/*	$OpenBSD: day.c,v 1.14 2001/11/19 19:02:13 mpech Exp $	*/
/*	$Id: day.c,v 1.3 2002/12/24 10:06:15 drey Exp $	*/

/*
 * Copyright (c) 1989, 1993, 1994
 *	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.
 */

#include <sys/types.h>
#include <sys/uio.h>

#include <ctype.h>
#include <err.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "pathnames.h"
#include "calendar.h"

#define WEEKLY 1
#define MONTHLY 2
#define YEARLY 3

struct tm *tp;
int *cumdays, offset;
char dayname[10];


/* 1-based month, 0-based days, cumulative */
int daytab[][14] = {
    {0, -1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364},
    {0, -1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
};

static char *days[] = {
    "sun", "mon", "tue", "wed", "thu", "fri", "sat", NULL,
};

static char *months[] = {
    "jan", "feb", "mar", "apr", "may", "jun",
    "jul", "aug", "sep", "oct", "nov", "dec", NULL,
};

static struct fixs fndays[8];	/* full national days names */
static struct fixs ndays[8];	/* short national days names */

static struct fixs fnmonths[13];	/* full national months names */
static struct fixs nmonths[13];	/* short national month names */

int isleap(int year)
{
    return (year % 4 == 0) && ((year % 400 == 0) || (year % 100 != 0));
}

void setnnames(void)
{
    char buf[80];
    int i, l;
    struct tm tm;

    for (i = 0; i < 7; i++) {
	tm.tm_wday = i;
	l = strftime(buf, sizeof(buf), "%a", &tm);
	for (; l > 0 && isspace((int) buf[l - 1]); l--);
	buf[l] = '\0';
	if (ndays[i].name != NULL)
	    free(ndays[i].name);
	if ((ndays[i].name = strdup(buf)) == NULL)
	    err(1, NULL);
	ndays[i].len = strlen(buf);

	l = strftime(buf, sizeof(buf), "%A", &tm);
	for (; l > 0 && isspace((int) buf[l - 1]); l--);
	buf[l] = '\0';
	if (fndays[i].name != NULL)
	    free(fndays[i].name);
	if ((fndays[i].name = strdup(buf)) == NULL)
	    err(1, NULL);
	fndays[i].len = strlen(buf);
    }

    for (i = 0; i < 12; i++) {
	tm.tm_mon = i;
	l = strftime(buf, sizeof(buf), "%b", &tm);
	for (; l > 0 && isspace((int) buf[l - 1]); l--);
	buf[l] = '\0';
	if (nmonths[i].name != NULL)
	    free(nmonths[i].name);
	if ((nmonths[i].name = strdup(buf)) == NULL)
	    err(1, NULL);
	nmonths[i].len = strlen(buf);

	l = strftime(buf, sizeof(buf), "%B", &tm);
	for (; l > 0 && isspace((int) buf[l - 1]); l--);
	buf[l] = '\0';
	if (fnmonths[i].name != NULL)
	    free(fnmonths[i].name);
	if ((fnmonths[i].name = strdup(buf)) == NULL)
	    err(1, NULL);
	fnmonths[i].len = strlen(buf);
    }
    /* Hardwired special events */
    spev[0].name = strdup(EASTER);
    spev[0].nlen = EASTERNAMELEN;
    spev[0].getev = easter;
    spev[1].name = strdup(PASKHA);
    spev[1].nlen = PASKHALEN;
    spev[1].getev = paskha;
    for (i = 0; i < NUMEV; i++) {
	if (spev[i].name == NULL)
	    err(1, NULL);
	spev[i].uname = NULL;
    }
}

void settime(time_t * now)
{
    tp = localtime(now);
    tp->tm_sec = 0;
    tp->tm_min = 0;
    /* Avoid getting caught by a timezone shift; set time to noon */
    tp->tm_isdst = 0;
    tp->tm_hour = 12;
    *now = mktime(tp);
    if (isleap(tp->tm_year + TM_YEAR_BASE))
	cumdays = daytab[1];
    else
	cumdays = daytab[0];
    /* Friday displays Monday's events */
    offset = tp->tm_wday == 5 ? 3 : 1;
    if (f_dayAfter)
	offset = 0;		/* Except not when range is set explicitly */

    setnnames();
}

/* convert [Year][Month]Day into unix time (since 1970)
 * Year: two or four digits, Month: two digits, Day: two digits
 */
time_t Mktime(char *date)
{
    time_t t;
    int len;
    struct tm tm;

