//
// DateTime.cpp
//
// Library: Foundation
// Package: DateTime
// Module:  DateTime
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#include "Poco/DateTime.h"
#include "Poco/Timespan.h"
#include <algorithm>
#include <cmath>


namespace Poco {


inline double DateTime::toJulianDay(Timestamp::UtcTimeVal utcTime)
{
	double utcDays = double(utcTime)/864000000000.0;
	return utcDays + 2299160.5; // first day of Gregorian reform (Oct 15 1582)
}


inline Timestamp::UtcTimeVal DateTime::toUtcTime(double julianDay)
{
	return Timestamp::UtcTimeVal((julianDay - 2299160.5)*864000000000.0);
}


DateTime::DateTime()
{
	Timestamp now;
	_utcTime = now.utcTime();
	computeGregorian(julianDay());
	computeDaytime();
}


DateTime::DateTime(const Timestamp& timestamp):
	_utcTime(timestamp.utcTime())
{
	computeGregorian(julianDay());
	computeDaytime();
}

	
DateTime::DateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond):
	_year(year),
	_month(month),
	_day(day),
	_hour(hour),
	_minute(minute),
	_second(second),
	_millisecond(millisecond),
	_microsecond(microsecond)
{
	poco_assert (year >= 0 && year <= 9999);
	poco_assert (month >= 1 && month <= 12);
	poco_assert (day >= 1 && day <= daysOfMonth(year, month));
	poco_assert (hour >= 0 && hour <= 23);
	poco_assert (minute >= 0 && minute <= 59);
	poco_assert (second >= 0 && second <= 60); // allow leap seconds
	poco_assert (millisecond >= 0 && millisecond <= 999);
	poco_assert (microsecond >= 0 && microsecond <= 999);
	
	_utcTime = toUtcTime(toJulianDay(year, month, day)) + 10*(hour*Timespan::HOURS + minute*Timespan::MINUTES + second*Timespan::SECONDS + millisecond*Timespan::MILLISECONDS + microsecond);
}


DateTime::DateTime(double julianDay):
	_utcTime(toUtcTime(julianDay))
{
	computeGregorian(julianDay);
}


DateTime::DateTime(Timestamp::UtcTimeVal utcTime, Timestamp::TimeDiff diff):
	_utcTime(utcTime + diff*10)
{
	computeGregorian(julianDay());
	computeDaytime();
}


DateTime::DateTime(const DateTime& dateTime):
	_utcTime(dateTime._utcTime),
	_year(dateTime._year),
	_month(dateTime._month),
	_day(dateTime._day),
	_hour(dateTime._hour),
	_minute(dateTime._minute),
	_second(dateTime._second),
	_millisecond(dateTime._millisecond),
	_microsecond(dateTime._microsecond)
{
}


DateTime::~DateTime()
{
}


DateTime& DateTime::operator = (const DateTime& dateTime)
{
	if (&dateTime != this)
	{
		_utcTime     = dateTime._utcTime;
		_year        = dateTime._year;
		_month       = dateTime._month;
		_day         = dateTime._day;
		_hour        = dateTime._hour;
		_minute      = dateTime._minute;
		_second      = dateTime._second;
		_millisecond = dateTime._millisecond;
		_microsecond = dateTime._microsecond;
	}
	return *this;
}

	
DateTime& DateTime::operator = (const Timestamp& timestamp)
{
	_utcTime = timestamp.utcTime();
	computeGregorian(julianDay());
	computeDaytime();
	return *this;
}


DateTime& DateTime::operator = (double julianDay)
{
	_utcTime = toUtcTime(julianDay);
	computeGregorian(julianDay);
	return *this;
}


DateTime& DateTime::assign(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond)
{
	poco_assert (year >= 0 && year <= 9999);
	poco_assert (month >= 1 && month <= 12);
	poco_assert (day >= 1 && day <= daysOfMonth(year, month));
	poco_assert (hour >= 0 && hour <= 23);
	poco_assert (minute >= 0 && minute <= 59);
	poco_assert (second >= 0 && second <= 60); // allow leap seconds
	poco_assert (millisecond >= 0 && millisecond <= 999);
	poco_assert (microsecond >= 0 && microsecond <= 999);

