/*  Utility programs for unit conversions and calendar
 */

static double PI = 3.14159265358979323846;
#include "/usr/local/wiro/tracking/wirotypes.h"
#include "/usr/local/wiro/tracking/wiro.h"
extern struct wiro_memory *tinfo;

char *intfmt = "%d";
char *lngfmt = "%ld";
char *dblfmt = "%lf";
char *strfmt = "%s";



/*		julian.c
 *
 * This program calculates Julian day number from calendar
 * date, and the date and day of the week from Julian day.
 * The Julian date is double precision floating point
 * with the origin used by astronomers.  The calendar output
 * converts fractions of a day into hours, minutes, and seconds.
 * There is no year 0.  Enter B.C. years as negative; i.e.,
 * 2 B.C. = -2.
 *
 * The approximate range of dates handled is 4713 B.C. to
 * 54,078 A.D.  This should be adequate for most applications.
 *
 * B.C. dates are calculated by extending the Gregorian sequence
 * of leap years and century years into the past.  This seems
 * the only sensible definition, but I don't know if it is
 * the official one.
 *
 * Note that the astronomical Julian day starts at noon on
 * the previous calendar day.  Thus at midnight in the morning
 * of the present calendar day the Julian date ends in .5;
 * it rolls over to tomorrow at noon today.
 *
 * The month finding algorithm is attributed to Meeus.
 *
 * - Steve Moshier
 */


char *months[12] = {
"January",
"February",
"March",
"April",
"May",
"June",
"July",
"August",
"September",
"October",
"November",
"December"
};

char *days[7] = {
"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday"
};

long cyear = 1986;
extern long cyear;
static int month = 1;
static double day = 1.0;
short yerend = 0;
extern short yerend;

double getdate()
{
double J;
double caltoj();

/* Get operator to type in a date.
 */
cyear = YEAR;

if( (cyear > 53994) || (cyear < -4713) )
	{
	printf( "Year out of range.\n" );
	goto err;
	}
if( cyear == 0 )
	{
	printf( "There is no year 0.\n" );
err:	J = 0.0;
	}

month = MONTH;

day = DAY;

/* Find the Julian day. */
J = caltoj(cyear,month,day);
printf( "Julian day %.1f\n", J );

return(J);
}



/*     Calculate Julian day from Gregorian calendar date
 */
double caltoj( year, month, day )
long year;
int month;
double day;
{
long y, a, b, c, e, m;
int BC;
double J;


BC = 0;
/* The origin should be chosen to be a century year
 * that is also a leap year.  We pick 4801 B.C.
 */
y = year + 4800;
if( year < 0 )
	{
	BC = 1;
	y += 1;
	}

/* The following magic arithmetic calculates a sequence
 * whose successive terms differ by the correct number of
 * days per calendar month.  It starts at 122 = March; January
 * and February come after December.
 */
m = month;
if( m <= 2 )
	{
	m += 12;
	y -= 1;
	}
e = (306 * (m+1))/10;

a = y/100;	/* number of centuries */
if( year <= 1582L )
	{
	if( year == 1582L )
		{
		if( month < 10 )
			goto julius;
		if( month > 10)
			goto gregor;
		if( day >= 15 )
			goto gregor;
		}
julius:
	printf( " Julian Calendar assumed.\n" );
	b = -38;
	}
else
	{ /* -number of century years that are not leap years */
gregor:
	b = (a/4) - a;
	}

c = (36525 * y)/100; /* Julian calendar years and leap years */

/* Add up these terms, plus offset from J 0 to 1 Jan 4801 B.C.
 * Also fudge for the 122 days from the month algorithm.
 */
J = b + c + e + day - 32167.5;
return( J );
}






/* Reduce x modulo 360 degrees
 */
double mod360(x)
double x;
{
long k;
double y;

k = x/360.0;
y = x  -  k * 360.0;
while( y < 0.0 )
	y += 360.0;
while( y > 360.0 )
	y -= 360.0;
return(y);
}




/* Reduce x modulo 2 pi
 */
#define TPI (2.0*PI)
double modtp(x)
double x;
{
int k;
double y;

y = floor( x/TPI );
y = x - y * TPI;
while( y < 0.0 )
	y += TPI;
while( y >= TPI )
	y -= TPI;
return(y);
}


/* Get operator to type in hours, minutes, and seconds
 */
static int hours = 0;
static int minutes = 0;
static double seconds = 0.0;

double gethms()
{
char s[40];
double t, x;
/*
getnum( "Time: Hours", &hours, intfmt );
getnum( "Minutes", &minutes, intfmt );
getnum( "Seconds", &seconds, dblfmt );
t = (3600.0*hours + 60.0*minutes + seconds)/86400.0;
*/
t = UT_TIME  / 24.0 ;
printf ("gethms returning %lf days  \n",t);
return(t);
}

getnum( msg, num, format )
char *msg;
double *num;
char *format;
{
char s[40];

printf( "%s (", msg );
if( format == strfmt )
	printf( format, num );
else if( format == dblfmt )
	printf( format, *(double *)num );
else if( format == intfmt )
	printf( format, *(int *)num );
else if( format == lngfmt )
	printf( format, *(long *)num );
else
	printf( "Illegal input format\n"  );
printf( ") ? ");
gets(s);
if( s[0] != '\0' )
	sscanf( s, format, num );
}