{-| Provides interface to the 'zlib' library.

-}

{-

Copyright (C) 2014 Google Inc.
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2. Redistributions in binary form must reproduce the above copyright
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PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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-}

module Ganeti.Codec
  ( compressZlib
  , decompressZlib
  ) where

import Prelude ()
import Ganeti.Prelude

import Codec.Compression.Zlib
import qualified Codec.Compression.Zlib.Internal as I
import Control.Monad (liftM)
import Control.Monad.Error.Class (MonadError(..))
import qualified Data.ByteString.Lazy as BL
import qualified Data.ByteString.Lazy.Internal as BL

import Ganeti.BasicTypes


-- | Compresses a lazy bytestring.
compressZlib :: BL.ByteString -> BL.ByteString
compressZlib = compressWith $
  defaultCompressParams { compressLevel = CompressionLevel 3 }

-- | Decompresses a lazy bytestring, throwing decoding errors using
-- 'throwError'.
decompressZlib :: (MonadError e m, FromString e)
               => BL.ByteString -> m BL.ByteString
decompressZlib = I.foldDecompressStream
                     (liftM . BL.chunk)
                     (return mempty)
                     (const $ throwError . mkFromString . ("Zlib: " ++))
                 . I.decompressWithErrors
                     I.zlibFormat
                     I.defaultDecompressParams