{- A "remote" that is just a filesystem directory.
 -
 - Copyright 2011-2012 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Remote.Directory (remote) where

import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString as S
import qualified Data.Map as M
import Data.Int

import Common.Annex
import Types.Remote
import Types.Creds
import qualified Git
import Config.Cost
import Config
import Utility.FileMode
import Remote.Helper.Special
import Remote.Helper.Encryptable
import Remote.Helper.Chunked
import Crypto
import Annex.Content
import Annex.UUID
import Utility.Metered

remote :: RemoteType
remote = RemoteType {
	typename = "directory",
	enumerate = findSpecialRemotes "directory",
	generate = gen,
	setup = directorySetup
}

gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
gen r u c gc = do
	cst <- remoteCost gc cheapRemoteCost
	let chunksize = chunkSize c
	return $ Just $ encryptableRemote c
		(storeEncrypted dir (getGpgEncParams (c,gc)) chunksize)
		(retrieveEncrypted dir chunksize)
		Remote {
			uuid = u,
			cost = cst,
			name = Git.repoDescribe r,
			storeKey = store dir chunksize,
			retrieveKeyFile = retrieve dir chunksize,
			retrieveKeyFileCheap = retrieveCheap dir chunksize,
			removeKey = remove dir,
			hasKey = checkPresent dir chunksize,
			hasKeyCheap = True,
			whereisKey = Nothing,
			remoteFsck = Nothing,
			repairRepo = Nothing,
			config = c,
			repo = r,
			gitconfig = gc,
			localpath = Just dir,
			readonly = False,
			availability = LocallyAvailable,
			remotetype = remote
		}
  where
	dir = fromMaybe (error "missing directory") $ remoteAnnexDirectory gc

directorySetup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
directorySetup mu _ c = do
	u <- maybe (liftIO genUUID) return mu
	-- verify configuration is sane
	let dir = fromMaybe (error "Specify directory=") $
		M.lookup "directory" c
	absdir <- liftIO $ absPath dir
	liftIO $ unlessM (doesDirectoryExist absdir) $
		error $ "Directory does not exist: " ++ absdir
	c' <- encryptionSetup c

	-- The directory is stored in git config, not in this remote's
	-- persistant state, so it can vary between hosts.
	gitConfigSpecialRemote u c' "directory" absdir
	return (M.delete "directory" c', u)

{- Locations to try to access a given Key in the Directory.
 - We try more than since we used to write to different hash directories. -}
locations :: FilePath -> Key -> [FilePath]
locations d k = map (d </>) (keyPaths k)

{- Directory where the file(s) for a key are stored. -}
storeDir :: FilePath -> Key -> FilePath
storeDir d k = addTrailingPathSeparator $ d </> hashDirLower k </> keyFile k

{- Where we store temporary data for a key as it's being uploaded. -}
tmpDir :: FilePath -> Key -> FilePath
tmpDir d k = addTrailingPathSeparator $ d </> "tmp" </> keyFile k

withCheckedFiles :: (FilePath -> IO Bool) -> ChunkSize -> FilePath -> Key -> ([FilePath] -> IO Bool) -> IO Bool
withCheckedFiles _ _ [] _ _ = return False
withCheckedFiles check Nothing d k a = go $ locations d k
  where
	go [] = return False
	go (f:fs) = ifM (check f) ( a [f] , go fs )
withCheckedFiles check (Just _) d k a = go $ locations d k
  where
	go [] = return False
	go (f:fs) = do
		let chunkcount = f ++ chunkCount
		ifM (check chunkcount)
			( do
				chunks <- listChunks f <$> readFile chunkcount
				ifM (allM check chunks)
					( a chunks , return False )
			, do
				chunks <- probeChunks f check
				if null chunks
					then go fs
					else a chunks
			)

withStoredFiles :: ChunkSize -> FilePath -> Key -> ([FilePath] -> IO Bool) -> IO Bool
withStoredFiles = withCheckedFiles doesFileExist

store :: FilePath -> ChunkSize -> Key -> AssociatedFile -> MeterUpdate -> Annex Bool
store d chunksize k _f p = sendAnnex k (void $ remove d k) $ \src ->
	metered (Just p) k $ \meterupdate -> 
		storeHelper d chunksize k k $ \dests ->
			case chunksize of
				Nothing -> do
					let dest = Prelude.head dests
					meteredWriteFile meterupdate dest
						=<< L.readFile src
					return [dest]
				Just _ ->
					storeSplit meterupdate chunksize dests
						=<< L.readFile src

storeEncrypted :: FilePath -> [CommandParam] -> ChunkSize -> (Cipher, Key) -> Key -> MeterUpdate -> Annex Bool
storeEncrypted d gpgOpts chunksize (cipher, enck) k p = sendAnnex k (void $ remove d enck) $ \src ->
	metered (Just p) k $ \meterupdate ->
		storeHelper d chunksize enck k $ \dests ->
			encrypt gpgOpts cipher (feedFile src) $ readBytes $ \b ->
				case chunksize of
					Nothing -> do
						let dest = Prelude.head dests
						meteredWriteFile meterupdate dest b
						return [dest]
					Just _ -> storeSplit meterupdate chunksize dests b

