start of generalizing remotes

Goal is to support multiple different types of remotes, some of which
are not git repositories. To that end, added a Remote class, and moved
git remote specific code into Remote.GitRemote.

Remotes.hs is still present as some code has not been converted to use the
new Remote class yet.

Remote.hs

@@ -0,0 +1,66 @@
+{- git-annex remotes
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Remote (
+	generate,
+	keyPossibilities,
+	remotesWithUUID,
+	remotesWithoutUUID
+) where
+
+import Control.Monad.State (liftIO)
+import Data.List
+
+import RemoteClass
+import qualified Remote.GitRemote
+import Types
+import UUID
+import qualified Annex
+import Trust
+import LocationLog
+
+{- add generators for new Remotes here -}
+generators :: [Annex [Remote]]
+generators = [Remote.GitRemote.generate]
+
+{- generates a list of all available Remotes -}
+generate :: Annex [Remote]
+generate = do
+	lists <- sequence generators
+	return $ concat lists
+
+{- Filters a list of remotes to ones that have the listed uuids. -}
+remotesWithUUID :: [Remote] -> [UUID] -> [Remote]
+remotesWithUUID rs us = filter (\r -> uuid r `elem` us) rs
+
+{- Filters a list of remotes to ones that do not have the listed uuids. -}
+remotesWithoutUUID :: [Remote] -> [UUID] -> [Remote]
+remotesWithoutUUID rs us = filter (\r -> uuid r `notElem` us) rs
+
+{- Cost ordered lists of remotes that the LocationLog indicate may have a key.
+ -
+ - Also returns a list of UUIDs that are trusted to have the key
+ - (some may not have configured remotes).
+ -}
+keyPossibilities :: Key -> Annex ([Remote], [UUID])
+keyPossibilities key = do
+	g <- Annex.gitRepo
+	u <- getUUID g
+	trusted <- trustGet Trusted
+
+	-- get uuids of all remotes that are recorded to have the key
+	uuids <- liftIO $ keyLocations g key
+	let validuuids = filter (/= u) uuids
+
+	-- note that validuuids is assumed to not have dups
+	let validtrusteduuids = intersect validuuids trusted
+
+	-- remotes that match uuids that have the key
+	allremotes <- generate
+	let validremotes = remotesWithUUID allremotes validuuids
+
+	return (sort validremotes, validtrusteduuids)