{- git-annex command
 -
 - Copyright 2014 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Command.MetaData where

import Common.Annex
import Command
import Logs.MetaData
import Types.MetaData

import qualified Data.Set as S

def :: [Command]
def = [command "metadata" (paramPair paramFile (paramRepeating "FIELD[+-]=VALUE")) seek
	SectionUtility "sets metadata of a file"]

seek :: CommandSeek
seek = withWords start

start :: [String] -> CommandStart
start (file:settings) = ifAnnexed file
	go
	(error $ "not an annexed file, so cannot add metadata: " ++ file)
  where
	go (k, _b) = do
		showStart "metadata" file
		next $ perform k (map parse settings)
start _ = error "specify a file and the metadata to set"

perform :: Key -> [Action] -> CommandPerform
perform k actions = do
	m <- getCurrentMetaData k
	if null actions
		then next $ cleanup m
		else do
			let m' = foldr apply m actions
			addMetaData k m'
			next $ cleanup m'
	
cleanup :: MetaData -> CommandCleanup
cleanup m = do
	showLongNote $ unlines $ concatMap showmeta $ fromMetaData $ currentMetaData m
	return True
  where
	showmeta (f, vs) = map (\v -> fromMetaField f ++ "=" ++ fromMetaValue v) $ S.toList vs

data Action
	= AddMeta MetaField MetaValue
	| DelMeta MetaField MetaValue
	| SetMeta MetaField MetaValue

parse :: String -> Action
parse p = case lastMaybe f of
	Just '+' -> AddMeta (mkf f') v
	Just '-' -> DelMeta (mkf f') v
	_ -> SetMeta (mkf f) v
  where
	(f, sv) = separate (== '=') p
	f' = beginning f
	v = toMetaValue sv
	mkf fld = fromMaybe (badfield fld) (toMetaField fld)
	badfield fld = error $ "Illegal metadata field name, \"" ++ fld ++ "\""

apply :: Action -> MetaData -> MetaData
apply (AddMeta f v) m = updateMetaData f v m
apply (DelMeta f oldv) m = updateMetaData f (unsetMetaValue oldv) m
apply (SetMeta f v) m = updateMetaData f v $
	foldr (updateMetaData f) m $
		map unsetMetaValue $ S.toList $ currentMetaDataValues f m