{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE MultiWayIf #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
module Reaktor.Plugins.System (new) where

import Blessings
import Control.Applicative
import Control.Concurrent (forkIO,threadDelay)
import Control.Concurrent.Async (race)
import Control.Exception
import qualified Data.HashMap.Lazy as M
import qualified Data.List as L
import qualified Data.Text.Extended as T
import qualified Data.Text.Encoding as T
import qualified Data.Text.IO as T
import qualified Data.Vector as V
import Prelude.Extended
import Reaktor
import Reaktor.Plugins.System.Internal
import System.Environment (getEnvironment)
import System.Exit
import System.FilePath.Posix (takeBaseName)
import System.IO (BufferMode(LineBuffering),hSetBuffering)
import System.IO (Handle,hClose,hPutStr,hIsEOF)
import System.IO.Error (catchIOError,isDoesNotExistError)
import System.Process
import System.Posix.Process (getProcessGroupIDOf)
import System.Posix.Signals (Signal,signalProcessGroup,killProcess)
import System.Posix.Types (ProcessGroupID)
import qualified Text.Regex.PCRE.Light as RE


new :: Config -> Actions -> IO (Message -> IO ())
new config@Config{..} actions@Actions{..} = do
    pure $ \case
        Message (Just prefix) cmd (msgtarget:text:[]) | elem cmd ["PRIVMSG", "JOIN"] -> do
          let hooks = maybe [] id (M.lookup cmd cHooks)
          mapM_ (\h -> run1 config actions h prefix msgtarget text) hooks

        Message (Just prefix) "JOIN" (channel:[]) -> do
          let hooks = maybe [] id (M.lookup "JOIN" cHooks)
          mapM_ (\h -> run1 config actions h prefix channel "") hooks

        _ -> pure ()


run1 :: Config -> Actions -> Hook -> Text -> Text -> Text -> IO ()
run1 Config{..} Actions{..} Hook{..} prefix msgtarget text = do
    nick <- aGetNick

    let
        match =
          case hPattern of
            Just p -> \s ->
              fmap (map T.decodeUtf8) $
              RE.match p (T.encodeUtf8 s) [RE.exec_no_utf8_check]
            Nothing -> const Nothing

        isActivated =
          case hActivate of
            Always -> pure ""
            Match -> match text >> pure ""
            Query ->
              let me = nick <> ":" in
              if
                | isQuery -> pure ""
                | T.isPrefixOf me text -> pure me
                | T.isPrefixOf "*:" text -> pure "*:"
                | otherwise -> mempty

        audience = if isQuery then from else msgtarget

        from = T.takeWhile (/='!') prefix

        -- TODO check if msgtarget is one of our channels?
        --      what if our nick has changed?
        isQuery = msgtarget == nick

    case isActivated of
      Just trigger -> do
        let
            cmdline = T.dropWhile (==' ') $ T.drop (T.length trigger) text
            resultPrefix = if isQuery then [] else [from <> ":"]

            captures = V.fromList $ fromMaybe [] (match cmdline)
            capture i = captures V.!? i

            name =
              case hCommand of
                Capture i -> fromMaybe "<unnamed>" (capture i)
                CaptureOr Command{..} -> T.pack $ takeBaseName $ commandPath

            command =
              case hCommand of
                Capture i -> (`M.lookup` hCommands) =<< capture i
                CaptureOr c -> Just c

            args =
              map (maybe "" T.unpack)
                $ L.dropWhileEnd isNothing
                -- $ map getArgument hArguments
                $ flip map hArguments
                $ \case
                  Capture i -> capture i
                  CaptureOr s -> Just s

        case command of
          Just Command{..} -> do
            baseEnv <- getEnvironment

            let
                logStr pid s = do
                  let p = name <> "[" <> T.show pid <> "] "
                  aLog $ SGR [38,5,247] (Plain p <> s)

                red :: Text -> Blessings Text
                red = SGR [31] . Plain

                onStart pid = logStr pid "started"
                onErrLine pid s = logStr pid $ "stderr: " <> red s
                onOutLine _ s = aSend (privmsg audience [s])
                onError pid e = logStr pid $ "failed: " <> red (T.show e)

                onExit pid = \case
                  ExitSuccess ->
                    logStr pid "stopped"
                  ExitFailure i ->
                    logStr pid $ "stopped with exit code " <>
                      red (T.show $ if i <= 127 then i else -256 + i)

                extraEnv =
                    [ ("_prefix", T.unpack prefix)
                    , ("_from", T.unpack from)
                    , ("_msgtarget", T.unpack msgtarget)
                    ]

                env =
                  M.toList $ mconcat
                    [ M.fromList extraEnv
                    , maybe mempty id commandEnv
                    , M.fromList baseEnv
                    ]

                cwd = commandWorkDir <|> hWorkDir <|> cWorkDir

            fork commandPath args cwd (Just env) "" hTimeout Callbacks{..}

          Nothing -> do
            let s = name <> ": command not found"
            aSend (privmsg audience (resultPrefix <> [s]))

      Nothing -> return ()

data Callbacks = Callbacks
    { onOutLine :: Pid -> Text -> IO ()
    , onErrLine :: Pid -> Text -> IO ()
    , onError :: Pid -> SomeException -> IO ()
    , onExit :: Pid -> ExitCode -> IO ()
    , onStart :: Pid -> IO ()
    }

fork :: FilePath
     -> [String]
     -> Maybe FilePath
     -> Maybe [(String, String)]
     -> String
     -> Maybe Int
     -> Callbacks
     -> IO ()
fork path args cwd env input hTimeout Callbacks{..} =
    forkIO (f `catch` onError (-1)) >> return ()
  where
    f = withCreateProcess p $ \(Just inh) (Just outh) (Just errh) ph -> do
      Just pid <- getPid ph
      pgid <- getProcessGroupIDOf pid

      onStart pid

      mapM_ forkIO [
          hPutStr inh input `finally` hClose inh,
          hWithLines outh (onOutLine pid),
          hWithLines errh (onErrLine pid)
        ]

      case hTimeout of
        Just time ->
          race (threadDelay time) (waitForProcess ph) >>= \case
            Left () -> onError pid (SomeException (ErrorCall "timeout"))
            Right code -> onExit pid code
        Nothing ->
          waitForProcess ph >>= onExit pid

      killProcessGroup pgid

    p = (proc path args)
          { cwd = cwd
          , env = env
          , std_in = CreatePipe
          , std_out = CreatePipe
          , std_err = CreatePipe
          , close_fds = True
          , create_group = True
          , new_session = True
          }


killProcessGroup :: ProcessGroupID -> IO ()
killProcessGroup = signalProcessGroup' killProcess

signalProcessGroup' :: Signal -> ProcessGroupID -> IO ()
signalProcessGroup' sig pgid =
    catchIOError
      (signalProcessGroup sig pgid)
      (\e -> if isDoesNotExistError e then return () else ioError e)


hWithLines :: Handle -> (Text -> IO ()) -> IO ()
hWithLines h f = do
    hSetBuffering h LineBuffering
    go `finally` hClose h
  where
    go =
      hIsEOF h >>= \case
        True -> return ()
        False -> T.hGetLine h >>= f >> go