClient :: String -> String
marshalForClient s = show (length s) ++ ":" ++ s

-- | Writes a message and signals ready for next command.
hPutClient :: Handle -> String -> IO ()
hPutClient h s = hPutStr h ('.' : marshalForClient s)

-- | Writes message, but signals there is more to come.
hPutClientChunk :: Handle -> String -> IO ()
hPutClientChunk h s = hPutStr h (' ' : marshalForClient s)

data DHTQuery nid ni = forall addr r tok. DHTQuery
    { qsearch  :: Search nid addr tok ni r
    , qhandler :: ni -> nid -> IO ([ni], [r], tok)
    , qshowR   :: r -> String
    , qshowTok :: tok -> Maybe String
    }

data DHT = forall nid ni. ( Show     ni
                          , Read     ni
                          , ToJSON   ni
                          , FromJSON ni
                          ) =>
    DHT
    { dhtBuckets :: TVar (BucketList ni)
    , dhtPing    :: ni -> IO Bool
    , dhtQuery   :: Map.Map String (DHTQuery nid ni)
    , dhtParseId :: String -> Either String nid
    }

nodesFileName :: String -> String
nodesFileName netname = netname ++ "-nodes.json"

saveNodes :: String -> DHT -> IO ()
saveNodes netname DHT{dhtBuckets} = do
    bkts <- atomically $ readTVar dhtBuckets
    let ns = map fst $ concat $ R.toList bkts
        bs = J.encode ns
        fname = nodesFileName netname
    L.writeFile fname bs

loadNodes :: FromJSON ni => String -> IO [ni]
loadNodes netname = do
    let fname = nodesFileName netname
    attempt <- tryIOError $ do
        J.decode <$> L.readFile fname
         >>= maybe (ioError $ userError "Nothing") return
    either (const $ return []) return attempt

pingNodes :: String -> DHT -> IO Bool
pingNodes netname DHT{dhtPing} = do
    let fname = nodesFileName netname
    attempt <- tryIOError $ do
        J.decode <$> L.readFile fname
         >>= maybe (ioError $ userError "Nothing") return
    case attempt of
        Left _   -> return False
        Right ns -> do fork $ do
                         myThreadId >>= flip labelThread ("pinging."++fname)
                         putStrLn $ "Forked "++show fname
                         withTaskGroup 10 $ \g -> do
                           mapTasks_ g (map dhtPing ns)
                         putStrLn $ "Load finished "++show fname
                       return True



reportTable :: Show ni => BucketList ni -> [(String,String)]
reportTable bkts = map (show *** show . fst)
                 $ concat
                 $ zipWith map (map (,) [0::Int ..])
                 $ R.toList
                 $ bkts

reportResult :: Show ni =>
    String
    -> (r -> String)
    -> (tok -> Maybe String)
    -> Handle
    -> Either String ([ni],[r],tok)
    -> IO ()
reportResult meth showR showTok h (Left e)            = hPutClient h e
reportResult meth showR showTok h (Right (ns,rs,tok)) = do
    hPutClient h $ showReport report
 where
    report = intercalate [("","")] [ tok_r , node_r , result_r ]

    tok_r = maybe [] (pure . ("token:",)) $ showTok tok

    node_r = map ( ("n",) . show ) ns

    result_r | (meth=="node") = []
             | otherwise      = map ( (take 1 meth,) . showR ) rs

data Session = Session
    { netname           :: String
    , dhts              :: Map.Map String DHT
    , externalAddresses :: IO [SockAddr]
    , swarms            :: Mainline.SwarmsDatabase
    , signalQuit        :: MVar ()
    }

clientSession s@Session{..} sock cnum h = do
    line <- map toLower . dropWhile isSpace <$> hGetLine h
    let (c,args) = second (dropWhile isSpace) $ break isSpace line
        cmd0 :: IO () -> IO ()
        cmd0 action = action >> clientSession s sock cnum h
        switchNetwork dest = do hPutClient h ("Network: "++dest)
                                clientSession s{netname=dest} sock cnum h
    case (c,args) of
        ("stop", _) -> do hPutClient h "Terminating DHT Daemon."
                          hClose h
                          putMVar signalQuit ()

