datetime.h

/* Copyright (c) 2021 Xie Meiyi(xiemeiyi@hust.edu.cn) and OceanBase and/or its affiliates. All rights reserved.
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//
// Created by Longda on 2010
//

#ifndef __COMMON_TIME_DATETIME_H__
#define __COMMON_TIME_DATETIME_H__

#include <math.h>
#include <stdint.h>
#include <sys/time.h>
#include <time.h>

#include <iomanip>
#include <iostream>

#include "common/defs.h"

namespace common {


/*
 *  \brief Date and time are represented as integer for ease of
 *   calculation and comparison.
 *
 *  Julian day number is the integer number of days that have elapsed since
 *  the defined as noon Universal Time (UT) Monday, January 1, 4713 BC.
 *
 *  Date and Time stored as a Julian day number and number of
 *  milliseconds since midnight.  Does not perform any timezone
 *  calculations.  All magic numbers and related calculations
 *  have been taken from:
 *
 *  \sa http://www.faqs.org/faqs/calendars.faq
 *  \sa http://scienceworld.wolfram.com/astronomy/JulianDate.html
 *  \sa http://scienceworld.wolfram.com/astronomy/GregorianCalendar.html
 *  \sa http://scienceworld.wolfram.com/astronomy/Weekday.html
 */

struct DateTime {
  int m_date;
  int m_time;

  enum {
    SECONDS_PER_DAY = 86400,
    SECONDS_PER_HOUR = 3600,
    SECONDS_PER_MIN = 60,
    MINUTES_PER_HOUR = 60,

    MILLIS_PER_DAY = 86400000,
    MILLIS_PER_HOUR = 3600000,
    MILLIS_PER_MIN = 60000,
    MILLIS_PER_SEC = 1000,

    // time_t epoch (1970-01-01) as a Julian date
    JULIAN_19700101 = 2440588
  };
  enum {
    MON_JAN = 1,
    MON_FEB = 2,
    MON_MAR = 3,
    MON_APR = 4,
    MON_MAY = 5,
    MON_JUN = 6,
    MON_JUL = 7,
    MON_AUG = 8,
    MON_SEP = 9,
    MON_OCT = 10,
    MON_NOV = 11,
    MON_DEC = 12
  };

  // Default constructor - initializes to zero
  DateTime() : m_date(0), m_time(0) {}

  // Construct from a Julian day number and time in millis
  DateTime(int date, int time) : m_date(date), m_time(time) {}

  // Construct from the specified components
  DateTime(int year, int month, int day, int hour, int minute, int second,
           int millis) {
    m_date = julian_date(year, month, day);
    m_time = make_hms(hour, minute, second, millis);
  }

  // Construct from the xml datetime format
  DateTime(std::string &xml_time);

  // check whether a string is valid with a xml datetime format
  static bool is_valid_xml_datetime(const std::string &str);

  // Load the referenced values with the year, month and day
  // portions of the date in a single operation
  inline void get_ymd(int &year, int &month, int &day) const {
    get_ymd(m_date, year, month, day);
  }

  // Load the referenced values with the hour, minute, second and
  // millisecond portions of the time in a single operation
  inline void get_hms(int &hour, int &minute, int &second, int &millis) const {
    int ticks = m_time / MILLIS_PER_SEC;
    hour = ticks / SECONDS_PER_HOUR;
    minute = (ticks / SECONDS_PER_MIN) % MINUTES_PER_HOUR;
    second = ticks % SECONDS_PER_MIN;
    millis = m_time % MILLIS_PER_SEC;
  }

  // Convert the DateTime to a time_t.  Note that this operation
  // can overflow on 32-bit platforms when we go beyond year 2038.
  inline time_t to_time_t() const {
    return (SECONDS_PER_DAY * (m_date - JULIAN_19700101) +
            m_time / MILLIS_PER_SEC);
  }

  // Convert the DateTime to a struct tm which is in UTC
  tm to_tm() const {
    int year, month, day;
    int hour, minute, second, millis;
    tm result = {0};

    get_ymd(year, month, day);
    get_hms(hour, minute, second, millis);

    result.tm_year = year - 1900;
    result.tm_mon = month - 1;
    result.tm_mday = day;
    result.tm_hour = hour;
    result.tm_min = minute;
    result.tm_sec = second;
    result.tm_isdst = -1;

    return result;
  }

  // Set the date portion of the DateTime
  void set_ymd(int year, int month, int day) {
    m_date = julian_date(year, month, day);
  }

