{- git-annex transfer information files and lock files
 -
 - Copyright 2012 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Logs.Transfer where

import Common.Annex
import Annex.Perms
import Annex.Exception
import Annex.UUID
import qualified Git
import Types.Remote
import Types.Key
import Utility.Percentage

import System.Posix.Types
import Data.Time.Clock
import Data.Time.Clock.POSIX
import Data.Time
import System.Locale
import Control.Concurrent

{- Enough information to uniquely identify a transfer, used as the filename
 - of the transfer information file. -}
data Transfer = Transfer
	{ transferDirection :: Direction
	, transferUUID :: UUID
	, transferKey :: Key
	}
	deriving (Eq, Ord, Read, Show)

{- Information about a Transfer, stored in the transfer information file.
 -
 - Note that the associatedFile may not correspond to a file in the local
 - git repository. It's some file, possibly relative to some directory,
 - of some repository, that was acted on to initiate the transfer.
 -}
data TransferInfo = TransferInfo
	{ startedTime :: Maybe POSIXTime
	, transferPid :: Maybe ProcessID
	, transferTid :: Maybe ThreadId
	, transferRemote :: Maybe Remote
	, bytesComplete :: Maybe Integer
	, associatedFile :: Maybe FilePath
	, transferPaused :: Bool
	}
	deriving (Show, Eq, Ord)

stubTransferInfo :: TransferInfo
stubTransferInfo = TransferInfo Nothing Nothing Nothing Nothing Nothing Nothing False

data Direction = Upload | Download
	deriving (Eq, Ord, Read, Show)

showLcDirection :: Direction -> String
showLcDirection Upload = "upload"
showLcDirection Download = "download"

readLcDirection :: String -> Maybe Direction
readLcDirection "upload" = Just Upload
readLcDirection "download" = Just Download
readLcDirection _ = Nothing

{- Transfers that will accomplish the same task. -}
equivilantTransfer :: Transfer -> Transfer -> Bool
equivilantTransfer t1 t2
	| transferDirection t1 == Download && transferDirection t2 == Download &&
	  transferKey t1 == transferKey t2 = True
	| otherwise = t1 == t2

percentComplete :: Transfer -> TransferInfo -> Maybe Percentage
percentComplete (Transfer { transferKey = key }) info =
	percentage <$> keySize key <*> Just (fromMaybe 0 $ bytesComplete info)

upload :: UUID -> Key -> AssociatedFile -> Annex Bool -> Annex Bool
upload u key file a = runTransfer (Transfer Upload u key) file a

download :: UUID -> Key -> AssociatedFile -> Annex Bool -> Annex Bool
download u key file a = runTransfer (Transfer Download u key) file a

{- Runs a transfer action. Creates and locks the lock file while the
 - action is running, and stores info in the transfer information
 - file. Will throw an error if the transfer is already in progress.
 -
 - If the transfer action returns False, the transfer info is 
 - left in the failedTransferDir.
 -}
runTransfer :: Transfer -> Maybe FilePath -> Annex Bool -> Annex Bool
runTransfer t file a = do
	tfile <- fromRepo $ transferFile t
	createAnnexDirectory $ takeDirectory tfile
	mode <- annexFileMode
	info <- liftIO $ TransferInfo
		<$> (Just . utcTimeToPOSIXSeconds <$> getCurrentTime)
		<*> pure Nothing -- pid not stored in file, so omitted for speed
		<*> pure Nothing -- tid ditto
		<*> pure Nothing -- not 0; transfer may be resuming
		<*> pure Nothing
		<*> pure file
		<*> pure False
	ok <- bracketIO (prep tfile mode info) (cleanup tfile) a
	unless ok $ failed info
	return ok
	where
		prep tfile mode info = do
			fd <- openFd (transferLockFile tfile) ReadWrite (Just mode)
				defaultFileFlags { trunc = True }
			locked <- catchMaybeIO $
				setLock fd (WriteLock, AbsoluteSeek, 0, 0)
			when (locked == Nothing) $
				error $ "transfer already in progress"
			writeTransferInfoFile info tfile
			return fd
		cleanup tfile fd = do
			void $ tryIO $ removeFile tfile
			void $ tryIO $ removeFile $ transferLockFile tfile
			closeFd fd
		failed info = do
			failedtfile <- fromRepo $ failedTransferFile t
			createAnnexDirectory $ takeDirectory failedtfile
			liftIO $ writeTransferInfoFile info failedtfile

{- If a transfer is still running, returns its TransferInfo. -}
checkTransfer :: Transfer -> Annex (Maybe TransferInfo)
checkTransfer t = do
	mode <- annexFileMode
	tfile <- fromRepo $ transferFile t
	mfd <- liftIO $ catchMaybeIO $
		openFd (transferLockFile tfile) ReadOnly (Just mode) defaultFileFlags
	case mfd of
		Nothing -> return Nothing -- failed to open file; not running
		Just fd -> do
			locked <- liftIO $
				getLock fd (WriteLock, AbsoluteSeek, 0, 0)
			liftIO $ closeFd fd
			case locked of
				Nothing -> return Nothing
				Just (pid, _) -> liftIO $ catchDefaultIO Nothing $
					readTransferInfoFile (Just pid) tfile

