/* 
 * strftime.c --
 *
 *	This file contains a modified version of the BSD 4.4 strftime
 *	function.
 *
 * This file is a modified version of the strftime.c file from the BSD 4.4
 * source.  See the copyright notice below for details on redistribution
 * restrictions.  The "license.terms" file does not apply to this file.
 *
 * Changes 2002 Copyright (c) 2002 ActiveState Corporation.
 *
 * RCS: @(#) $Id: strftime.c,v 1.10.2.1 2004/05/18 21:52:56 kennykb Exp $
 */

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or 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 the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

#if defined(LIBC_SCCS)
static char *rcsid = "$Id: strftime.c,v 1.10.2.1 2004/05/18 21:52:56 kennykb Exp $";
#endif /* LIBC_SCCS */

#include <time.h>
#include <string.h>
#include <locale.h>
#include "tclInt.h"
#include "tclPort.h"

#define TM_YEAR_BASE   1900
#define IsLeapYear(x)   ((x % 4 == 0) && (x % 100 != 0 || x % 400 == 0))

typedef struct {
    const char *abday[7];
    const char *day[7];
    const char *abmon[12];
    const char *mon[12];
    const char *am_pm[2];
    const char *d_t_fmt;
    const char *d_fmt;
    const char *t_fmt;
    const char *t_fmt_ampm;
} _TimeLocale;

/*
 * This is the C locale default.  On Windows, if we wanted to make this
 * localized, we would use GetLocaleInfo to get the correct values.
 * It may be acceptable to do localization of month/day names, as the
 * numerical values would be considered the locale-independent versions.
 */
static const _TimeLocale _DefaultTimeLocale = 
{
    {
	"Sun","Mon","Tue","Wed","Thu","Fri","Sat",
    },
    {
	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
	"Friday", "Saturday"
    },
    {
	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
    },
    {
	"January", "February", "March", "April", "May", "June", "July",
	"August", "September", "October", "November", "December"
    },
    {
	"AM", "PM"
    },
    "%a %b %d %H:%M:%S %Y",
    "%m/%d/%y",
    "%H:%M:%S",
    "%I:%M:%S %p"
};

static const _TimeLocale *_CurrentTimeLocale = &_DefaultTimeLocale;

static int isGMT;
static size_t gsize;
static char *pt;
static int		 _add _ANSI_ARGS_((const char* str));
static int		_conv _ANSI_ARGS_((int n, int digits, int pad));
static int		_secs _ANSI_ARGS_((const struct tm *t));
static size_t		_fmt _ANSI_ARGS_((const char *format,
			    const struct tm *t));
static int ISO8601Week _ANSI_ARGS_((CONST struct tm* t, int *year ));

size_t
TclpStrftime(s, maxsize, format, t, useGMT)
    char *s;
    size_t maxsize;
    const char *format;
    const struct tm *t;
    int useGMT;
{
    if (format[0] == '%' && format[1] == 'Q') {
	/* Format as a stardate */
	sprintf(s, "Stardate %2d%03d.%01d",
		(((t->tm_year + TM_YEAR_BASE) + 377) - 2323),
		(((t->tm_yday + 1) * 1000) /
			(365 + IsLeapYear((t->tm_year + TM_YEAR_BASE)))),
		(((t->tm_hour * 60) + t->tm_min)/144));
	return(strlen(s));
    }

    isGMT = useGMT;
    /*
     * We may be able to skip this for useGMT, but it should be harmless.
     * -- hobbs
     */
    tzset();

    pt = s;
    if ((gsize = maxsize) < 1)
	return(0);
    if (_fmt(format, t)) {
	*pt = '\0';
	return(maxsize - gsize);
    }
    return(0);
}

#define SUN_WEEK(t)	(((t)->tm_yday + 7 - \
				((t)->tm_wday)) / 7)
#define MON_WEEK(t)	(((t)->tm_yday + 7 - \
				((t)->tm_wday ? (t)->tm_wday - 1 : 6)) / 7)

