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// Copyright (c) 2017-2022 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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#include "uuid.h"
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#include <workerd/util/entropy.h>
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#include <kj/compat/http.h>
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#include <kj/debug.h>
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#include <cstdlib>
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namespace workerd {
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namespace {
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constexpr char HEX_DIGITS[] = "0123456789abcdef";
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}  // namespace
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kj::String randomUUID(kj::Maybe<kj::EntropySource&> optionalEntropySource) {
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  kj::FixedArray<kj::byte, 16> buffer;
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  KJ_IF_SOME(entropySource, optionalEntropySource) {
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    entropySource.generate(buffer);
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  } else {
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    getEntropy(buffer);
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  }
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  buffer[6] = static_cast<kj::byte>((buffer[6] & 0x0f) | 0x40);
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  buffer[8] = static_cast<kj::byte>((buffer[8] & 0x3f) | 0x80);
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#define HEX(b) (char)(HEX_DIGITS[(b >> 4) & 0xf]), (char)(HEX_DIGITS[b & 0xf])
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  // The format for Random UUID's is established in
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  // https://www.rfc-editor.org/rfc/rfc4122.txt
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  // xxxxxxxx-xxxx-Axxx-Bxxx-xxxxxxxxxxxx
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  //
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  // The sequence is 16 hex-encoded random bytes
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  // divided into 1 4-byte, 3 2-byte, and 1 6-byte
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  // groups. The four most significant bits of the
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  // 7th byte (A) are set to 0100xxxx (0x40), while
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  // the two most significant bits of the 9th byte (B)
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  // are set to 10xxxxxx (0x80). These are the key bits
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  // that identify the type and version of the uuid.
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  // All other bits are random. That ends up meaning
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  // that in the serialized uuid, the first character
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  // of the third grouping is always a 4, and the first
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  // character of the fourth grouping is always either
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  // an a, b, 8, or 9.
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  // clang-format off
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  return kj::String(kj::arr<char>(
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    HEX(buffer[0]),
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    HEX(buffer[1]),
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    HEX(buffer[2]),
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    HEX(buffer[3]),
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    '-',
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    HEX(buffer[4]),
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    HEX(buffer[5]),
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    '-',
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    HEX(buffer[6]),
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    HEX(buffer[7]),
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    '-',
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    HEX(buffer[8]),
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    HEX(buffer[9]),
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    '-',
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    HEX(buffer[10]),
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    HEX(buffer[11]),
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    HEX(buffer[12]),
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    HEX(buffer[13]),
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    HEX(buffer[14]),
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    HEX(buffer[15]),
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    '\0'
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  ));
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  // clang-format on
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#undef HEX
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}
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kj::Maybe<UUID> UUID::fromUpperLower(uint64_t upper, uint64_t lower) {
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  if (upper == 0 && lower == 0) {
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    return kj::none;
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  }
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  return UUID(upper, lower);
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}
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kj::Maybe<UUID> UUID::fromString(kj::StringPtr str) {
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  if (str.size() != 36u) {
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    return kj::none;
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  }
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  uint64_t upper = 0;
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  uint64_t lower = 0;
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  auto begin = str.cStr();
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  char* p;
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  upper += (strtoull(begin, &p, 16) << 32u);
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  if (p - begin != 8 || *p != '-') {
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    return kj::none;
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  }
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  upper += (strtoull(++p, &p, 16) << 16u);
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  if (p - begin != 13 || *p != '-') {
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    return kj::none;
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  }
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  upper += (strtoull(++p, &p, 16));
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  if (p - begin != 18 || *p != '-') {
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    return kj::none;
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  }
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  lower += (strtoull(++p, &p, 16) << 48u);
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  if (p - begin != 23 || *p != '-') {
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    return kj::none;
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  }
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  lower += (strtoull(++p, &p, 16));
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  if (p - begin != 36) {
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    return kj::none;
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  }
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  if (upper == 0 && lower == 0) {
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    return kj::none;
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  }
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  return UUID(upper, lower);
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}
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kj::String UUID::toString() const {
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  // clang-format off
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  return kj::str(
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    HEX_DIGITS[(upper >> 60u) & 0xf],
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    HEX_DIGITS[(upper >> 56u) & 0xf],
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    HEX_DIGITS[(upper >> 52u) & 0xf],
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    HEX_DIGITS[(upper >> 48u) & 0xf],
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    HEX_DIGITS[(upper >> 44u) & 0xf],
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    HEX_DIGITS[(upper >> 40u) & 0xf],
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    HEX_DIGITS[(upper >> 36u) & 0xf],
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    HEX_DIGITS[(upper >> 32u) & 0xf],
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    '-',
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    HEX_DIGITS[(upper >> 28u) & 0xf],
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    HEX_DIGITS[(upper >> 24u) & 0xf],
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    HEX_DIGITS[(upper >> 20u) & 0xf],
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    HEX_DIGITS[(upper >> 16u) & 0xf],
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    '-',
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    HEX_DIGITS[(upper >> 12u) & 0xf],
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    HEX_DIGITS[(upper >>  8u) & 0xf],
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    HEX_DIGITS[(upper >>  4u) & 0xf],
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    HEX_DIGITS[(upper >>  0u) & 0xf],
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    '-',
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    HEX_DIGITS[(lower >> 60u) & 0xf],
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    HEX_DIGITS[(lower >> 56u) & 0xf],
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    HEX_DIGITS[(lower >> 52u) & 0xf],
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    HEX_DIGITS[(lower >> 48u) & 0xf],
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    '-',
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    HEX_DIGITS[(lower >> 44u) & 0xf],
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    HEX_DIGITS[(lower >> 40u) & 0xf],
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    HEX_DIGITS[(lower >> 36u) & 0xf],
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    HEX_DIGITS[(lower >> 32u) & 0xf],
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    HEX_DIGITS[(lower >> 28u) & 0xf],
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    HEX_DIGITS[(lower >> 24u) & 0xf],
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    HEX_DIGITS[(lower >> 20u) & 0xf],
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    HEX_DIGITS[(lower >> 16u) & 0xf],
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    HEX_DIGITS[(lower >> 12u) & 0xf],
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    HEX_DIGITS[(lower >>  8u) & 0xf],
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    HEX_DIGITS[(lower >>  4u) & 0xf],
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    HEX_DIGITS[(lower >>  0u) & 0xf]
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  );
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  // clang-format on
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}
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}  // namespace workerd