    (void) time(&t);
    tp = localtime(&t);

    len = strlen(date);
    if (len < 2)
	return ((time_t) - 1);
    tm.tm_sec = 0;
    tm.tm_min = 0;
    /* Avoid getting caught by a timezone shift; set time to noon */
    tm.tm_isdst = 0;
    tm.tm_hour = 12;
    tm.tm_wday = 0;
    tm.tm_mday = tp->tm_mday;
    tm.tm_mon = tp->tm_mon;
    tm.tm_year = tp->tm_year;

    /* Day */
    tm.tm_mday = atoi(date + len - 2);

    /* Month */
    if (len >= 4) {
	*(date + len - 2) = '\0';
	tm.tm_mon = atoi(date + len - 4) - 1;
    }

    /* Year */
    if (len >= 6) {
	*(date + len - 4) = '\0';
	tm.tm_year = atoi(date);

	/* tm_year up TM_YEAR_BASE ... */
	if (tm.tm_year < 69)	/* Y2K */
	    tm.tm_year += 2000 - TM_YEAR_BASE;
	else if (tm.tm_year < 100)
	    tm.tm_year += 1900 - TM_YEAR_BASE;
	else if (tm.tm_year > TM_YEAR_BASE)
	    tm.tm_year -= TM_YEAR_BASE;
    }
#if DEBUG
    printf("Mktime: %d %d %d %s\n", (int) mktime(&tm), (int) t, len,
	   asctime(&tm));
#endif
    return (mktime(&tm));
}

/*
 * Possible date formats include any combination of:
 *	3-charmonth			(January, Jan, Jan)
 *	3-charweekday			(Friday, Monday, mon.)
 *	numeric month or day		(1, 2, 04)
 *
 * Any character except \t or '*' may separate them, or they may not be
 * separated.  Any line following a line that is matched, that starts
 * with \t, is shown along with the matched line.
 */
struct match *isnow(char *endp, int bodun)
{
    int day = 0, flags = 0, month = 0, v1, v2, i;
    int monthp, dayp, varp = 0;
    struct match *matches = NULL, *tmp, *tmp2;
    int interval = YEARLY;	/* how frequently the event repeats. */
    int vwd = 0;		/* Variable weekday */
    time_t tdiff, ttmp;
    struct tm tmtmp;

    /*
     * CONVENTION
     *
     * Month:     1-12
     * Monthname: Jan .. Dec
     * Day:       1-31
     * Weekday:   Mon-Sun
     *
     */

    /* read first field */
    /* didn't recognize anything, skip it */
    if (!(v1 = getfield(endp, &endp, &flags)))
	return (NULL);

    /* adjust bodun rate */
    if (bodun && !bodun_always)
	bodun = !(arc4random() % 3);

    /* Easter or Easter depending days */
    if (flags & F_SPECIAL)
	vwd = v1;

    /*
     * 1. {Weekday,Day} XYZ ...
     *
     *    where Day is > 12
     */
    else if (flags & F_ISDAY || v1 > 12) {

	/* found a day; day: 13-31 or weekday: 1-7 */
	day = v1;

	/* {Day,Weekday} {Month,Monthname} ... */
	/* if no recognizable month, assume just a day alone -- this is
	 * very unlikely and can only happen after the first 12 days.
	 * --find month or use current month */
	if (!(month = getfield(endp, &endp, &flags))) {
	    month = tp->tm_mon + 1;
	    /* F_ISDAY is set only if a weekday was spelled out */
	    /* F_ISDAY must be set if 0 < day < 8 */
	    if ((day <= 7) && (day >= 1))
		interval = WEEKLY;
	    else
		interval = MONTHLY;
	} else if ((day <= 7) && (day >= 1))
	    day += 10;
	/* it's a weekday; make it the first one of the month */
	if (month == -1) {
	    month = tp->tm_mon + 1;
	    interval = MONTHLY;
	}
	if ((month > 12) || (month < 1))
	    return (NULL);
    }

