module DNS (
  normalize
  )
where

import qualified Data.ByteString.Char8 as BS (
  append,
  last,
  map,
  pack )
import Data.Char (toLower)
import Network.DNS.Types (Domain)

-- | Normalize the given name by lowercasing and appending a trailing
--   dot (the root) if necessary.
normalize :: Domain -> Domain
normalize = normalize_case . normalize_root


normalize_root :: Domain -> Domain
normalize_root d
  | BS.last d == '.' = d
  | otherwise = d `BS.append` trailing_dot
    where
      trailing_dot = BS.pack "."


normalize_case :: Domain -> Domain
normalize_case = BS.map toLower