module Git
  ( withWorkingTree,
    getCommitHashes,
  )
where

import Control.Exception (finally)
import Data.ByteString.Lazy.Char8 qualified as LB8
import Data.Text qualified as T
import Data.Text.Encoding qualified as T
import Process (proc, sh, sh_)
import System.Directory (createDirectoryIfMissing)
import System.FilePath (dropTrailingPathSeparator, takeDirectory)

-- | Runs an IO-action within a working tree.
withWorkingTree :: FilePath -> T.Text -> IO a -> IO a
withWorkingTree path hash action = do
  createDirectoryIfMissing True (takeDirectory (dropTrailingPathSeparator path))
  sh_ $ proc "git worktree add --quiet --detach % %" path hash
  action `finally` do
    sh_ $ proc "git worktree remove --force %" path

getCommitHashes :: IO [T.Text]
getCommitHashes = T.lines . T.decodeUtf8 . LB8.toStrict <$> sh "git log --format=%H"