/* newlib/libc/time/strftime.c %z format STC */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define TZ	"TZ=NZST-12NZDT,M9.5.0,M4.1.0/3"
#define DFMT	"%04d-%02d-%02d %03d %-3d %02d:%02d%+03ld00%s(%s)\t%s\n" //:%02d
#define TFMT	"%F %j %a %R%z (%Z)"

#define EPOCH	1970
#define YADD	1900
#define MADD	 1
#define DADD	 1
#define YR_MTH	12
#define MTH_DAY	30
#define DAY_HR	24
#define HR_MIN	60
#define MIN_S	60
#define HR_S	(HR_MIN*MIN_S)

/* extra is total days over 30 in preceding months - net total 5/year */
#define S(extra,yr,mth,day,hr)	\
	((((((yr) - EPOCH)*YR_MTH + ((mth) - 1))*MTH_DAY + (extra) + (day) - 1)\
		*DAY_HR + (hr))*HR_S)


int
dump( struct tm* tp, char *label) {
    return printf( DFMT, tp->tm_year + YADD, tp->tm_mon + MADD, tp->tm_mday,
		tp->tm_yday + DADD, tp->tm_wday,
		tp->tm_hour, tp->tm_min,			// tp->tm_sec,
# ifdef __TM_GMTOFF
		tp->__TM_GMTOFF/HR_S,
# elif  __USE_BSD
		tp->tm_gmtoff/HR_S,
# else
		tp->__tm_gmtoff/HR_S,
# endif
		tp->tm_isdst < 0 ? "?" : tp->tm_isdst ? "d" : "s",
# ifdef __TM_ZONE
		tp->__TM_ZONE,
# elif  __USE_BSD
		tp->tm_zone,
# else
		tp->__tm_zone,
# endif
		label
	  	);
}


int
test( time_t tt ) {
    char	ss[BUFSIZ]	= "";
    struct tm *	tp;
    size_t	st;
    int		rc;

    if (EOF == (rc = puts( "" )))			return 5;
    if (!(tp = gmtime( &tt )))				return 1;
    if ((rc = dump( tp, "gm" )) <= 0)			return -rc;
    if (!(tp = localtime( &tt )))			return 2;
    if ((rc = dump( tp, "local" )) <= 0)		return -rc;
    if (-1 == (tt = mktime( tp )))			return 3;
    if ((rc = dump( tp, "mk" )) <= 0)			return -rc;
    if ((st = strftime( ss, sizeof ss, TFMT, tp)) <= 0)	return 4;
    if (EOF == (rc = puts( ss )))			return 5;

    return 0;
}


int
main( void ) {
    int	rc;

    if ((rc = putenv( TZ )))			return rc;
    if (EOF == (rc = puts( getenv( "TZ" ))))	return 6;
    /*		   extra  year  m day hour	*/
    if ((rc = test( S( 0, 1970, 1,  1,  0))))	return rc;
    if ((rc = test( S( 0, 1970, 4,  4, 13))))	return rc;
    if ((rc = test( S( 0, 1970, 4,  4, 14))))	return rc;
    if ((rc = test( S( 3, 1970, 9, 26, 13))))	return rc;
    if ((rc = test( S( 3, 1970, 9, 26, 14))))	return rc;
    if ((rc = test( S( 5, 1971, 1,  1,  0))))	return rc;
    if ((rc = test( S( 5, 1971, 4,  3, 13))))	return rc;
    if ((rc = test( S( 5, 1971, 4,  3, 14))))	return rc;

    return rc;
}