	_utcTime     = toUtcTime(toJulianDay(year, month, day)) + 10*(hour*Timespan::HOURS + minute*Timespan::MINUTES + second*Timespan::SECONDS + millisecond*Timespan::MILLISECONDS + microsecond);
	_year        = year;
	_month       = month;
	_day         = day;
	_hour        = hour;
	_minute      = minute;
	_second      = second;
	_millisecond = millisecond;
	_microsecond = microsecond;
	
	return *this;
}


void DateTime::swap(DateTime& dateTime)
{
	std::swap(_utcTime, dateTime._utcTime);
	std::swap(_year, dateTime._year);
	std::swap(_month, dateTime._month);
	std::swap(_day, dateTime._day);
	std::swap(_hour, dateTime._hour);
	std::swap(_minute, dateTime._minute);
	std::swap(_second, dateTime._second);
	std::swap(_millisecond, dateTime._millisecond);
	std::swap(_microsecond, dateTime._microsecond);
}


int DateTime::dayOfWeek() const
{
	return int((std::floor(julianDay() + 1.5))) % 7;
}


int DateTime::dayOfYear() const
{
	int doy = 0;
	for (int month = 1; month < _month; ++month)
		doy += daysOfMonth(_year, month);
	doy += _day;
	return doy;
}


int DateTime::daysOfMonth(int year, int month)
{
	poco_assert (month >= 1 && month <= 12);

	static int daysOfMonthTable[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
	
	if (month == 2 && isLeapYear(year))
		return 29;
	else
		return daysOfMonthTable[month];
}


bool DateTime::isValid(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond)
{
	return
		(year >= 0 && year <= 9999) &&
		(month >= 1 && month <= 12) &&
		(day >= 1 && day <= daysOfMonth(year, month)) &&
		(hour >= 0 && hour <= 23) &&
		(minute >= 0 && minute <= 59) &&
		(second >= 0 && second <= 60) &&
		(millisecond >= 0 && millisecond <= 999) &&
		(microsecond >= 0 && microsecond <= 999);
}


int DateTime::week(int firstDayOfWeek) const
{
	poco_assert (firstDayOfWeek >= 0 && firstDayOfWeek <= 6);

	/// find the first firstDayOfWeek.
	int baseDay = 1;
	while (DateTime(_year, 1, baseDay).dayOfWeek() != firstDayOfWeek) ++baseDay;

	int doy  = dayOfYear();
	int offs = baseDay <= 4 ? 0 : 1; 
	if (doy < baseDay)
		return offs;
	else
		return (doy - baseDay)/7 + 1 + offs;
}


double DateTime::julianDay() const
{
	return toJulianDay(_utcTime);
}


DateTime DateTime::operator + (const Timespan& span) const
{
	return DateTime(_utcTime, span.totalMicroseconds());
}


DateTime DateTime::operator - (const Timespan& span) const
{
	return DateTime(_utcTime, -span.totalMicroseconds());
}


Timespan DateTime::operator - (const DateTime& dateTime) const
{
	return Timespan((_utcTime - dateTime._utcTime)/10);
}


DateTime& DateTime::operator += (const Timespan& span)
{
	_utcTime += span.totalMicroseconds()*10;
	computeGregorian(julianDay());
	computeDaytime();
	return *this;
}


DateTime& DateTime::operator -= (const Timespan& span)
{
	_utcTime -= span.totalMicroseconds()*10;
	computeGregorian(julianDay());
	computeDaytime();
	return *this;
}


void DateTime::makeUTC(int tzd)
{
	operator -= (Timespan(((Timestamp::TimeDiff) tzd)*Timespan::SECONDS));
}

	
void DateTime::makeLocal(int tzd)
{
	operator += (Timespan(((Timestamp::TimeDiff) tzd)*Timespan::SECONDS));
}


double DateTime::toJulianDay(int year, int month, int day, int hour, int minute, int second, int millisecond, int microsecond)
{
	// lookup table for (153*month - 457)/5 - note that 3 <= month <= 14.
	static int lookup[] = {-91, -60, -30, 0, 31, 61, 92, 122, 153, 184, 214, 245, 275, 306, 337};
 
