incomplete multiple --from / --to support

Note that --from foo --to bar is still not allowed by the option parser.
The goal of this change is only to support the same action over a group
of remotes, not multiple different actions. For the same reason
--to here --to foo is not allowed, since that's really two different
actions.

Each file is processed for all listed remotes in turn, so this is not
the same as two git-annex commands run in sequence. Instead, it allows
concurrent actions to several remotes.

Only move and transferkey converted so far. The code in Command.Move is
ugly and needs to be refactored and generalized.
Build fails due to unconverted modules.

This commit was sponsored by Fernando Jimenez on Patreon.

CmdLine/GitAnnex/Options.hs

@@ -119,18 +119,16 @@ parseRemoteOption = DeferredParse
 	. Just
 
 -- | From or To a remote.
-data FromToOptions
-	= FromRemote (DeferredParse Remote)
-	| ToRemote (DeferredParse Remote)
+data FromToOptions r = From r | To r
 
-instance DeferredParseClass FromToOptions where
-	finishParse (FromRemote v) = FromRemote <$> finishParse v
-	finishParse (ToRemote v) = ToRemote <$> finishParse v
+instance DeferredParseClass (FromToOptions [DeferredParse r]) where
+	finishParse (From l) = From <$> finishParse l
+	finishParse (To l) = To <$> finishParse l
 
-parseFromToOptions :: Parser FromToOptions
+parseFromToOptions :: Parser (FromToOptions [DeferredParse Remote])
 parseFromToOptions = 
-	(FromRemote . parseRemoteOption <$> parseFromOption) 
-	<|> (ToRemote . parseRemoteOption <$> parseToOption)
+	(From . map parseRemoteOption <$> some parseFromOption) 
+	<|> (To . map parseRemoteOption <$> some parseToOption)
 
 parseFromOption :: Parser RemoteName
 parseFromOption = strOption
@@ -147,21 +145,25 @@ parseToOption = strOption
 	)
 
 -- | Like FromToOptions, but with a special --to=here
-type FromToHereOptions = Either ToHere FromToOptions
+type FromToHereOptions r = Either ToHere (FromToOptions r)
 
 data ToHere = ToHere
 
-parseFromToHereOptions :: Parser FromToHereOptions
+parseFromToHereOptions :: Parser (FromToHereOptions [DeferredParse Remote])
 parseFromToHereOptions = parsefrom <|> parseto
   where
-	parsefrom = Right . FromRemote . parseRemoteOption <$> parseFromOption
-	parseto = herespecialcase <$> parseToOption
+	parsefrom = Right . From . map parseRemoteOption <$> some parseFromOption
+	parseto = herespecialcase <$> some parseToOption
 	  where
-		herespecialcase "here" = Left ToHere
-		herespecialcase "." = Left ToHere
-		herespecialcase n = Right $ ToRemote $ parseRemoteOption n
+		herespecialcase l
+			| any ishere l && all ishere l = Left ToHere
+			| any ishere l = fail "Cannot mix --to=here with --to=remote"
+			| otherwise = Right $ To $ map parseRemoteOption l
+		ishere "here" = True
+		ishere "." = True
+		ishere _ = False
 
-instance DeferredParseClass FromToHereOptions where
+instance DeferredParseClass (FromToHereOptions [DeferredParse r]) where
 	finishParse = either (pure . Left) (Right <$$> finishParse)
 
 -- Options for acting on keys, rather than work tree files.