    /* 2. {Monthname} XYZ ... */
    else if (flags & F_ISMONTH) {
	month = v1;
	if (month == -1) {
	    month = tp->tm_mon + 1;
	    interval = MONTHLY;
	}
	/* Monthname {day,weekday} */
	/* if no recognizable day, assume the first day in month */
	if (!(day = getfield(endp, &endp, &flags)))
	    day = 1;
	/* If a weekday was spelled out without an ordering,
	 * assume the first of that day in the month */
	if ((flags & F_ISDAY) && (day >= 1) && (day <= 7))
	    day += 10;
    }

    /* Hm ... */
    else {
	v2 = getfield(endp, &endp, &flags);

	/*
	 * {Day} {Monthname} ...
	 * where Day <= 12
	 */
	if (flags & F_ISMONTH) {
	    day = v1;
	    month = v2;
	    if (month == -1) {
		month = tp->tm_mon + 1;
		interval = MONTHLY;
	    }
	}

	/* {Month} {Weekday,Day} ...  */
	else {
	    /* F_ISDAY set, v2 > 12, or no way to tell */
	    month = v1;
	    /* if no recognizable day, assume the first */
	    day = v2 ? v2 : 1;
	    if ((flags & F_ISDAY) && (day >= 1) && (day <= 7))
		day += 10;
	}
    }

    /* convert Weekday into *next*  Day,
     * e.g.: 'Sunday' -> 22
     *       'SundayLast' -> ??
     */
    if (flags & F_ISDAY) {
#if DEBUG
	fprintf(stderr, "\nday: %d %s month %d\n", day, endp, month);
#endif

	varp = 1;
	/* variable weekday, SundayLast, MondayFirst ... */
	if (day < 0 || day >= 10)
	    vwd = day;
	else {
	    day = tp->tm_mday + (((day - 1) - tp->tm_wday + 7) % 7);
	    interval = WEEKLY;
	}
    } else
	/* Check for silliness.  Note we still catch Feb 29 */
    if (!(flags & F_SPECIAL) &&
	    (day > (cumdays[month + 1] - cumdays[month]) || day < 1)) {
	if (!
	    ((month == 2 && day == 29)
	     || (interval == MONTHLY && day <= 31)))
	    return (NULL);
    }

    if (!(flags & F_SPECIAL)) {
	monthp = month;
	dayp = day;
	day = cumdays[month] + day;
#if DEBUG
	fprintf(stderr, "day2: day %d(%d) yday %d\n", dayp, day,
		tp->tm_yday);
#endif
	/* Speed up processing for the most common situation:  yearly events
	 * when the interval being checked is less than a month or so (this
	 * could be less than a year, but then we have to start worrying about
	 * leap years).  Only one event can match, and it's easy to find.
	 * Note we can't check special events, because they can wander widely.
	 */
	if (((v1 = offset + f_dayAfter) < 50) && (interval == YEARLY)) {
	    memcpy(&tmtmp, tp, sizeof(struct tm));
	    tmtmp.tm_mday = dayp;
	    tmtmp.tm_mon = monthp - 1;
	    if (vwd) {
		/* We want the event next year if it's late now
		 * this year.  The 50-day limit means we don't have to
		 * worry if next year is or isn't a leap year.
		 */
		if (tp->tm_yday > 300 && tmtmp.tm_mon <= 1)
		    variable_weekday(&vwd, tmtmp.tm_mon + 1,
				     tmtmp.tm_year + TM_YEAR_BASE + 1);
		else
		    variable_weekday(&vwd, tmtmp.tm_mon + 1,
				     tmtmp.tm_year + TM_YEAR_BASE);
		day = cumdays[tmtmp.tm_mon + 1] + vwd;
		tmtmp.tm_mday = vwd;
	    }
	    v2 = day - tp->tm_yday;
	    if ((v2 > v1) || (v2 < 0)) {
		if ((v2 += isleap(tp->tm_year + TM_YEAR_BASE) ? 366 : 365)
		    <= v1)
		    tmtmp.tm_year++;
		else if (!bodun || (day - tp->tm_yday) != -1)
		    return (NULL);
	    }
	    if ((tmp = malloc(sizeof(struct match))) == NULL)
		err(1, NULL);

	    if (bodun && (day - tp->tm_yday) == -1) {
		tmp->when = f_time - 1 * SECSPERDAY;
		tmtmp.tm_mday++;
		tmp->bodun = 1;
	    } else {
		tmp->when = f_time + v2 * SECSPERDAY;
		tmp->bodun = 0;
	    }

