/* Like datefmt, but for the Mayan calendars */
/* Needs cleanup */

#include <u.h>
#include <libc.h>

/* Unix epoch, Jan 1, 1970, is "13 Chikchan 3 K'ank'in, 12.17.16.7.5" */

/* Tzolk'in: 260-day count */
/* 20 names, 13 numbers, both incrementing daily */
/* Numbers used were 1-13 */

char *tzolkin_d[]=
{
	"Imix'", "Ik'", "Ak'b'al", "K'an", "Chikchan",
	"Kimi", "Manik'", "lamat", "Muluk", "Ok",
	"Chuwen", "Eb'", "B'en", "Ix", "Men",
	"K'ib'", "Kab'an", "Etz'nab'", "Kawak", "Ajaw",
};

/* Haab': 365-day count */
/* 18 months of 20 days, plus five days */
/* Days of the month went from 0-19 (per most research) */

char *haab_m[]=
{
	"Pop", "Wo'", "Sip'", "Sotz'", "Sek", "Xul",
	"Yaxk'in'", "Mol", "Ch'en", "Yax", "Sak'", "Keh",
	"Mak", "K'ank'in", "Muwan'", "Pax", "K'ayab", "Kumk'u",
	"Wayeb'",
};

/* Long Count */
/* Most inscriptions usually used just the first 5 places */
/* K'in (day) */
/* Winal is 20 K'in */
/* Tun is 18 Winal */
/* K'atun is 20 Tun */
/* B'ak'tun is 20 K'atun */

/* Piktun is 20 B'ak'tun */
/* Kalabtun is 20 Piktun */
/* K'inchiltun is 20 Kalabtun */
/* Alautun is 20 K'inchiltun */

/* Codes: aAbB  dD       H    kK LmMnN      rR  tTuU  wW X   Z % */

typedef
struct Lc
{
	int kin;
	int winal;
	int tun;
	int katun;
	int baktun;

	int piktun;
	int kalabtun;
	int kinchiltun;
	int alautun;
} Lc;

typedef
struct Maya_t
{
	int trecena;
	int name;
	int hdn;		/* Haab' day number; internal only. */
	int number;
	int month;
	Lc longcount;
} Maya_t;

char *format_t(char *, Maya_t);
Maya_t* init(long);
ulong now;

void
usage(void)
{
	fprint(2, "usage: %s [-t seconds] format\n", argv0);
	exits("usage");
}

void
main(int argc, char *argv[])
{
	Maya_t *now_m;

	now = time(0);

	ARGBEGIN{
	case 't':
		now = strtoul(EARGF(usage()), 0, 0);
		break;
	default:
		usage();
	}ARGEND

	if(! argc == 1)
		usage();

	now_m = init(now);

	print("%s", format_t(argv[0], *now_m));

	exits(0);
}

/* Generate a Maya_t; analogous to /sys/src/libc/9sys/ctime.c:/^gmtime */
Maya_t*
init(long tim)
{
	long day;
	long d_winal, d_tun, d_katun, d_baktun;	/* Days per winal, &c. */
	static Maya_t mt;

	/*
	 * break initial number into days
	 */
	day = tim / 86400L;
	if(tim % 86400L < 0)
		day -= 1;

	d_winal=20;
	d_tun=20*18;
	d_katun=20*18*20;
	d_baktun=20*18*20*20;

	mt.trecena=((12+day)%13)+1;	/* 1-13, not 0-12 */
	mt.name=(4+day)%20;
	mt.hdn=(263+day)%365;
	mt.number=(mt.hdn)%20;
	mt.month=(((mt.hdn)/20))%19;

