{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE OverloadedStrings #-}

module Batchd.Daemon.SSH where

import Control.Monad
import Control.Monad.Trans
import Control.Exception as E
import Control.Concurrent
import qualified Control.Monad.Catch as MC
import Data.Maybe
import Data.Int
import qualified Data.Map as M
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import qualified Data.Text.IO as TIO
import qualified Data.ByteString as B
import Data.Conduit
import qualified Data.Conduit.Combinators as C
import qualified Data.Conduit.List as CL
import Data.Text.Format.Heavy
import Network.SSH.Client.LibSSH2
import Network.SSH.Client.LibSSH2.Conduit
import System.Log.Heavy
import System.FilePath
import System.Environment
import System.Exit
import System.IO (hClose, openTempFile, Handle)
import System.Directory (getTemporaryDirectory, removeFile)

import Batchd.Core.Common.Types
import Batchd.Daemon.Types
import Batchd.Core.Daemon.Hosts
import Batchd.Core.Daemon.Logging
import Batchd.Common.Types

getKnownHosts :: IO FilePath
getKnownHosts = do
  home <- getEnv "HOME"
  return $ home </> ".ssh" </> "known_hosts"

getDfltPublicKey :: IO FilePath
getDfltPublicKey = do
  home <- getEnv "HOME"
  return $ home </> ".ssh" </> "id_rsa.pub"

getDfltPrivateKey :: IO FilePath
getDfltPrivateKey = do
  home <- getEnv "HOME"
  return $ home </> ".ssh" </> "id_rsa"

accountForDefaultHostKeys :: Host -> IO Host
accountForDefaultHostKeys host = do
  def_public_key <- liftIO getDfltPublicKey
  def_private_key <- liftIO getDfltPrivateKey
  return $ host {
             hPublicKey = Just $ fromMaybe def_public_key (hPublicKey host)
           , hPrivateKey = Just $ fromMaybe def_private_key (hPrivateKey host)
          }

withSshOnHost :: HostController -> Host -> (Session -> Daemon a) -> Daemon a
withSshOnHost controller host actions = do
    known_hosts <- liftIO getKnownHosts
    def_public_key <- liftIO getDfltPublicKey
    def_private_key <- liftIO getDfltPrivateKey
    let passphrase = hPassphrase host
        public_key = fromMaybe def_public_key $ hPublicKey host
        private_key = fromMaybe def_private_key $ hPrivateKey host
        user = hUserName host
        port = hPort host
        original_hostname = hHostName host

    $(putMessage config_level) "Target host settings: {}" (Single $ Shown host)
    mbActualHostName <- liftIO $ getActualHostName controller (hControllerId host)
    hostname <- case mbActualHostName of
                  Nothing -> return original_hostname
                  Just actual -> do
                    $debug "Actual hostname of host `{}' is {}" (hName host, actual)
                    return actual
    $info "CONNECTING TO {} => {}@{}:{}" (original_hostname, user, hostname, port)
    wrapDaemon (withSSH2 known_hosts public_key private_key (T.unpack passphrase) (T.unpack user) (T.unpack hostname) port) $ \session -> do
      $debug "Connected to {}:{}." (hostname, port)
      actions session

ignoringIOErrors :: MC.MonadCatch m => m () -> m ()
ignoringIOErrors ioe = ioe `MC.catch` (\e -> const (return ()) (e :: IOError))

withTempFile :: FilePath -> (FilePath -> Handle -> Daemon a) -> Daemon a
withTempFile name actions = do
  tmpDir <- liftIO $ getTemporaryDirectory
  MC.bracket (liftIO $ openTempFile tmpDir name)
             (\(name, handle) -> ignoringIOErrors $ liftIO $ removeFile name)
             (uncurry actions)

withRemoteScript :: Session -> FilePath -> Int64 -> [T.Text] -> (String -> Daemon a) -> Daemon a
withRemoteScript session scriptsDir jobId commands actions = do
  if length commands == 1
    then actions (T.unpack $ head commands)
    else do
      let scriptText = formatScript commands
          scriptName = TL.unpack $ format "batchd_job_{}.script" (Single jobId)
      withTempFile scriptName $ \tmpPath tmpHandle -> do
        liftIO $ TIO.hPutStr tmpHandle scriptText
        liftIO $ hClose tmpHandle
        uploadFiles [tmpPath] scriptsDir session
        actions (scriptsDir </> takeFileName tmpPath)

execCommandsOnHost :: HostController -> Host -> [T.Text] -> Daemon ExitCode
execCommandsOnHost controller host commands =
      withSshOnHost controller host $ \session -> go ExitSuccess session commands
  where
    go :: ExitCode -> Session -> [T.Text] -> Daemon ExitCode
    go prevEc _ [] = return prevEc
    go prevEc session (command : commands) = do
      $info "Executing at {}: {}" (hName host, command)
      (Just commandHandle, commandOutput) <- liftIO $ execCommand True session (T.unpack command)
      lts <- askLoggingStateM
      liftIO $
          commandOutput =$= C.decodeUtf8 =$= C.linesUnbounded $$ CL.mapM_ $ \line ->
            infoIO lts $(here) "output> {}" (Single line)
      rc <- liftIO $ getReturnCode commandHandle
      $info "Exit code: {}" (Single rc)
      if rc == 0
        then go ExitSuccess session commands
        else return (ExitFailure rc)

retrieveOutput :: JobInfo -> JobType -> CommandsHandle -> Source IO B.ByteString -> ResultsChan -> IO ExitCode
retrieveOutput job jtype commandHandle commandOutput resultChan = do
    commandOutput =$= C.decodeUtf8 =$= C.linesUnbounded $$ CL.mapM_ $ \line ->
        writeChan resultChan (job, StdoutLine line)
    rc <- getReturnCode commandHandle
    let ec = if rc == 0
               then ExitSuccess
               else ExitFailure rc
    writeChan resultChan (job, Exited ec (jtOnFail jtype))
    return ec

getInputFiles :: JobType -> JobInfo -> [FilePath]
getInputFiles jt job =
  [T.unpack value | (name, value) <- M.assocs (jiParams job), getParamType jt name == Just InputFile]

getOutputFiles :: JobType -> JobInfo -> [FilePath]
getOutputFiles jt job =
  [T.unpack value | (name, value) <- M.assocs (jiParams job), getParamType jt name == Just OutputFile]

uploadFiles :: [FilePath] -> FilePath -> Session -> Daemon ()
uploadFiles files input_directory session =
  forM_ files $ \path -> do
    let remotePath = input_directory </> takeFileName path
    $info "Uploading `{}' to `{}'" (path, remotePath)
    size <- liftIO $ scpSendFile session 0o777 path remotePath
                       `catch` (\(e :: SomeException) -> throw (UploadException path e))
    $debug "Done ({} bytes)." (Single size)

downloadFiles :: FilePath -> [FilePath] -> Session -> Daemon ()
downloadFiles output_directory files session =
  forM_ files $ \path -> do
    let remotePath = output_directory </> takeFileName path
    $info "Downlooading `{}' to `{}'" (remotePath, path)
    liftIO $ scpReceiveFile session remotePath path
              `catch` (\(e :: SomeException) -> throw (DownloadException path e))
    $debug "Done." ()