{- Standard git remotes.
 -
 - Copyright 2011-2012 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote.Git (
	remote,
	configRead,
	repoAvail,
) where

import qualified Data.Map as M
import Control.Exception.Extensible

import Common.Annex
import Utility.CopyFile
import Utility.Rsync
import Remote.Helper.Ssh
import Types.Remote
import qualified Git
import qualified Git.Config
import qualified Git.Construct
import qualified Annex
import Logs.Presence
import Logs.Transfer
import Annex.UUID
import Annex.Exception
import qualified Annex.Content
import qualified Annex.BranchState
import qualified Annex.Branch
import qualified Utility.Url as Url
import Utility.TempFile
import Config
import Init
import Types.Key
import qualified Fields

import Control.Concurrent
import System.Process (std_in, std_err)

remote :: RemoteType
remote = RemoteType {
	typename = "git",
	enumerate = list,
	generate = gen,
	setup = error "not supported"
}

list :: Annex [Git.Repo]
list = do
	c <- fromRepo Git.config
	rs <- mapM (tweakurl c) =<< fromRepo Git.remotes
	mapM configRead rs
	where
		annexurl n = "remote." ++ n ++ ".annexurl"
		tweakurl c r = do
			let n = fromJust $ Git.remoteName r
			case M.lookup (annexurl n) c of
				Nothing -> return r
				Just url -> inRepo $ \g ->
					Git.Construct.remoteNamed n $
						Git.Construct.fromRemoteLocation url g

{- It's assumed to be cheap to read the config of non-URL remotes, so this is
 - done each time git-annex is run in a way that uses remotes.
 -
 - Conversely, the config of an URL remote is only read when there is no
 - cached UUID value. -}
configRead :: Git.Repo -> Annex Git.Repo
configRead r = do
	notignored <- repoNotIgnored r
	u <- getRepoUUID r
	case (repoCheap r, notignored, u) of
		(_, False, _) -> return r
		(True, _, _) -> tryGitConfigRead r
		(False, _, NoUUID) -> tryGitConfigRead r
		_ -> return r

repoCheap :: Git.Repo -> Bool
repoCheap = not . Git.repoIsUrl

gen :: Git.Repo -> UUID -> Maybe RemoteConfig -> Annex Remote
gen r u _ = new <$> remoteCost r defcst
	where
		defcst = if repoCheap r then cheapRemoteCost else expensiveRemoteCost
		new cst = Remote 
			{ uuid = u
			, cost = cst
			, name = Git.repoDescribe r
			, storeKey = copyToRemote r
			, retrieveKeyFile = copyFromRemote r
			, retrieveKeyFileCheap = copyFromRemoteCheap r
			, removeKey = dropKey r
			, hasKey = inAnnex r
			, hasKeyCheap = repoCheap r
			, whereisKey = Nothing
			, config = Nothing
			, localpath = if Git.repoIsLocal r || Git.repoIsLocalUnknown r
				then Just $ Git.repoPath r
				else Nothing
			, repo = r
			, readonly = Git.repoIsHttp r
			, remotetype = remote
			}
		

{- Checks relatively inexpensively if a repository is available for use. -}
repoAvail :: Git.Repo -> Annex Bool
repoAvail r 
	| Git.repoIsHttp r = return True
	| Git.repoIsUrl r = return True
	| Git.repoIsLocalUnknown r = return False
	| otherwise = liftIO $ catchBoolIO $ onLocal r $ return True

{- Avoids performing an action on a local repository that's not usable.
 - Does not check that the repository is still available on disk. -}
guardUsable :: Git.Repo -> a -> Annex a -> Annex a
guardUsable r onerr a
	| Git.repoIsLocalUnknown r = return onerr
	| otherwise = a

{- Tries to read the config for a specified remote, updates state, and
 - returns the updated repo. -}
tryGitConfigRead :: Git.Repo -> Annex Git.Repo
tryGitConfigRead r 
	| not $ M.null $ Git.config r = return r -- already read
	| Git.repoIsSsh r = store $ onRemote r (pipedconfig, r) "configlist" [] []
	| Git.repoIsHttp r = do
		headers <- getHttpHeaders
		store $ safely $ geturlconfig headers
	| Git.repoIsUrl r = return r
	| otherwise = store $ safely $ onLocal r $ do 
		ensureInitialized
		Annex.getState Annex.repo
	where
		-- Reading config can fail due to IO error or
		-- for other reasons; catch all possible exceptions.
		safely a = either (const $ return r) return
				=<< liftIO (try a :: IO (Either SomeException Git.Repo))

		pipedconfig cmd params = safely $
			withHandle StdoutHandle createProcessSuccess p $
				Git.Config.hRead r
			where
				p = proc cmd $ toCommand params

		geturlconfig headers = do
			s <- Url.get (Git.repoLocation r ++ "/config") headers
			withTempFile "git-annex.tmp" $ \tmpfile h -> do
				hPutStr h s
				hClose h
				pipedconfig "git" [Param "config", Param "--null", Param "--list", Param "--file", File tmpfile]

		store = observe $ \r' -> do
			g <- gitRepo
			let l = Git.remotes g
			let g' = g { Git.remotes = exchange l r' }
			Annex.changeState $ \s -> s { Annex.repo = g' }

		exchange [] _ = []
		exchange (old:ls) new
			| Git.remoteName old == Git.remoteName new =
				new : exchange ls new
			| otherwise =
				old : exchange ls new