	/* Pick & set an epoch. Make sure mt.longcount & day match. */

	mt.longcount.alautun=0;
	mt.longcount.kinchiltun=0;
	mt.longcount.kalabtun=0;
	mt.longcount.piktun=0;

	mt.longcount.baktun=12;
	mt.longcount.katun=17;
	mt.longcount.tun=16;
	mt.longcount.winal=7;
	mt.longcount.kin=5;

	if(day>0) {
		mt.longcount.kin = (mt.longcount.kin + day)%20;
		day -= mt.longcount.kin-5;
		mt.longcount.winal = (mt.longcount.winal + day/d_winal)%18;
		day -= (mt.longcount.winal-7)*d_winal;
		mt.longcount.tun = (mt.longcount.tun + day/d_tun)%20;
		day -= (mt.longcount.tun-16)*d_tun;
		mt.longcount.katun = (mt.longcount.katun + day/d_katun)%20;
		day -= (mt.longcount.katun-17)*d_katun;
		mt.longcount.baktun = (mt.longcount.baktun + day/d_baktun)%20;
//		day -= (mt.longcount.baktun-12)*d_baktun;

	} else if(day<0) {
print("NEGATIVE DAY: BOGUS VALUES!	");
		;
	}

	return &mt;
}


char *
format_t(char *format, Maya_t m)
{
	char *outb;
	int i;

	outb="";

	for(i = 0; i < strlen(format); i++){
		if(format[i] != '%') {
			outb=smprint("%s%c", outb, format[i]);
		}
		else switch(format[++i]){

			/* Tzolk'in dates "1 Imix'", "12 Men", &c */
			case 'T':
				outb=smprint("%s%s", outb, format_t("%R %N", m));
				break;
			case 'r':
				outb=smprint("%s%.2d", outb, m.trecena);
				break;
			case 'R':
				outb=smprint("%s%d", outb, m.trecena);
				break;
//			case 'n':
//				outb=smprint("%s%.2d", outb, m.name);
//				break;
			case 'N':
				outb=smprint("%s%s", outb, tzolkin_d[m.name]);
				break;

			/* Haab' dates "0 Pop", "3 Wo", &c */
			case 'H':
				outb=smprint("%s%s", outb, format_t("%D %M", m));
				break;
			case 'd':
				outb=smprint("%s%.2d", outb, m.number);
				break;
			case 'D':
				outb=smprint("%s%d", outb, m.number);
				break;
			case 'm':
				outb=smprint("%s%.2d", outb, m.month);
				break;
			case 'M':
				outb=smprint("%s%s", outb, haab_m[m.month]);
				break;

			/* Written together as "1 Imix' 0 Pop", "12 Men 3 Wo", &c */
			case 'X':
				outb=smprint("%s%s", outb, format_t("%T %H", m));
				break;

			/* Long Count and components */
			case 'L':
				outb=smprint("%s%s", outb, format_t("%B.%A.%U.%W.%K", m));
				break;
			case 'k':
				outb=smprint("%s%.2d", outb, m.longcount.kin);
				break;
			case 'K':
				outb=smprint("%s%d", outb, m.longcount.kin);
				break;
			case 'w':
				outb=smprint("%s%.2d", outb, m.longcount.winal);
				break;
			case 'W':
				outb=smprint("%s%d", outb, m.longcount.winal);
				break;
			case 'u':
				outb=smprint("%s%.2d", outb, m.longcount.tun);
				break;
			case 'U':
				outb=smprint("%s%d", outb, m.longcount.tun);
				break;
			case 'a':
				outb=smprint("%s%.2d", outb, m.longcount.katun);
				break;
			case 'A':
				outb=smprint("%s%d", outb, m.longcount.katun);
				break;
			case 'b':
				outb=smprint("%s%.2d", outb, m.longcount.baktun);
				break;
			case 'B':
				outb=smprint("%s%d", outb, m.longcount.baktun);
				break;

			/* Need higher-order long count places */

			/* Everything together. How were these really written? */
			case 'Z':
				outb=smprint("%s%s", outb, format_t("%X %L", m));
				break;
			case '+':
				outb=smprint("%s%s\n", outb, format_t("%Z", m));
				break;

			/* Literals and others */
			case ' ':
				outb=smprint("%s%s", outb, "% ");
				break;
			case '%':
				outb=smprint("%s%s", outb, "%");
				break;
			case 'n':
				outb=smprint("%s%s", outb, "\n");
				break;
			case 't':
				outb=smprint("%s%s", outb, "	");
				break;
			default:
				break;
			}
	}
	return outb;
}