{- git-annex v1 -> v2 upgrade support
 -
 - Copyright 2011 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Upgrade.V1 where

import System.Posix.Types
import Data.Char

import Common.Annex
import Types.Key
import Annex.Content
import Logs.Presence
import qualified Annex.Queue
import qualified Git
import qualified Git.LsFiles as LsFiles
import Backend
import Annex.Version
import Utility.FileMode
import Utility.Tmp
import qualified Upgrade.V2

-- v2 adds hashing of filenames of content and location log files.
-- Key information is encoded in filenames differently, so
-- both content and location log files move around, and symlinks
-- to content need to be changed.
-- 
-- When upgrading a v1 key to v2, file size metadata ought to be
-- added to the key (unless it is a WORM key, which encoded
-- mtime:size in v1). This can only be done when the file content
-- is present. Since upgrades need to happen consistently, 
-- (so that two repos get changed the same way by the upgrade, and
-- will merge), that metadata cannot be added on upgrade.
--
-- Note that file size metadata
-- will only be used for detecting situations where git-annex
-- would run out of disk space, so if some keys don't have it,
-- the impact is minor. At least initially. It could be used in the
-- future by smart auto-repo balancing code, etc.
--
-- Anyway, since v2 plans ahead for other metadata being included
-- in keys, there should probably be a way to update a key.
-- Something similar to the migrate subcommand could be used,
-- and users could then run that at their leisure.

upgrade :: Annex Bool
upgrade = do
	showAction "v1 to v2"
	
	ifM (fromRepo Git.repoIsLocalBare)
		( do
			moveContent
			setVersion defaultVersion
		, do
			moveContent
			updateSymlinks
			moveLocationLogs
	
			Annex.Queue.flush
			setVersion defaultVersion
		)
	
	Upgrade.V2.upgrade

moveContent :: Annex ()
moveContent = do
	showAction "moving content"
	files <- getKeyFilesPresent1
	forM_ files move
  where
	move f = do
		let k = fileKey1 (takeFileName f)
		let d = parentDir f
		liftIO $ allowWrite d
		liftIO $ allowWrite f
		moveAnnex k f
		liftIO $ removeDirectory d

updateSymlinks :: Annex ()
updateSymlinks = do
	showAction "updating symlinks"
	top <- fromRepo Git.repoPath
	(files, cleanup) <- inRepo $ LsFiles.inRepo [top]
	forM_ files fixlink
	void $ liftIO cleanup
  where
	fixlink f = do
		r <- lookupFile1 f
		case r of
			Nothing -> noop
			Just (k, _) -> do
				link <- inRepo $ gitAnnexLink f k
				liftIO $ removeFile f
				liftIO $ createSymbolicLink link f
				Annex.Queue.addCommand "add" [Param "--"] [f]

moveLocationLogs :: Annex ()
moveLocationLogs = do
	showAction "moving location logs"
	logkeys <- oldlocationlogs
	forM_ logkeys move
  where
	oldlocationlogs = do
		dir <- fromRepo Upgrade.V2.gitStateDir
		ifM (liftIO $ doesDirectoryExist dir)
			( mapMaybe oldlog2key
				<$> (liftIO $ getDirectoryContents dir)
			, return []
			)
	move (l, k) = do
		dest <- fromRepo $ logFile2 k
		dir <- fromRepo Upgrade.V2.gitStateDir
		let f = dir </> l
		liftIO $ createDirectoryIfMissing True (parentDir dest)
		-- could just git mv, but this way deals with
		-- log files that are not checked into git,
		-- as well as merging with already upgraded
		-- logs that have been pulled from elsewhere
		old <- liftIO $ readLog1 f
		new <- liftIO $ readLog1 dest
		liftIO $ writeLog1 dest (old++new)
		Annex.Queue.addCommand "add" [Param "--"] [dest]
		Annex.Queue.addCommand "add" [Param "--"] [f]
		Annex.Queue.addCommand "rm" [Param "--quiet", Param "-f", Param "--"] [f]

oldlog2key :: FilePath -> Maybe (FilePath, Key)
oldlog2key l
	| drop len l == ".log" && sane = Just (l, k)
	| otherwise = Nothing
  where
	len = length l - 4
	k = readKey1 (take len l)
	sane = (not . null $ keyName k) && (not . null $ keyBackendName k)