        ("quit", _) -> hPutClient h "" >> hClose h

        ("pid", _) -> cmd0 $ do
                    pid <- getProcessID
                    hPutClient h (show pid)
        ("external-ip", _) -> cmd0 $ do
                    unlines . map (either show show . Mainline.either4or6) <$> externalAddresses
                        >>= hPutClient h
#ifdef THREAD_DEBUG
        ("threads", _) -> cmd0 $ do
                    ts <- threadsInformation
                    tm <- getCurrentTime
                    let r = map (\PerThread{..} -> (show lbl,show (diffUTCTime tm startTime))) ts
                    hPutClient h $ showReport r
        ("mem", s) -> cmd0 $ do
                    case s of
                        "gc" -> do hPutClient h "Performing garbage collection..."
                                   performMajorGC
                        "" -> do
                            is_enabled <- getGCStatsEnabled
                            if is_enabled
                             then do
                                GCStats{..} <- getGCStats
                                let r = [ ("bytesAllocated", show bytesAllocated)
                                        , ("numGcs", show numGcs)
                                        , ("maxBytesUsed", show maxBytesUsed)
                                        , ("numByteUsageSamples", show numByteUsageSamples)
                                        , ("cumulativeBytesUsed", show cumulativeBytesUsed)
                                        , ("bytesCopied", show bytesCopied)
                                        , ("currentBytesUsed", show currentBytesUsed)
                                        , ("currentBytesSlop", show currentBytesSlop)
                                        , ("maxBytesSlop", show maxBytesSlop)
                                        , ("peakMegabytesAllocated", show peakMegabytesAllocated)
                                        , ("mutatorCpuSeconds", show mutatorCpuSeconds)
                                        , ("mutatorWallSeconds", show mutatorWallSeconds)
                                        , ("gcCpuSeconds", show gcCpuSeconds)
                                        , ("gcWallSeconds", show gcWallSeconds)
                                        , ("cpuSeconds", show cpuSeconds)
                                        , ("wallSeconds", show wallSeconds)
                                        , ("parTotBytesCopied", show parTotBytesCopied)
                                        , ("parMaxBytesCopied", show parMaxBytesCopied)
                                        ]
                                hPutClient h $ showReport r
                            else hPutClient h "Run with +RTS -T to obtain live memory-usage information."
                        _ -> hPutClient h "error."

#endif
        ("ls", _) | Just DHT{dhtBuckets} <- Map.lookup netname dhts
                    -> cmd0 $ do
                        bkts <- atomically $ readTVar dhtBuckets
                        let r = reportTable bkts
                        hPutClient h $
                            showReport $
                                    r ++ [ ("buckets", show $ R.shape bkts)
                                         , ("node-id", show $ thisNode bkts)
                                         , ("network", netname) ]

        ("ping", s) | Just DHT{dhtPing} <- Map.lookup netname dhts
                    -> cmd0 $ do
                        case readEither s of
                          Right addr -> do result <- dhtPing addr
                                           let rs = [" ", show result]
                                           hPutClient h $ unlines rs
                          Left er -> hPutClient h er
        ("g", s) | Just DHT{..} <- Map.lookup netname dhts
                    -> cmd0 $ do
                        -- arguments: method
                        --            nid
                        --            (optional dest-ni)
                        self <- atomically $ thisNode <$> readTVar dhtBuckets
                        let (method,xs) = break isSpace $ dropWhile isSpace s
                            (nidstr,ys) = break isSpace $ dropWhile isSpace xs
                            destination = dropWhile isSpace ys
                            goQuery qry = either (hPutClient h . ("Bad search target: "++))
                                                 (goTarget qry)
                                                 $ dhtParseId nidstr
                            goTarget DHTQuery{..} nid =
                                go nid >>= reportResult method qshowR qshowTok h
                              where
                                go | null destination = fmap Right . qhandler self
                                   | otherwise        = case readEither destination of
                                        Right ni -> fmap (maybe (Left "Timeout.") Right)
                                                    . flip (searchQuery qsearch) ni
                                        Left  e  -> const $ return $ Left ("Bad destination: "++e)
                        maybe (hPutClient h ("Unsupported method: "++method))
                              goQuery
                              $ Map.lookup method dhtQuery

        ("save", _) | Just dht <- Map.lookup netname dhts
                    -> cmd0 $ do
                        saveNodes netname dht
                        hPutClient h $ "Saved " ++ nodesFileName netname ++ "."

        ("load", _) | Just dht <- Map.lookup netname dhts
                    -> cmd0 $ do
                        b <- pingNodes netname dht
                        if b then hPutClient h $ "Pinging " ++ nodesFileName netname ++ "."
                             else hPutClient h $ "Failed: " ++ nodesFileName netname ++ "."

