DateTime.h

//-*- C++ -*-
//-*- coding: utf-8 -*-
//
//
// Author: Piyush Agram
// Copyright 2017-2018
 
#pragma once
 
#include "forward.h"
 
#include <cassert>
#include <cmath>
#include <iostream>
#include <string>

class isce3::core::DateTime {
public:
    int year;
    int months;
    int days;
    int hours;
    int minutes;
    int seconds;
    double frac;

    DateTime() : DateTime(1970, 1, 1) {};

    DateTime(double ord);

    DateTime(int yy, int mm, int dd);

    DateTime(int yy, int mm, int dd, int hh, int mn, int ss);

    DateTime(int yy, int mm, int dd, int hh, int mn, double ss);

    DateTime(int yy, int mm, int dd, int hh, int mn, int ss, double ff);

    DateTime(const DateTime& ts);

    explicit DateTime(const std::string&);

    void _init(int yy, int mm, int dd, int hh, int mn, int ss, double ff);
    void _normalize_time();
    void _normalize_date();
    void _normalize();
 
    explicit operator std::string() const { return isoformat(); }
 
    // Comparison operators
    bool operator<(const DateTime& ts) const;
    bool operator>(const DateTime& ts) const;
    bool operator<=(const DateTime& ts) const;
    bool operator>=(const DateTime& ts) const;
    bool operator==(const DateTime& ts) const;
    bool operator!=(const DateTime& ts) const;
 
    // Math operators
    DateTime& operator=(const DateTime& ts);
    DateTime& operator+=(const TimeDelta& ts);
    DateTime& operator+=(const double& s);
    DateTime& operator-=(const TimeDelta& ts);
    DateTime& operator-=(const double& s);
 
    DateTime operator+(const TimeDelta& ts) const;
    DateTime operator+(const double& s) const;
    DateTime operator-(const TimeDelta& ts) const;
    DateTime operator-(const double& s) const;
 
    TimeDelta operator-(const DateTime& ts) const;

    bool isClose(const DateTime& ts) const;

    bool isClose(const DateTime& ts, const TimeDelta& errtol) const;

    int dayOfYear() const;

    double secondsOfDay() const;

    int dayOfWeek() const;

    double ordinal() const;

    double secondsSinceEpoch() const;

    double secondsSinceEpoch(const DateTime&) const;

    void secondsSinceEpoch(double);

    std::string isoformat() const;

    void strptime(std::string);

    static bool isIsoFormat(const std::string& datetime_str);
};
 
// Some constants
namespace isce3 { namespace core {
 
std::ostream& operator<<(std::ostream&, const DateTime&);
 
// Constants for default constructors
const DateTime MIN_DATE_TIME = DateTime(1970, 1, 1);
const std::string UNINITIALIZED_STRING = "uninitialized";
 
static const int DaysInMonths[] = {31, 28, 31, 30, 31, 30,
                                   31, 31, 30, 31, 30, 31};
 
static const int DaysBeforeMonths[] = {0,   31,  59,  90,  120, 151,
                                       181, 212, 243, 273, 304, 334};
static const int DAY_TO_YEAR = 365;
static const int DAYSPER100 = 36524;
static const int DAYSPER400 = 146097;
static const int DAYSPER4 = 1461;
static const int MAXORDINAL = 3652059;
 
inline constexpr double TOL_SECONDS = 1e-9;
 
// time section and fractional seconds are optional
// to support trailing  white space, add ( )* to the
// end of ISOFMT8601
static constexpr auto ISOFMT8601 =
        "[1-9][0-9]{3}-[0-1][0-9]-[0-3][0-9](|(T| "
        ")[0-2][0-9]:[0-5][0-9]:[0-6][0-9](|(\\.|\\:|\\,)([0-9]*)))";
 
// Handful of utility functions
bool _is_leap(int);
int _days_in_month(int, int);
int _days_before_year(int);
int _days_before_month(int, int);
int _ymd_to_ord(int, int, int);
void _ord_to_ymd(int, int&, int&, int&);
}} // namespace isce3::core