	    (void) mktime(&tmtmp);
	    if (strftime(tmp->print_date, sizeof(tmp->print_date),
			 /*    "%a %b %d", &tm);  Skip weekdays */
			 "%b %d", &tmtmp) == 0)
		tmp->print_date[sizeof(tmp->print_date) - 1] = '\0';

	    tmp->var = varp;
	    tmp->next = NULL;
	    return (tmp);
	}
    } else {
	varp = 1;
	/* Set up v1 to the event number and ... */
	v1 = vwd % (NUMEV + 1) - 1;
	vwd /= (NUMEV + 1);
	if (v1 < 0) {
	    v1 += NUMEV + 1;
	    vwd--;
	}
	dayp = monthp = 1;	/* Why not */
    }

    /* Compare to past and coming instances of the event.  The i == 0 part
     * of the loop corresponds to this specific instance.  Note that we
     * can leave things sort of higgledy-piggledy since a mktime() happens
     * on this before anything gets printed.  Also note that even though
     * we've effectively gotten rid of f_dayBefore, we still have to check
     * the one prior event for situations like "the 31st of every month"
     * and "yearly" events which could happen twice in one year but not in
     * the next */
    tmp2 = matches;
    for (i = -1; i < 2; i++) {
	memcpy(&tmtmp, tp, sizeof(struct tm));
	tmtmp.tm_mday = dayp;
	tmtmp.tm_mon = month = monthp - 1;
	do {
	    v2 = 0;
	    switch (interval) {
	    case WEEKLY:
		tmtmp.tm_mday += 7 * i;
		break;
	    case MONTHLY:
		month += i;
		tmtmp.tm_mon = month;
		switch (tmtmp.tm_mon) {
		case -1:
		    tmtmp.tm_mon = month = 11;
		    tmtmp.tm_year--;
		    break;
		case 12:
		    tmtmp.tm_mon = month = 0;
		    tmtmp.tm_year++;
		    break;
		}
		if (vwd) {
		    v1 = vwd;
		    variable_weekday(&v1, tmtmp.tm_mon + 1,
				     tmtmp.tm_year + TM_YEAR_BASE);
		    tmtmp.tm_mday = v1;
		} else
		    tmtmp.tm_mday = dayp;
		break;
	    case YEARLY:
	    default:
		tmtmp.tm_year += i;
		if (flags & F_SPECIAL) {
		    tmtmp.tm_mon = 0;	/* Gee, mktime() is nice */
		    tmtmp.tm_mday = spev[v1].getev(tmtmp.tm_year +
						   TM_YEAR_BASE) + vwd;
		} else if (vwd) {
		    v1 = vwd;
		    variable_weekday(&v1, tmtmp.tm_mon + 1,
				     tmtmp.tm_year + TM_YEAR_BASE);
		    tmtmp.tm_mday = v1;
		} else {
		    /* Need the following to keep Feb 29 from
		     * becoming Mar 1 */
		    tmtmp.tm_mday = dayp;
		    tmtmp.tm_mon = monthp - 1;
		}
		break;
	    }
	    /* How many days apart are we */
	    if ((ttmp = mktime(&tmtmp)) == -1)
		warnx("time out of range: %s", endp);
	    else {
		tdiff = difftime(ttmp, f_time) / SECSPERDAY;
		if (tdiff <= offset + f_dayAfter || (bodun && tdiff == -1)) {
		    if (tdiff >= 0 || (bodun && tdiff == -1)) {
			if ((tmp = malloc(sizeof(struct match))) == NULL)
			    err(1, NULL);
			tmp->when = ttmp;
			if (strftime
			    (tmp->print_date, sizeof(tmp->print_date),
			     /*    "%a %b %d", &tm);  Skip weekdays */
			     "%b %d", &tmtmp) == 0)
			    tmp->print_date[sizeof(tmp->print_date) - 1] =
				'\0';
			tmp->bodun = bodun && tdiff == -1;
			tmp->var = varp;
			tmp->next = NULL;
			if (tmp2)
			    tmp2->next = tmp;
			else
			    matches = tmp;
			tmp2 = tmp;
			v2 = (i == 1) ? 1 : 0;
		    }
		} else
		    i = 2;	/* No point checking in the future */
	    }
	}
	while (v2 != 0);
    }
    return (matches);
}


