-- Copyright 2018 Google LLC
--
-- Licensed under the Apache License, Version 2.0 (the "License"); you may not
-- use this file except in compliance with the License. You may obtain a copy of
-- the License at
--
--     https://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-- License for the specific language governing permissions and limitations under
-- the License.

{-# OPTIONS_GHC -Wno-missing-methods #-}
{-# OPTIONS_GHC -Wno-orphans #-}

module Internal.Digest
  ( evpMd5, evpSha1, evpSha224, evpSha256, evpSha384, evpSha512
  , mallocEvpMdCtx
  , evpDigestInitEx, evpDigestUpdate, evpDigestFinalEx
  , evpMaxMdSize
  ) where

import Foreign
  (FinalizerPtr, ForeignPtr, Ptr, Storable(alignment, sizeOf),
   addForeignPtrFinalizer, mallocForeignPtr, withForeignPtr)
import Foreign.C.Types
import Foreign.Ptr.Cast (asVoidPtr)

{#import Internal.Base#}
import Result

#include <openssl/digest.h>

evpMd5, evpSha1, evpSha224, evpSha256, evpSha384, evpSha512 :: Ptr EvpMd
evpMd5    = {#call pure EVP_md5 as ^#}
evpSha1   = {#call pure EVP_sha1 as ^#}
evpSha224 = {#call pure EVP_sha224 as ^#}
evpSha256 = {#call pure EVP_sha256 as ^#}
evpSha384 = {#call pure EVP_sha384 as ^#}
evpSha512 = {#call pure EVP_sha512 as ^#}

-- | Memory-safe allocator for 'EvpMdCtx'.
mallocEvpMdCtx :: IO (ForeignPtr EvpMdCtx)
mallocEvpMdCtx = do
  fp <- mallocForeignPtr
  withForeignPtr fp {#call EVP_MD_CTX_init as ^#}
  addForeignPtrFinalizer btlsFinalizeEvpMdCtxPtr fp
  return fp

foreign import ccall "&btlsFinalizeEvpMdCtx"
  btlsFinalizeEvpMdCtxPtr :: FinalizerPtr EvpMdCtx

evpDigestInitEx :: Ptr EvpMdCtx -> Ptr EvpMd -> Ptr Engine -> IO ()
evpDigestInitEx ctx md engine =
  requireSuccess $ {#call EVP_DigestInit_ex as ^#} ctx md engine

evpDigestUpdate :: Ptr EvpMdCtx -> Ptr a -> CULong -> IO ()
evpDigestUpdate ctx md bytes =
  alwaysSucceeds $ {#call EVP_DigestUpdate as ^#} ctx (asVoidPtr md) bytes

evpDigestFinalEx :: Ptr EvpMdCtx -> Ptr CUChar -> Ptr CUInt -> IO ()
evpDigestFinalEx ctx mdOut outSize =
  alwaysSucceeds $ {#call EVP_DigestFinal_ex as ^#} ctx mdOut outSize

evpMaxMdSize :: Int
evpMaxMdSize = {#const EVP_MAX_MD_SIZE#}

instance Storable EvpMdCtx where
  sizeOf _ = {#sizeof EVP_MD_CTX#}
  alignment _ = {#alignof EVP_MD_CTX#}