Hash.hs

{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS -fno-warn-orphans  #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  Hocker.Types.Hash
-- Copyright   :  (C) 2016 Awake Networks
-- License     :  Apache-2.0
-- Maintainer  :  Awake Networks <opensource@awakenetworks.com>
-- Stability   :  stable
----------------------------------------------------------------------------

module Hocker.Types.Hash where

import qualified Crypto.Hash             as Hash
import qualified Data.ByteArray          as BA
import qualified Data.ByteArray.Encoding as BA
import qualified Data.ByteString.Char8   as C8
import           Data.Semigroup          ((<>))
import qualified Data.Text
import qualified Options.Applicative     as Options
import           Options.Generic

toBytes :: C8.ByteString -> Either String BA.Bytes
toBytes = BA.convertFromBase BA.Base16

readSHA256 :: C8.ByteString -> Maybe (Hash.Digest Hash.SHA256)
readSHA256 = either (const Nothing) Hash.digestFromByteString . toBytes

instance ParseField (Hash.Digest Hash.SHA256) where
  readField = Options.maybeReader (readSHA256 . C8.pack)
  parseField h _ _ =
      (Options.option (Options.maybeReader (readSHA256 . C8.pack)) $
       ( Options.metavar "SHA256"
       <> Options.short 'l'
       <> Options.long "layer"
       <> maybe mempty (Options.help . Data.Text.unpack) h
       )
      )

instance ParseFields (Hash.Digest Hash.SHA256) where
instance ParseRecord (Hash.Digest Hash.SHA256) where
  parseRecord = fmap getOnly parseRecord