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

{-# LANGUAGE CPP #-}

module Logs.Transfer where

import Types.Transfer
import Types.ActionItem
import Annex.Common
import Annex.Perms
import qualified Git
import Utility.Metered
import Utility.Percentage
import Utility.PID
import Annex.LockPool
import Logs.TimeStamp
import Logs.File

import Data.Time.Clock
import Data.Time.Clock.POSIX
import Control.Concurrent

describeTransfer :: Transfer -> TransferInfo -> String
describeTransfer t info = unwords
	[ show $ transferDirection t
	, show $ transferUUID t
	, actionItemDesc
		(ActionItemAssociatedFile (associatedFile info))
		(transferKey t)
	, show $ bytesComplete info
	]

{- 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)

{- Generates a callback that can be called as transfer progresses to update
 - the transfer info file. Also returns the file it'll be updating, 
 - an action that sets up the file with appropriate permissions,
 - which should be run after locking the transfer lock file, but
 - before using the callback, and a MVar that can be used to read
 - the number of bytesComplete. -}
mkProgressUpdater :: Transfer -> TransferInfo -> Annex (MeterUpdate, FilePath, Annex (), MVar Integer)
mkProgressUpdater t info = do
	tfile <- fromRepo $ transferFile t
	let createtfile = void $ tryNonAsync $ writeTransferInfoFile info tfile
	mvar <- liftIO $ newMVar 0
	return (liftIO . updater tfile mvar, tfile, createtfile, mvar)
  where
	updater tfile mvar b = modifyMVar_ mvar $ \oldbytes -> do
		let newbytes = fromBytesProcessed b
		if newbytes - oldbytes >= mindelta
			then do
				let info' = info { bytesComplete = Just newbytes }
				_ <- tryIO $ updateTransferInfoFile info' tfile
				return newbytes
			else return oldbytes
	{- The minimum change in bytesComplete that is worth
	 - updating a transfer info file for is 1% of the total
	 - keySize, rounded down. -}
	mindelta = case keySize (transferKey t) of
		Just sz -> sz `div` 100
		Nothing -> 100 * 1024 -- arbitrarily, 100 kb

startTransferInfo :: AssociatedFile -> IO TransferInfo
startTransferInfo afile = TransferInfo
	<$> (Just . utcTimeToPOSIXSeconds <$> getCurrentTime)
#ifndef mingw32_HOST_OS
	<*> pure Nothing -- pid not stored in file, so omitted for speed
#else
	<*> (Just <$> getPID)
#endif
	<*> pure Nothing -- tid ditto
	<*> pure Nothing -- not 0; transfer may be resuming
	<*> pure Nothing
	<*> pure afile
	<*> pure False

{- If a transfer is still running, returns its TransferInfo.
 - 
 - If no transfer is running, attempts to clean up the stale
 - lock and info files. This can happen if a transfer process was
 - interrupted.
 -}
checkTransfer :: Transfer -> Annex (Maybe TransferInfo)
checkTransfer t = do
	tfile <- fromRepo $ transferFile t
	let lck = transferLockFile tfile
	let cleanstale = do
		void $ tryIO $ removeFile tfile
		void $ tryIO $ removeFile lck
#ifndef mingw32_HOST_OS
	v <- getLockStatus lck
	case v of
		StatusLockedBy pid -> liftIO $ catchDefaultIO Nothing $
			readTransferInfoFile (Just pid) tfile
		_ -> do
			-- Take a non-blocking lock while deleting
			-- the stale lock file. Ignore failure
			-- due to permissions problems, races, etc.
			void $ tryIO $ do
				mode <- annexFileMode
				r <- tryLockExclusive (Just mode) lck
				case r of
					Just lockhandle -> liftIO $ do
						cleanstale
						dropLock lockhandle
					_ -> noop
			return Nothing
#else
	v <- liftIO $ lockShared lck
	liftIO $ case v of
		Nothing -> catchDefaultIO Nothing $
			readTransferInfoFile Nothing tfile
		Just lockhandle -> do
			dropLock lockhandle
			cleanstale
			return Nothing
#endif

{- Gets all currently running transfers. -}
getTransfers :: Annex [(Transfer, TransferInfo)]
getTransfers = getTransfers' [Download, Upload] (const True)

getTransfers' :: [Direction] -> (Key -> Bool) -> Annex [(Transfer, TransferInfo)]
getTransfers' dirs wanted = do
	transfers <- filter (wanted . transferKey)
		<$> mapMaybe parseTransferFile . concat <$> 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) dirs
	running (_, i) = isJust i

