module Data.ULID.Random (
ULIDRandom,
mkCryptoULIDRandom,
mkULIDRandom,
getULIDRandom
) where
import Crypto.Random
import Data.Binary
import Data.Bits
import qualified Data.ByteString as BS
import Data.List (foldl', unfoldr)
import Data.Word
import System.Random
import qualified Data.ULID.Crockford as CR
newtype ULIDRandom = ULIDRandom BS.ByteString
deriving (Eq)
mkCryptoULIDRandom :: CryptoRandomGen g => g -> Either GenError (ULIDRandom, g)
mkCryptoULIDRandom g = do
(b, g2) <- genBytes 10 g
return (ULIDRandom b, g2)
mkULIDRandom :: RandomGen g => g -> (ULIDRandom, g)
mkULIDRandom g = let
(g1, g2) = split g
genbytes = (BS.pack) . take 10 . randoms
in (ULIDRandom $ genbytes g, g2)
getULIDRandom :: IO ULIDRandom
getULIDRandom = fst <$> mkULIDRandom <$> newStdGen
unroll :: Integer -> [Word8]
unroll = unfoldr step
where
step 0 = Nothing
step i = Just (fromIntegral i, i `shiftR` 8)
roll :: [Word8] -> Integer
roll = foldl' unstep 0 . reverse
where
unstep a b = a `shiftL` 8 .|. fromIntegral b
instance Show ULIDRandom where
show (ULIDRandom r) = (CR.encode) 16.roll.(BS.unpack) $ r
instance Read ULIDRandom where
readsPrec _ = map (\(c,r)->(ULIDRandom $ (BS.pack) $ unroll c, r)) . (CR.decode) 16