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module Repo (
Repo, Commit, commitId,
CommitId, showCommitId,
TreeId, showTreeId,
openRepo,
readBranch,
readTag,
listCommits,
getTreeId,
getCommitTitle,
getCommitMessage,
checkoutAt,
readCommittedFile,
watchBranch,
watchTags,
) where
import Control.Concurrent
import Control.Concurrent.STM
import Control.Exception
import Control.Monad
import Control.Monad.IO.Class
import Data.ByteString (ByteString)
import Data.ByteString.Char8 qualified as BC
import Data.ByteString.Lazy qualified as BL
import Data.Function
import Data.Map (Map)
import Data.Map qualified as M
import Data.Maybe
import Data.Text (Text)
import Data.Text qualified as T
import Data.Text.Encoding
import System.Directory
import System.Exit
import System.FilePath
import System.INotify
import System.Process
data Repo
= GitRepo
{ gitDir :: FilePath
, gitLock :: MVar ()
, gitInotify :: MVar (Maybe ( INotify, TChan Text ))
, gitWatchedBranches :: MVar (Map Text [ TVar (Maybe Commit) ])
}
data Commit = Commit
{ commitRepo :: Repo
, commitId_ :: CommitId
, commitDetails :: MVar (Maybe CommitDetails)
}
commitId :: Commit -> CommitId
commitId = commitId_
data CommitDetails = CommitDetails
{ commitTreeId :: TreeId
, commitTitle :: Text
, commitMessage :: Text
}
instance Eq Repo where
(==) = (==) `on` gitLock
instance Eq Commit where
x == y = commitRepo x == commitRepo y &&
commitId_ x == commitId_ y
newtype CommitId = CommitId ByteString
deriving (Eq, Ord)
showCommitId :: CommitId -> String
showCommitId (CommitId cid) = BC.unpack cid
newtype TreeId = TreeId ByteString
deriving (Eq, Ord)
showTreeId :: TreeId -> String
showTreeId (TreeId tid) = BC.unpack tid
openRepo :: FilePath -> IO (Maybe Repo)
openRepo path = do
findGitDir >>= \case
Just gitDir -> do
gitLock <- newMVar ()
gitInotify <- newMVar Nothing
gitWatchedBranches <- newMVar M.empty
return $ Just GitRepo {..}
Nothing -> do
return Nothing
where
tryGitDir gpath = readProcessWithExitCode "git" [ "rev-parse", "--resolve-git-dir", gpath ] "" >>= \case
( ExitSuccess, out, _ ) | dir : _ <- lines out -> return (Just dir)
_ -> return Nothing
findGitDir = do
tryGitDir path >>= \case
Just dir -> return (Just dir)
Nothing -> tryGitDir (path </> ".git") >>= \case
Just dir -> return (Just dir)
_ -> return Nothing
readCommitFromFile :: MonadIO m => Repo -> FilePath -> m (Maybe Commit)
readCommitFromFile commitRepo@GitRepo {..} path = liftIO $ do
try @IOException (BC.readFile $ gitDir </> path) >>= \case
Right content | (cid : _) <- BC.lines content -> do
let commitId_ = CommitId cid
commitDetails <- newMVar Nothing
return $ Just Commit {..}
_ -> do
return Nothing
readBranch :: MonadIO m => Repo -> Text -> m (Maybe Commit)
readBranch repo branch = readCommitFromFile repo ("refs/heads" </> T.unpack branch)
readTag :: MonadIO m => Repo -> Text -> m (Maybe Commit)
readTag repo tag = readCommitFromFile repo ("refs/tags" </> T.unpack tag)
listCommits :: MonadIO m => Repo -> String -> m [ Commit ]
listCommits commitRepo range = liftIO $ do
out <- readProcess "git" [ "log", "--pretty=%H", "--first-parent", "--reverse", range ] ""
forM (lines out) $ \cid -> do
let commitId_ = CommitId (BC.pack cid)
commitDetails <- newMVar Nothing
return Commit {..}
getCommitDetails :: (MonadIO m, MonadFail m) => Commit -> m CommitDetails
