module UUID where

import Data.Patch.ObjectMap ( ObjectMap(..), UUID(..), findPath )
import Data.Path ( SubPath )
import Control.Monad.IO.Class( MonadIO(..) )
import qualified Codec.Binary.Base64Url as B64
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as BC
import System.Random ( randomRIO )
import Types

instance FixedSize UUID where
  fixedSize _ = 32
  toBS (UUID x) = x
  fromBS = UUID


rootUUID :: UUID
rootUUID = UUID . BC.pack $ replicate 28 '\0' ++ "ROOT"

makeUUID :: MonadIO m => m UUID
makeUUID = do x <- liftIO $ randomRIO (0,2^(256 ::Integer) :: Integer)
              return $ UUID (toBS x B.empty)
  where toBS :: Integer -> B.ByteString -> B.ByteString
        toBS 0 s = s
        toBS x s = toBS (x `div` 256) $ B.cons (fromIntegral $ x `mod` 256) s

findUUID :: SubPath -> Gorsvet (Maybe UUID)
findUUID path =
  do mb <- findPath path rootUUID =<< shadow
     case mb of
       Just (uuid, _) -> return (Just uuid)
       Nothing -> return Nothing

formatUUID :: UUID -> String
formatUUID (UUID x) = B64.encode $ B.unpack x