module Hsbot.Irc.Core
    ( startIrcbot
    ) where

import Control.Concurrent
import Control.Exception (AsyncException, Handler (..), IOException, catch, catches)
import Control.Monad.State
import qualified Data.Map as M
import Data.Maybe (fromMaybe)
import Network
import Prelude hiding (catch)
import System.IO
import System.Posix.IO (fdToHandle, handleToFd)
import System.Posix.Types (Fd)

import Hsbot.Irc.Command
import Hsbot.Irc.Config
import Hsbot.Irc.Message
import Hsbot.Irc.Plugin
import Hsbot.Irc.Server
import Hsbot.Irc.Types
import Hsbot.Types

-- | IrcBot's main entry point
startIrcbot :: IrcConfig -> Chan BotMsg -> Chan BotMsg -> Maybe String -> IO ()
startIrcbot config masterChan myChan txtResumeData = do
    let resumeData = case txtResumeData of
            Just txtData -> read txtData :: ResumeData  -- TODO : catch exception
            Nothing -> M.empty :: ResumeData
    print resumeData
    putStrLn "[IrcBot] Opening communication channel... "
    chan <- newChan :: IO (Chan IrcBotMsg)
    handle <- case M.lookup "HANDLE" resumeData of
        Just txtFd -> do
            let fd = read txtFd :: Fd
            fdToHandle fd
        Nothing -> do
            putStrLn $ concat ["[IrcBot] Connecting to ", ircConfigAddress config, "... "]
            handle <- connectTo (ircConfigAddress config) (ircConfigPort config)
            hSetBuffering handle NoBuffering
            hSetEncoding handle utf8
            return handle
    fd <- handleToFd handle
    putStrLn "[IrcBot] Spawning reader threads..."
    myOwnThreadId  <- myThreadId
    readerThreadId <- forkIO $ ircBotReader handle chan myOwnThreadId
    masterReaderThreadId <- forkIO $ ircBotMasterReader myChan chan
    putStrLn "[IrcBot] Initializing server connection..."
    let ircServerState = IrcServerState { ircServerId            = ircConfigAddress config
                                        , ircServerChannels      = []
                                        , ircServerNickname      = ircConfigNickname config
                                        , ircServerCommandPrefix = ircConfigCommandPrefix config
                                        , ircServerChan          = chan }
        ircBotState = IrcBotState { ircBotPlugins              = M.empty
                                  , ircBotCommands             = M.empty
                                  , ircBotChan                 = chan
                                  , ircBotMasterChan           = masterChan
                                  , ircBotServerState          = ircServerState
                                  , ircBotHandle               = handle
                                  , ircBotConfig               = config
                                  , ircBotResumeData           = M.singleton "HANDLE" (show fd) }
    ircBotState' <- execStateT (initBotServerConnection config) ircBotState
    putStrLn "[IrcBot] Spawning plugins..."
    ircBotState'' <- execStateT spawnIrcPlugins ircBotState'
    putStrLn "[IrcBot] Entering Core loop... "
    ircBotState''' <- (execStateT ircBotLoop ircBotState'') `catches` [ Handler (\ (_ :: IOException) -> return (ircBotState''))
                                                                      , Handler (\ (_ :: AsyncException) -> return (ircBotState'')) ]
    putStrLn "[IrcBot] Killing reader threads..."
    killThread readerThreadId
    killThread masterReaderThreadId
    putStrLn "[IrcBot] Killing active plugins... "
    let resumeData' = ircBotResumeData ircBotState'''
        ircPlugins = read (fromMaybe [] (M.lookup "PLUGINS" resumeData')) :: [String]
    evalStateT (mapM_ killIrcPlugin ircPlugins) ircBotState'''
    return ()

--resumeIrcBot
--resumeIrcBot

-- | Runs the IrcBot's reader loop
ircBotReader :: Handle -> Chan IrcBotMsg -> ThreadId -> IO ()
ircBotReader handle chan fatherThreadId = forever $ do
    str <- (hGetLine handle) `catch` handleIOException
    let msg = parseIrcMsg str
    case msg of
        Right msg' -> writeChan chan (InIrcMsg msg')
        _          -> return ()
  where
    handleIOException :: IOException -> IO (String)
    handleIOException ioException = do
        throwTo fatherThreadId ioException
        myId <- myThreadId
        killThread myId
        return ""