getCommitDetails Commit {..} = do
let GitRepo {..} = commitRepo
liftIO $ do
modifyMVar commitDetails $ \case
cur@(Just details) -> do
return ( cur, details )
Nothing -> do
( infoPart, _ : title : message ) <-
fmap (span (not . null) . lines) $
withMVar gitLock $ \_ -> do
readProcess "git" [ "--git-dir=" <> gitDir, "cat-file", "commit", showCommitId commitId_ ] ""
let info = map (fmap (drop 1) . span (/= ' ')) infoPart
Just commitTreeId <- return $ TreeId . BC.pack <$> lookup "tree" info
let commitTitle = T.pack title
let commitMessage = T.pack $ unlines $ dropWhile null message
let details = CommitDetails {..}
return ( Just details, details )
getTreeId :: (MonadIO m, MonadFail m) => Commit -> m TreeId
getTreeId = fmap commitTreeId . getCommitDetails
getCommitTitle :: (MonadIO m, MonadFail m) => Commit -> m Text
getCommitTitle = fmap commitTitle . getCommitDetails
getCommitMessage :: (MonadIO m, MonadFail m) => Commit -> m Text
getCommitMessage = fmap commitMessage . getCommitDetails
checkoutAt :: (MonadIO m, MonadFail m) => Commit -> FilePath -> m ()
checkoutAt Commit {..} dest = do
let GitRepo {..} = commitRepo
liftIO $ withMVar gitLock $ \_ -> do
"" <- readProcess "git" [ "clone", "--quiet", "--shared", "--no-checkout", gitDir, dest ] ""
"" <- readProcess "git" [ "-C", dest, "restore", "--worktree", "--source=" <> showCommitId commitId_, "--", "." ] ""
removeDirectoryRecursive $ dest </> ".git"
readCommittedFile :: Commit -> FilePath -> IO (Maybe BL.ByteString)
readCommittedFile Commit {..} path = do
let GitRepo {..} = commitRepo
liftIO $ withMVar gitLock $ \_ -> do
let cmd = (proc "git" [ "--git-dir=" <> gitDir, "cat-file", "blob", showCommitId commitId_ <> ":" <> path ])
{ std_in = NoStream
, std_out = CreatePipe
}
createProcess cmd >>= \( _, mbstdout, _, ph ) -> if
| Just stdout <- mbstdout -> do
content <- BL.hGetContents stdout
-- check if there will be some output:
case BL.uncons content of
Just (c, _) -> c `seq` return ()
Nothing -> return ()
getProcessExitCode ph >>= \case
Just code | code /= ExitSuccess ->
return Nothing
_ ->
return (Just content)
| otherwise -> error "createProcess must return stdout handle"
repoInotify :: Repo -> IO ( INotify, TChan Text )
repoInotify repo@GitRepo {..} = modifyMVar gitInotify $ \case
cur@(Just info) ->
return ( cur, info )
Nothing -> do
inotify <- initINotify
tagsChan <- newBroadcastTChanIO
let info = ( inotify, tagsChan )
_ <- addWatch inotify [ MoveIn ] (BC.pack headsDir) $ \event -> do
let branch = decodeUtf8 $ filePath event
tvars <- fromMaybe [] . M.lookup branch <$> readMVar gitWatchedBranches
when (not $ null tvars) $ do
commit <- readBranch repo branch
atomically $ do
mapM_ (`writeTVar` commit) tvars
_ <- addWatch inotify [ MoveIn ] (BC.pack tagsDir) $ \event -> do
let tag = decodeUtf8 $ filePath event
atomically $ writeTChan tagsChan tag
return ( Just info, info )
where
headsDir = gitDir </> "refs/heads"
tagsDir = gitDir </> "refs/tags"
watchBranch :: Repo -> Text -> IO (STM (Maybe Commit))
watchBranch repo@GitRepo {..} branch = do
var <- newTVarIO =<< readBranch repo branch
void $ repoInotify repo
modifyMVar_ gitWatchedBranches $ return . M.insertWith (++) branch [ var ]
return $ readTVar var
watchTags :: Repo -> IO (TChan Text)
watchTags repo = do
tagsChan <- snd <$> repoInotify repo
atomically $ dupTChan tagsChan
|