{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE NoMonomorphismRestriction #-}
{-# LANGUAGE OverloadedStrings #-}
module Sync.MerkleTree.Sync
    ( child
    , local
    , parent
    , openStreams
    , mkChanStreams
    , StreamPair(..)
    , Direction(..)
    ) where

import Control.Concurrent(newChan)
import Control.Monad
import Control.Monad.State
import Data.Monoid
import System.FilePath
import Prelude hiding (lookup)
import Sync.MerkleTree.Trie
import Sync.MerkleTree.Types
import System.IO
import System.IO.Streams(InputStream, OutputStream)
import Data.ByteString(ByteString)
import qualified Data.Serialize as SE
import qualified Data.ByteString as BS
import qualified System.IO.Streams as ST
import qualified System.IO.Streams.Concurrent as ST

import Sync.MerkleTree.Analyse
import Sync.MerkleTree.CommTypes
import Sync.MerkleTree.Client
import Sync.MerkleTree.Server
import Sync.MerkleTree.Util.RequestMonad

data StreamPair
    = StreamPair
    { sp_in :: InputStream ByteString
    , sp_out :: OutputStream ByteString
    }

openStreams :: Handle -> Handle -> IO StreamPair
openStreams hIn hOut =
    do inStream <- ST.handleToInputStream hIn
       outStream <- ST.handleToOutputStream hOut
       return $ StreamPair { sp_in = inStream, sp_out = outStream }

mkChanStreams :: IO (InputStream ByteString, OutputStream ByteString)
mkChanStreams =
    do chan <- newChan
       liftM2 (,) (ST.chanToInput chan) (ST.chanToOutput chan)

instance Protocol RequestMonad where
    queryHashReq = request . QueryHash
    querySetReq = request . QuerySet
    queryFileReq = request . QueryFile
    queryFileContReq = request . QueryFileCont
    logReq = request . Log
    terminateReq = request Terminate

instance ClientMonad RequestMonad where
    split = splitRequests

instance ClientMonad ServerMonad where
    split xs = liftM mconcat $ sequence xs

data Direction
    = FromRemote
    | ToRemote

child :: StreamPair -> IO ()
child streams =
    do launchMessage <- getFromInputStream (sp_in streams)
       serverOrClient (read launchMessage) streams

parent :: StreamPair -> FilePath -> FilePath -> Direction -> ClientServerOptions -> IO ()
parent streams source destination direction clientServerOpts =
    case direction of
      FromRemote ->
        do respond (sp_out streams) $ show $ mkLaunchMessage Server source
           serverOrClient (mkLaunchMessage Client destination) streams
      ToRemote ->
        do respond (sp_out streams) $ show $ mkLaunchMessage Client destination
           serverOrClient (mkLaunchMessage Server source) streams
    where
      mkLaunchMessage side dir =
          LaunchMessage
          { lm_dir = dir
          , lm_clientServerOptions = clientServerOpts
          , lm_protocolVersion = thisProtocolVersion
          , lm_side = side
          }

respond :: (Show a, SE.Serialize a) => OutputStream ByteString -> a -> IO ()
respond os = mapM_ (flip ST.write os . Just) . (:[BS.empty]) . SE.encode

local :: ClientServerOptions -> FilePath -> FilePath -> IO ()
local cs source destination =
    do sourceDir <- liftM (mkTrie 0) $ analyseDirectory source (cs_ignore cs) Root
       destinationDir <- liftM (mkTrie 0) $ analyseDirectory destination (cs_ignore cs) Root
       evalStateT (abstractClient cs destination destinationDir) (startServerState source sourceDir)

serverOrClient :: LaunchMessage -> StreamPair -> IO ()
serverOrClient lm streams
    | lm_protocolVersion lm == thisProtocolVersion =
        let side =
                case lm_side lm of
                  Server -> server
                  Client -> client (lm_clientServerOptions lm)
        in do entries <- analyseDirectory (lm_dir lm) (cs_ignore $ lm_clientServerOptions lm) Root
              side entries (lm_dir lm) streams
    | otherwise = fail "Incompatible sync-mht versions."

server :: [Entry] -> FilePath -> StreamPair -> IO ()
server entries fp streams = evalStateT loop (startServerState fp $ mkTrie 0 entries)
    where
       serverRespond = liftIO . respond (sp_out streams)
       loop =
           do req <- liftIO $ getFromInputStream (sp_in streams)
              case req of
                QueryHash l -> queryHashReq l >>= serverRespond >> loop
                QuerySet l -> querySetReq l >>= serverRespond >> loop
                QueryFile f -> queryFileReq f >>= serverRespond >> loop
                QueryFileCont c -> queryFileContReq c >>= serverRespond >> loop
                Log t -> logReq t >>= serverRespond >> loop
                Terminate -> terminateReq >>= serverRespond >> return ()

client :: ClientServerOptions -> [Entry] -> FilePath -> StreamPair -> IO ()
client cs entries fp streams =
    runRequestMonad (sp_in streams) (sp_out streams) $ abstractClient cs fp $ mkTrie 0 entries