{- git-annex command
 -
 - Copyright 2010 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Command.Move where

import Control.Monad.State (liftIO)

import Command
import qualified Command.Drop
import qualified Annex
import qualified AnnexQueue
import LocationLog
import Types
import Content
import qualified Remote
import UUID
import Messages
import Utility

command :: [Command]
command = [repoCommand "move" paramPath seek
	"move content of files to/from another repository"]

seek :: [CommandSeek]
seek = [withFilesInGit $ start True]

{- Move (or copy) a file either --to or --from a repository.
 -
 - This only operates on the cached file content; it does not involve
 - moving data in the key-value backend. -}
start :: Bool -> CommandStartString
start move file = do
	to <- Annex.getState Annex.toremote
	from <- Annex.getState Annex.fromremote
	case (from, to) of
		(Nothing, Nothing) -> error "specify either --from or --to"
		(Nothing, Just name) -> do
			dest <- Remote.byName name
			toStart dest move file
		(Just name, Nothing) -> do
			src <- Remote.byName name
			fromStart src move file
		(_ ,  _) -> error "only one of --from or --to can be specified"

showAction :: Bool -> FilePath -> Annex ()
showAction True file = showStart "move" file
showAction False file = showStart "copy" file

{- Used to log a change in a remote's having a key. The change is logged
 - in the local repo, not on the remote. The process of transferring the
 - key to the remote, or removing the key from it *may* log the change
 - on the remote, but this cannot be relied on. For example, it's not done
 - for bare repos. -}
remoteHasKey :: Remote.Remote Annex -> Key -> Bool -> Annex ()
remoteHasKey remote key present	= do
	g <- Annex.gitRepo
	let remoteuuid = Remote.uuid remote
	logfile <- liftIO $ logChange g key remoteuuid status
	AnnexQueue.add "add" [Param "--"] logfile
	where
		status = if present then ValuePresent else ValueMissing

{- Moves (or copies) the content of an annexed file to a remote.
 -
 - If the remote already has the content, it is still removed from
 - the current repository.
 -
 - Note that unlike drop, this does not honor annex.numcopies.
 - A file's content can be moved even if there are insufficient copies to
 - allow it to be dropped.
 -}
toStart :: Remote.Remote Annex -> Bool -> CommandStartString
toStart dest move file = isAnnexed file $ \(key, _) -> do
	g <- Annex.gitRepo
	u <- getUUID g
	ishere <- inAnnex key
	if not ishere || u == Remote.uuid dest
		then return Nothing -- not here, so nothing to do
		else do
			showAction move file
			return $ Just $ toPerform dest move key
toPerform :: Remote.Remote Annex -> Bool -> Key -> CommandPerform
toPerform dest move key = do
	-- Checking the remote is expensive, so not done in the start step.
	-- In fast mode, location tracking is assumed to be correct,
	-- and an explicit check is not done, when copying. When moving,
	-- it has to be done, to avoid inaverdent data loss.
	fast <- Annex.getState Annex.fast
	isthere <- if fast && not move && not (Remote.hasKeyCheap dest)
		then do
			(remotes, _) <- Remote.keyPossibilities key
			return $ Right $ dest `elem` remotes
		else Remote.hasKey dest key
	case isthere of
		Left err -> do
			showNote $ show err
			return Nothing
		Right False -> do
			showNote $ "to " ++ Remote.name dest ++ "..."
			ok <- Remote.storeKey dest key
			if ok
				then return $ Just $ toCleanup dest move key
				else return Nothing -- failed
		Right True -> return $ Just $ toCleanup dest move key
toCleanup :: Remote.Remote Annex -> Bool -> Key -> CommandCleanup
toCleanup dest move key = do
	remoteHasKey dest key True
	if move
		then Command.Drop.cleanup key
		else return True

{- Moves (or copies) the content of an annexed file from a remote
 - to the current repository.
 -
 - If the current repository already has the content, it is still removed
 - from the remote.
 -}
fromStart :: Remote.Remote Annex -> Bool -> CommandStartString
fromStart src move file = isAnnexed file $ \(key, _) -> do
	g <- Annex.gitRepo
	u <- getUUID g
	(remotes, _) <- Remote.keyPossibilities key
	if (u == Remote.uuid src) || (null $ filter (== src) remotes)
		then return Nothing
		else do
			showAction move file
			return $ Just $ fromPerform src move key
fromPerform :: Remote.Remote Annex -> Bool -> Key -> CommandPerform
fromPerform src move key = do
	ishere <- inAnnex key
	if ishere
		then return $ Just $ fromCleanup src move key
		else do
			showNote $ "from " ++ Remote.name src ++ "..."
			ok <- getViaTmp key $ Remote.retrieveKeyFile src key
			if ok
				then return $ Just $ fromCleanup src move key
				else return Nothing -- fail
fromCleanup :: Remote.Remote Annex -> Bool -> Key -> CommandCleanup
fromCleanup src True key = do
	ok <- Remote.removeKey src key
	-- better safe than sorry: assume the src dropped the key
	-- even if it seemed to fail; the failure could have occurred
	-- after it really dropped it
	remoteHasKey src key False
	return ok
fromCleanup _ False _ = return True