int getmonth(char *s)
{
    char **p;
    struct fixs *n;

    for (n = fnmonths; n->name; ++n)
	if (!strncasecmp(s, n->name, n->len))
	    return ((n - fnmonths) + 1);
    for (n = nmonths; n->name; ++n)
	if (!strncasecmp(s, n->name, n->len))
	    return ((n - nmonths) + 1);
    for (p = months; *p; ++p)
	if (!strncasecmp(s, *p, 3))
	    return ((p - months) + 1);
    return (0);
}


int getday(char *s)
{
    char **p;
    struct fixs *n;

    for (n = fndays; n->name; ++n)
	if (!strncasecmp(s, n->name, n->len))
	    return ((n - fndays) + 1);
    for (n = ndays; n->name; ++n)
	if (!strncasecmp(s, n->name, n->len))
	    return ((n - ndays) + 1);
    for (p = days; *p; ++p)
	if (!strncasecmp(s, *p, 3))
	    return ((p - days) + 1);
    return (0);
}

/* return offset for variable weekdays
 * -1 -> last weekday in month
 * +1 -> first weekday in month
 * ... etc ...
 */
int getdayvar(char *s)
{
    int offset;


    offset = strlen(s);

    /* Sun+1 or Wednesday-2
     *    ^              ^   */

    /* printf ("x: %s %s %d\n", s, s + offset - 2, offset); */
    switch (*(s + offset - 2)) {
    case '-':
    case '+':
	return (atoi(s + offset - 2));
	break;
    }

    /*
     * some aliases: last, first, second, third, fourth
     */

    /* last */
    if (offset > 4 && !strcasecmp(s + offset - 4, "last"))
	return (-1);
    else if (offset > 5 && !strcasecmp(s + offset - 5, "first"))
	return (+1);
    else if (offset > 6 && !strcasecmp(s + offset - 6, "second"))
	return (+2);
    else if (offset > 5 && !strcasecmp(s + offset - 5, "third"))
	return (+3);
    else if (offset > 6 && !strcasecmp(s + offset - 6, "fourth"))
	return (+4);

    /* no offset detected */
    return (0);
}


int foy(int year)
{
    /* 0-6; what weekday Jan 1 is */
    year--;
    return ((1 - year / 100 + year / 400 + (int) (365.25 * year)) % 7);
}



void variable_weekday(int *day, int month, int year)
{
    int v1, v2;
    int *cumdays;
    int day1;

    if (isleap(year))
	cumdays = daytab[1];
    else
	cumdays = daytab[0];
    day1 = foy(year);
    /* negative offset; last, -4 .. -1 */
    if (*day < 0) {
	v1 = *day / 10 - 1;	/* offset -4 ... -1 */
	*day = 10 + (*day % 10);	/* day 1 ... 7 */

	/* which weekday the end of the month is (1-7) */
	v2 = (cumdays[month + 1] + day1) % 7 + 1;

	/* and subtract enough days */
	*day = cumdays[month + 1] - cumdays[month] +
	    (v1 + 1) * 7 - (v2 - *day + 7) % 7;
#if DEBUG
	fprintf(stderr, "\nMonth %d ends on weekday %d\n", month, v2);
#endif
    }

    /* first, second ... +1 ... +5 */
    else {
	v1 = *day / 10;		/* offset */
	*day = *day % 10;

	/* which weekday the first of the month is (1-7) */
	v2 = (cumdays[month] + 1 + day1) % 7 + 1;

	/* and add enough days */
	*day = 1 + (v1 - 1) * 7 + (*day - v2 + 7) % 7;
#if DEBUG
	fprintf(stderr, "\nMonth %d starts on weekday %d\n", month, v2);
#endif
    }
}