static size_t
_fmt(format, t)
    const char *format;
    const struct tm *t;
{
#ifdef WIN32
#define BUF_SIZ 256
    TCHAR buf[BUF_SIZ];
    SYSTEMTIME syst = {
	t->tm_year + 1900,
	t->tm_mon + 1,
	t->tm_wday,
	t->tm_mday,
	t->tm_hour,
	t->tm_min,
	t->tm_sec,
	0,
    };
#endif
    for (; *format; ++format) {
	if (*format == '%') {
	    ++format;
	    if (*format == 'E') {
				/* Alternate Era */
		++format;
	    } else if (*format == 'O') {
				/* Alternate numeric symbols */
		++format;
	    }
	    switch(*format) {
		case '\0':
		    --format;
		    break;
		case 'A':
		    if (t->tm_wday < 0 || t->tm_wday > 6)
			return(0);
		    if (!_add(_CurrentTimeLocale->day[t->tm_wday]))
			return(0);
		    continue;
		case 'a':
		    if (t->tm_wday < 0 || t->tm_wday > 6)
			return(0);
		    if (!_add(_CurrentTimeLocale->abday[t->tm_wday]))
			return(0);
		    continue;
		case 'B':
		    if (t->tm_mon < 0 || t->tm_mon > 11)
			return(0);
		    if (!_add(_CurrentTimeLocale->mon[t->tm_mon]))
			return(0);
		    continue;
		case 'b':
		case 'h':
		    if (t->tm_mon < 0 || t->tm_mon > 11)
			return(0);
		    if (!_add(_CurrentTimeLocale->abmon[t->tm_mon]))
			return(0);
		    continue;
		case 'C':
		    if (!_conv((t->tm_year + TM_YEAR_BASE) / 100,
			    2, '0'))
			return(0);
		    continue;
		case 'D':
		    if (!_fmt("%m/%d/%y", t))
			return(0);
		    continue;
		case 'd':
		    if (!_conv(t->tm_mday, 2, '0'))
			return(0);
		    continue;
		case 'e':
		    if (!_conv(t->tm_mday, 2, ' '))
			return(0);
		    continue;
	        case 'g':
		    {
			int year;
			ISO8601Week( t, &year );
			if ( !_conv( year%100, 2, '0' ) ) {
			    return( 0 );
			}
			continue;
		    }
	        case 'G':
		    {
			int year;
			ISO8601Week( t, &year );
			if ( !_conv( year, 4, '0' ) ) {
			    return( 0 );
			}
			continue;
		    }
		case 'H':
		    if (!_conv(t->tm_hour, 2, '0'))
			return(0);
		    continue;
		case 'I':
		    if (!_conv(t->tm_hour % 12 ?
			    t->tm_hour % 12 : 12, 2, '0'))
			return(0);
		    continue;
		case 'j':
		    if (!_conv(t->tm_yday + 1, 3, '0'))
			return(0);
		    continue;
		case 'k':
		    if (!_conv(t->tm_hour, 2, ' '))
			return(0);
		    continue;
		case 'l':
		    if (!_conv(t->tm_hour % 12 ?
			    t->tm_hour % 12: 12, 2, ' '))
			return(0);
		    continue;
		case 'M':
		    if (!_conv(t->tm_min, 2, '0'))
			return(0);
		    continue;
		case 'm':
		    if (!_conv(t->tm_mon + 1, 2, '0'))
			return(0);
		    continue;
		case 'n':
		    if (!_add("\n"))
			return(0);
		    continue;
		case 'p':
		    if (!_add(_CurrentTimeLocale->am_pm[t->tm_hour >= 12]))
			return(0);
		    continue;
		case 'R':
		    if (!_fmt("%H:%M", t))
			return(0);
		    continue;
		case 'r':
		    if (!_fmt(_CurrentTimeLocale->t_fmt_ampm, t))
			return(0);
		    continue;
		case 'S':
		    if (!_conv(t->tm_sec, 2, '0'))
			return(0);
		    continue;
		case 's':
		    if (!_secs(t))
			return(0);
		    continue;
		case 'T':
		    if (!_fmt("%H:%M:%S", t))
			return(0);
		    continue;
		case 't':
		    if (!_add("\t"))
			return(0);
		    continue;
		case 'U':
		    if (!_conv(SUN_WEEK(t), 2, '0'))
			return(0);
		    continue;
		case 'u':
		    if (!_conv(t->tm_wday ? t->tm_wday : 7, 1, '0'))
			return(0);
		    continue;
		case 'V':
		{
		    int week = ISO8601Week( t, NULL );
		    if (!_conv(week, 2, '0'))
			return(0);
		    continue;
		}
		case 'W':
		    if (!_conv(MON_WEEK(t), 2, '0'))
			return(0);
		    continue;
		case 'w':
		    if (!_conv(t->tm_wday, 1, '0'))
			return(0);
		    continue;
#ifdef WIN32
		/*
		 * To properly handle the localized time routines on Windows,
		 * we must make use of the special localized calls.
		 */
		case 'c':
		    if (!GetDateFormat(LOCALE_USER_DEFAULT, DATE_LONGDATE,
			    &syst, NULL, buf, BUF_SIZ) || !_add(buf)
			    || !_add(" ")) {
			return(0);
		    }
		    /*
		     * %c is created with LONGDATE + " " + TIME on Windows,
		     * so continue to %X case here.
		     */
		case 'X':
		    if (!GetTimeFormat(LOCALE_USER_DEFAULT, 0,
			    &syst, NULL, buf, BUF_SIZ) || !_add(buf)) {
			return(0);
		    }
		    continue;
		case 'x':
		    if (!GetDateFormat(LOCALE_USER_DEFAULT, DATE_SHORTDATE,
			    &syst, NULL, buf, BUF_SIZ) || !_add(buf)) {
			return(0);
		    }
		    continue;
#else
		case 'c':
		    if (!_fmt(_CurrentTimeLocale->d_t_fmt, t))
			return(0);
		    continue;
		case 'x':
		    if (!_fmt(_CurrentTimeLocale->d_fmt, t))
			return(0);
		    continue;
		case 'X':
		    if (!_fmt(_CurrentTimeLocale->t_fmt, t))
			return(0);
		    continue;
#endif
		case 'y':
		    if (!_conv((t->tm_year + TM_YEAR_BASE) % 100,
			    2, '0'))
			return(0);
		    continue;
		case 'Y':
		    if (!_conv((t->tm_year + TM_YEAR_BASE), 4, '0'))
			return(0);
		    continue;
		case 'Z': {
		    char *name = (isGMT ? "GMT" : TclpGetTZName(t->tm_isdst));
		    if (name && !_add(name)) {
			return 0;
		    }
		    continue;
		}
		case '%':
		    /*
		     * X311J/88-090 (4.12.3.5): if conversion char is
		     * undefined, behavior is undefined.  Print out the
		     * character itself as printf(3) does.
		     */
		default:
		    break;
	    }
	}
	if (!gsize--)
	    return(0);
	*pt++ = *format;
    }
    return(gsize);
}

