// Copyright 2020 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.

#include "internal/crypto_cros/secure_hash.h"

#include <stddef.h>

#include <memory>

#include "internal/crypto_cros/openssl_util.h"
#include <openssl/mem.h>
#include <openssl/sha.h>

namespace nearby::crypto {

namespace {

class SecureHashSHA256 : public SecureHash {
 public:
  SecureHashSHA256() {
    // Ensure that CPU features detection is performed before using
    // BoringSSL. This will enable hw accelerated implementations.
    EnsureOpenSSLInit();
    SHA256_Init(&ctx_);
  }

  SecureHashSHA256(const SecureHashSHA256& other) {
    memcpy(&ctx_, &other.ctx_, sizeof(ctx_));
  }

  ~SecureHashSHA256() override { OPENSSL_cleanse(&ctx_, sizeof(ctx_)); }

  void Update(const void* input, size_t len) override {
    SHA256_Update(&ctx_, static_cast<const unsigned char*>(input), len);
  }

  void Finish(void* output, size_t len) override {
    ScopedOpenSSLSafeSizeBuffer<SHA256_DIGEST_LENGTH> result(
        static_cast<unsigned char*>(output), len);
    SHA256_Final(result.safe_buffer(), &ctx_);
  }

  std::unique_ptr<SecureHash> Clone() const override {
    return std::make_unique<SecureHashSHA256>(*this);
  }

  size_t GetHashLength() const override { return SHA256_DIGEST_LENGTH; }

 private:
  SHA256_CTX ctx_;
};

}  // namespace

std::unique_ptr<SecureHash> SecureHash::Create(Algorithm algorithm) {
  switch (algorithm) {
    case SHA256:
      return std::make_unique<SecureHashSHA256>();
    default:
      //  NOTIMPLEMENTED();
      return nullptr;
  }
}

}  // namespace nearby::crypto