libepoch/include/epoch.h

#ifndef LIBEPOCH_H
#define LIBEPOCH_H 1

#include <stdint.h>

#define SECONDS_PER_MINUTE 60
#define SECONDS_PER_HOUR   60 * 60
#define SECONDS_PER_DAY    60 * 60 * 24

typedef enum {
    normalYear,
    leapYear,
} yearTag;

typedef struct {
    yearTag tag;
    uint32_t year;
} Year;

typedef enum {
    January   = 1,
    February  = 2,
    March     = 3,
    April     = 4,
    May       = 5,
    June      = 6,
    July      = 7,
    August    = 8,
    September = 9,
    October   = 10,
    November  = 11,
    December  = 12,
} Month;

typedef enum {
    Thursday  = 0,
    Friday    = 1,
    Saturday  = 2,
    Sunday    = 3,
    Monday    = 4,
    Tuesday   = 5,
    Wednesday = 6,
} Weekday;

typedef enum {
    Offset,
    UTC,
} timeZoneTag;

typedef enum {
    Positive,
    Negative,
} offsetSign;

typedef struct {
    offsetSign sign;
    uint8_t    hours;
    uint8_t    minutes;
} TzOffset;

typedef struct {
    timeZoneTag tag;
    TzOffset *offset;
} TimeZone;

void yearNew(Year *year, int32_t inner);
uint16_t yearGetDays(Year *year);
int64_t yearGetSeconds(Year *year);
int32_t yearGetInner(Year *year);
void yearIncrement(Year *year);
void yearDecrement(Year *year);

uint8_t monthGetDays(Month month, Year *year);
uint32_t monthGetSeconds(Month month, Year *year);
int monthIncrement(Month *month);
int monthDecrement(Month *month);
const char* monthName(Month month);
const char* monthAbbr(Month month);
int parseMonth(const char *s);

const char* weekdayName(Weekday day);
const char* weekdayAbbr(Weekday day);
int parseWeekday(const char *s);

int offsetNew(TzOffset *offs, offsetSign sign, uint8_t hours, uint8_t minutes);
void printTz(TimeZone *zone);

#endif // !LIBEPOCH_H