{- git-update-index library
 -
 - Copyright 2011, 2012 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Git.UpdateIndex (
	Streamer,
	stream_update_index,
	update_index_line,
	ls_tree
) where

import System.Cmd.Utils

import Common
import Git
import Git.Command

{- Streamers are passed a callback and should feed it lines in the form
 - read by update-index, and generated by ls-tree. -}
type Streamer = (String -> IO ()) -> IO ()

{- Streams content into update-index from a list of Streamers. -}
stream_update_index :: Repo -> [Streamer] -> IO ()
stream_update_index repo as = do
	(p, h) <- hPipeTo "git" (toCommand $ gitCommandLine params repo)
	fileEncoding h
	forM_ as (stream h)
	hClose h
	forceSuccess p
	where
		params = map Param ["update-index", "-z", "--index-info"]
		stream h a = a (streamer h)
		streamer h s = do
			hPutStr h s
			hPutStr h "\0"

{- Generates a line suitable to be fed into update-index, to add
 - a given file with a given sha. -}
update_index_line :: Sha -> FilePath -> String
update_index_line sha file = "100644 blob " ++ show sha ++ "\t" ++ file

{- Gets the current tree for a ref. -}
ls_tree :: Ref -> Repo -> Streamer
ls_tree (Ref x) repo streamer = mapM_ streamer =<< pipeNullSplit params repo
	where
		params = map Param ["ls-tree", "-z", "-r", "--full-tree", x]