{- A remote that is only accessible by rsync.
 -
 - Copyright 2011 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote.Rsync (remote) where

import qualified Data.ByteString.Lazy.Char8 as L
import Control.Exception.Extensible (IOException)
import qualified Data.Map as M
import Control.Monad.State (liftIO)
import System.FilePath
import System.Directory
import System.Posix.Files
import System.Posix.Process

import Types
import Types.Remote
import qualified Git
import qualified Annex
import UUID
import Locations
import Config
import Content
import Utility
import Remote.Special
import Remote.Encryptable
import Crypto
import Messages
import Utility.RsyncFile

type RsyncUrl = String

data RsyncOpts = RsyncOpts {
	rsyncUrl :: RsyncUrl,
	rsyncOptions :: [CommandParam]
}

remote :: RemoteType Annex
remote = RemoteType {
	typename = "rsync",
	enumerate = findSpecialRemotes "rsyncurl",
	generate = gen,
	setup = rsyncSetup
}

gen :: Git.Repo -> UUID -> Maybe RemoteConfig -> Annex (Remote Annex)
gen r u c = do
	o <- genRsyncOpts r
	cst <- remoteCost r expensiveRemoteCost
	return $ encryptableRemote c
		(storeEncrypted o)
		(retrieveEncrypted o)
		Remote {
			uuid = u,
			cost = cst,
			name = Git.repoDescribe r,
 			storeKey = store o,
			retrieveKeyFile = retrieve o,
			removeKey = remove o,
			hasKey = checkPresent r o,
			hasKeyCheap = False,
			config = Nothing
		}

genRsyncOpts :: Git.Repo -> Annex RsyncOpts
genRsyncOpts r = do
	url <- getConfig r "rsyncurl" (error "missing rsyncurl")
	opts <- getConfig r "rsync-options" ""
	return $ RsyncOpts url $ map Param $ filter safe $ words opts
	where
		safe o
			-- Don't allow user to pass --delete to rsync;
			-- that could cause it to delete other keys
			-- in the same hash bucket as a key it sends.
			| o == "--delete" = False
			| o == "--delete-excluded" = False
			| otherwise = True

rsyncSetup :: UUID -> RemoteConfig -> Annex RemoteConfig
rsyncSetup u c = do
	-- verify configuration is sane
	let url = maybe (error "Specify rsyncurl=") id $
		M.lookup "rsyncurl" c
	c' <- encryptionSetup c

	-- The rsyncurl is stored in git config, not only in this remote's
	-- persistant state, so it can vary between hosts.
	gitConfigSpecialRemote u c' "rsyncurl" url
	return c'

rsyncKey :: RsyncOpts -> Key -> String
rsyncKey o k = rsyncUrl o </> hashDirMixed k </> f </> f
        where
                f = keyFile k

store :: RsyncOpts -> Key -> Annex Bool
store o k = do
	g <- Annex.gitRepo
	rsyncSend o k (gitAnnexLocation g k)

storeEncrypted :: RsyncOpts -> (Cipher, Key) -> Key -> Annex Bool
storeEncrypted o (cipher, enck) k = withTmp enck $ \tmp -> do
	g <- Annex.gitRepo
	let f = gitAnnexLocation g k
	liftIO $ withEncryptedContent cipher (L.readFile f) $ \s -> L.writeFile tmp s
	rsyncSend o enck tmp

retrieve :: RsyncOpts -> Key -> FilePath -> Annex Bool
retrieve o k f = rsyncRemote o
	-- use inplace when retrieving to support resuming
	[ Param "--inplace"
	, Param $ rsyncKey o k
	, Param f
	]

retrieveEncrypted :: RsyncOpts -> (Cipher, Key) -> FilePath -> Annex Bool
retrieveEncrypted o (cipher, enck) f = withTmp enck $ \tmp -> do
	res <- retrieve o enck tmp
	if res
		then liftIO $ catchBool $ do
			withDecryptedContent cipher (L.readFile tmp) $ L.writeFile f
			return True
		else return res

remove :: RsyncOpts -> Key -> Annex Bool
remove o k = withRsyncScratchDir $ \tmp -> do
	{- Send an empty directory to rysnc as the parent directory
         - of the file to remove. -}
	let dummy = tmp </> keyFile k
	liftIO $ createDirectoryIfMissing True dummy
	liftIO $ rsync $ rsyncOptions o ++
		[ Params "--delete --recursive"
		, partialParams
		, Param $ addTrailingPathSeparator dummy
		, Param $ parentDir $ rsyncKey o k
		]

checkPresent :: Git.Repo -> RsyncOpts -> Key -> Annex (Either IOException Bool)
checkPresent r o k = do
	showNote ("checking " ++ Git.repoDescribe r ++ "...")
	-- note: Does not currently differnetiate between rsync failing
	-- to connect, and the file not being present.
	res <- liftIO $ boolSystem "sh" [Param "-c", Param cmd]
	return $ Right res
	where
		cmd = "rsync --quiet " ++ testfile ++ " 2>/dev/null"
		testfile = shellEscape $ rsyncKey o k

{- Rsync params to enable resumes of sending files safely,
 - ensure that files are only moved into place once complete
 -}
partialParams :: CommandParam
partialParams = Params "--no-inplace --partial --partial-dir=.rsync-partial"

{- Runs an action in an empty scratch directory that can be used to build
 - up trees for rsync. -}
withRsyncScratchDir :: (FilePath -> Annex Bool) -> Annex Bool
withRsyncScratchDir a = do
	g <- Annex.gitRepo
	pid <- liftIO $ getProcessID
	let tmp = gitAnnexTmpDir g </> "rsynctmp" </> show pid
	nuke tmp
	liftIO $ createDirectoryIfMissing True $ tmp
	res <- a tmp
	nuke tmp
	return res
	where
		nuke d = liftIO $ 
			doesDirectoryExist d >>? removeDirectoryRecursive d

rsyncRemote :: RsyncOpts -> [CommandParam] -> Annex Bool
rsyncRemote o params = do
	showProgress -- make way for progress bar
	res <- liftIO $ rsync $ rsyncOptions o ++ defaultParams ++ params
	if res
		then return res
		else do
			showLongNote "rsync failed -- run git annex again to resume file transfer"
			return res
	where
		defaultParams = [Params "--progress"]

{- To send a single key is slightly tricky; need to build up a temporary
   directory structure to pass to rsync so it can create the hash
   directories. -}
rsyncSend :: RsyncOpts -> Key -> FilePath -> Annex Bool
rsyncSend o k src = withRsyncScratchDir $ \tmp -> do
	let dest = tmp </> hashDirMixed k </> f </> f
	liftIO $ createDirectoryIfMissing True $ parentDir $ dest
	liftIO $ createLink src dest
	res <- rsyncRemote o
		[ Param "--recursive"
		, partialParams
 		  -- tmp/ to send contents of tmp dir
		, Param $ addTrailingPathSeparator tmp
		, Param $ rsyncUrl o
		]
	return res
	where
		f = keyFile k