/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 *     Copyright 2017 Couchbase, Inc.
 *
 *   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
 *
 *       http://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 "uuid.h"

#include "string_hex.h"

#include <cstddef>
#include <cstdint>
#include <random>
#include <stdexcept>
#include <string>
#include <string_view>

void
couchbase::core::uuid::random(couchbase::core::uuid::uuid_t& uuid)
{
  static thread_local std::mt19937_64 gen{ std::random_device()() };
  std::uniform_int_distribution<std::uint64_t> dis;

  // The uuid is 16 bytes, which is the same as two 64-bit integers
  auto* ptr = reinterpret_cast<std::uint64_t*>(uuid.data());
  ptr[0] = dis(gen);
  ptr[1] = dis(gen);

  // Make sure that it looks like a version 4
  uuid[6] &= 0x0f;
  uuid[6] |= 0x40;
}

auto
couchbase::core::uuid::random() -> couchbase::core::uuid::uuid_t
{
  uuid_t ret;
  random(ret);
  return ret;
}

auto
couchbase::core::uuid::from_string(std::string_view str) -> couchbase::core::uuid::uuid_t
{
  uuid_t ret;
  if (str.size() != 36) {
    throw std::invalid_argument("couchbase::core::uuid::from_string: string was wrong size got: " +
                                std::to_string(str.size()) + " (expected: 36)");
  }

  std::size_t jj = 0;
  for (std::size_t ii = 0; ii < 36; ii += 2) {
    switch (ii) {
      case 8:
      case 13:
      case 18:
      case 23:
        if (str[ii] != '-') {
          throw std::invalid_argument("couchbase::core::uuid::from_string: hyphen not found where "
                                      "expected");
        }
        ++ii;
        [[fallthrough]];
      default:
        // TODO(CXXCBC-549): clang-tidy-19 reports issue with subscript
        // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-constant-array-index)
        ret[jj++] = static_cast<std::uint8_t>(from_hex({ str.data() + ii, 2 }));
    }
  }
  return ret;
}

inline auto
to_char(std::uint8_t c) -> char
{
  if (c <= 9) {
    return static_cast<char>('0' + c);
  }
  return static_cast<char>('a' + (c - 10));
}

auto
couchbase::core::uuid::to_string(const couchbase::core::uuid::uuid_t& uuid) -> std::string
{
  std::string ret(36, '-');
  std::size_t i = 0;

  for (const auto& byte : uuid) {
    ret[i] = to_char(static_cast<std::uint8_t>(byte >> 4U) & 0x0fU);
    ++i;
    ret[i] = to_char(byte & 0x0fU);
    ++i;
    if (i == 6 || i == 11 || i == 16 || i == 21) {
      ++i;
    }
  }
  return ret;
}