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// MARKER(update_precomp.py): autogen include statement, do not remove
#include "precompiled_i18npool.hxx"

#include <stdlib.h>
#include <math.h>

#include "calendar_hijri.hxx"

using namespace ::com::sun::star::uno;
using namespace ::com::sun::star::lang;
using namespace ::com::sun::star::i18n;
using namespace ::rtl;

#define ERROR RuntimeException()

#define GREGORIAN_CROSSOVER 2299161

// not used
//static UErrorCode status; // status is shared in all calls to Calendar, it has to be reset for each call.

// radians per degree (pi/180)
const double Calendar_hijri::RadPerDeg		= 0.01745329251994329577;

// Synodic Period (mean time between 2 successive new moon: 29d, 12 hr, 44min, 3sec
const double Calendar_hijri::SynPeriod		= 29.53058868;
const double Calendar_hijri::SynMonth		= 365.25/29.53058868;	// Solar days in a year/SynPeriod

// Julian day on Jan 1, 1900
const double Calendar_hijri::jd1900		= 2415020.75933;

// Reference point: March 26, 2001 == 1422 Hijri == 1252 Synodial month from 1900
const sal_Int32 Calendar_hijri::SynRef		= 1252;
const sal_Int32 Calendar_hijri::GregRef		= 1422;

// Local time specific to Saudi Arabia
const double Calendar_hijri::SA_TimeZone	= 3.0;

const double Calendar_hijri::EveningPeriod	= 6.0;

const sal_Int32 Calendar_hijri::LeapYear[] = {
	2, 5, 7, 10, 13, 16, 18, 21, 24, 26, 29
};

Calendar_hijri::Calendar_hijri()
{
	cCalendar = "com.sun.star.i18n.Calendar_hijri";
}

#define FIELDS  ((1 << CalendarFieldIndex::ERA) | (1 << CalendarFieldIndex::YEAR) | (1 << CalendarFieldIndex::MONTH) | (1 << CalendarFieldIndex::DAY_OF_MONTH)) 

// map field value from hijri calendar to gregorian calendar
void Calendar_hijri::mapToGregorian() throw(RuntimeException)
{
	if (fieldSet & FIELDS) {
	    sal_Int32 day = (sal_Int32)fieldSetValue[CalendarFieldIndex::DAY_OF_MONTH];
	    sal_Int32 month = (sal_Int32)fieldSetValue[CalendarFieldIndex::MONTH] + 1;
	    sal_Int32 year = (sal_Int32)fieldSetValue[CalendarFieldIndex::YEAR];
	    if (fieldSetValue[CalendarFieldIndex::ERA] == 0)
		year *= -1;

	    ToGregorian(&day, &month, &year);

	    fieldSetValue[CalendarFieldIndex::ERA] = year <= 0 ? 0 : 1;
	    fieldSetValue[CalendarFieldIndex::MONTH] = sal::static_int_cast<sal_Int16>(month - 1);
	    fieldSetValue[CalendarFieldIndex::DAY_OF_MONTH] = (sal_Int16) day;
	    fieldSetValue[CalendarFieldIndex::YEAR] = (sal_Int16) abs(year);
	    fieldSet |= FIELDS;
	}
}

// map field value from gregorian calendar to hijri calendar
void Calendar_hijri::mapFromGregorian() throw(RuntimeException)
{
	sal_Int32 month, day, year;

	day = (sal_Int32)fieldValue[CalendarFieldIndex::DAY_OF_MONTH];
	month = (sal_Int32)fieldValue[CalendarFieldIndex::MONTH] + 1;
	year = (sal_Int32)fieldValue[CalendarFieldIndex::YEAR];
	if (fieldValue[CalendarFieldIndex::ERA] == 0)
	    year *= -1;