  // Set the time portion of the DateTime
  void set_hms(int hour, int minute, int second, int millis) {
    m_time = make_hms(hour, minute, second, millis);
  }

  // Clear the date portion of the DateTime
  void clear_date() { m_date = 0; }

  // Clear the time portion of the DateTime
  void clear_time() { m_time = 0; }

  // Set the internal date and time members
  void set(int date, int time) {
    m_date = date;
    m_time = time;
  }

  // Initialize from another DateTime
  void set(const DateTime &other) {
    m_date = other.m_date;
    m_time = other.m_time;
  }

  // Add a number of seconds to this
  void operator+=(int seconds) {
    int d = seconds / SECONDS_PER_DAY;
    int s = seconds % SECONDS_PER_DAY;

    m_date += d;
    m_time += s * MILLIS_PER_SEC;

    if (m_time > MILLIS_PER_DAY) {
      m_date++;
      m_time %= MILLIS_PER_DAY;
    } else if (m_time < 0) {
      m_date--;
      m_time += MILLIS_PER_DAY;
    }
  }

  // Return date and time as a string in XML Schema Date-Time format
  std::string to_xml_date_time();

  // Return time_t from XML schema date-time format.
  time_t str_to_time_t(std::string &xml_str);

  // Return xml time str from time_t.
  std::string time_t_to_xml_str(time_t timet);

  // Return time_t str from time_t.
  std::string time_t_to_str(int timet);

  // Return time_t string from XML schema date-time format.
  std::string str_to_time_t_str(std::string &xml_str);

  // Helper method to convert a broken down time to a number of
  // milliseconds since midnight
  static int make_hms(int hour, int minute, int second, int millis) {
    return MILLIS_PER_SEC *
               (SECONDS_PER_HOUR * hour + SECONDS_PER_MIN * minute + second) +
           millis;
  }

  // Return the current wall-clock time as a DateTime
  static DateTime now();

  // Return the current wall-clock time as time_t
  time_t nowtimet();

  // Convert a time_t and optional milliseconds to a DateTime
  static DateTime from_time_t(time_t t, int millis = 0) {
    struct tm tmbuf;
    tm *tm = gmtime_r(&t, &tmbuf);
    return from_tm(*tm, millis);
  }

  // Convert a tm and optional milliseconds to a DateTime.  \note
  // the tm structure is assumed to contain a date specified in UTC
  static DateTime from_tm(const tm &tm, int millis = 0) {
    return DateTime(julian_date(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday),
                    make_hms(tm.tm_hour, tm.tm_min, tm.tm_sec, millis));
  }

  // Helper method to calculate a Julian day number.
  static int julian_date(int year, int month, int day) {
    int a = (14 - month) / 12;
    int y = year + 4800 - a;
    int m = month + 12 * a - 3;
    return (day + int((153 * m + 2) / 5) + y * 365 + int(y / 4) - int(y / 100) +
            int(y / 400) - 32045);
  }

  // Convert a Julian day number to a year, month and day
  static void get_ymd(int jday, int &year, int &month, int &day) {
    int a = jday + 32044;
    int b = (4 * a + 3) / 146097;
    int c = a - int((b * 146097) / 4);
    int d = (4 * c + 3) / 1461;
    int e = c - int((1461 * d) / 4);
    int m = (5 * e + 2) / 153;
    day = e - int((153 * m + 2) / 5) + 1;
    month = m + 3 - 12 * int(m / 10);
    year = b * 100 + d - 4800 + int(m / 10);
  }

  // Return a human-friendly string representation of the timestamp,
  // expressed in terms of the local timezone
  std::string to_string_local() {
    const time_t tt = to_time_t();
    // 'man asctime' specifies that buffer must be at least 26 bytes
    char buffer[32];
    struct tm tm;
    asctime_r(localtime_r(&tt, &tm), &(buffer[0]));
    std::string s(buffer);
    return s;
  }

  // Return a human-friendly string representation of the timestamp,
  // expressed in terms of Coordinated Universal Time (UTC)
  std::string to_string_utc() {
    const time_t tt = to_time_t();
    // 'man asctime' specifies that buffer must be at least 26 bytes
    char buffer[32];
    struct tm tm;
    asctime_r(gmtime_r(&tt, &tm), &(buffer[0]));
    std::string s(buffer);
    return s;
  }

  // add duration to this time
  time_t add_duration(std::string xml_dur);

  // add duration to this time
  void add_duration_date_time(std::string xml_dur);

  // add duration to this time
  int max_day_in_month_for(int year, int month);

