{- git-annex remotes
 -
 - Copyright 2011 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote (
	Remote,
	uuid,
	name,
	storeKey,
	retrieveKeyFile,
	removeKey,
	hasKey,
	hasKeyCheap,

	remoteTypes,
	byName,
	nameToUUID,
	keyPossibilities,
	remotesWithUUID,
	remotesWithoutUUID,

	remoteLog,
	readRemoteLog,
	configSet,
	keyValToMap
) where

import Control.Monad.State (liftIO)
import Control.Monad (when, liftM)
import Data.List
import qualified Data.Map as M
import Data.Maybe

import RemoteClass
import Types
import UUID
import qualified Annex
import Trust
import LocationLog
import Locations
import Utility

import qualified Remote.Git
import qualified Remote.S3

remoteTypes :: [RemoteType Annex]
remoteTypes =
	[ Remote.Git.remote
	, Remote.S3.remote
	]

{- Builds a list of all available Remotes.
 - Since doing so can be expensive, the list is cached. -}
genList :: Annex [Remote Annex]
genList = do
	rs <- Annex.getState Annex.remotes
	if null rs
		then do
			l <- mapM generator remoteTypes
			rs' <- getConfigs (concat l)
			Annex.changeState $ \s -> s { Annex.remotes = rs' }
			return rs'
		else return rs

{- Looks up a remote by name. (Or by UUID.) -}
byName :: String -> Annex (Remote Annex)
byName "" = error "no remote specified"
byName n = do
	allremotes <- genList
	let match = filter matching allremotes
	when (null match) $ error $
		"there is no git remote named \"" ++ n ++ "\""
	return $ head match
	where
		matching r = n == name r || n == uuid r

{- Looks up a remote by name (or by UUID), and returns its UUID. -}
nameToUUID :: String -> Annex UUID
nameToUUID "." = do -- special case for current repo
	g <- Annex.gitRepo
	getUUID g
nameToUUID n = liftM uuid (byName n)

{- 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 Annex], [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 <- genList
	let validremotes = remotesWithUUID allremotes validuuids

	return (sort validremotes, validtrusteduuids)

{- Filters a list of remotes to ones that have the listed uuids. -}
remotesWithUUID :: [Remote Annex] -> [UUID] -> [Remote Annex]
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 Annex] -> [UUID] -> [Remote Annex]
remotesWithoutUUID rs us = filter (\r -> uuid r `notElem` us) rs

{- Filename of remote.log. -}
remoteLog :: Annex FilePath
remoteLog = do
	g <- Annex.gitRepo
	return $ gitStateDir g ++ "remote.log"

{- Load stored config into remotes.
 -
 - This way, the log is read once, lazily, so if no remotes access
 - their config, no work is done.
 -}
getConfigs :: [Remote Annex] -> Annex [Remote Annex]
getConfigs rs = do
	m <- readRemoteLog
	return $ map (get m) rs
	where
		get m r = r { config = M.lookup (uuid r) m }

{- Adds or updates a remote's config in the log. -}
configSet :: UUID -> M.Map String String -> Annex ()
configSet u c = do
	m <- readRemoteLog
	l <- remoteLog
	liftIO $ safeWriteFile l $ unlines $ sort $
		map toline $ M.toList $ M.insert u c m
	where
		toline (u', c') = u' ++ " " ++ (unwords $ mapToKeyVal c')

{- Map of remotes by uuid containing key/value config maps. -}
readRemoteLog :: Annex (M.Map UUID (M.Map String String))
readRemoteLog = do
	l <- remoteLog
	s <- liftIO $ catch (readFile l) ignoreerror
	return $ remoteLogParse s
	where
		ignoreerror _ = return ""

remoteLogParse :: String -> M.Map UUID (M.Map String String)
remoteLogParse s =
	M.fromList $ catMaybes $ map parseline $ filter (not . null) $ lines s
	where
		parseline l
			| length w > 2 = Just (u, c)
			| otherwise = Nothing
			where
				w = words l
				u = w !! 0
				c = keyValToMap $ tail w

{- Given Strings like "key=value", generates a Map. -}
keyValToMap :: [String] -> M.Map String String
keyValToMap ws = M.fromList $ map (/=/) ws
	where
		(/=/) s = (k, v)
			where
				k = takeWhile (/= '=') s
				v = drop (1 + length k) s

mapToKeyVal :: M.Map String String -> [String]
mapToKeyVal m = map toword $ sort $ M.toList m
	where
		toword (k, v) = k ++ "=" ++ v