-- WORM backend keys: "WORM:mtime:size:filename"
-- all the rest: "backend:key"
--
-- If the file looks like "WORM:XXX-...", then it was created by mixing
-- v2 and v1; that infelicity is worked around by treating the value
-- as the v2 key that it is.
readKey1 :: String -> Key
readKey1 v
	| mixup = fromJust $ file2key $ intercalate ":" $ Prelude.tail bits
	| otherwise = Key
		{ keyName = n
		, keyBackendName = b
		, keySize = s
		, keyMtime = t
		}
  where
	bits = split ":" v
	b = Prelude.head bits
	n = intercalate ":" $ drop (if wormy then 3 else 1) bits
	t = if wormy
		then Just (Prelude.read (bits !! 1) :: EpochTime)
		else Nothing
	s = if wormy
		then Just (Prelude.read (bits !! 2) :: Integer)
		else Nothing
	wormy = Prelude.head bits == "WORM"
	mixup = wormy && isUpper (Prelude.head $ bits !! 1)

showKey1 :: Key -> String
showKey1 Key { keyName = n , keyBackendName = b, keySize = s, keyMtime = t } =
	intercalate ":" $ filter (not . null) [b, showifhere t, showifhere s, n]
  where
	showifhere Nothing = ""
	showifhere (Just v) = show v

keyFile1 :: Key -> FilePath
keyFile1 key = replace "/" "%" $ replace "%" "&s" $ replace "&" "&a"  $ showKey1 key

fileKey1 :: FilePath -> Key
fileKey1 file = readKey1 $
	replace "&a" "&" $ replace "&s" "%" $ replace "%" "/" file

writeLog1 :: FilePath -> [LogLine] -> IO ()
writeLog1 file ls = viaTmp writeFile file (showLog ls)

readLog1 :: FilePath -> IO [LogLine]
readLog1 file = catchDefaultIO [] $
	parseLog <$> readFileStrict file

lookupFile1 :: FilePath -> Annex (Maybe (Key, Backend))
lookupFile1 file = do
	tl <- liftIO $ tryIO getsymlink
	case tl of
		Left _ -> return Nothing
		Right l -> makekey l
  where
	getsymlink = takeFileName <$> readSymbolicLink file
	makekey l = case maybeLookupBackendName bname of
		Nothing -> do
			unless (null kname || null bname ||
			        not (isLinkToAnnex l)) $
				warning skip
			return Nothing
		Just backend -> return $ Just (k, backend)
	  where
		k = fileKey1 l
		bname = keyBackendName k
		kname = keyName k
		skip = "skipping " ++ file ++ 
			" (unknown backend " ++ bname ++ ")"

getKeyFilesPresent1 :: Annex [FilePath]
getKeyFilesPresent1  = getKeyFilesPresent1' =<< fromRepo gitAnnexObjectDir
getKeyFilesPresent1' :: FilePath -> Annex [FilePath]
getKeyFilesPresent1' dir =
	ifM (liftIO $ doesDirectoryExist dir)
		(  do
			dirs <- liftIO $ getDirectoryContents dir
			let files = map (\d -> dir ++ "/" ++ d ++ "/" ++ takeFileName d) dirs
			liftIO $ filterM present files
		, return []
		)
  where
	present f = do
		result <- tryIO $ getFileStatus f
		case result of
			Right s -> return $ isRegularFile s
			Left _ -> return False

logFile1 :: Git.Repo -> Key -> String
logFile1 repo key = Upgrade.V2.gitStateDir repo ++ keyFile1 key ++ ".log"

logFile2 :: Key -> Git.Repo -> String
logFile2 = logFile' hashDirLower

logFile' :: (Key -> FilePath) -> Key -> Git.Repo -> String
logFile' hasher key repo =
	gitStateDir repo ++ hasher key ++ keyFile key ++ ".log"

stateDir :: FilePath
stateDir = addTrailingPathSeparator ".git-annex"

gitStateDir :: Git.Repo -> FilePath
gitStateDir repo = addTrailingPathSeparator $ Git.repoPath repo </> stateDir
