{- git-annex assistant sanity checker
 -
 - Copyright 2012, 2013 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Assistant.Threads.SanityChecker (
	sanityCheckerStartupThread,
	sanityCheckerDailyThread,
	sanityCheckerHourlyThread
) where

import Assistant.Common
import Assistant.DaemonStatus
import Assistant.Alert
import Assistant.Repair
import qualified Git.LsFiles
import qualified Git.Command
import qualified Git.Config
import Utility.ThreadScheduler
import qualified Assistant.Threads.Watcher as Watcher
import Utility.LogFile
import Utility.Batch
import Utility.NotificationBroadcaster
import Config
import Utility.HumanTime
import Git.Repair

import Data.Time.Clock.POSIX
import qualified Data.Set as S

{- This thread runs once at startup, and most other threads wait for it
 - to finish. (However, the webapp thread does not, to prevent the UI
 - being nonresponsive.) -}
sanityCheckerStartupThread :: Maybe Duration -> NamedThread
sanityCheckerStartupThread startupdelay = namedThreadUnchecked "SanityCheckerStartup" $ do
	{- Stale git locks can prevent commits from happening, etc. -}
	void $ repairStaleGitLocks =<< liftAnnex gitRepo

	{- A corrupt index file can prevent the assistant from working at
	 - all, so detect and repair. -}
	ifM (not <$> liftAnnex (inRepo (checkIndex S.empty)))
		( do
			notice ["corrupt index file found at startup; removing and restaging"]
			liftAnnex $ inRepo nukeIndex
			{- Normally the startup scan avoids re-staging files,
			 - but with the index deleted, everything needs to be
			 - restaged. -}
			modifyDaemonStatus_ $ \s -> s { forceRestage = True }
		, whenM (liftAnnex $ inRepo missingIndex) $ do
			debug ["no index file; restaging"]
			modifyDaemonStatus_ $ \s -> s { forceRestage = True }
		)

	{- If there's a startup delay, it's done here. -}
	liftIO $ maybe noop (threadDelaySeconds . Seconds . fromIntegral . durationSeconds) startupdelay

	{- Notify other threads that the startup sanity check is done. -}
	status <- getDaemonStatus
	liftIO $ sendNotification $ startupSanityCheckNotifier status

{- This thread wakes up hourly for inxepensive frequent sanity checks. -}
sanityCheckerHourlyThread :: NamedThread
sanityCheckerHourlyThread = namedThread "SanityCheckerHourly" $ forever $ do
	liftIO $ threadDelaySeconds $ Seconds oneHour
	hourlyCheck

{- This thread wakes up daily to make sure the tree is in good shape. -}
sanityCheckerDailyThread :: NamedThread
sanityCheckerDailyThread = namedThread "SanityCheckerDaily" $ forever $ do
	waitForNextCheck

	debug ["starting sanity check"]
	void $ alertWhile sanityCheckAlert go
	debug ["sanity check complete"]
  where
	go = do
		modifyDaemonStatus_ $ \s -> s { sanityCheckRunning = True }

		now <- liftIO getPOSIXTime -- before check started
		r <- either showerr return =<< (tryIO . batch) <~> dailyCheck

		modifyDaemonStatus_ $ \s -> s
			{ sanityCheckRunning = False
			, lastSanityCheck = Just now
			}

		return r

	showerr e = do
		liftAnnex $ warning $ show e
		return False

{- Only run one check per day, from the time of the last check. -}
waitForNextCheck :: Assistant ()
waitForNextCheck = do
	v <- lastSanityCheck <$> getDaemonStatus
	now <- liftIO getPOSIXTime
	liftIO $ threadDelaySeconds $ Seconds $ calcdelay now v
  where
	calcdelay _ Nothing = oneDay
	calcdelay now (Just lastcheck)
		| lastcheck < now = max oneDay $
			oneDay - truncate (now - lastcheck)
		| otherwise = oneDay

{- It's important to stay out of the Annex monad as much as possible while
 - running potentially expensive parts of this check, since remaining in it
 - will block the watcher. -}
dailyCheck :: Assistant Bool
dailyCheck = do
	g <- liftAnnex gitRepo

	-- Find old unstaged symlinks, and add them to git.
	(unstaged, cleanup) <- liftIO $ Git.LsFiles.notInRepo False ["."] g
	now <- liftIO getPOSIXTime
	forM_ unstaged $ \file -> do
		ms <- liftIO $ catchMaybeIO $ getSymbolicLinkStatus file
		case ms of
			Just s	| toonew (statusChangeTime s) now -> noop
				| isSymbolicLink s -> addsymlink file ms
			_ -> noop
	liftIO $ void cleanup

	{- Allow git-gc to run once per day. More frequent gc is avoided
	 - by default to avoid slowing things down. Only run repacks when 100x
	 - the usual number of loose objects are present; we tend
	 - to have a lot of small objects and they should not be a
	 - significant size. -}
	when (Git.Config.getMaybe "gc.auto" g == Just "0") $
		liftIO $ void $ Git.Command.runBool
			[ Param "-c", Param "gc.auto=670000"
			, Param "gc"
			, Param "--auto"
			] g

	return True
  where
	toonew timestamp now = now < (realToFrac (timestamp + slop) :: POSIXTime)
	slop = fromIntegral tenMinutes
	insanity msg = do
		liftAnnex $ warning msg
		void $ addAlert $ sanityCheckFixAlert msg
	addsymlink file s = do
		isdirect <- liftAnnex isDirect
		Watcher.runHandler (Watcher.onAddSymlink isdirect) file s
		insanity $ "found unstaged symlink: " ++ file

hourlyCheck :: Assistant ()
hourlyCheck = checkLogSize 0

{- Rotate logs until log file size is < 1 mb. -}
checkLogSize :: Int -> Assistant ()
checkLogSize n = do
	f <- liftAnnex $ fromRepo gitAnnexLogFile
	logs <- liftIO $ listLogs f
	totalsize <- liftIO $ sum <$> mapM filesize logs
	when (totalsize > oneMegabyte) $ do
		notice ["Rotated logs due to size:", show totalsize]
		liftIO $ openLog f >>= redirLog
		when (n < maxLogs + 1) $
			checkLogSize $ n + 1
  where
	filesize f = fromIntegral . fileSize <$> liftIO (getFileStatus f)

oneMegabyte :: Int
oneMegabyte = 1000000

oneHour :: Int
oneHour = 60 * 60

oneDay :: Int
oneDay = 24 * oneHour