// Copyright (c) 2011 The LevelDB Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file. See the AUTHORS file for names of contributors.

#include "util/logging.h"

#include <cstdarg>

#include <cstdio>

#include <cstdlib>

#include <limits>

#include "leveldb/env.h"

#include "leveldb/slice.h"

namespace leveldb {

void AppendNumberTo(std::string* str, uint64_t num) {

  char buf[30];

  std::snprintf(buf, sizeof(buf), "%llu", static_cast<unsigned long long>(num));

  str->append(buf);

}

void AppendEscapedStringTo(std::string* str, const Slice& value) {

  for (size_t i = 0; i < value.size(); i++) {

    char c = value[i];

    if (c >= ' ' && c <= '~') {

      str->push_back(c);

    } else {

      char buf[10];

      std::snprintf(buf, sizeof(buf), "\\x%02x",

                    static_cast<unsigned int>(c) & 0xff);

      str->append(buf);

    }

  }

}

std::string NumberToString(uint64_t num) {

  std::string r;

  AppendNumberTo(&r, num);

  return r;

}

std::string EscapeString(const Slice& value) {

  std::string r;

  AppendEscapedStringTo(&r, value);

  return r;

}

bool ConsumeDecimalNumber(Slice* in, uint64_t* val) {

  // Constants that will be optimized away.

  constexpr const uint64_t kMaxUint64 = std::numeric_limits<uint64_t>::max();

  constexpr const char kLastDigitOfMaxUint64 =

      '0' + static_cast<char>(kMaxUint64 % 10);

  uint64_t value = 0;

  // reinterpret_cast-ing from char* to uint8_t* to avoid signedness.

  const uint8_t* start = reinterpret_cast<const uint8_t*>(in->data());

  const uint8_t* end = start + in->size();

  const uint8_t* current = start;

  for (; current != end; ++current) {

    const uint8_t ch = *current;

    if (ch < '0' || ch > '9') break;

    // Overflow check.

    // kMaxUint64 / 10 is also constant and will be optimized away.

    if (value > kMaxUint64 / 10 ||

        (value == kMaxUint64 / 10 && ch > kLastDigitOfMaxUint64)) {

      return false;

    }

    value = (value * 10) + (ch - '0');

  }

  *val = value;

  const size_t digits_consumed = current - start;

  in->remove_prefix(digits_consumed);

  return digits_consumed != 0;

}

}  // namespace leveldb