/* Miscellaneous time-related utilities
*
* Copyright (C) 1998 The Free Software Foundation
*
* Authors: Federico Mena <federico@nuclecu.unam.mx>
* Miguel de Icaza <miguel@nuclecu.unam.mx>
*/
#include <libgnome/libgnome.h>
#include <string.h>
#include "timeutil.h"
void
print_time_t (time_t t)
{
struct tm *tm = localtime (&t);
printf ("%d/%02d/%02d %02d:%02d:%02d",
1900 + tm->tm_year, tm->tm_mon+1, tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
}
char *
isodate_from_time_t (time_t t)
{
struct tm *tm;
static char isotime [40];
tm = localtime (&t);
strftime (isotime, sizeof (isotime)-1, "%Y%m%dT%H%M%S", tm);
return isotime;
}
time_t
time_add_minutes (time_t time, int minutes)
{
struct tm *tm = localtime (&time);
time_t new_time;
tm->tm_min += minutes;
if ((new_time = mktime (tm)) == -1) {
g_message ("time_add_minutes(): mktime() could not handle "
"adding %d minutes with\n", minutes);
print_time_t (time);
printf ("\n");
return time;
}
return new_time;
}
/* Adds a day onto the time, using local time.
Note that if clocks go forward due to daylight savings time, there are
some non-existent local times, so the hour may be changed to make it a
valid time. This also means that it may not be wise to keep calling
time_add_day() to step through a certain period - if the hour gets changed
to make it valid time, any further calls to time_add_day() will also return
this hour, which may not be what you want. */
time_t
time_add_day (time_t time, int days)
{
struct tm *tm = localtime (&time);
time_t new_time;
#if 0
int dst_flag = tm->tm_isdst;
#endif
tm->tm_mday += days;
tm->tm_isdst = -1;
if ((new_time = mktime (tm)) == -1) {
g_message ("time_add_day(): mktime() could not handling adding %d days with\n",
days);
print_time_t (time);
printf ("\n");
return time;
}
#if 0
/* I don't know what this is for. See also time_day_begin() and
time_day_end(). - Damon. */
if (dst_flag > tm->tm_isdst) {
tm->tm_hour++;
new_time += 3600;
} else if (dst_flag < tm->tm_isdst) {
tm->tm_hour--;
new_time -= 3600;
}
#endif
return new_time;
}
time_t
time_add_week (time_t time, int weeks)
{
return time_add_day (time, weeks * 7);
}
time_t
time_add_month (time_t time, int months)
{
struct tm *tm = localtime (&time);
time_t new_time;
int mday;
mday = tm->tm_mday;
tm->tm_mon += months;
tm->tm_isdst = -1;
if ((new_time = mktime (tm)) == -1) {
g_message ("time_add_month(): mktime() could not handling adding %d months with\n",
months);
print_time_t (time);
printf ("\n");
return time;
}
tm = localtime (&new_time);
if (tm->tm_mday < mday) {
tm->tm_mon--;
tm->tm_mday = time_days_in_month (tm->tm_year+1900, tm->tm_mon);
return new_time = mktime (tm);
}
else
return new_time;
}
time_t
time_add_year (time_t time, int years)
{
struct tm *tm = localtime (&time);
time_t new_time;
tm->tm_year += years;
if ((new_time = mktime (tm)) == -1) {
g_message ("time_add_year(): mktime() could not handling adding %d years with\n",
years);
print_time_t (time);
printf ("\n");
return time;
}
return new_time;
}
/* Number of days in a month, for normal and leap years */
static const int days_in_month[2][12] = {
{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
};
/* Returns whether the specified year is a leap year */
static int
is_leap_year (int year)
{
if (year <= 1752)
return !(year % 4);
else
return (!(year % 4) && (year % 100)) || !(year % 400);
}
int
time_days_in_month (int year, int month)
{
g_return_val_if_fail (year >= 1900, 0);
g_return_val_if_fail ((month >= 0) && (month < 12), 0);
return days_in_month [is_leap_year (year)][month];
}
time_t
time_from_day (int year, int month, int day)
{
struct tm tm;
memset (&tm, 0, sizeof (tm));
tm.tm_year = year - 1900;
tm.tm_mon = month;
tm.tm_mday = day;
tm.tm_isdst = -1;
return mktime (&tm);
}
time_t
time_year_begin (time_t t)
{
struct tm tm;
tm = *localtime (&t);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_mon = 0;
tm.tm_mday = 1;
tm.tm_isdst = -1;
return mktime (&tm);
}
time_t
time_year_end (time_t t)
{
struct tm tm;
tm = *localtime (&t);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_mon = 0;
tm.tm_mday = 1;
tm.tm_year++;
tm.tm_isdst = -1;
return mktime (&tm);
}
time_t
time_month_begin (time_t t)
{
struct tm tm;
tm = *localtime (&t);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_mday = 1;
tm.tm_isdst = -1;
return mktime (&tm);
}
time_t
time_month_end (time_t t)
{
struct tm tm;
tm = *localtime (&t);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_mday = 1;
tm.tm_mon++;
tm.tm_isdst = -1;
return mktime (&tm);
}
time_t
time_week_begin (time_t t)
{
struct tm tm;
/* FIXME: make it take week_starts_on_monday into account */
tm = *localtime (&t);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_mday -= tm.tm_wday;
tm.tm_isdst = -1;
return mktime (&tm);
}
time_t
time_week_end (time_t t)
{
struct tm tm;
/* FIXME: make it take week_starts_on_monday into account */
tm = *localtime (&t);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_mday += 7 - tm.tm_wday;
tm.tm_isdst = -1;
return mktime (&tm);
}
/* Returns the start of the day, according to the local time. */
time_t
time_day_begin (time_t t)
{
struct tm tm;
tm = *localtime (&t);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_isdst = -1;
return mktime (&tm);
}
/* Returns the end of the day, according to the local time. */
time_t
time_day_end (time_t t)
{
struct tm tm;
tm = *localtime (&t);
tm.tm_mday++;
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
tm.tm_isdst = -1;
return mktime (&tm);
}
