/*
 * Copyright (c) 1994 Powerdog Industries.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer
 *    in the documentation and/or other materials provided with the
 *    distribution.
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgement:
 *	This product includes software developed by Powerdog Industries.
 * 4. The name of Powerdog Industries may not be used to endorse or
 *    promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY POWERDOG INDUSTRIES ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE POWERDOG INDUSTRIES BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef lint
/*
static char copyright[] =
"@(#) Copyright (c) 1994 Powerdog Industries.  All rights reserved.";
static char sccsid[] = "@(#)strptime.c	1.0 (Powerdog) 94/03/27";
*/
#endif /* not lint */

#include <lib.h>

#include <time.h>
#include <ctype.h>
#include <locale.h>
#include <string.h>

#define asizeof(a)	((int)(sizeof (a) / sizeof ((a)[0])))

struct mydtconv {
    char	*abbrev_month_names[12];
    char	*month_names[12];
    char	*abbrev_weekday_names[7];
    char	*weekday_names[7];
    char	*time_format;
    char	*sdate_format;
    char	*dtime_format;
    char	*am_string;
    char	*pm_string;
    char	*ldate_format;
};

static struct mydtconv	En_US = {
    { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
      "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" },
    { "January", "February", "March", "April",
      "May", "June", "July", "August",
      "September", "October", "November", "December" },
    { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" },
    { "Sunday", "Monday", "Tuesday", "Wednesday",
      "Thursday", "Friday", "Saturday" },
    "%H:%M:%S",
    "%m/%d/%y",
    "%a %b %e %T %Z %Y",
    "AM",
    "PM",
    "%A, %B, %e, %Y"
};

char	*
mystrptime(const char *buf, const char *fmt, struct tm *tm)
{
    char	c;
    const char	*ptr;
    int	i, len = 0;

    ptr = fmt;
    while (*ptr != 0)
    {
	if (*buf == 0)
	    break;

	c = *ptr++;

	if (c != '%')
	{
	    if (isspace(c))
		while (*buf != 0 && isspace(*buf))
		    buf++;
	    else if (c != *buf++)
		return 0;
	    continue;
	}

	c = *ptr++;
	switch (c)
	{
	    case 0:
	    case '%':
		if (*buf++ != '%')
		    return 0;
		break;

	    case 'C':
		buf = mystrptime(buf, En_US.ldate_format, tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'c':
		buf = mystrptime(buf, "%x %X", tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'D':
		buf = mystrptime(buf, "%m/%d/%y", tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'R':
		buf = mystrptime(buf, "%H:%M", tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'r':
		buf = mystrptime(buf, "%I:%M:%S %p", tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'T':
		buf = mystrptime(buf, "%H:%M:%S", tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'X':
		buf = mystrptime(buf, En_US.time_format, tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'x':
		buf = mystrptime(buf, En_US.sdate_format, tm);
		if (buf == 0)
		    return 0;
		break;

	    case 'j':
		if (!isdigit(*buf))
		    return 0;

		for (i = 0; *buf != 0 && isdigit(*buf); buf++)
		{
		    i *= 10;
		    i += *buf - '0';
		}
		if (i > 365)
		    return 0;

		tm->tm_yday = i;
		break;

	    case 'M':
	    case 'S':
		if (*buf == 0 || isspace(*buf))
		    break;

		if (!isdigit(*buf))
		    return 0;

		for (i = 0; *buf != 0 && isdigit(*buf); buf++)
		{
		    i *= 10;
		    i += *buf - '0';
		}
		if (i > 59)
		    return 0;

		if (c == 'M')
		    tm->tm_min = i;
		else
		    tm->tm_sec = i;

		if (*buf != 0 && isspace(*buf))
		    while (*ptr != 0 && !isspace(*ptr))
			ptr++;
		break;

	    case 'H':
	    case 'I':
	    case 'k':
	    case 'l':
		if (!isdigit(*buf))
		    return 0;

