module History.Cache (cached) where

import Data.Binary (Binary, decodeFileOrFail, encodeFile)
import Data.Text qualified as T
import Git qualified
import System.Directory (createDirectoryIfMissing, doesFileExist)
import System.FilePath ((</>))

cached :: Binary a => T.Text -> (T.Text -> IO a) -> IO a
cached hash func = do
  root <- Git.getRootDir
  createDirectoryIfMissing True (root </> ".anissue")
  let file = (root </> ".anissue" </> T.unpack hash)
  doesFileExist file >>= \case
    True ->
      decodeFileOrFail file >>= \case
        Left _ -> generate file
        Right blob -> pure blob
    False -> generate file
  where
    generate file = do
      blob <- func hash
      encodeFile file blob
      pure blob