{- Gets all currently running transfers. -}
getTransfers :: Annex [(Transfer, TransferInfo)]
getTransfers = do
	transfers <- catMaybes . map parseTransferFile . concat <$> findfiles
	infos <- mapM checkTransfer transfers
	return $ map (\(t, Just i) -> (t, i)) $
		filter running $ zip transfers infos
	where
		findfiles = liftIO . mapM dirContentsRecursive
			=<< mapM (fromRepo . transferDir)
				[Download, Upload]
		running (_, i) = isJust i

{- Gets failed transfers for a given remote UUID. -}
getFailedTransfers :: UUID -> Annex [(Transfer, TransferInfo)]
getFailedTransfers u = catMaybes <$> (liftIO . getpairs =<< concat <$> findfiles)
	where
		getpairs = mapM $ \f -> do
			let mt = parseTransferFile f
			mi <- readTransferInfoFile Nothing f
			return $ case (mt, mi) of
				(Just t, Just i) -> Just (t, i)
				_ -> Nothing
		findfiles = liftIO . mapM dirContentsRecursive
			=<< mapM (fromRepo . failedTransferDir u)
				[Download, Upload]

removeFailedTransfer :: Transfer -> Annex ()
removeFailedTransfer t = do
	f <- fromRepo $ failedTransferFile t
	liftIO $ void $ tryIO $ removeFile f

{- The transfer information file to use for a given Transfer. -}
transferFile :: Transfer -> Git.Repo -> FilePath
transferFile (Transfer direction u key) r = transferDir direction r
	</> fromUUID u
	</> keyFile key

{- The transfer information file to use to record a failed Transfer -}
failedTransferFile :: Transfer -> Git.Repo -> FilePath
failedTransferFile (Transfer direction u key) r = failedTransferDir u direction r
	</> keyFile key

{- The transfer lock file corresponding to a given transfer info file. -}
transferLockFile :: FilePath -> FilePath
transferLockFile infofile = let (d,f) = splitFileName infofile in
	combine d ("lck." ++ f)

{- Parses a transfer information filename to a Transfer. -}
parseTransferFile :: FilePath -> Maybe Transfer
parseTransferFile file
	| "lck." `isPrefixOf` (takeFileName file) = Nothing
	| otherwise = case drop (length bits - 3) bits of
		[direction, u, key] -> Transfer
			<$> readLcDirection direction
			<*> pure (toUUID u)
			<*> fileKey key
		_ -> Nothing
	where
		bits = splitDirectories file

writeTransferInfoFile :: TransferInfo -> FilePath -> IO ()
writeTransferInfoFile info tfile = do
	h <- openFile tfile WriteMode
	fileEncoding h
	hPutStr h $ writeTransferInfo info
	hClose h

writeTransferInfo :: TransferInfo -> String
writeTransferInfo info = unlines
	-- transferPid is not included; instead obtained by looking at
	-- the process that locks the file.
	[ maybe "" show $ startedTime info
	-- bytesComplete is not included; changes too fast 
	, fromMaybe "" $ associatedFile info -- comes last; arbitrary content
	]

readTransferInfoFile :: (Maybe ProcessID) -> FilePath -> IO (Maybe TransferInfo)
readTransferInfoFile mpid tfile = do
	h <- openFile tfile ReadMode
	fileEncoding h
	hClose h `after` (readTransferInfo mpid <$> hGetContentsStrict h)

readTransferInfo :: (Maybe ProcessID) -> String -> Maybe TransferInfo
readTransferInfo mpid s =
	case bits of
		[time] -> TransferInfo
			<$> (Just <$> parsePOSIXTime time)
			<*> pure mpid
			<*> pure Nothing
			<*> pure Nothing
			<*> pure Nothing
			<*> pure (if null filename then Nothing else Just filename)
			<*> pure False
		_ -> Nothing
	where
		(bits, filebits) = splitAt 1 $ lines s 
		filename = join "\n" filebits

parsePOSIXTime :: String -> Maybe POSIXTime
parsePOSIXTime s = utcTimeToPOSIXSeconds
	<$> parseTime defaultTimeLocale "%s%Qs" s

{- The directory holding transfer information files for a given Direction. -}
transferDir :: Direction -> Git.Repo -> FilePath
transferDir direction r = gitAnnexTransferDir r </> showLcDirection direction

{- The directory holding failed transfer information files for a given
 - Direction and UUID -}
failedTransferDir :: UUID -> Direction -> Git.Repo -> FilePath
failedTransferDir u direction r = gitAnnexTransferDir r
	</> "failed"
	</> showLcDirection direction
	</> fromUUID u