	// day to double
	double dday = double(day) + ((double((hour*60 + minute)*60 + second)*1000 + millisecond)*1000 + microsecond)/86400000000.0;
	if (month < 3)
	{
		month += 12;
		--year;
	}
	double dyear = double(year);
	return dday + lookup[month] + 365*year + std::floor(dyear/4) - std::floor(dyear/100) + std::floor(dyear/400) + 1721118.5;
}


void DateTime::checkLimit(short& lower, short& higher, short limit)
{
	if (lower >= limit)
	{
		higher += short(lower / limit);
		lower   = short(lower % limit);
	}
}


void DateTime::normalize()
{
	checkLimit(_microsecond, _millisecond, 1000);
	checkLimit(_millisecond, _second, 1000);
	checkLimit(_second, _minute, 60);
	checkLimit(_minute, _hour, 60);
	checkLimit(_hour, _day, 24);

	if (_day > daysOfMonth(_year, _month))
	{
		_day -= daysOfMonth(_year, _month);
		if (++_month > 12)
		{
			++_year;
			_month -= 12;
		}
	}
}


void DateTime::computeGregorian(double julianDay)
{
	double z    = std::floor(julianDay - 1721118.5);
	double r    = julianDay - 1721118.5 - z;
	double g    = z - 0.25;
	double a    = std::floor(g / 36524.25);
	double b    = a - std::floor(a/4);
	_year       = short(std::floor((b + g)/365.25));
	double c    = b + z - std::floor(365.25*_year);
	_month      = short(std::floor((5*c + 456)/153));
	double dday = c - std::floor((153.0*_month - 457)/5) + r;
	_day        = short(dday);
	if (_month > 12)
	{
		++_year;
		_month -= 12;
	}
	r      *= 24;
	_hour   = short(std::floor(r));
	r      -= std::floor(r);
	r      *= 60;
	_minute = short(std::floor(r));
	r      -= std::floor(r);
	r      *= 60;
	_second = short(std::floor(r));
	r      -= std::floor(r);
	r      *= 1000;
	_millisecond = short(std::floor(r));
	r      -= std::floor(r);
	r      *= 1000;
	_microsecond = short(r + 0.5);

	normalize();

	poco_assert_dbg (_month >= 1 && _month <= 12);
	poco_assert_dbg (_day >= 1 && _day <= daysOfMonth(_year, _month));
	poco_assert_dbg (_hour >= 0 && _hour <= 23);
	poco_assert_dbg (_minute >= 0 && _minute <= 59);
	poco_assert_dbg (_second >= 0 && _second <= 59);
	poco_assert_dbg (_millisecond >= 0 && _millisecond <= 999);
	poco_assert_dbg (_microsecond >= 0 && _microsecond <= 999);
}


void DateTime::computeDaytime()
{
	Timespan span(_utcTime/10);
	int hour = span.hours();
	// Due to double rounding issues, the previous call to computeGregorian()
	// may have crossed into the next or previous day. We need to correct that.
	if (hour == 23 && _hour == 0)
	{
		_day--;
		if (_day == 0)
		{
			_month--;
			if (_month == 0)
			{
				_month = 12;
				_year--;
			}
			_day = daysOfMonth(_year, _month);
		}
	}
	else if (hour == 0 && _hour == 23)
	{
		_day++;
		if (_day > daysOfMonth(_year, _month))
		{
			_month++;
			if (_month > 12)
			{
				_month = 1;
				_year++;
			}
			_day = 1;
		}
	}
	_hour        = hour;
	_minute      = span.minutes();
	_second      = span.seconds();
	_millisecond = span.milliseconds();
	_microsecond = span.microseconds();
}


} // namespace Poco