{- Checks if a given remote has the content for a key inAnnex.
 - If the remote cannot be accessed, or if it cannot determine
 - whether it has the content, returns a Left error message.
 -}
inAnnex :: Git.Repo -> Key -> Annex (Either String Bool)
inAnnex r key
	| Git.repoIsHttp r = checkhttp =<< getHttpHeaders
	| Git.repoIsUrl r = checkremote
	| otherwise = checklocal
	where
		checkhttp headers = liftIO $ go undefined $ keyUrls r key
			where
				go e [] = return $ Left e
				go _ (u:us) = do
					res <- catchMsgIO $
						Url.check u headers (keySize key)
					case res of
						Left e -> go e us
						v -> return v
		checkremote = do
			showAction $ "checking " ++ Git.repoDescribe r
			onRemote r (check, unknown) "inannex" [Param (key2file key)] []
			where
				check c p = dispatch <$> safeSystem c p
				dispatch ExitSuccess = Right True
				dispatch (ExitFailure 1) = Right False
				dispatch _ = unknown
		checklocal = guardUsable r unknown $ dispatch <$> check
			where
				check = liftIO $ catchMsgIO $ onLocal r $
					Annex.Content.inAnnexSafe key
				dispatch (Left e) = Left e
				dispatch (Right (Just b)) = Right b
				dispatch (Right Nothing) = unknown
		unknown = Left $ "unable to check " ++ Git.repoDescribe r

{- Runs an action on a local repository inexpensively, by making an annex
 - monad using that repository. -}
onLocal :: Git.Repo -> Annex a -> IO a
onLocal r a = do
	s <- Annex.new r
	Annex.eval s $ do
		-- No need to update the branch; its data is not used
		-- for anything onLocal is used to do.
		Annex.BranchState.disableUpdate
		a

keyUrls :: Git.Repo -> Key -> [String]
keyUrls r key = map tourl (annexLocations key)
	where
		tourl l = Git.repoLocation r ++ "/" ++ l

dropKey :: Git.Repo -> Key -> Annex Bool
dropKey r key
	| not $ Git.repoIsUrl r =
		guardUsable r False $ commitOnCleanup r $ liftIO $ onLocal r $ do
			ensureInitialized
			whenM (Annex.Content.inAnnex key) $ do
				Annex.Content.lockContent key $
					Annex.Content.removeAnnex key
				Annex.Content.logStatus key InfoMissing
				Annex.Content.saveState True
			return True
	| Git.repoIsHttp r = error "dropping from http repo not supported"
	| otherwise = commitOnCleanup r $ onRemote r (boolSystem, False) "dropkey"
		[ Params "--quiet --force"
		, Param $ key2file key
		]
		[]

{- Tries to copy a key's content from a remote's annex to a file. -}
copyFromRemote :: Git.Repo -> Key -> AssociatedFile -> FilePath -> Annex Bool
copyFromRemote r key file dest
	| not $ Git.repoIsUrl r = guardUsable r False $ do
		params <- rsyncParams r
		u <- getUUID
		-- run copy from perspective of remote
		liftIO $ onLocal r $ do
			ensureInitialized
			loc <- inRepo $ gitAnnexLocation key
			upload u key file noRetry $
				rsyncOrCopyFile params loc dest
	| Git.repoIsSsh r = feedprogressback $ \feeder -> 
		rsyncHelper (Just feeder) 
			=<< rsyncParamsRemote r True key dest file
	| Git.repoIsHttp r = Annex.Content.downloadUrl (keyUrls r key) dest
	| otherwise = error "copying from non-ssh, non-http repo not supported"
	where
		{- Feed local rsync's progress info back to the remote,
		 - by forking a feeder thread that runs
		 - git-annex-shell transferinfo at the same time
		 - git-annex-shell sendkey is running.
		 -
		 - Note that it actually waits for rsync to indicate
		 - progress before starting transferinfo, in order
		 - to ensure ssh connection caching works and reuses 
		 - the connection set up for the sendkey.
		 -
		 - Also note that older git-annex-shell does not support
		 - transferinfo, so stderr is dropped and failure ignored.
		 -}
		feedprogressback a = do
			u <- getUUID
			let fields = (Fields.remoteUUID, fromUUID u)
				: maybe [] (\f -> [(Fields.associatedFile, f)]) file
			Just (cmd, params) <- git_annex_shell r "transferinfo" 
				[Param $ key2file key] fields
			v <- liftIO $ newEmptySampleVar
			tid <- liftIO $ forkIO $ void $ tryIO $ do
				bytes <- readSampleVar v
				p <- createProcess $
					 (proc cmd (toCommand params))
						{ std_in = CreatePipe
						, std_err = CreatePipe
						}
				hClose $ stderrHandle p
				let h = stdinHandle p
				let send b = do
					hPutStrLn h $ show b
					hFlush h
				send bytes
				forever $
					send =<< readSampleVar v
			let feeder = writeSampleVar v
			bracketIO noop (const $ tryIO $ killThread tid) (a feeder)