		for (i = 0; *buf != 0 && isdigit(*buf); buf++)
		{
		    i *= 10;
		    i += *buf - '0';
		}
		if (c == 'H' || c == 'k') {
		    if (i > 23)
			return 0;
		} else if (i > 11)
		    return 0;

		tm->tm_hour = i;

		if (*buf != 0 && isspace(*buf))
		    while (*ptr != 0 && !isspace(*ptr))
			ptr++;
		break;

	    case 'p':
		len = strlen(En_US.am_string);
		if (mystrncasecmp(buf, En_US.am_string, len) == 0)
		{
		    if (tm->tm_hour > 12)
			return 0;
		    if (tm->tm_hour == 12)
			tm->tm_hour = 0;
		    buf += len;
		    break;
		}

		len = strlen(En_US.pm_string);
		if (mystrncasecmp(buf, En_US.pm_string, len) == 0)
		{
		    if (tm->tm_hour > 12)
			return 0;
		    if (tm->tm_hour != 12)
			tm->tm_hour += 12;
		    buf += len;
		    break;
		}

		return 0;

	    case 'A':
	    case 'a':
		for (i = 0; i < asizeof(En_US.weekday_names); i++)
		{
		    len = strlen(En_US.weekday_names[i]);
		    if (mystrncasecmp(buf,
				      En_US.weekday_names[i],
				      len) == 0)
			break;

		    len = strlen(En_US.abbrev_weekday_names[i]);
		    if (mystrncasecmp(buf,
				      En_US.abbrev_weekday_names[i],
				      len) == 0)
			break;
		}
		if (i == asizeof(En_US.weekday_names))
		    return 0;

		tm->tm_wday = i;
		buf += len;
		break;

	    case 'd':
	    case 'e':
		if (!isdigit(*buf))
		    return 0;

		for (i = 0; *buf != 0 && isdigit(*buf); buf++)
		{
		    i *= 10;
		    i += *buf - '0';
		}
		if (i > 31)
		    return 0;

		tm->tm_mday = i;

		if (*buf != 0 && isspace(*buf))
		    while (*ptr != 0 && !isspace(*ptr))
			ptr++;
		break;

	    case 'B':
	    case 'b':
	    case 'h':
		for (i = 0; i < asizeof(En_US.month_names); i++)
		{
		    len = strlen(En_US.month_names[i]);
		    if (mystrncasecmp(buf,
				      En_US.month_names[i],
				      len) == 0)
			break;

		    len = strlen(En_US.abbrev_month_names[i]);
		    if (mystrncasecmp(buf,
				      En_US.abbrev_month_names[i],
				      len) == 0)
			break;
		}
		if (i == asizeof(En_US.month_names))
		    return 0;

		tm->tm_mon = i;
		buf += len;
		break;

	    case 'm':
		if (!isdigit(*buf))
		    return 0;

		for (i = 0; *buf != 0 && isdigit(*buf); buf++)
		{
		    i *= 10;
		    i += *buf - '0';
		}
		if (i < 1 || i > 12)
		    return 0;

		tm->tm_mon = i - 1;

		if (*buf != 0 && isspace(*buf))
		    while (*ptr != 0 && !isspace(*ptr))
			ptr++;
		break;

	    case 'Y':
	    case 'y':
		if (*buf == 0 || isspace(*buf))
		    break;

		if (!isdigit(*buf))
		    return 0;

		for (i = 0; *buf != 0 && isdigit(*buf); buf++)
		{
		    i *= 10;
		    i += *buf - '0';
		}
		if (c == 'y' && i < 69)	/* Unix Epoch pivot year */
		    i += 100;
		if (c == 'Y')
		    i -= 1900;
		if (i < 0)
		    return 0;

		tm->tm_year = i;

		if (*buf != 0 && isspace(*buf))
		    while (*ptr != 0 && !isspace(*ptr))
			ptr++;
		break;
	}
    }

    return (char *) buf;
}