{- Splits a ByteString into chunks and writes to dests, obeying configured
 - chunk size (not to be confused with the L.ByteString chunk size).
 - Note: Must always write at least one file, even for empty ByteString. -}
storeSplit :: MeterUpdate -> ChunkSize -> [FilePath] -> L.ByteString -> IO [FilePath]
storeSplit _ Nothing _ _ = error "bad storeSplit call"
storeSplit _ _ [] _ = error "bad storeSplit call"
storeSplit meterupdate (Just chunksize) alldests@(firstdest:_) b
	| L.null b = do
		-- must always write at least one file, even for empty
		L.writeFile firstdest b
		return [firstdest]
	| otherwise = storeSplit' meterupdate chunksize alldests (L.toChunks b) []
storeSplit' :: MeterUpdate -> Int64 -> [FilePath] -> [S.ByteString] -> [FilePath] -> IO [FilePath]
storeSplit' _ _ [] _ _ = error "ran out of dests"
storeSplit' _ _  _ [] c = return $ reverse c
storeSplit' meterupdate chunksize (d:dests) bs c = do
	bs' <- withFile d WriteMode $
		feed zeroBytesProcessed chunksize bs
	storeSplit' meterupdate chunksize dests bs' (d:c)
  where
	feed _ _ [] _ = return []
	feed bytes sz (l:ls) h = do
		let len = S.length l
		let s = fromIntegral len
		if s <= sz || sz == chunksize
			then do
				S.hPut h l
				let bytes' = addBytesProcessed bytes len
				meterupdate bytes'
				feed bytes' (sz - s) ls h
			else return (l:ls)

storeHelper :: FilePath -> ChunkSize -> Key -> Key -> ([FilePath] -> IO [FilePath]) -> Annex Bool
storeHelper d chunksize key origkey storer = check <&&> go
  where
	tmpdir = tmpDir d key
	destdir = storeDir d key
	{- An encrypted key does not have a known size,
	 - so check that the size of the original key is available as free
	 - space. -}
	check = do
		liftIO $ createDirectoryIfMissing True tmpdir
		checkDiskSpace (Just tmpdir) origkey 0
	go = liftIO $ catchBoolIO $
		storeChunks key tmpdir destdir chunksize storer recorder finalizer
	finalizer tmp dest = do
		void $ tryIO $ allowWrite dest -- may already exist
		void $ tryIO $ removeDirectoryRecursive dest -- or not exist
		createDirectoryIfMissing True (parentDir dest)
		renameDirectory tmp dest
		-- may fail on some filesystems
		void $ tryIO $ do
			mapM_ preventWrite =<< dirContents dest
			preventWrite dest
	recorder f s = do
		void $ tryIO $ allowWrite f
		writeFile f s
		void $ tryIO $ preventWrite f

retrieve :: FilePath -> ChunkSize -> Key -> AssociatedFile -> FilePath -> MeterUpdate -> Annex Bool
retrieve d chunksize k _ f p = metered (Just p) k $ \meterupdate ->
	liftIO $ withStoredFiles chunksize d k $ \files ->
		catchBoolIO $ do
			meteredWriteFileChunks meterupdate f files L.readFile
			return True

retrieveEncrypted :: FilePath -> ChunkSize -> (Cipher, Key) -> Key -> FilePath -> MeterUpdate -> Annex Bool
retrieveEncrypted d chunksize (cipher, enck) k f p = metered (Just p) k $ \meterupdate ->
	liftIO $ withStoredFiles chunksize d enck $ \files ->
		catchBoolIO $ do
			decrypt cipher (feeder files) $
				readBytes $ meteredWriteFile meterupdate f
			return True
  where
	feeder files h = forM_ files $ L.hPut h <=< L.readFile

retrieveCheap :: FilePath -> ChunkSize -> Key -> FilePath -> Annex Bool
retrieveCheap _ (Just _) _ _ = return False -- no cheap retrieval for chunks
#ifndef mingw32_HOST_OS
retrieveCheap d _ k f = liftIO $ withStoredFiles Nothing d k go
  where
	go [file] = catchBoolIO $ createSymbolicLink file f >> return True
	go _files = return False
#else
retrieveCheap _ _ _ _ = return False
#endif

remove :: FilePath -> Key -> Annex Bool
remove d k = liftIO $ do
	void $ tryIO $ allowWrite dir
#ifdef mingw32_HOST_OS
	{- Windows needs the files inside the directory to be writable
	 - before it can delete them. -}
	void $ tryIO $ mapM_ allowWrite =<< dirContents dir
#endif
	catchBoolIO $ do
		removeDirectoryRecursive dir
		return True
  where
	dir = storeDir d k

checkPresent :: FilePath -> ChunkSize -> Key -> Annex (Either String Bool)
checkPresent d chunksize k = liftIO $ catchMsgIO $ withStoredFiles chunksize d k $
	const $ return True -- withStoredFiles checked that it exists