-- | Reads the Master's chan
ircBotMasterReader :: Chan BotMsg -> Chan IrcBotMsg -> IO ()
ircBotMasterReader masterChan _ = forever $ do
    _ <- readChan masterChan
    return ()
    -- TODO : handle botMsg

-- | Initialize the bot's server connection
initBotServerConnection :: IrcConfig -> IrcBot ()
initBotServerConnection config = do
    ircBot <- get
    let ircServerState = ircBotServerState ircBot
    ircServerState' <- execStateT (initServerConnection config) ircServerState
    put $ ircBot { ircBotServerState = ircServerState' }

-- | Run the IrcBot's main loop
ircBotLoop :: IrcBot ()
ircBotLoop = forever $ do
    chan <- gets ircBotChan
    msg  <- liftIO $ readChan chan
    case msg of
        InIrcMsg inIrcMsg   -> dispatchMessage $ InIrcMsg inIrcMsg
        OutIrcMsg outIrcMsg -> sendThisMessage outIrcMsg
        IntIrcCmd intIrcCmd -> do
            reboot <- processInternalCommand $ IntIrcCmd intIrcCmd
            reportUpdate
            if reboot == BotReboot
              then processRebootCommand
              else return ()
  where
    sendThisMessage :: IrcMsg -> IrcBot ()
    sendThisMessage outputMsg = do
        let str = serializeIrcMsg outputMsg
        handle <- gets ircBotHandle
        liftIO $ hPutStr handle (str ++ "\r\n")

-- | Dispatches an input message
dispatchMessage :: IrcBotMsg -> IrcBot ()
dispatchMessage (InIrcMsg inIrcMsg) = do
    config  <- gets ircBotConfig
    plugins <- gets ircBotPlugins
    cmds    <- gets ircBotCommands
    if (isPluginCommand config)
      then
        let key         = tail . head $ words getMsgContent
            pluginNames = fromMaybe [] $ M.lookup key cmds
            plugins'    = fromMaybe [] $ mapM (flip M.lookup plugins) pluginNames
        in mapM_ (sendRunCommand (tail getMsgContent) . first) plugins'
      else
        mapM_ (sendToPlugin (InIrcMsg inIrcMsg) . first) (M.elems plugins)
  where
    isPluginCommand :: IrcConfig -> Bool
    isPluginCommand config =
        and [ ircMsgCommand inIrcMsg == "PRIVMSG"
        , (head getMsgContent) == ircConfigCommandPrefix config ]
    sendRunCommand :: String -> IrcPluginState -> IrcBot ()
    sendRunCommand cmd plugin =  sendToPlugin (IntIrcCmd $ IrcCmd "RUN" "CORE" (ircPluginName plugin) cmd inIrcMsg) plugin
    getMsgContent :: String
    getMsgContent = unwords . tail $ ircMsgParameters inIrcMsg
dispatchMessage _ = return ()

-- | Reports an update to the master bot
reportUpdate :: IrcBot ()
reportUpdate = do
    ircbot <- get
    let masterChan = ircBotMasterChan ircbot
        msg = UpdMsg $ ResMsg { resMsgFrom = ircConfigName $ ircBotConfig ircbot
                              , resMsgData = ircBotResumeData ircbot }
    liftIO $ writeChan masterChan msg

-- | Process a reboot command
processRebootCommand :: IrcBot ()
processRebootCommand = do
    ircbot <- get
    let masterChan = ircBotMasterChan ircbot
        msg = IntMsg $ Msg { msgType  = "REBOOT"
                           , msgFrom  = ircConfigName $ ircBotConfig ircbot
                           , msgTo    = "CORE"
                           , msgStuff = show $ ircBotResumeData ircbot
                           }
    liftIO $ writeChan masterChan msg