{- Number of bytes remaining to download from matching downloads that are in
 - progress. -}
sizeOfDownloadsInProgress :: (Key -> Bool) -> Annex Integer
sizeOfDownloadsInProgress wanted = sum . map remaining
	<$> getTransfers' [Download] wanted
  where
	remaining (t, info) =
		case (keySize (transferKey t), bytesComplete info) of
			(Just sz, Just done) -> sz - done
			(Just sz, Nothing) -> sz
			(Nothing, _) -> 0

{- 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]

clearFailedTransfers :: UUID -> Annex [(Transfer, TransferInfo)]
clearFailedTransfers u = do
	failed <- getFailedTransfers u
	mapM_ (removeFailedTransfer . fst) failed
	return failed

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

recordFailedTransfer :: Transfer -> TransferInfo -> Annex ()
recordFailedTransfer t info = do
	failedtfile <- fromRepo $ failedTransferFile t
	writeTransferInfoFile info failedtfile

{- The transfer information file to use for a given Transfer. -}
transferFile :: Transfer -> Git.Repo -> FilePath
transferFile (Transfer direction u key) r = transferDir direction r
	</> filter (/= '/') (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
			<$> parseDirection direction
			<*> pure (toUUID u)
			<*> fileKey key
		_ -> Nothing
  where
	bits = splitDirectories file

writeTransferInfoFile :: TransferInfo -> FilePath -> Annex ()
writeTransferInfoFile info tfile = writeLogFile tfile $ writeTransferInfo info

-- The file keeps whatever permissions it has, so should be used only
-- after it's been created with the right perms by writeTransferInfoFile.
updateTransferInfoFile :: TransferInfo -> FilePath -> IO ()
updateTransferInfoFile info tfile = writeFile tfile $ writeTransferInfo info

{- File format is a header line containing the startedTime and any
 - bytesComplete value. Followed by a newline and the associatedFile.
 -
 - On unix, the transferPid is not included; instead it is obtained
 - by looking at the process that locks the file.
 -
 - On windows, the transferPid is included, as a second line.
 -}
writeTransferInfo :: TransferInfo -> String
writeTransferInfo info = unlines
	[ (maybe "" show $ startedTime info) ++
	  (maybe "" (\b -> ' ' : show b) (bytesComplete info))
#ifdef mingw32_HOST_OS
	, maybe "" show (transferPid info)
#endif
	-- comes last; arbitrary content
	, let AssociatedFile afile = associatedFile info
	  in fromMaybe "" afile
	]

readTransferInfoFile :: Maybe PID -> FilePath -> IO (Maybe TransferInfo)
readTransferInfoFile mpid tfile = catchDefaultIO Nothing $
	readTransferInfo mpid <$> readFileStrict tfile

readTransferInfo :: Maybe PID -> String -> Maybe TransferInfo
readTransferInfo mpid s = TransferInfo
	<$> time
#ifdef mingw32_HOST_OS
	<*> pure (if isJust mpid then mpid else mpid')
#else
	<*> pure mpid
#endif
	<*> pure Nothing
	<*> pure Nothing
	<*> bytes
	<*> pure (AssociatedFile (if null filename then Nothing else Just filename))
	<*> pure False
  where
#ifdef mingw32_HOST_OS
	(firstline, otherlines) = separate (== '\n') s
	(secondline, rest) = separate (== '\n') otherlines
	mpid' = readish secondline
#else
	(firstline, rest) = separate (== '\n') s
#endif
	filename
		| end rest == "\n" = beginning rest
		| otherwise = rest
	bits = splitc ' ' firstline
	numbits = length bits
	time = if numbits > 0
		then Just <$> parsePOSIXTime =<< headMaybe bits
		else pure Nothing -- not failure
	bytes = if numbits > 1
		then Just <$> readish =<< headMaybe (drop 1 bits)
		else pure Nothing -- not failure

{- The directory holding transfer information files for a given Direction. -}
transferDir :: Direction -> Git.Repo -> FilePath
transferDir direction r = gitAnnexTransferDir r </> formatDirection 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"
	</> formatDirection direction
	</> filter (/= '/') (fromUUID u)

prop_read_write_transferinfo :: TransferInfo -> Bool
prop_read_write_transferinfo info
	| isJust (transferRemote info) = True -- remote not stored
	| isJust (transferTid info) = True -- tid not stored
	| otherwise = Just (info { transferPaused = False }) == info'
  where
	info' = readTransferInfo (transferPid info) (writeTransferInfo info)

