timer.hpp

#pragma once

#include <chrono>
#include <cstdint>
#include <ctime>
#include <string>

namespace base
{
/// Cross platform timer
class Timer
{
  std::chrono::steady_clock::time_point m_startTime;

public:
  explicit Timer(bool start = true);

  /// @return current UTC time in seconds, elapsed from 1970.
  static double LocalTime();

  /// @return Elapsed time from start (@see Reset).
  inline std::chrono::steady_clock::duration TimeElapsed() const { return std::chrono::steady_clock::now() - m_startTime; }

  template <typename Duration>
  inline Duration TimeElapsedAs() const
  {
    return std::chrono::duration_cast<Duration>(TimeElapsed());
  }

  inline double ElapsedSeconds() const { return TimeElapsedAs<std::chrono::duration<double>>().count(); }

  inline void Reset() { m_startTime = std::chrono::steady_clock::now(); }
};

std::string FormatCurrentTime();

/// Generates timestamp for a specified day.
/// \param year     The number of years since 1900.
/// \param month    The number of month since January, in the range 0 to 11.
/// \param day      The day of the month, in the range 1 to 31.
/// \return Timestamp.
uint32_t GenerateYYMMDD(int year, int month, int day);
uint32_t GenerateYYMMDD(uint64_t secondsSinceEpoch);
uint64_t YYMMDDToSecondsSinceEpoch(uint32_t yymmdd);

uint64_t SecondsSinceEpoch();

/// Always creates strings in UTC time: 1997-07-16T07:30:15Z
/// Returns empty string on error
std::string TimestampToString(time_t time);

std::string SecondsSinceEpochToString(uint64_t secondsSinceEpoch);

time_t const INVALID_TIME_STAMP = -1;

/// Accepts strings in UTC format: 1997-07-16T07:30:15Z
/// And with custom time offset:   1997-07-16T10:30:15+03:00
/// @return INVALID_TIME_STAMP if string is invalid
time_t StringToTimestamp(std::string const & s);


/// High resolution timer to use in comparison tests.
class HighResTimer
{
  typedef std::chrono::high_resolution_clock::time_point PointT;
  PointT m_start;

public:
  explicit HighResTimer(bool start = true);

  void Reset();
  uint64_t ElapsedNano() const;
  uint64_t ElapsedMillis() const;
  double ElapsedSeconds() const;
};

time_t SecondsSinceEpochToTimeT(uint64_t secondsSinceEpoch);
uint64_t TimeTToSecondsSinceEpoch(time_t time);
}  // namespace base