/*
   =============================================================================
	date.c -- date - with format capabilities
	Version 1 -- 1988-01-14
   =============================================================================
*/

#include	"types.h"
#include	"utmp.h"
#include        "stdio.h"
#include	"time.h"

#define	MONTH		itoa(tim->tm_mon+1, cp,2)
#define	DAY		itoa(tim->tm_mday, cp, 2)
#define	YEAR		itoa(tim->tm_year, cp, 2)
#define	HOUR		itoa(tim->tm_hour, cp, 2)
#define	MINUTE		itoa(tim->tm_min, cp, 2)
#define	SECOND		itoa(tim->tm_sec, cp, 2)
#define	JULIAN		itoa(tim->tm_yday+1, cp, 3)
#define	WEEKDAY		itoa(tim->tm_wday, cp, 1)
#define	MODHOUR		itoa(h, cp, 2)
#define	dysize(A)	(((A) % 4) ? 365 : 366)

int dmsize[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

char	month[12][3] = {

	"Jan","Feb","Mar","Apr",
	"May","Jun","Jul","Aug",
	"Sep","Oct","Nov","Dec"
};

char	days[7][3] = {

	"Sun","Mon","Tue","Wed",
	"Thu","Fri","Sat"
};

char	*itoa();
char	*cbp;
long	timbuf;

struct	utmp	wtmp[2] = {

	{"", "", OTIME_MSG, 0, OLD_TIME, 0, 0, 0},
	{"", "", NTIME_MSG, 0, NEW_TIME, 0, 0, 0}
};

/*
   =============================================================================
	gpair() -- get 2 digits
   =============================================================================
*/

int
gpair()
{
	register int c, d;
	register char *cp;

	cp = cbp;

	if(*cp == 0)
		return(-1);

	c = (*cp++ - '0') * 10;

	if (c<0 || c>100)
		return(-1);

	if(*cp == 0)
		return(-1);

	if ((d = *cp++ - '0') < 0 || d > 9)
		return(-1);

	cbp = cp;

	return (c+d);
}

/*  */

/*
   =============================================================================
	gtime() -- get time
   =============================================================================
*/

int
gtime()
{
	register int i;
	register int y, t;
	int d, h, m;
	long nt;

	tzset();

	t = gpair();

	if (t < 1 OR t > 12)
		return(1);

	d = gpair();

	if(d < 1 OR d > 31)
		return(1);

	h = gpair();

	if (h EQ 24) {

		h = 0;
		d++;
	}

	m = gpair();

	if (m < 0 OR m > 59)
		return(1);

	y = gpair();

	if (y < 0) {

		(void) time(&nt);
		y = localtime(&nt)->tm_year;
	}

	if (*cbp EQ 'p')
		h += 12;

	if (h < 0 OR h > 23)
		return(1);

	timbuf = 0;
	y += 1900;

	for(i = 1970; i < y; i++)
		timbuf += dysize(i);

	/* Leap year */

	if (dysize(y) EQ 366 AND t GE 3)
		timbuf += 1;

	while (--t)
		timbuf += dmsize[t - 1];

	timbuf += (d - 1);
	timbuf *= 24;
	timbuf += h;
	timbuf *= 60;
	timbuf += m;
	timbuf *= 60;

	return(0);
}

/*  */

/*
   =============================================================================
	itoa(i,ptr,dig)
   =============================================================================
*/

char *
itoa(i, ptr, dig)
register  int	i;
register  char	*ptr;
register  int	dig;
{
	switch(dig)	{

		case 3:
			*ptr++ = i/100 + '0';
			i = i - i / 100 * 100;

		case 2:
			*ptr++ = i / 10 + '0';

		case 1:	
			*ptr++ = i % 10 + '0';
	}

	return(ptr);
}

/*  */

main(argc, argv)
int	argc;
int	**argv;
{
	register char	*aptr, *cp, c;
	int	 h, hflag, i, tfailed, wf;
	long	tbuf, time(), lseek();
	struct	tm  *tim;
	char	 buf[200], *tzn;

	tfailed = 0;

	if(argc > 1) {

		cbp = (char *)argv[1];

		if(*cbp == '+')	{

			hflag = 0;

			for(cp=buf;cp< &buf[200];)
				*cp++ = '\0';

