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.

1 files changed, 110 insertions, 0 deletions

diff --git a/Logs.hs b/Logs.hs
new file mode 100644
index 000000000..6339efa13
--- /dev/null
+++ b/Logs.hs
@@ -0,0 +1,110 @@
+{- git-annex log file names
+ -
+ - Copyright 2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Logs where
+
+import Common.Annex
+import Types.Key
+
+data LogVariety = UUIDBasedLog | PresenceLog Key
+	deriving (Show)
+
+{- Converts a path from the git-annex branch into one of the varieties
+ - of logs used by git-annex, if it's a known path. -}
+getLogVariety :: FilePath -> Maybe LogVariety
+getLogVariety f
+	| f `elem` uuidBasedLogs = Just UUIDBasedLog
+	| otherwise = PresenceLog <$> firstJust (presenceLogs f)
+
+{- All the uuid-based logs stored in the git-annex branch. -}
+uuidBasedLogs :: [FilePath]
+uuidBasedLogs =
+	[ uuidLog
+	, remoteLog
+	, trustLog
+	, groupLog 
+	, preferredContentLog
+	]
+
+{- All the ways to get a key from a presence log file -}
+presenceLogs :: FilePath -> [Maybe Key]
+presenceLogs f =
+	[ urlLogFileKey f
+	, locationLogFileKey f
+	]
+
+uuidLog :: FilePath
+uuidLog = "uuid.log"
+
+remoteLog :: FilePath
+remoteLog = "remote.log"
+
+trustLog :: FilePath
+trustLog = "trust.log"
+
+groupLog :: FilePath
+groupLog = "group.log"
+
+preferredContentLog :: FilePath
+preferredContentLog = "preferred-content.log"
+
+{- The pathname of the location log file for a given key. -}
+locationLogFile :: Key -> String
+locationLogFile key = hashDirLower key ++ keyFile key ++ ".log"
+
+{- Converts a pathname into a key if it's a location log. -}
+locationLogFileKey :: FilePath -> Maybe Key
+locationLogFileKey path
+	| ["remote", "web"] `isPrefixOf` splitDirectories dir = Nothing
+        | ext == ".log" = fileKey base
+        | otherwise = Nothing
+  where
+	(dir, file) = splitFileName path
+        (base, ext) = splitAt (length file - 4) file
+
+{- The filename of the url log for a given key. -}
+urlLogFile :: Key -> FilePath
+urlLogFile key = hashDirLower key </> keyFile key ++ urlLogExt
+
+{- Old versions stored the urls elsewhere. -}
+oldurlLogs :: Key -> [FilePath]
+oldurlLogs key =
+	[ "remote/web" </> hashDirLower key </> key2file key ++ ".log"
+	, "remote/web" </> hashDirLower key </> keyFile key ++ ".log"
+	]
+
+urlLogExt :: String
+urlLogExt = ".log.web"
+
+{- Converts a url log file into a key.
+ - (Does not work on oldurlLogs.) -}
+urlLogFileKey :: FilePath -> Maybe Key
+urlLogFileKey path
+	| ext == urlLogExt = fileKey base
+	| otherwise = Nothing
+  where
+  	file = takeFileName path
+	(base, ext) = splitAt (length file - extlen) file
+	extlen = length urlLogExt
+
+{- Does not work on oldurllogs. -}
+isUrlLog :: FilePath -> Bool
+isUrlLog file = urlLogExt `isSuffixOf` file
+
+prop_logs_sane :: Key -> Bool
+prop_logs_sane dummykey = all id
+	[ isNothing (getLogVariety "unknown")
+	, expect isUUIDBasedLog (getLogVariety uuidLog)
+	, expect isPresenceLog (getLogVariety $ locationLogFile dummykey)
+	, expect isPresenceLog (getLogVariety $ urlLogFile dummykey)
+	]
+  where
+  	expect = maybe False
+  	isUUIDBasedLog UUIDBasedLog = True
+	isUUIDBasedLog _ = False
+	isPresenceLog (PresenceLog k) = k == dummykey
+	isPresenceLog _ = False