/* 
 * getdate() %y checker
 * Author: Andrew Josey, (ajosey@xopen.org)
 *
 * Contributions by Walter Mecky 
 *
 * Determine window for the getdate() function.
 * 
 * Note that UNIX systems are required only to be able to
 * represent dates up until between Jan 1 1970 and Jan 1 2038,
 * some systems may be able to handle a wider range but its
 * not required. See comment to E_NOLINE_IN_INPUT.
 *
 * Based on the idea seen for a  test for strptime on comp.unix.aix
 * reworked to allow for the Jan 1 1970 - Jan 1 2038 limits on 
 * some systems.
 *
 * $Log: getdate.c,v $
 * Revision 1.6  1999/02/05 09:55:59  mew
 * It's not necessary now to change #defines for systems with smaller
 * intervalls. It's all done automatically.
 *
 *
 * Revision 1.4  1999/02/02 10:45:05  mew
 * Use stdio instead of system calls for enhanced portability
 *
 * Revision 1.2  1998/01/23  11:28:13  mew
 * No core dumps any more. Error message instead.
 * Does not need an extra mask file.
 */

#ifndef lint
static char *_version = "@(#)getdate_win.c 1.1 - 98/06/08";
#endif
#include <stdio.h>
#include <string.h>
#include <time.h>
extern int getdate_err;
#include <stdlib.h>
#ifdef sun
#include <tzfile.h>
#else
#define TM_YEAR_BASE 1900
#endif

#define TOG_START 0   
#define TOG_END 100
/*
 * Error code of my getdate(3C) if it cannot handle the year.
 * This may happen for years between 1900 and 1969.
 */
#define E_NOLINE_IN_INPUT 7
	
static char * tmpf;
static void cleanup(void)
{
	remove(tmpf);
}

main()
{
	int i;
	struct tm *tm_ptr;
	char buf[9];
	int years[100];
	char * cp;
	FILE * fp;
	char datemsk[] = "%d/%m/%y\n";
	char envstr[] = "DATEMSK=";

	if ((tmpf = tmpnam(NULL)) == NULL) {
		perror("tmpfname");
		fprintf(stderr, "Error: cannot create temp filename\n");
		return 1;
	}
	if ((fp = fopen(tmpf, "w")) == NULL) {
		perror("fopen");
		return 2;
	}
	atexit(cleanup);
	if (fputs(datemsk,fp ) == EOF) {
		perror("fputs");
		return 3;
	}
	fclose(fp);
	if ((cp = malloc(sizeof envstr + strlen(tmpf) + 1)) == NULL) {
		perror("malloc");
		return 1;
	}

	strcpy(cp, envstr);
	strcat(cp, tmpf);
	putenv(cp);

	/*
	 * run over the whole intervall and notice the year or the errorcode.
	 * the errorcode is stored with a minus sign.
	 */
	for (i = TOG_START ; i < TOG_END; i++) {
		sprintf(buf, "01/01/%02d", i);
		if ((tm_ptr = getdate (buf)) == NULL) {
				years[i] = -E_NOLINE_IN_INPUT;
/* exclude code block for the moment */
/*
			if (getdate_err == E_NOLINE_IN_INPUT)
				years[i] = -E_NOLINE_IN_INPUT;
			else {
				fprintf(stderr, "getdate: error %d\n", 
					getdate_err);
				return 1;
			}
*/
		}
		else {
			years[i] = tm_ptr->tm_year + TM_YEAR_BASE;
		}
#ifdef DEBUG
		printf("years[%d]=%d\n", i, years[i]);
#endif
	}

	/*
	 * Here comes the output.
	 * 2 windows are printet: a-b c-d
	 * a is the year for the two digit year 00.
	 * b is the last year in the same century as a.
	 * c is one year after b.
	 * d is the last year in the same century as c.
	 * At least you should see this: 2000-2038 1969-1999.
	 * It will be a bug in getdate(3C) if one window is smaller.
	 */
	printf("getdate(3C) window: %04d-", years[0]);
	for (i = 1; i <  TOG_END; i++) {
		if (years[i] == -E_NOLINE_IN_INPUT) {
#ifdef DEBUG
			printf("\noutp1 aborted. years[%d]=%d\n", i, years[i]);
#endif
			break;
		} else {
			/*
			 * Note: the condition here is true if 2 years are in
			 * different centuries: 19 -> 20 or 20 -> 19.
			 */
			if (years[i-1] / 100 != years[i] / 100)
				printf("%04d %04d-", years[i-1], years[i]);
		}
	}
	printf("%04d ", years[i-1]);

	if (i < TOG_END) {
		while (i < TOG_END && years[++i] < 0)
			/*empty*/ ;
		if (i < TOG_END) {
			printf("%04d-", years[i++]);
			for (; i <  TOG_END; i++) {
				if (years[i-1] / 100 != years[i] / 100)
					printf("%04d %04d-", years[i-1], years[i]);
			}
			printf("%04d", years[TOG_END-1]);
		}
	}
	printf("\n");

	return 0;
}