rekey: Added --batch mode.

Would have liked to make the Parser parse the file and key pairs, but it
seems that optparse-applicative is unable to handle eg:

	many ((,) <$> argument <*> argument)

This commit was sponsored by Thomas Hochstein on Patreon.

CHANGELOG

@@ -13,6 +13,7 @@ git-annex (6.20161119) UNRELEASED; urgency=medium
   * rmurl: Added --batch mode.
   * fromkey: Accept multiple pairs of files and keys.
     Thanks, Daniel Brooks.
+  * rekey: Added --batch mode.
 
  -- Joey Hess <id@joeyh.name>  Mon, 21 Nov 2016 11:27:50 -0400
 

Command/ReKey.hs

@@ -25,15 +25,39 @@ cmd = notDirect $
 	command "rekey" SectionPlumbing
 		"change keys used for files"
 		(paramRepeating $ paramPair paramPath paramKey)
-		(withParams seek)
+		(seek <$$> optParser)
 
-seek :: CmdParams -> CommandSeek
-seek = withPairs start
+data ReKeyOptions = ReKeyOptions
+	{ reKeyThese :: CmdParams
+	, batchOption :: BatchMode
+	}
 
-start :: (FilePath, String) -> CommandStart
-start (file, keyname) = ifAnnexed file go stop
+optParser :: CmdParamsDesc -> Parser ReKeyOptions
+optParser desc = ReKeyOptions
+	<$> cmdParams desc
+	<*> parseBatchOption
+
+-- Split on the last space, since a FilePath can contain whitespace,
+-- but a Key very rarely does.
+batchParser :: String -> Either String (FilePath, Key)
+batchParser s = case separate (== ' ') (reverse s) of
+	(rk, rf)
+		| null rk || null rf -> Left "Expected: \"file key\""
+		| otherwise -> case file2key (reverse rk) of
+			Nothing -> Left "bad key"
+			Just k -> Right (reverse rf, k)
+
+seek :: ReKeyOptions -> CommandSeek
+seek o = case batchOption o of
+	Batch -> batchInput batchParser (batchCommandAction . start)
+	NoBatch -> withPairs (start . parsekey) (reKeyThese o)
+  where
+	parsekey (file, skey) =
+		(file, fromMaybe (giveup "bad key") (file2key skey))
+
+start :: (FilePath, Key) -> CommandStart
+start (file, newkey) = ifAnnexed file go stop
   where
-	newkey = fromMaybe (giveup "bad key") $ file2key keyname
 	go oldkey
 		| oldkey == newkey = stop
 		| otherwise = do

Command/RmUrl.hs

@@ -10,7 +10,6 @@ module Command.RmUrl where
 import Command
 import Logs.Web
 import qualified Remote
-import CmdLine.Batch
 
 cmd :: Command
 cmd = notBareRepo $

doc/git-annex-rekey.mdwn

@@ -20,6 +20,12 @@ Multiple pairs of file and key can be given in a single command line.
   Allow rekeying of even files whose content is not currently available.
   Use with caution.
 
+* `--batch`
+
+  Enables batch mode, in which lines are read from stdin.
+  Each line should contain the file, and the new key to use for that file,
+  separated by a single space.
+
 # SEE ALSO
 
 [[git-annex]](1)