copyFromRemoteCheap :: Git.Repo -> Key -> FilePath -> Annex Bool
copyFromRemoteCheap r key file
	| not $ Git.repoIsUrl r = guardUsable r False $ do
		loc <- liftIO $ gitAnnexLocation key r
		liftIO $ catchBoolIO $ createSymbolicLink loc file >> return True
	| Git.repoIsSsh r =
		ifM (Annex.Content.preseedTmp key file)
			( copyFromRemote r key Nothing file
			, return False
			)
	| otherwise = return False

{- Tries to copy a key's content to a remote's annex. -}
copyToRemote :: Git.Repo -> Key -> AssociatedFile -> MeterUpdate -> Annex Bool
copyToRemote r key file p
	| not $ Git.repoIsUrl r = guardUsable r False $ commitOnCleanup r $ do
		keysrc <- inRepo $ gitAnnexLocation key
		params <- rsyncParams r
		u <- getUUID
		-- run copy from perspective of remote
		liftIO $ onLocal r $ ifM (Annex.Content.inAnnex key)
			( return False
			, do
				ensureInitialized
				download u key file noRetry $
					Annex.Content.saveState True `after`
						Annex.Content.getViaTmp key
							(\d -> rsyncOrCopyFile params keysrc d p)
			)
	| Git.repoIsSsh r = commitOnCleanup r $ do
		keysrc <- inRepo $ gitAnnexLocation key
		rsyncHelper (Just p) =<< rsyncParamsRemote r False key keysrc file
	| otherwise = error "copying to non-ssh repo not supported"

rsyncHelper :: Maybe MeterUpdate -> [CommandParam] -> Annex Bool
rsyncHelper callback params = do
	showOutput -- make way for progress bar
	ifM (liftIO $ (maybe rsync rsyncProgress callback) params)
		( return True
		, do
			showLongNote "rsync failed -- run git annex again to resume file transfer"
			return False
		)

{- Copys a file with rsync unless both locations are on the same
 - filesystem. Then cp could be faster. -}
rsyncOrCopyFile :: [CommandParam] -> FilePath -> FilePath -> MeterUpdate -> Annex Bool
rsyncOrCopyFile rsyncparams src dest p =
	ifM (sameDeviceIds src dest) (docopy, dorsync)
	where
		sameDeviceIds a b = (==) <$> (getDeviceId a) <*> (getDeviceId b)
		getDeviceId f = deviceID <$> liftIO (getFileStatus $ parentDir f)
		dorsync = rsyncHelper (Just p) $
			rsyncparams ++ [Param src, Param dest]
		docopy = liftIO $ bracket
			(forkIO $ watchfilesize 0)
			(void . tryIO . killThread)
			(const $ copyFileExternal src dest)
		watchfilesize oldsz = do
			threadDelay 500000 -- 0.5 seconds
			v <- catchMaybeIO $
				fromIntegral . fileSize
					<$> getFileStatus dest
			case v of
				Just sz
					| sz /= oldsz -> do
						p sz
						watchfilesize sz
				_ -> watchfilesize oldsz

{- Generates rsync parameters that ssh to the remote and asks it
 - to either receive or send the key's content. -}
rsyncParamsRemote :: Git.Repo -> Bool -> Key -> FilePath -> AssociatedFile -> Annex [CommandParam]
rsyncParamsRemote r sending key file afile = do
	u <- getUUID
	let fields = (Fields.remoteUUID, fromUUID u)
		: maybe [] (\f -> [(Fields.associatedFile, f)]) afile
	Just (shellcmd, shellparams) <- git_annex_shell r
		(if sending 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
	if sending
		then return $ o ++ rsyncopts eparam dummy (File file)
		else return $ 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:"

rsyncParams :: Git.Repo -> Annex [CommandParam]
rsyncParams r = do
	o <- getRemoteConfig r "rsync-options" ""
	return $ options ++ map Param (words o)
	where
 		-- --inplace to resume partial files
		options = [Params "-p --progress --inplace"]

commitOnCleanup :: Git.Repo -> Annex a -> Annex a
commitOnCleanup r a = go `after` a
	where
		go = Annex.addCleanup (Git.repoLocation r) cleanup
		cleanup
			| not $ Git.repoIsUrl r = liftIO $ onLocal r $
				doQuietSideAction $
					Annex.Branch.commit "update"
			| otherwise = void $ do
				Just (shellcmd, shellparams) <-
					git_annex_shell r "commit" [] []
				-- Throw away stderr, since the remote may not
				-- have a new enough git-annex shell to
				-- support committing.
				let cmd = shellcmd ++ " "
					++ unwords (map shellEscape $ toCommand shellparams)
					++ ">/dev/null 2>/dev/null"
				liftIO $ boolSystem "sh" [Param "-c", Param cmd]