{- Web url logs.
 -
 - Copyright 2011, 2013 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Logs.Web (
	URLString,
	webUUID,
	getUrls,
	setUrlPresent,
	setUrlMissing,
	urlLog,
	urlLogKey,
	knownUrls
) where

import qualified Data.ByteString.Lazy.Char8 as L

import Common.Annex
import Logs.Presence
import Logs.Location
import Types.Key
import qualified Annex.Branch
import Annex.CatFile
import qualified Git
import qualified Git.LsFiles

type URLString = String

-- Dummy uuid for the whole web. Do not alter.
webUUID :: UUID
webUUID = UUID "00000000-0000-0000-0000-000000000001"

urlLogExt :: String
urlLogExt = ".log.web"

urlLog :: Key -> FilePath
urlLog key = hashDirLower key </> keyFile key ++ urlLogExt

{- Converts a url log file into a key.
 - (Does not work on oldurlLogs.) -}
urlLogKey :: FilePath -> Maybe Key
urlLogKey file
	| ext == urlLogExt = fileKey base
	| otherwise = Nothing
  where
  	(base, ext) = splitAt (length file - extlen) file
	extlen = length urlLogExt

isUrlLog :: FilePath -> Bool
isUrlLog file = urlLogExt `isSuffixOf` file

{- Used to store the urls elsewhere. -}
oldurlLogs :: Key -> [FilePath]
oldurlLogs key = 
	[ "remote/web" </> hashDirLower key </> key2file key ++ ".log"
	, "remote/web" </> hashDirLower key </> keyFile key ++ ".log"
	]

{- Gets all urls that a key might be available from. -}
getUrls :: Key -> Annex [URLString]
getUrls key = go $ urlLog key : oldurlLogs key
  where
	go [] = return []
	go (l:ls) = do
		us <- currentLog l
		if null us
			then go ls
			else return us

setUrlPresent :: Key -> URLString -> Annex ()
setUrlPresent key url = do
	us <- getUrls key
	unless (url `elem` us) $ do
		addLog (urlLog key) =<< logNow InfoPresent url
		-- update location log to indicate that the web has the key
		logChange key webUUID InfoPresent

setUrlMissing :: Key -> URLString -> Annex ()
setUrlMissing key url = do
	addLog (urlLog key) =<< logNow InfoMissing url
	whenM (null <$> getUrls key) $
		logChange key webUUID InfoMissing

{- Finds all known urls. -}
knownUrls :: Annex [URLString]
knownUrls = do
	{- Ensure the git-annex branch's index file is up-to-date and
	 - any journaled changes are reflected in it, since we're going
	 - to query its index directly. -}
	Annex.Branch.update
	Annex.Branch.commit "update"
	Annex.Branch.withIndex $ do
		top <- fromRepo Git.repoPath
		(l, cleanup) <- inRepo $ Git.LsFiles.stagedDetails [top]
		r <- mapM (geturls . snd) $ filter (isUrlLog . fst) l
		void $ liftIO cleanup
		return $ concat r
  where
	geturls Nothing = return []
  	geturls (Just logsha) = getLog . L.unpack <$> catObject logsha