/*
* calc.c Calculations to work out what day it is etc for the Calendar
*
* Most of this stuff was taken from the gcal source by Thomas Esken.
* <esken@uni-muenster.de>
* gcal is a text-based calendar program
*/
#include <time.h>
#include <glib.h>
#include <ctype.h>
#include "calcs.h"
#include <config.h>
#ifndef HAVE_STRCASECMP
int strcasecmp(const char * /*s1*/, const char * /*s2*/);
#endif
/* Number of days in a month */
static const int dvec[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
/* Number of past days of a month */
static const int mvec[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
Greg_struct greg_reform_date[6] = {
/* {int year, int month, int f_day, int l_day} */
{ 1582, 10, 5, 14 },
{ 1700, 2, 19, 28 },
{ 1752, 9, 3, 13 },
{ 1753, 2, 18, 28 },
/* must be left with all zeroes */
{ 0,0,0,0 }
};
Greg_struct *greg=greg_reform_date;
/*
* Computes the number of days in February and returns them,
*/
int days_of_february(const int year)
{
return((year&3) ? 28 : (!(year%100)&&(year%400)) ? 28 : 29);
}
int is_leap_year(const int year)
{
return (days_of_february(year) == 29);
}
/*
* Check wether a given date is calid.
*/
int valid_date(const int day, const int month, const int year)
{
if ( day < 1
|| month < MONTH_MIN
|| month > MONTH_MAX
|| ( (month != 2)
&& (day > dvec[month-1]))
|| ( (month == 2)
&& (day > days_of_february (year))))
return(FALSE);
return(TRUE);
}
/*
* Set a date back one day (to yesterday's date)
*/
void prev_date(int *day, int *month, int *year)
{
(*day)--;
if ( !*day || !valid_date(*day, *month, *year)) {
(*month)--;
if (*month < MONTH_MIN) {
*month = MONTH_MAX;
(*year)--;
}
if (*month ==2)
*day = days_of_february(*year);
else
*day = dvec[*month-1];
}
} /* prev_date */
/*
* Set a date forward one day (to tomorrow's date)
*/
void next_date(int *day, int *month, int *year)
{
(*day)++;
if (!valid_date(*day, *month, *year)) {
*day = DAY_MIN;
if (*month == MONTH_MAX) {
*month = MONTH_MIN;
(*year)++;
} else
(*month)++;
}
} /* next_date */
/*
* Get date from the system
*/
void get_system_date(int *day, int *month, int *year)
{
auto struct tm *sys_date;
auto time_t sys_time;
sys_time = time((time_t *)NULL);
sys_date = localtime(&sys_time);
*day = sys_date->tm_mday;
*month = sys_date->tm_mon + 1;
*year = sys_date->tm_year;
if (*year < CENTURY)
*year += CENTURY;
} /* get_system_date */
/*
* Given a string with the name of a month, return 1..12 or 0 if not found
*/
int month_atoi(const char *string)
{
int i;
for (i = MONTH_MIN; i <= MONTH_MAX; i++)
if (strcasecmp(string, (char *)get_month_name(i)) == 0)
return i;
return 0;
}
int day_atoi(const char *string)
{
int i;
for (i = DAY_MIN; i <= DAY_MAX; i++)
if (strcasecmp(string, (char *)get_day_name(i)) == 0)
return i;
return 0;
}
/*
* Returns ordinal suffix (st, nd, rd, th) for a day
*/
const char *day_suffix(int day)
{
static const char *suffix[]={"th", "st", "nd", "rd"};
register int i;
i = 0;
if (day > 100)
day %= 100;
if (day < 11 || day > 13)
i = day % 10;
if (i > 3)
i = 0;
return(suffix[i]);
} /* day_suffix */
/*
* Returns the short name of the day of week, format "%-3s"
*/
const char *short3_day_name(const int day)
{
static const char *name[]={"invalid day", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"};
return(((day<DAY_MIN)||(day>DAY_MAX)) ? name[0] : name[day]);
} /* short3_day_name */
/*
* Returns the short name of day of week
*/
const char *short_day_name(const int day)
{
static const char *name[]={"invalid day", "Mo", "Tu", "We", "Th", "Fr", "Sa", "Su"};
return(((day<DAY_MIN)||(day>DAY_MAX)) ? name[0] : name[day]);
} /* short_day_name */
/*
* Returns the complete name of the day
*/
const char *get_day_name(const int day)
{
static const char *name[]={"invalid day", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"};
return(((day<DAY_MIN)||(day>DAY_MAX)) ? name[0] : name[day]);
} /* day_name */
/*
* Returns the short name of the month
*/
const char *short_month_name(const int month)
{
static const char *name[]={ "invalid month", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
return(((month<MONTH_MIN)||(month>MONTH_MAX)) ? name[0] : name[month]);
} /* short_month_name() */
/*
* Returns the name of the month
*/
const char *get_month_name(const int month)
{
static const char *name[]={ "invalid month", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
return(((month<MONTH_MIN)||(month>MONTH_MAX)) ? name[0] : name[month]);
} /* month_name() */
/*
* Compute the absolute number of days of the given date since 1 Jan 0001
* respecting the missing period of the Gregorian Reformation
* I am glad someone else worked this one out!! - cs
*/
unsigned long int date2num(const int day, const int month, const int year)
{
auto unsigned long int julian_days;
julian_days = (unsigned long int)((year-1)*(unsigned long int)(DAY_LAST)+((year-1)>>2));
if (year > greg->year
|| ( (year == greg->year)
&& ( month > greg->month
|| ( (month == greg->month)
&& (day > greg->last_day)))))
julian_days -= (unsigned long int)(greg->last_day - greg->first_day + 1);
if (year > greg->year) {
julian_days += (((year-1) / 400) - (greg->year / 400));
julian_days -= (((year-1) / 100) - (greg->year / 100));
if (!(greg->year % 100) && (greg->year % 400))
julian_days--;
}
julian_days += (unsigned long int)mvec[month-1];
julian_days += day;
if ( (days_of_february(year) == 29) && (month > 2))
julian_days++;
return(julian_days);
} /* date2num */
/*
* Computes the weekday of a Gregorian/Julian calendar date
* (month must be 1..12) returns 1..7 (mo..su)
*/
int weekday_of_date(const int day, const int month, const int year)
{
auto unsigned long int julian_days=date2num(day, month,year)%DAY_MAX;
return((julian_days>2) ? (int)julian_days-2 : (int)julian_days+5);
} /* weekday_of_date() */