	// Get Hijri date
	getHijri(&day, &month, &year);

	fieldValue[CalendarFieldIndex::DAY_OF_MONTH] = (sal_Int16)day;
	fieldValue[CalendarFieldIndex::MONTH] = sal::static_int_cast<sal_Int16>(month - 1);
	fieldValue[CalendarFieldIndex::YEAR] = (sal_Int16) abs(year);
	fieldValue[CalendarFieldIndex::ERA] = (sal_Int16) year < 1 ? 0 : 1;
}

//
// This function returns the Julian date/time of the Nth new moon since
// January 1900.  The synodic month is passed as parameter.
//
// Adapted from "Astronomical  Formulae for Calculators" by 
// Jean Meeus, Third Edition, Willmann-Bell, 1985.
//
double
Calendar_hijri::NewMoon(sal_Int32 n)
{
	double jd, t, t2, t3, k, ma, sa, tf, xtra;
	k = n;
	t = k/1236.85;	// Time in Julian centuries from 1900 January 0.5
	t2 = t * t;
	t3 = t2 * t;

	// Mean time of phase
	jd =  jd1900
		+ SynPeriod * k
		- 0.0001178 * t2
		- 0.000000155 * t3 
		+ 0.00033 * sin(RadPerDeg * (166.56 + 132.87 * t - 0.009173 * t2));

	// Sun's mean anomaly in radian
	sa =  RadPerDeg * (359.2242
				+ 29.10535608 * k 
				- 0.0000333 * t2
				- 0.00000347 * t3);

	// Moon's mean anomaly
	ma =  RadPerDeg * (306.0253 
				+ 385.81691806 * k
				+ 0.0107306 * t2
				+ 0.00001236 * t3);

	// Moon's argument of latitude
	tf = RadPerDeg * 2.0 * (21.2964
				+ 390.67050646 * k
				- 0.0016528 * t2
				- 0.00000239 * t3);

	// should reduce to interval between 0 to 1.0 before calculating further
	// Corrections for New Moon
	xtra = (0.1734 - 0.000393 * t) * sin(sa)
		+ 0.0021 * sin(sa * 2)
		- 0.4068 * sin(ma)
		+ 0.0161 * sin(2 * ma)
		- 0.0004 * sin(3 * ma)
		+ 0.0104 * sin(tf)
		- 0.0051 * sin(sa + ma)
		- 0.0074 * sin(sa - ma)
		+ 0.0004 * sin(tf + sa)
		- 0.0004 * sin(tf - sa)
		- 0.0006 * sin(tf + ma)
		+ 0.0010 * sin(tf - ma)
		+ 0.0005 * sin(sa + 2 * ma);

	// convert from Ephemeris Time (ET) to (approximate) Universal Time (UT)
	jd += xtra - (0.41 + 1.2053 * t + 0.4992 * t2)/1440;

	return (jd);
}

// Get Hijri Date
void
Calendar_hijri::getHijri(sal_Int32 *day, sal_Int32 *month, sal_Int32 *year)
{
	double prevday;
//	double dayfraction;
	sal_Int32 syndiff;
	sal_Int32 newsyn;
	double newjd;
	double julday;
	sal_Int32 synmonth;

	// Get Julian Day from Gregorian
	julday = getJulianDay(*day, *month, *year);

	// obtain approx. of how many Synodic months since the beginning of the year 1900
	synmonth = (sal_Int32)(0.5 + (julday - jd1900)/SynPeriod);

	newsyn = synmonth;
	prevday = (sal_Int32)julday - 0.5;

	do {
		newjd = NewMoon(newsyn);

		// Decrement syndonic months
		newsyn--;
	} while (newjd > prevday);
	newsyn++;

	// difference from reference point
	syndiff = newsyn - SynRef;

	// Round up the day
	*day = (sal_Int32)(((sal_Int32)julday) - newjd + 0.5);
	*month =  (syndiff % 12) + 1; 

	// currently not supported
	//dayOfYear = (sal_Int32)(month * SynPeriod + day);
	*year = GregRef + (sal_Int32)(syndiff / 12);

