{- git-annex remote access with ssh and git-annex-shell
 -
 - Copyright 2011-2018 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote.Helper.Ssh where

import Annex.Common
import qualified Annex
import qualified Git
import qualified Git.Url
import Annex.UUID
import Annex.Ssh
import CmdLine.GitAnnexShell.Fields (Field, fieldName)
import qualified CmdLine.GitAnnexShell.Fields as Fields
import Remote.Helper.Messages
import Messages.Progress
import Utility.Metered
import Utility.Rsync
import Utility.SshHost
import Types.Remote
import Types.Transfer
import Config
import qualified P2P.Protocol as P2P
import qualified P2P.IO as P2P

import Control.Concurrent.Async
import Control.Concurrent.STM

toRepo :: ConsumeStdin -> Git.Repo -> RemoteGitConfig -> SshCommand -> Annex (FilePath, [CommandParam])
toRepo cs r gc remotecmd = do
	let host = maybe
		(giveup "bad ssh url")
		(either error id . mkSshHost)
		(Git.Url.hostuser r)
	sshCommand cs (host, Git.Url.port r) gc remotecmd

{- Generates parameters to run a git-annex-shell command on a remote
 - repository. -}
git_annex_shell :: ConsumeStdin -> Git.Repo -> String -> [CommandParam] -> [(Field, String)] -> Annex (Maybe (FilePath, [CommandParam]))
git_annex_shell cs r command params fields
	| not $ Git.repoIsUrl r = do
		shellopts <- getshellopts
		return $ Just (shellcmd, shellopts ++ fieldopts)
	| Git.repoIsSsh r = do
		gc <- Annex.getRemoteGitConfig r
		u <- getRepoUUID r
		shellopts <- getshellopts
		let sshcmd = unwords $
			fromMaybe shellcmd (remoteAnnexShell gc)
				: map shellEscape (toCommand shellopts) ++
			uuidcheck u ++
			map shellEscape (toCommand fieldopts)
		Just <$> toRepo cs r gc sshcmd
	| otherwise = return Nothing
  where
	dir = Git.repoPath r
	shellcmd = "git-annex-shell"
	getshellopts = do
		debug <- liftIO debugEnabled
		let params' = if debug
			then Param "--debug" : params
			else params
		return (Param command : File dir : params')
	uuidcheck NoUUID = []
	uuidcheck (UUID u) = ["--uuid", u]
	fieldopts
		| null fields = []
		| otherwise = fieldsep : map fieldopt fields ++ [fieldsep]
	fieldsep = Param "--"
	fieldopt (field, value) = Param $
		fieldName field ++ "=" ++ value

{- Uses a supplied function (such as boolSystem) to run a git-annex-shell
 - command on a remote.
 -
 - Or, if the remote does not support running remote commands, returns
 - a specified error value. -}
onRemote 
	:: ConsumeStdin
	-> Git.Repo
	-> (FilePath -> [CommandParam] -> IO a, Annex a)
	-> String
	-> [CommandParam]
	-> [(Field, String)]
	-> Annex a
onRemote cs r (with, errorval) command params fields = do
	s <- git_annex_shell cs r command params fields
	case s of
		Just (c, ps) -> liftIO $ with c ps
		Nothing -> errorval

{- Checks if a remote contains a key. -}
inAnnex :: Git.Repo -> Key -> Annex Bool
inAnnex r k = do
	showChecking r
	onRemote NoConsumeStdin r (runcheck, cantCheck r) "inannex" [Param $ key2file k] []
  where
	runcheck c p = dispatch =<< safeSystem c p
	dispatch ExitSuccess = return True
	dispatch (ExitFailure 1) = return False
	dispatch _ = cantCheck r

{- Removes a key from a remote. -}
dropKey :: Git.Repo -> Key -> Annex Bool
dropKey r key = onRemote NoConsumeStdin r (boolSystem, return False) "dropkey"
	[ Param "--quiet", Param "--force"
	, Param $ key2file key
	]
	[]

rsyncHelper :: Maybe MeterUpdate -> [CommandParam] -> Annex Bool
rsyncHelper m params = do
	showOutput -- make way for progress bar
	a <- case m of
		Nothing -> return $ rsync params
		Just meter -> do
			oh <- mkOutputHandler
			return $ rsyncProgress oh meter params
	ifM (liftIO a)
		( return True
		, do
			showLongNote "rsync failed -- run git annex again to resume file transfer"
			return False
		)

{- Generates rsync parameters that ssh to the remote and asks it
 - to either receive or send the key's content. -}
rsyncParamsRemote :: Bool -> Remote -> Direction -> Key -> FilePath -> AssociatedFile -> Annex [CommandParam]
rsyncParamsRemote unlocked r direction key file (AssociatedFile afile) = do
	u <- getUUID
	let fields = (Fields.remoteUUID, fromUUID u)
		: (Fields.unlocked, if unlocked then "1" else "")
		-- Send direct field for unlocked content, for backwards
		-- compatability.
		: (Fields.direct, if unlocked then "1" else "")
		: maybe [] (\f -> [(Fields.associatedFile, f)]) afile
	Just (shellcmd, shellparams) <- git_annex_shell ConsumeStdin (repo r)
		(if direction == Download then "sendkey" else "recvkey")
		[ Param $ key2file key ]
		fields
	-- Convert the ssh command into rsync command line.
	let eparam = rsyncShell (Param shellcmd:shellparams)
	o <- rsyncParams r direction
	return $ if direction == Download
		then o ++ rsyncopts eparam dummy (File file)
		else o ++ rsyncopts eparam (File file) dummy
  where
	rsyncopts ps source dest
		| end ps == [dashdash] = ps ++ [source, dest]
		| otherwise = ps ++ [dashdash, source, dest]
	dashdash = Param "--"
	{- The rsync shell parameter controls where rsync
	 - goes, so the source/dest parameter can be a dummy value,
	 - that just enables remote rsync mode.
	 - For maximum compatability with some patched rsyncs,
	 - the dummy value needs to still contain a hostname,
	 - even though this hostname will never be used. -}
	dummy = Param "dummy:"

