// Copyright 2022 The Centipede Authors.

//

// 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 "./common/hash.h"

#include <cstddef>

#include <cstdint>

#include <string>

#include <string_view>

#include "./common/defs.h"

#include "./common/sha1.h"

namespace centipede {

std::string Hash(ByteSpan span) {

  // Compute SHA1.

  uint8_t sha1[kShaDigestLength];

  SHA1(span.data(), span.size(), sha1);

  // Convert SHA1 to text.

  static_assert(kHashLen == 2 * kShaDigestLength);

  char sha1_hex_text[kHashLen];

  static const char hex[16] = {'0', '1', '2', '3', '4', '5', '6', '7',

                               '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

  for (size_t i = 0; i < kShaDigestLength; i++) {

    sha1_hex_text[i * 2 + 0] = hex[sha1[i] / 16];

    sha1_hex_text[i * 2 + 1] = hex[sha1[i] % 16];

  }

  return {sha1_hex_text, sha1_hex_text + kHashLen};

}

std::string Hash(std::string_view str) {

  static_assert(sizeof(decltype(str)::value_type) == sizeof(uint8_t));

  return Hash(AsByteSpan(str));

}

}  // namespace centipede