gnc-datetime.hpp

/********************************************************************\
 * gnc-datetime.cpp -- Date and Time classes for GnuCash            *
 *                                                                  *
 * Copyright 2015 John Ralls <jralls@ceridwen.us>                   *
 *                                                                  *
 * This program is free software; you can redistribute it and/or    *
 * modify it under the terms of the GNU General Public License as   *
 * published by the Free Software Foundation; either version 2 of   *
 * the License, or (at your option) any later version.              *
 *                                                                  *
 * This program is distributed in the hope that it will be useful,  *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of   *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the    *
 * GNU General Public License for more details.                     *
 *                                                                  *
 * You should have received a copy of the GNU General Public License*
 * along with this program; if not, contact:                        *
 *                                                                  *
 * Free Software Foundation           Voice:  +1-617-542-5942       *
 * 51 Franklin Street, Fifth Floor    Fax:    +1-617-542-2652       *
 * Boston, MA  02110-1301,  USA       gnu@gnu.org                   *
 *                                                                  *
\********************************************************************/

#ifndef __GNC_DATETIME_HPP__
#define  __GNC_DATETIME_HPP__

#include <cstdint>
#include <memory>
#include <string>
#include <vector>
#include <functional>
#include <optional>

#include <boost/date_time/gregorian/gregorian.hpp>

typedef struct
{
    int year;  //1400-9999
    int month; //1-12
    int day; //1-31
} gnc_ymd;

enum class DayPart {
    start,    // 00:00 local
    neutral,  // 10:59 UTC
    end,      // 23:59 local
};

class GncDateTimeImpl;
class GncDateImpl;
class GncDate;
using time64 = int64_t;
constexpr const time64 MINTIME = -17987443200;
constexpr const time64 MAXTIME = 253402214400;

class GncDateTime
{
public:
    GncDateTime();
    GncDateTime(const time64 time);
    GncDateTime(const struct tm tm);
    GncDateTime(const GncDate& date, DayPart part = DayPart::neutral);
    GncDateTime(const std::string& str);
    GncDateTime(const char* str);
    ~GncDateTime();
    void now();
    explicit operator time64() const;
    explicit operator struct tm() const;
    long offset()const;
    struct tm utc_tm() const;
    GncDate date() const;
    bool isnull (void) { return m_impl == nullptr; }
    std::string format(const char* format) const;
    std::string format_zulu(const char* format) const;
    std::string format_iso8601() const;
    static std::string timestamp();
    
private:
    std::unique_ptr<GncDateTimeImpl> m_impl;
};

using StringToDate = std::function<boost::gregorian::date(const std::string&)>;

class GncDateFormat
{
public:
    GncDateFormat (const char* fmt, const char* re) :
    m_fmt(fmt), m_re(re) {}
    GncDateFormat (const char* fmt, StringToDate str_to_date, const char* re) :
        m_fmt(fmt), m_re(re), m_str_to_date(str_to_date) {}
    GncDateFormat (const char* fmt, StringToDate str_to_date) :
        m_fmt(fmt), m_str_to_date(str_to_date) {}
    const std::string m_fmt;
private:
    const std::string m_re;
    std::optional<StringToDate> m_str_to_date;

    friend class GncDateImpl;
};

class GncDate
{
    public:
        static const std::vector<GncDateFormat> c_formats;
        GncDate();
        GncDate(int year, int month, int day);
        GncDate(const std::string str, const std::string fmt);
        GncDate(std::unique_ptr<GncDateImpl> impl);
        GncDate(const GncDate&);
        GncDate(GncDate&&);
        ~GncDate();
        GncDate& operator=(const GncDate&);
        GncDate& operator=(GncDate&&);
        void today();
        gnc_ymd year_month_day() const;
        std::string format(const char* format);
        bool isnull (void) { return m_impl == nullptr; }

private:
    std::unique_ptr<GncDateImpl> m_impl;

    friend GncDateTime::GncDateTime(const GncDate&, DayPart);
    friend bool operator<(const GncDate&, const GncDate&);
    friend bool operator>(const GncDate&, const GncDate&);
    friend bool operator==(const GncDate&, const GncDate&);
    friend bool operator<=(const GncDate&, const GncDate&);
    friend bool operator>=(const GncDate&, const GncDate&);
    friend bool operator!=(const GncDate&, const GncDate&);
};

bool operator<(const GncDate& a, const GncDate& b);
bool operator>(const GncDate& a, const GncDate& b);
bool operator==(const GncDate& a, const GncDate& b);
bool operator<=(const GncDate& a, const GncDate& b);
bool operator>=(const GncDate& a, const GncDate& b);
bool operator!=(const GncDate& a, const GncDate& b);
#endif // __GNC_DATETIME_HPP__