refactor git-annex branch log filename code into central location

Having one module that knows about all the filenames used on the branch
allows working back from an arbitrary filename to enough information about
it to implement dropping dead remotes and doing other log file compacting
as part of a forget transition.

Logs/Location.hs

@@ -20,12 +20,11 @@ module Logs.Location (
 	loggedLocations,
 	loggedKeys,
 	loggedKeysFor,
-	logFile,
-	logFileKey
 ) where
 
 import Common.Annex
 import qualified Annex.Branch
+import Logs
 import Logs.Presence
 import Annex.UUID
 
@@ -37,19 +36,19 @@ logStatus key status = do
 
 {- Log a change in the presence of a key's value in a repository. -}
 logChange :: Key -> UUID -> LogStatus -> Annex ()
-logChange key (UUID u) s = addLog (logFile key) =<< logNow s u
+logChange key (UUID u) s = addLog (locationLogFile key) =<< logNow s u
 logChange _ NoUUID _ = noop
 
 {- Returns a list of repository UUIDs that, according to the log, have
  - the value of a key.
  -}
 loggedLocations :: Key -> Annex [UUID]
-loggedLocations key = map toUUID <$> (currentLog . logFile) key
+loggedLocations key = map toUUID <$> (currentLog . locationLogFile) key
 
 {- Finds all keys that have location log information.
  - (There may be duplicate keys in the list.) -}
 loggedKeys :: Annex [Key]
-loggedKeys = mapMaybe (logFileKey . takeFileName) <$> Annex.Branch.files
+loggedKeys = mapMaybe locationLogFileKey <$> Annex.Branch.files
 
 {- Finds all keys that have location log information indicating
  - they are present for the specified repository. -}
@@ -62,15 +61,3 @@ loggedKeysFor u = filterM isthere =<< loggedKeys
 		us <- loggedLocations k
 		let !there = u `elem` us
 		return there
-
-{- The filename of the log file for a given key. -}
-logFile :: Key -> String
-logFile key = hashDirLower key ++ keyFile key ++ ".log"
-
-{- Converts a log filename into a key. -}
-logFileKey :: FilePath -> Maybe Key
-logFileKey file
-	| ext == ".log" = fileKey base
-	| otherwise = Nothing
-  where
-	(base, ext) = splitAt (length file - 4) file