        ("swarms", s) -> cmd0 $ do
                    let fltr = case s of
                                    ('-':'v':cs) | all isSpace (take 1 cs)
                                      -> const True
                                    _ -> (\(h,c,n) -> c/=0 )
                    ss <- atomically $ Peers.knownSwarms <$> readTVar (Mainline.contactInfo swarms)
                    let r = map (\(h,c,n) -> (unwords [show h,show c], maybe "" show n))
                            $ filter fltr ss
                    hPutClient h $ showReport r

        ("peers", s) -> cmd0 $ case readEither s of
                        Right ih -> do
                            ps <- atomically $ Peers.lookup ih <$> readTVar (Mainline.contactInfo swarms)
                            hPutClient h $ showReport $ map (((,) "") . show . pPrint) ps
                        Left er -> hPutClient h er

        (n, _) | n `elem` Map.keys dhts -> switchNetwork n

        _    -> cmd0 $ hPutClient h "error."


readExternals :: [TVar (BucketList Mainline.NodeInfo)] -> IO [SockAddr]
readExternals vars = do
    as <- atomically $ mapM (fmap (Mainline.nodeAddr . selfNode) . readTVar) vars
    -- TODO: Filter to only global addresses?
    return as

defaultPort = "6881"

main = do
    args <- getArgs
    p <- case take 2 (dropWhile (/="-p") args) of
                ["-p",port] | not ("-" `isPrefixOf` port) -> return port
                ("-p":_)      -> error "Port not specified! (-p PORT)"
                _             -> return defaultPort
    addr <- getBindAddress p True{- ipv6 -}

    (bt,btR,swarms) <- Mainline.newClient addr

    -- Restore peer database before forking the listener thread.
    peerdb <- left show <$> tryIOError (L.readFile "bt-peers.dat")
    either (hPutStrLn stderr . ("bt-peers.dat: "++))
           (atomically . writeTVar (Mainline.contactInfo swarms))
           (peerdb >>= S.decodeLazy)

    quitBt <- forkListener bt

    tox <- return $ error "TODO: Tox.newClient"
    quitTox <- return $ return () -- TODO: forkListener tox

    let mainlineDHT bkts = DHT
            { dhtBuckets = bkts btR
            , dhtPing    = Mainline.ping bt
            , dhtQuery   = Map.fromList
                            [ ("node", DHTQuery (Mainline.nodeSearch bt)
                                                (\ni -> fmap Mainline.unwrapNodes
                                                        . Mainline.findNodeH btR ni
                                                        . flip Mainline.FindNode (Just Mainline.Want_Both))
                                                show
                                                (const Nothing))
                            , ("peer", DHTQuery (Mainline.peerSearch bt)
                                                (\ni -> fmap Mainline.unwrapPeers
                                                        . Mainline.getPeersH btR swarms ni
                                                        . flip Mainline.GetPeers (Just Mainline.Want_Both)
                                                        . (read . show)) -- TODO: InfoHash -> NodeId
                                                show
                                                (Just . show))
                            ]
            , dhtParseId = readEither :: String -> Either String Mainline.NodeId
            }
        dhts = Map.fromList
                [ ("bt4", mainlineDHT Mainline.routing4)
                , ("bt6", mainlineDHT Mainline.routing6)
                ]

    waitForSignal <- do
        signalQuit <- newEmptyMVar
        let session = clientSession $ Session
                { netname           = "bt4" -- initial default DHT
                , dhts              = dhts  -- all DHTs
                , signalQuit        = signalQuit
                , swarms            = swarms
                , externalAddresses = readExternals
                                        [ Mainline.routing4 btR
                                        , Mainline.routing6 btR
                                        ]
                }
        srv <- streamServer (withSession session) (SockAddrUnix "dht.sock")
        return $ do
            () <- takeMVar signalQuit
            quitListening srv

    let bkts4 = Mainline.routing4 btR
    btSaved4 <- loadNodes "bt4" :: IO [Mainline.NodeInfo]
    putStrLn $ "Loaded "++show (length btSaved4)++" nodes for bt4."
    fallbackNodes4 <- Mainline.bootstrapNodes Mainline.Want_IP4
    fork $ do
        myThreadId >>= flip labelThread "bootstrap.Mainline4"
        bootstrap (Mainline.nodeSearch bt) bkts4 (Mainline.ping bt) btSaved4 fallbackNodes4
        saveNodes "bt4" (dhts Map.! "bt4")

    btSaved6 <- loadNodes "bt6"
    putStrLn $ "Loaded "++show (length btSaved6)++" nodes for bt6."
    let bkts6 = Mainline.routing6 btR
    fallbackNodes6 <- Mainline.bootstrapNodes Mainline.Want_IP6
    fork $ do
        myThreadId >>= flip labelThread "bootstrap.Mainline6"
        bootstrap (Mainline.nodeSearch bt) bkts6 (Mainline.ping bt) btSaved6 fallbackNodes6
        saveNodes "bt6" (dhts Map.! "bt6")

    hPutStr stderr $ showReport $ map (("bootstrap (IPv4)",) . show) fallbackNodes4
                                  ++ map (("bootstrap (IPv6)",) . show) fallbackNodes6

    waitForSignal

    quitBt
    quitTox

    swarmsdb <- atomically $ readTVar (Mainline.contactInfo swarms)
    L.writeFile "bt-peers.dat" $ S.encodeLazy swarmsdb