  // parse the duration string and convert it to struct tm
  void parse_duration(std::string dur_str, struct tm &tm_t);
};

inline bool operator==(const DateTime &lhs, const DateTime &rhs) {
  return lhs.m_date == rhs.m_date && lhs.m_time == rhs.m_time;
}

inline bool operator!=(const DateTime &lhs, const DateTime &rhs) {
  return !(lhs == rhs);
}

inline bool operator<(const DateTime &lhs, const DateTime &rhs) {
  if (lhs.m_date < rhs.m_date)
    return true;
  else if (lhs.m_date > rhs.m_date)
    return false;
  else if (lhs.m_time < rhs.m_time)
    return true;
  return false;
}

inline bool operator>(const DateTime &lhs, const DateTime &rhs) {
  return !(lhs == rhs || lhs < rhs);
}

inline bool operator<=(const DateTime &lhs, const DateTime &rhs) {
  return lhs == rhs || lhs < rhs;
}

inline bool operator>=(const DateTime &lhs, const DateTime &rhs) {
  return lhs == rhs || lhs > rhs;
}

// Calculate the difference between two DateTime values and return
// the result as a number of seconds
inline int operator-(const DateTime &lhs, const DateTime &rhs) {
  return (DateTime::SECONDS_PER_DAY * (lhs.m_date - rhs.m_date) +
          // Truncate the millis before subtracting
          lhs.m_time / 1000 - rhs.m_time / 1000);
}

// Date and Time represented in UTC.
class TimeStamp : public DateTime {
public:
  // Defaults to the current date and time
  TimeStamp() : DateTime(DateTime::now()) {}

  // Defaults to the current date
  TimeStamp(int hour, int minute, int second, int millisecond = 0)
      : DateTime(DateTime::now()) {
    set_hms(hour, minute, second, millisecond);
  }

  TimeStamp(int hour, int minute, int second, int date, int month, int year)
      : DateTime(year, month, date, hour, minute, second, 0) {}

  TimeStamp(int hour, int minute, int second, int millisecond, int date,
            int month, int year)
      : DateTime(year, month, date, hour, minute, second, millisecond) {}

  TimeStamp(time_t time, int millisecond = 0)
      : DateTime(from_time_t(time, millisecond)) {}

  TimeStamp(const tm *time, int millisecond = 0)
      : DateTime(from_tm(*time, millisecond)) {}

  void set_current() { set(DateTime::now()); }
};

// Time only represented in UTC.
class Time : public DateTime {
public:
  // Defaults to the current time
  Time() { set_current(); }

  Time(const DateTime &val) : DateTime(val) { clear_date(); }

  Time(int hour, int minute, int second, int millisecond = 0) {
    set_hms(hour, minute, second, millisecond);
  }

  Time(time_t time, int millisecond = 0)
      : DateTime(from_time_t(time, millisecond)) {
    clear_date();
  }

  Time(const tm *time, int millisecond = 0)
      : DateTime(from_tm(*time, millisecond)) {
    clear_date();
  }

  // Set to the current time.
  void set_current() {
    DateTime d = now();
    m_time = d.m_time;
  }
};

// Date only represented in UTC.
class Date : public DateTime {
public:
  // Defaults to the current date
  Date() { set_current(); }

  Date(const DateTime &val) : DateTime(val) { clear_time(); }

  Date(int date, int month, int year)
      : DateTime(year, month, date, 0, 0, 0, 0) {}

  Date(long sec) : DateTime(sec / DateTime::SECONDS_PER_DAY, 0) {}

  Date(const tm *time) : DateTime(from_tm(*time)) { clear_time(); }

  // Set to the current time.
  void set_current() {
    DateTime d = now();
    m_date = d.m_date;
  }
};

class Now {
public:
  static inline s64_t sec() {
    struct timeval tv;
    gettimeofday(&tv, 0);
    time_t sec = tv.tv_sec;
    // Round up if necessary
    if (tv.tv_usec > 500 * 1000)
      sec++;
    return sec;
  }

  static inline s64_t usec() {
    struct timeval tv;
    gettimeofday(&tv, 0);
    return (s64_t)tv.tv_sec * 1000000 + tv.tv_usec;
  }

  static inline s64_t msec() {
    struct timeval tv;
    gettimeofday(&tv, 0);
    s64_t msec = (s64_t)tv.tv_sec * 1000 + tv.tv_usec / 1000;
    if (tv.tv_usec % 1000 >= 500)
      msec++;
    return msec;
  }

  static std::string unique();
};

} //namespace common
#endif //__COMMON_TIME_DATETIME_H__