{- A remote that provides hooks to run shell commands.
 -
 - Copyright 2011 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote.Hook (remote) where

import Common.Annex
import Types.Remote
import Types.Key
import Types.Creds
import qualified Git
import Config
import Config.Cost
import Annex.UUID
import Remote.Helper.Special
import Utility.Env

import qualified Data.Map as M

type Action = String
type HookName = String

remote :: RemoteType
remote = RemoteType {
	typename = "hook",
	enumerate = findSpecialRemotes "hooktype",
	generate = gen,
	setup = hookSetup
}

gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
gen r u c gc = do
	cst <- remoteCost gc expensiveRemoteCost
	return $ Just $ specialRemote c
		(simplyPrepare $ store hooktype)
		(simplyPrepare $ retrieve hooktype)
		(simplyPrepare $ remove hooktype)
		(simplyPrepare $ checkKey r hooktype)
		Remote
			{ uuid = u
			, cost = cst
			, name = Git.repoDescribe r
			, storeKey = storeKeyDummy
			, retrieveKeyFile = retreiveKeyFileDummy
			, retrieveKeyFileCheap = retrieveCheap hooktype
			, removeKey = removeKeyDummy
			, checkPresent = checkPresentDummy
			, checkPresentCheap = False
			, whereisKey = Nothing
			, remoteFsck = Nothing
			, repairRepo = Nothing
			, config = c
			, localpath = Nothing
			, repo = r
			, gitconfig = gc
			, readonly = False
			, availability = GloballyAvailable
			, remotetype = remote
			, mkUnavailable = gen r u c $
				gc { remoteAnnexHookType = Just "!dne!" }
			, getInfo = return [("hooktype", hooktype)]
			, claimUrl = Nothing
			, checkUrl = Nothing
			}
  where
	hooktype = fromMaybe (error "missing hooktype") $ remoteAnnexHookType gc

hookSetup :: Maybe UUID -> Maybe CredPair -> RemoteConfig -> Annex (RemoteConfig, UUID)
hookSetup mu _ c = do
	u <- maybe (liftIO genUUID) return mu
	let hooktype = fromMaybe (error "Specify hooktype=") $
		M.lookup "hooktype" c
	(c', _encsetup) <- encryptionSetup c
	gitConfigSpecialRemote u c' "hooktype" hooktype
	return (c', u)

hookEnv :: Action -> Key -> Maybe FilePath -> IO (Maybe [(String, String)])
hookEnv action k f = Just <$> mergeenv (fileenv f ++ keyenv)
  where
	mergeenv l = addEntries l <$> getEnvironment
	envvar s v = ("ANNEX_" ++ s, v)
	keyenv = catMaybes
		[ Just $ envvar "KEY" (key2file k)
		, Just $ envvar "ACTION" action
		, envvar "HASH_1" <$> headMaybe hashbits
		, envvar "HASH_2" <$> headMaybe (drop 1 hashbits)
		]
	fileenv Nothing = []
	fileenv (Just file) =  [envvar "FILE" file]
	hashbits = map takeDirectory $ splitPath $ hashDirMixed def k

lookupHook :: HookName -> Action -> Annex (Maybe String)
lookupHook hookname action = do
	command <- getConfig (annexConfig hook) ""
	if null command
		then do
			fallback <- getConfig (annexConfig hookfallback) ""
			if null fallback
				then do
					warning $ "missing configuration for " ++ hook ++ " or " ++ hookfallback
					return Nothing
				else return $ Just fallback
		else return $ Just command
  where
	hook = hookname ++ "-" ++ action ++ "-hook"
	hookfallback = hookname ++ "-hook"

runHook :: HookName -> Action -> Key -> Maybe FilePath -> Annex Bool -> Annex Bool
runHook hook action k f a = maybe (return False) run =<< lookupHook hook action
  where
	run command = do
		showOutput -- make way for hook output
		ifM (liftIO $ boolSystemEnv "sh" [Param "-c", Param command] =<< hookEnv action k f)
			( a
			, do
				warning $ hook ++ " hook exited nonzero!"
				return False
			)

store :: HookName -> Storer
store h = fileStorer $ \k src _p ->
	runHook h "store" k (Just src) $ return True

retrieve :: HookName -> Retriever
retrieve h = fileRetriever $ \d k _p ->
	unlessM (runHook h "retrieve" k (Just d) $ return True) $
		error "failed to retrieve content"

retrieveCheap :: HookName -> Key -> FilePath -> Annex Bool
retrieveCheap _ _ _ = return False

remove :: HookName -> Remover
remove h k = runHook h "remove" k Nothing $ return True

checkKey :: Git.Repo -> HookName -> CheckPresent
checkKey r h k = do
	showAction $ "checking " ++ Git.repoDescribe r
	v <- lookupHook h action
	liftIO $ check v
  where
	action = "checkpresent"
	findkey s = key2file k `elem` lines s
	check Nothing = error $ action ++ " hook misconfigured"
	check (Just hook) = do
		environ <- hookEnv action k Nothing
		findkey <$> readProcessEnv "sh" ["-c", hook] environ