	// If month negative, consider it previous year
	if (syndiff != 0 && *month <= 0) {
		*month += 12;
		(*year)--;
	}

	// If Before Hijri subtract 1
	if (*year <= 0) (*year)--;
}

void
Calendar_hijri::ToGregorian(sal_Int32 *day, sal_Int32 *month, sal_Int32 *year)
{
    sal_Int32 nmonth;
//    double dayfraction;
    double jday;
//    sal_Int32 dayint;

    if ( *year < 0 ) (*year)++;

    // Number of month from reference point
    nmonth = *month + *year * 12 - (GregRef * 12 + 1);

    // Add Synodic Reference point
    nmonth += SynRef;

    // Get Julian days add time too
    jday = NewMoon(nmonth) + *day;

    // Round-up
    jday = (double)((sal_Int32)(jday + 0.5));

    // Use algorithm from "Numerical Recipes in C"
    getGregorianDay((sal_Int32)jday, day, month, year);

    // Julian -> Gregorian only works for non-negative year
    if ( *year <= 0 ) {
	*day = -1;
	*month = -1;
	*year = -1;
    }
}

/* this algorithm is taken from "Numerical Recipes in C", 2nd ed, pp 14-15. */
/* this algorithm only valid for non-negative gregorian year                */
void
Calendar_hijri::getGregorianDay(sal_Int32 lJulianDay, sal_Int32 *pnDay, sal_Int32 *pnMonth, sal_Int32 *pnYear)
{
    /* working variables */
    long lFactorA, lFactorB, lFactorC, lFactorD, lFactorE;
    long lAdjust;

    /* test whether to adjust for the Gregorian calendar crossover */
    if (lJulianDay >= GREGORIAN_CROSSOVER) {
	/* calculate a small adjustment */
	lAdjust = (long) (((float) (lJulianDay - 1867216) - 0.25) / 36524.25);

	lFactorA = lJulianDay + 1 + lAdjust - ((long) (0.25 * lAdjust));

    } else {
	/* no adjustment needed */
	lFactorA = lJulianDay;
    }

    lFactorB = lFactorA + 1524;
    lFactorC = (long) (6680.0 + ((float) (lFactorB - 2439870) - 122.1) / 365.25);
    lFactorD = (long) (365 * lFactorC + (0.25 * lFactorC));
    lFactorE = (long) ((lFactorB - lFactorD) / 30.6001);

    /* now, pull out the day number */
    *pnDay = lFactorB - lFactorD - (long) (30.6001 * lFactorE);

    /* ...and the month, adjusting it if necessary */
    *pnMonth = lFactorE - 1;
    if (*pnMonth > 12)
	(*pnMonth) -= 12;

    /* ...and similarly for the year */
    *pnYear = lFactorC - 4715;
    if (*pnMonth > 2)
	(*pnYear)--;

// Negative year adjustments
    if (*pnYear <= 0)
	(*pnYear)--;
}

double
Calendar_hijri::getJulianDay(sal_Int32 day, sal_Int32 month, sal_Int32 year)
{
    double jy, jm;

    if( year == 0 ) {
	return -1.0;
    }

    if( year == 1582 && month == 10 && day > 4 && day < 15 ) {
	return -1.0;
    }

    if( month > 2 ) {
	jy = year;
	jm = month + 1;
    } else {
	jy = year - 1;
	jm = month + 13;
    }

    sal_Int32 intgr = (sal_Int32)((sal_Int32)(365.25 * jy) + (sal_Int32)(30.6001 * jm) + day + 1720995 );

    //check for switch to Gregorian calendar
    double gregcal = 15 + 31 * ( 10 + 12 * 1582 );

    if( day + 31 * (month + 12 * year) >= gregcal ) {
	double ja;
	ja = (sal_Int32)(0.01 * jy);
	intgr += (sal_Int32)(2 - ja + (sal_Int32)(0.25 * ja));
    }

    return (double) intgr;
}