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

module Remote.Hook (remote) where

import qualified Data.ByteString.Lazy.Char8 as L
import Control.Exception.Extensible (IOException)
import qualified Data.Map as M
import Control.Monad.State (liftIO)
import System.FilePath
import System.Posix.Process hiding (executeFile)
import System.Posix.IO
import System.IO
import System.IO.Error (try)
import System.Exit

import Types
import Types.Remote
import qualified Git
import qualified Annex
import UUID
import Locations
import Config
import Content
import Utility
import Remote.Special
import Remote.Encryptable
import Crypto
import Messages

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

gen :: Git.Repo -> UUID -> Maybe RemoteConfig -> Annex (Remote Annex)
gen r u c = do
	hooktype <- getConfig r "hooktype" (error "missing hooktype")
	cst <- remoteCost r expensiveRemoteCost
	return $ encryptableRemote c
		(storeEncrypted hooktype)
		(retrieveEncrypted hooktype)
		Remote {
			uuid = u,
			cost = cst,
			name = Git.repoDescribe r,
 			storeKey = store hooktype,
			retrieveKeyFile = retrieve hooktype,
			removeKey = remove hooktype,
			hasKey = checkPresent r hooktype,
			hasKeyCheap = False,
			config = Nothing
		}

hookSetup :: UUID -> RemoteConfig -> Annex RemoteConfig
hookSetup u c = do
	let hooktype = maybe (error "Specify hooktype=") id $
		M.lookup "hooktype" c
	c' <- encryptionSetup c
	gitConfigSpecialRemote u c' "hooktype" hooktype
	return c'

hookEnv :: Key -> Maybe FilePath -> Maybe [(String, String)]
hookEnv k f = Just $ fileenv f ++ keyenv
	where
		env s v = ("ANNEX_" ++ s, v)
		keyenv =
			[ env "KEY" (show k)
			, env "HASH_1" (hashbits !! 0)
			, env "HASH_2" (hashbits !! 1)
			]
		fileenv Nothing = []
		fileenv (Just file) =  [env "FILE" file]
		hashbits = map takeDirectory $ splitPath $ hashDirMixed k

lookupHook :: String -> String -> Annex (Maybe String)
lookupHook hooktype hook =do
	g <- Annex.gitRepo
	command <- getConfig g hookname ""
	if null command
		then do
			warning $ "missing configuration for " ++ hookname
			return Nothing
		else return $ Just command
	where
		hookname =  hooktype ++ "-" ++ hook ++ "-hook"

runHook :: String -> String -> Key -> Maybe FilePath -> Annex Bool -> Annex Bool
runHook hooktype hook k f a = maybe (return False) run =<< lookupHook hooktype hook
	where
		run command = do
			showProgress -- make way for hook output
			res <- liftIO $ boolSystemEnv
				"sh" [Param "-c", Param command] $ hookEnv k f
			if res
				then a
				else do
					warning $ hook ++ " hook exited nonzero!"
					return res

store :: String -> Key -> Annex Bool
store h k = do
	g <- Annex.gitRepo
	runHook h "store" k (Just $ gitAnnexLocation g k) $ return True

storeEncrypted :: String -> (Cipher, Key) -> Key -> Annex Bool
storeEncrypted h (cipher, enck) k = withTmp enck $ \tmp -> do
	g <- Annex.gitRepo
	let f = gitAnnexLocation g k
	liftIO $ withEncryptedContent cipher (L.readFile f) $ \s -> L.writeFile tmp s
	runHook h "store" enck (Just tmp) $ return True

retrieve :: String -> Key -> FilePath -> Annex Bool
retrieve h k f = runHook h "retrieve" k (Just f) $ return True

retrieveEncrypted :: String -> (Cipher, Key) -> FilePath -> Annex Bool
retrieveEncrypted h (cipher, enck) f = withTmp enck $ \tmp ->
	runHook h "retrieve" enck (Just tmp) $ liftIO $ catchBool $ do
		withDecryptedContent cipher (L.readFile tmp) $ L.writeFile f
		return True

remove :: String -> Key -> Annex Bool
remove h k = runHook h "remove" k Nothing $ do return True

checkPresent :: Git.Repo -> String -> Key -> Annex (Either IOException Bool)
checkPresent r h k = do
	showNote ("checking " ++ Git.repoDescribe r ++ "...")
	v <- lookupHook h "checkpresent"
	liftIO (try (check v) ::IO (Either IOException Bool))
	where
		findkey s = (show k) `elem` (lines s)
		env = hookEnv k Nothing
		check Nothing = error "checkpresent hook misconfigured"
		check (Just hook) = do
			(frompipe, topipe) <- createPipe
			pid <- forkProcess $ do
				_ <- dupTo topipe stdOutput
				closeFd frompipe
				executeFile "sh" True ["-c", hook] env
			closeFd topipe
			fromh <- fdToHandle frompipe
			reply <- hGetContentsStrict fromh
			hClose fromh
			s <- getProcessStatus True False pid
			case s of
				Just (Exited (ExitSuccess)) -> return $ findkey reply
				_ -> error "checkpresent hook failed"