{- git-annex content ingestion
 -
 - Copyright 2010-2015 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Annex.Ingest (
	lockDown,
	ingest,
	finishIngestDirect,
	addLink,
	makeLink,
	restoreFile,
	forceParams,
) where

import Common.Annex
import Types.KeySource
import Backend
import Annex.Content
import Annex.Content.Direct
import Annex.Perms
import Annex.Link
import Annex.MetaData
import qualified Annex
import qualified Annex.Queue
import Config
import Utility.InodeCache
import Annex.ReplaceFile
import Utility.Tmp
import Utility.CopyFile
import Annex.InodeSentinal
import Annex.Version
#ifdef WITH_CLIBS
#ifndef __ANDROID__
import Utility.Touch
#endif
#endif

import Control.Exception (IOException)

{- The file that's being ingested is locked down before a key is generated,
 - to prevent it from being modified in between. This lock down is not
 - perfect at best (and pretty weak at worst). For example, it does not
 - guard against files that are already opened for write by another process.
 - So a KeySource is returned. Its inodeCache can be used to detect any
 - changes that might be made to the file after it was locked down.
 -
 - When possible, the file is hard linked to a temp directory. This guards
 - against some changes, like deletion or overwrite of the file, and
 - allows lsof checks to be done more efficiently when adding a lot of files.
 -
 - Lockdown can fail if a file gets deleted, and Nothing will be returned.
 -}
lockDown :: FilePath -> Annex (Maybe KeySource)
lockDown = either 
		(\e -> warning (show e) >> return Nothing)
		(return . Just)
	<=< lockDown'

lockDown' :: FilePath -> Annex (Either IOException KeySource)
lockDown' file = ifM crippledFileSystem
	( withTSDelta $ liftIO . tryIO . nohardlink
	, tryIO $ do
		tmp <- fromRepo gitAnnexTmpMiscDir
		createAnnexDirectory tmp
		go tmp
	)
  where
	{- In indirect mode, the write bit is removed from the file as part
	 - of lock down to guard against further writes, and because objects
	 - in the annex have their write bit disabled anyway.
	 -
	 - Freezing the content early also lets us fail early when
	 - someone else owns the file.
	 -
	 - This is not done in direct mode, because files there need to
	 - remain writable at all times.
	-}
	go tmp = do
		unlessM isDirect $
			freezeContent file
		withTSDelta $ \delta -> liftIO $ do
			(tmpfile, h) <- openTempFile tmp $
				relatedTemplate $ takeFileName file
			hClose h
			nukeFile tmpfile
			withhardlink delta tmpfile `catchIO` const (nohardlink delta)
	nohardlink delta = do
		cache <- genInodeCache file delta
		return KeySource
			{ keyFilename = file
			, contentLocation = file
			, inodeCache = cache
			}
	withhardlink delta tmpfile = do
		createLink file tmpfile
		cache <- genInodeCache tmpfile delta
		return KeySource
			{ keyFilename = file
			, contentLocation = tmpfile
			, inodeCache = cache
			}

{- Ingests a locked down file into the annex.
 -
 - In direct mode, leaves the file alone, and just updates bookkeeping
 - information.
 -}
ingest :: Maybe KeySource -> Annex (Maybe Key, Maybe InodeCache)
ingest Nothing = return (Nothing, Nothing)
ingest (Just source) = withTSDelta $ \delta -> do
	backend <- chooseBackend $ keyFilename source
	k <- genKey source backend
	let src = contentLocation source
	ms <- liftIO $ catchMaybeIO $ getFileStatus src
	mcache <- maybe (pure Nothing) (liftIO . toInodeCache delta src) ms
	case (mcache, inodeCache source) of
		(_, Nothing) -> go k mcache ms
		(Just newc, Just c) | compareStrong c newc -> go k mcache ms
		_ -> failure "changed while it was being added"
  where
	go k mcache ms = ifM isDirect
		( godirect k mcache ms
		, goindirect k mcache ms
		)

	goindirect (Just (key, _)) mcache ms = do
		catchNonAsync (moveAnnex key $ contentLocation source)
			(restoreFile (keyFilename source) key)
		maybe noop (genMetaData key (keyFilename source)) ms
		liftIO $ nukeFile $ keyFilename source
		return (Just key, mcache)
	goindirect _ _ _ = failure "failed to generate a key"

	godirect (Just (key, _)) (Just cache) ms = do
		addInodeCache key cache
		maybe noop (genMetaData key (keyFilename source)) ms
		finishIngestDirect key source
		return (Just key, Just cache)
	godirect _ _ _ = failure "failed to generate a key"

	failure msg = do
		warning $ keyFilename source ++ " " ++ msg
		when (contentLocation source /= keyFilename source) $
			liftIO $ nukeFile $ contentLocation source
		return (Nothing, Nothing)

finishIngestDirect :: Key -> KeySource -> Annex ()
finishIngestDirect key source = do
	void $ addAssociatedFile key $ keyFilename source
	when (contentLocation source /= keyFilename source) $
		liftIO $ nukeFile $ contentLocation source

	{- Copy to any other locations using the same key. -}
	otherfs <- filter (/= keyFilename source) <$> associatedFiles key
	forM_ otherfs $
		addContentWhenNotPresent key (keyFilename source)

{- On error, put the file back so it doesn't seem to have vanished.
 - This can be called before or after the symlink is in place. -}
restoreFile :: FilePath -> Key -> SomeException -> Annex a
restoreFile file key e = do
	whenM (inAnnex key) $ do
		liftIO $ nukeFile file
		-- The key could be used by other files too, so leave the
		-- content in the annex, and make a copy back to the file.
		obj <- calcRepo $ gitAnnexLocation key
		unlessM (liftIO $ copyFileExternal CopyTimeStamps obj file) $
			warning $ "Unable to restore content of " ++ file ++ "; it should be located in " ++ obj
		thawContent file
	throwM e

{- Creates the symlink to the annexed content, returns the link target. -}
makeLink :: FilePath -> Key -> Maybe InodeCache -> Annex String
makeLink file key mcache = flip catchNonAsync (restoreFile file key) $ do
	l <- calcRepo $ gitAnnexLink file key
	replaceFile file $ makeAnnexLink l

	-- touch symlink to have same time as the original file,
	-- as provided in the InodeCache
	case mcache of
#if defined(WITH_CLIBS) && ! defined(__ANDROID__)
		Just c -> liftIO $ touch file (TimeSpec $ inodeCacheToMtime c) False
#else
		Just _ -> noop
#endif
		Nothing -> noop

	return l

{- Creates the symlink to the annexed content, and stages it in git.
 -
 - As long as the filesystem supports symlinks, we use
 - git add, rather than directly staging the symlink to git.
 - Using git add is best because it allows the queuing to work
 - and is faster (staging the symlink runs hash-object commands each time).
 - Also, using git add allows it to skip gitignored files, unless forced
 - to include them.
 -}
addLink :: FilePath -> Key -> Maybe InodeCache -> Annex ()
addLink file key mcache = ifM (coreSymlinks <$> Annex.getGitConfig)
	( do
		_ <- makeLink file key mcache
		ps <- forceParams
		Annex.Queue.addCommand "add" (ps++[Param "--"]) [file]
	, do
		l <- makeLink file key mcache
		addAnnexLink l file
	)

{- Parameters to pass to git add, forcing addition of ignored files. -}
forceParams :: Annex [CommandParam]
forceParams = ifM (Annex.getState Annex.force)
	( return [Param "-f"]
	, return []
	)