import
  # Internals
  ../constantine/hashes/h_sha256,
  # Helpers
  ../helpers/prng_unsafe,
  # Third-party
  stew/byteutils

# Deal with platform mess
# --------------------------------------------------------------------
when defined(windows):
  when sizeof(int) == 8:
    const DLLSSLName* = "(libssl-1_1-x64|ssleay64|libssl64).dll"
  else:
    const DLLSSLName* = "(libssl-1_1|ssleay32|libssl32).dll"
else:
  when defined(macosx):
    const versions = "(.1.1|.38|.39|.41|.43|.44|.45|.46|.47|.48|.10|.1.0.2|.1.0.1|.1.0.0|.0.9.9|.0.9.8|)"
  else:
    const versions = "(.1.1|.1.0.2|.1.0.1|.1.0.0|.0.9.9|.0.9.8|.48|.47|.46|.45|.44|.43|.41|.39|.38|.10|)"

  when defined(macosx):
    const DLLSSLName* = "libssl" & versions & ".dylib"
  elif defined(genode):
    const DLLSSLName* = "libssl.lib.so"
  else:
    const DLLSSLName* = "libssl.so" & versions

# OpenSSL wrapper
# --------------------------------------------------------------------

proc SHA256[T: byte|char](
       msg: openarray[T],
       digest: ptr array[32, byte] = nil
     ): ptr array[32, byte] {.cdecl, dynlib: DLLSSLName, importc.}

proc SHA256_OpenSSL[T: byte|char](
       digest: var array[32, byte],
       s: openarray[T]) =
  discard SHA256(s, digest.addr)

# Test
# --------------------------------------------------------------------

echo "\n------------------------------------------------------\n"
const SmallSizeIters = 128
const LargeSizeIters =  10

proc sanityABC =
  var bufCt: array[32, byte]
  let msg = "abc"

  let hashed = hexToByteArray[32](
    "BA7816BF8F01CFEA414140DE5DAE2223" &
    "B00361A396177A9CB410FF61F20015AD")

  sha256.hash(bufCt, msg)

  doAssert bufCt == hashed

proc sanityABC2 =
  var bufCt: array[32, byte]
  let msg = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"

  let hashed = hexToByteArray[32](
    "248D6A61D20638B8E5C026930C3E6039" &
    "A33CE45964FF2167F6ECEDD419DB06C1")

  sha256.hash(bufCt, msg)

  doAssert bufCt == hashed

proc innerTest(rng: var RngState, sizeRange: Slice[int]) =
  let size = rng.random_unsafe(sizeRange)
  let msg = rng.random_byte_seq(size)

  var bufCt, bufOssl: array[32, byte]

  sha256.hash(bufCt, msg)
  SHA256_OpenSSL(bufOssl, msg)
  doAssert bufCt == bufOssl

proc chunkTest(rng: var RngState, sizeRange: Slice[int]) =
  let size = rng.random_unsafe(sizeRange)
  let msg = rng.random_byte_seq(size)

  let chunkSize = rng.random_unsafe(2 ..< 20)

  var bufOnePass: array[32, byte]
  sha256.hash(bufOnePass, msg)

  var bufChunked: array[32, byte]
  let maxChunk = max(2, sizeRange.b div 10) # Consume up to 10% at once

  var ctx: Sha256Context
  ctx.init()
  var cur = 0
  while size - cur > 0:
    let chunkSize = rng.random_unsafe(0 ..< maxChunk)
    let stop = min(cur+chunkSize-1, size-1)
    let consumed = stop-cur+1
    ctx.update(msg.toOpenArray(cur, stop))
    cur += consumed

  ctx.finish(bufChunked)

  doAssert bufOnePass == bufChunked

proc main() =
  echo "SHA256 - sanity checks"
  sanityABC()
  sanityABC2()

  echo "SHA256 - Starting differential testing vs OpenSSL"

  var rng: RngState
  rng.seed(0xFACADE)

  echo "SHA256 - 0 <= size < 64 - exhaustive"
  for i in 0 ..< 64:
    rng.innerTest(i .. i)

  echo "SHA256 - 0 <= size < 64 - exhaustive chunked"
  for i in 0 ..< 64:
    rng.chunkTest(i .. i)

  echo "SHA256 - 64 <= size < 1024B"
  for _ in 0 ..< SmallSizeIters:
    rng.innerTest(0 ..< 1024)

  echo "SHA256 - 64 <= size < 1024B - chunked"
  for _ in 0 ..< SmallSizeIters:
    rng.chunkTest(0 ..< 1024)

  echo "SHA256 - 1MB <= size < 50MB"
  for _ in 0 ..< LargeSizeIters:
    rng.innerTest(1_000_000 ..< 50_000_000)

  echo "SHA256 - Differential testing vs OpenSSL - SUCCESS"

main()