{- git-annex command
 -
 - Copyright 2012 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Command.Vicfg where

import qualified Data.Map as M
import qualified Data.Set as S
import System.Environment (getEnv)
import Data.Tuple (swap)
import Data.Char (isSpace)

import Common.Annex
import Command
import Annex.Perms
import Types.TrustLevel
import Types.Group
import Logs.Trust
import Logs.Group
import Logs.PreferredContent
import Types.StandardGroups
import Remote

def :: [Command]
def = [command "vicfg" paramNothing seek
	SectionSetup "edit git-annex's configuration"]

seek :: [CommandSeek]
seek = [withNothing start]

start :: CommandStart
start = do
	f <- fromRepo gitAnnexTmpCfgFile
	createAnnexDirectory $ parentDir f
	cfg <- getCfg
	descs <- uuidDescriptions
	liftIO $ writeFile f $ genCfg cfg descs
	vicfg cfg f
	stop

vicfg :: Cfg -> FilePath -> Annex ()
vicfg curcfg f = do
	vi <- liftIO $ catchDefaultIO "vi" $ getEnv "EDITOR"
	-- Allow EDITOR to be processed by the shell, so it can contain options.
	unlessM (liftIO $ boolSystem "sh" [Param "-c", Param $ unwords [vi, shellEscape f]]) $
		error $ vi ++ " exited nonzero; aborting"
	r <- parseCfg curcfg <$> liftIO (readFileStrict f)
	liftIO $ nukeFile f
	case r of
		Left s -> do
			liftIO $ writeFile f s
			vicfg curcfg f
		Right newcfg -> setCfg curcfg newcfg

data Cfg = Cfg
	{ cfgTrustMap :: TrustMap
	, cfgGroupMap :: M.Map UUID (S.Set Group)
	, cfgPreferredContentMap :: M.Map UUID String
	}

getCfg :: Annex Cfg
getCfg = Cfg
	<$> trustMapRaw -- without local trust overrides
	<*> (groupsByUUID <$> groupMap)
	<*> preferredContentMapRaw

setCfg :: Cfg -> Cfg -> Annex ()
setCfg curcfg newcfg = do
	let (trustchanges, groupchanges, preferredcontentchanges) = diffCfg curcfg newcfg
	mapM_ (uncurry trustSet) $ M.toList trustchanges
	mapM_ (uncurry groupSet) $ M.toList groupchanges
	mapM_ (uncurry preferredContentSet) $ M.toList preferredcontentchanges

diffCfg :: Cfg -> Cfg -> (TrustMap, M.Map UUID (S.Set Group), M.Map UUID String)
diffCfg curcfg newcfg = (diff cfgTrustMap, diff cfgGroupMap, diff cfgPreferredContentMap)
  where
	diff f = M.differenceWith (\x y -> if x == y then Nothing else Just x)
		(f newcfg) (f curcfg)

genCfg :: Cfg -> M.Map UUID String -> String
genCfg cfg descs = unlines $ concat [intro, trust, groups, preferredcontent]
  where
	intro =
		[ com "git-annex configuration"
		, com ""
		, com "Changes saved to this file will be recorded in the git-annex branch."
		, com ""
		, com "Lines in this file have the format:"
		, com "  setting uuid = value"
		]

	trust = settings cfgTrustMap
		[ ""
		, com "Repository trust configuration"
		, com "(Valid trust levels: " ++ trustlevels ++ ")"
		]
		(\(t, u) -> line "trust" u $ showTrustLevel t)
		(\u -> lcom $ line "trust" u $ showTrustLevel SemiTrusted)
	  where
	  	trustlevels = unwords $ map showTrustLevel [Trusted .. DeadTrusted]

	groups = settings cfgGroupMap
		[ ""
		, com "Repository groups"
		, com $ "(Standard groups: " ++ grouplist ++ ")"
		, com "(Separate group names with spaces)"
		]
		(\(s, u) -> line "group" u $ unwords $ S.toList s)
		(\u -> lcom $ line "group" u "")
	  where
	  	grouplist = unwords $ map fromStandardGroup [minBound..]

	preferredcontent = settings cfgPreferredContentMap
		[ ""
		, com "Repository preferred contents"
		]
		(\(s, u) -> line "content" u s)
		(\u -> line "content" u "")

	settings field desc showvals showdefaults = concat
		[ desc
		, concatMap showvals $ sort $ map swap $ M.toList $ field cfg
		, concatMap (lcom . showdefaults) $ missing field
		]

	line setting u value =
		[ com $ "(for " ++ fromMaybe "" (M.lookup u descs) ++ ")"
		, unwords [setting, fromUUID u, "=", value]
		]
	lcom = map (\l -> if "#" `isPrefixOf` l then l else '#' : l)
	missing field = S.toList $ M.keysSet descs `S.difference` M.keysSet (field cfg)

{- If there's a parse error, returns a new version of the file,
 - with the problem lines noted. -}
parseCfg :: Cfg -> String -> Either String Cfg
parseCfg curcfg = go [] curcfg . lines
  where
	go c cfg []
		| null (mapMaybe fst c) = Right cfg
		| otherwise = Left $ unlines $
			badheader ++ concatMap showerr (reverse c)
	go c cfg (l:ls) = case parse (dropWhile isSpace l) cfg of
		Left msg -> go ((Just msg, l):c) cfg ls
		Right cfg' -> go ((Nothing, l):c) cfg' ls

	parse l cfg
		| null l = Right cfg
		| "#" `isPrefixOf` l = Right cfg
		| null setting || null u = Left "missing repository uuid"
		| otherwise = handle cfg (toUUID u) setting value'
	  where
		(setting, rest) = separate isSpace l
		(r, value) = separate (== '=') rest
		value' = trimspace value
		u = reverse $ trimspace $ reverse $ trimspace r
		trimspace = dropWhile isSpace

	handle cfg u setting value
		| setting == "trust" = case readTrustLevel value of
			Nothing -> badval "trust value" value
			Just t ->
				let m = M.insert u t (cfgTrustMap cfg)
				in Right $ cfg { cfgTrustMap = m }
		| setting == "group" =
			let m = M.insert u (S.fromList $ words value) (cfgGroupMap cfg)
			in Right $ cfg { cfgGroupMap = m }
		| setting == "content" = 
			case checkPreferredContentExpression value of
				Just e -> Left e
				Nothing ->
					let m = M.insert u value (cfgPreferredContentMap cfg)
					in Right $ cfg { cfgPreferredContentMap = m }
		| otherwise = badval "setting" setting

	showerr (Just msg, l) = [parseerr ++ msg, l]
	showerr (Nothing, l)
		-- filter out the header and parse error lines
		-- from any previous parse failure
		| any (`isPrefixOf` l) (parseerr:badheader) = []
		| otherwise = [l]

	badval desc val = Left $ "unknown " ++ desc ++ " \"" ++ val ++ "\""
	badheader = 
		[ com "There was a problem parsing your input."
		, com "Search for \"Parse error\" to find the bad lines."
		, com "Either fix the bad lines, or delete them (to discard your changes)."
		]
	parseerr = com "Parse error in next line: "

com :: String -> String
com s = "# " ++ s