-- --inplace to resume partial files
--
-- Only use --perms when not on a crippled file system, as rsync
-- will fail trying to restore file perms onto a filesystem that does not
-- support them.
rsyncParams :: Remote -> Direction -> Annex [CommandParam]
rsyncParams r direction = do
	crippled <- crippledFileSystem
	return $ map Param $ catMaybes
		[ Just "--progress"
		, Just "--inplace"
		, if crippled then Nothing else Just "--perms"
		] 
		++ remoteAnnexRsyncOptions gc ++ dps
  where
	dps
		| direction == Download = remoteAnnexRsyncDownloadOptions gc
		| otherwise = remoteAnnexRsyncUploadOptions gc
	gc = gitconfig r

-- Used by git-annex-shell lockcontent to indicate the content is
-- successfully locked.
contentLockedMarker :: String
contentLockedMarker = "OK"

-- A connection over ssh to git-annex shell speaking the P2P protocol.
type P2PSshConnection = P2P.ClosableConnection (P2P.P2PConnection, ProcessHandle)

closeP2PSshConnection :: P2PSshConnection -> IO P2PSshConnection
closeP2PSshConnection P2P.ClosedConnection = return P2P.ClosedConnection
closeP2PSshConnection (P2P.OpenConnection (conn, pid)) = do
	P2P.closeConnection conn
	void $ async $ waitForProcess pid
	return P2P.ClosedConnection

-- Pool of connections over ssh to git-annex-shell p2pstdio.
type P2PSshConnectionPool = TVar (Maybe P2PSshConnectionPoolState)

data P2PSshConnectionPoolState
	= P2PSshConnections [P2PSshConnection]
	-- Remotes using an old version of git-annex-shell don't support P2P
	| P2PSshUnsupported

mkP2PSshConnectionPool :: Annex P2PSshConnectionPool
mkP2PSshConnectionPool = liftIO $ newTVarIO Nothing

-- Takes a connection from the pool, if any are available, otherwise
-- tries to open a new one.
getP2PSshConnection :: Remote -> P2PSshConnectionPool -> Annex (Maybe P2PSshConnection)
getP2PSshConnection r connpool = getexistingconn >>= \case
	Nothing -> return Nothing
	Just Nothing -> openP2PSshConnection r connpool
	Just (Just c) -> return (Just c)
  where
	getexistingconn = liftIO $ atomically $ readTVar connpool >>= \case
		Just P2PSshUnsupported -> return Nothing
		Just (P2PSshConnections (c:cs)) -> do
			writeTVar connpool (Just (P2PSshConnections cs))
			return (Just (Just c))
		Just (P2PSshConnections []) -> return (Just Nothing)
		Nothing -> return (Just Nothing)

-- Add a connection to the pool, unless it's closed.
storeP2PSshConnection :: P2PSshConnectionPool -> P2PSshConnection -> IO ()
storeP2PSshConnection _ P2P.ClosedConnection = return ()
storeP2PSshConnection connpool conn = atomically $ modifyTVar' connpool $ \case
	Just (P2PSshConnections cs) -> Just (P2PSshConnections (conn:cs))
	_ -> Just (P2PSshConnections [conn])

-- Try to open a P2PSshConnection.
-- The new connection is not added to the pool, so it's available
-- for the caller to use.
-- If the remote does not support the P2P protocol, that's remembered in 
-- the connection pool.
openP2PSshConnection :: Remote -> P2PSshConnectionPool -> Annex (Maybe P2PSshConnection)
openP2PSshConnection r connpool = 
	git_annex_shell ConsumeStdin (repo r) "p2pstdio" [] [] >>= \case
		Nothing -> do
			liftIO $ rememberunsupported
			return Nothing
		Just (cmd, params) -> start cmd params
  where
	start cmd params = liftIO $ withNullHandle $ \nullh -> do
		-- stderr is discarded because old versions of git-annex
		-- shell always error
		(Just from, Just to, Nothing, pid) <- createProcess $
			(proc cmd (toCommand params))
				{ std_in = CreatePipe
				, std_out = CreatePipe
				, std_err = UseHandle nullh
				}
		let conn = P2P.P2PConnection
			{ P2P.connRepo = repo r
			, P2P.connCheckAuth = const False
			, P2P.connIhdl = from
			, P2P.connOhdl = to
			}
		let c = P2P.OpenConnection (conn, pid)
		-- When the connection is successful, the peer
		-- will send an AUTH_SUCCESS with its uuid.
		tryNonAsync (P2P.runNetProto conn $ P2P.postAuth) >>= \case
			Right (Right (Just theiruuid)) | theiruuid == uuid r ->
				return $ Just c
			_ -> do
				void $ closeP2PSshConnection c
				rememberunsupported
				return Nothing
	rememberunsupported = atomically $
		modifyTVar' connpool $
			maybe (Just P2PSshUnsupported) Just