static int
_secs(t)
    const struct tm *t;
{
    static char buf[15];
    register time_t s;
    register char *p;
    struct tm tmp;

    /* Make a copy, mktime(3) modifies the tm struct. */
    tmp = *t;
    s = mktime(&tmp);
    for (p = buf + sizeof(buf) - 2; s > 0 && p > buf; s /= 10)
	*p-- = (char)(s % 10 + '0');
    return(_add(++p));
}

static int
_conv(n, digits, pad)
    int n, digits;
    int pad;
{
    static char buf[10];
    register char *p;

    for (p = buf + sizeof(buf) - 2; n > 0 && p > buf; n /= 10, --digits)
	*p-- = (char)(n % 10 + '0');
    while (p > buf && digits-- > 0)
	*p-- = (char) pad;
    return(_add(++p));
}

static int
_add(str)
    const char *str;
{
    for (;; ++pt, --gsize) {
	if (!gsize)
	    return(0);
	if (!(*pt = *str++))
	    return(1);
    }
}

static int
ISO8601Week( t, year )
    CONST struct tm* t;
    int* year;
{
    /* Find the day-of-year of the Thursday in
     * the week in question. */
    
    int ydayThursday;
    int week;
    if ( t->tm_wday == 0 ) {
	ydayThursday = t->tm_yday - 3;
    } else {
	ydayThursday = t->tm_yday - t->tm_wday + 4;
    }
    
    if ( ydayThursday < 0 ) {
	
	/* This is the last week of the previous year. */
	if ( IsLeapYear(( t->tm_year + TM_YEAR_BASE - 1 )) ) {
	    ydayThursday += 366;
	} else {
	    ydayThursday += 365;
	}
	week = ydayThursday / 7 + 1;
	if ( year != NULL ) {
	    *year = t->tm_year + 1899;
	}
	
    } else if ( ( IsLeapYear(( t -> tm_year + TM_YEAR_BASE ))
		  && ydayThursday >= 366 )
		|| ( !IsLeapYear(( t -> tm_year
				   + TM_YEAR_BASE ))
		     && ydayThursday >= 365 ) ) {
	
	/* This is week 1 of the following year */
	
	week = 1;
	if ( year != NULL ) {
	    *year = t->tm_year + 1901;
	}
	
    } else {
	
	week = ydayThursday / 7 + 1;
	if ( year != NULL ) {
	    *year = t->tm_year + 1900;
	}
	
    }

    return week;
    
}