			(void) time(&tbuf);
			tim = localtime(&tbuf);
			aptr = (char *)argv[1];
			aptr++;
			cp = buf;

			while(c = *aptr++) {

			if(c == '%')
			switch(*aptr++) {

			case '%':
				*cp++ = '%';
				continue;

			case 'n':
				*cp++ = '\n';
				continue;

			case 't':
				*cp++ = '\t';
				continue;

			case 'm' :
				cp = MONTH;
				continue;

			case 'd':
				cp = DAY;
				continue;

			case 'y' :
				cp = YEAR;
				continue;

			case 'D':
				cp = MONTH;
				*cp++ = '/';
				cp = DAY;
				*cp++ = '/';
				cp = YEAR;
				continue;

			case 'H':
				cp = HOUR;
				continue;

			case 'M':
				cp = MINUTE;
				continue;

			case 'S':
				cp = SECOND;
				continue;

			case 'T':
				cp = HOUR;
				*cp++ = ':';
				cp = MINUTE;
				*cp++ = ':';
				cp = SECOND;
				continue;

			case 'j':
				cp = JULIAN;
				continue;

			case 'w':
				cp = WEEKDAY;
				continue;

			case 'r':
				if((h = tim->tm_hour) >= 12)
					hflag++;

				if((h %= 12) == 0)
					h = 12;

				cp = MODHOUR;
				*cp++ = ':';
				cp = MINUTE;
				*cp++ = ':';
				cp = SECOND;
				*cp++ = ' ';

				if(hflag)
					*cp++ = 'P';
				else
					*cp++ = 'A';

				*cp++ = 'M';
				continue;

			case 'h':
				for(i=0; i<3; i++)
					*cp++ = month[tim->tm_mon][i];
				continue;

			case 'a':
				for(i=0; i<3; i++)
					*cp++ = days[tim->tm_wday][i];
				continue;

			default:
				(void) fprintf(stderr, "date: bad format character - %c\n", *--aptr);
				exit(2);
			}	/* endsw */

			*cp++ = c;

			}	/* endwh */

			*cp = '\n';
			(void) write(1,buf,(cp - &buf[0]) + 1);
			exit(0);
		}

		if(*cbp == '-') {

			(void) fprintf(stderr,"date: no TOY clock\n");
			exit(2);
		}

		if(gtime()) {

			(void) fprintf(stderr,"date: bad conversion\n");
			exit(2);
		}

	/* convert to Greenwich time, on assumption of Standard time. */

		timbuf += timezone;

	/* Now fix up to local daylight time. */

		if (localtime(&timbuf)->tm_isdst)
			timbuf += -1*60*60;

		(void) time(&wtmp[0].ut_time);

		if(stime(&timbuf) < 0) {

			tfailed++;
			(void) fprintf(stderr, "date: no permission\n");

		} else {
			(void) time(&wtmp[1].ut_time);

/*	Attempt to write entries to the utmp file and to the wtmp file.	*/

			pututline(&wtmp[0]) ;
			pututline(&wtmp[1]) ;

			if ((wf = open(WTMP_FILE, 1)) >= 0) {

				(void) lseek(wf, 0L, 2);
				(void) write(wf, (char *)wtmp, sizeof(wtmp));
			}
		}
	}

	if (tfailed==0)
		(void) time(&timbuf);

	cbp = ctime(&timbuf);
	(void) write(1, cbp, 20);
	tzn = tzname[localtime(&timbuf)->tm_isdst];

	if (tzn)
		(void) write(1, tzn, 3);

	(void) write(1, cbp + 19, 6);
	exit(tfailed ? 2 : 0);
}