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

cachedMaybe :: Binary a => Maybe T.Text -> IO a -> IO a
cachedMaybe Nothing func = func
cachedMaybe (Just key) func = cached key func