/**
 * TODO file description
 * 
 * Created on 2019/09/13.
 */

#ifndef CSPEMU_DATETIME_H
#define CSPEMU_DATETIME_H

#include <stdbool.h>
#include <stdint.h>

enum weekday {
    MONDAY = 1,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY,
    SATURDAY,
    SUNDAY
};
_Static_assert(MONDAY==1, "enum weekday numbering Mon");
_Static_assert(SUNDAY==7, "enum weekday numbering Sun");

enum month {
    JANUARY = 1,
    FEBRUARY,
    MARCH,
    APRIL,
    MAY,
    JUNE,
    JULY,
    AUGUST,
    SEPTEMBER,
    OCTOBER,
    NOVEMBER,
    DECEMBER
};
_Static_assert(JANUARY==1, "enum month numbering Jan");
_Static_assert(DECEMBER==12, "enum month numbering Dec");

/** Abbreviated weekday names */
extern const char *DT_WKDAY_NAMES[];
/** Full-length weekday names */
extern const char *DT_WKDAY_NAMES_FULL[];
/** Abbreviated month names */
extern const char *DT_MONTH_NAMES[];
/** Full-length month names */
extern const char *DT_MONTH_NAMES_FULL[];

typedef struct datetime {
    uint16_t year;
    enum month month;
    uint8_t day;
    uint8_t hour;
    uint8_t min;
    uint8_t sec;
    enum weekday wkday; // 1=monday
} datetime_t;

// Templates for printf
#define DT_FORMAT_DATE   "%d/%d/%d"
#define DT_SUBS_DATE(dt) (dt).year, (dt).month, (dt).day

#define DT_FORMAT_TIME   "%d:%02d:%02d"
#define DT_SUBS_TIME(dt) (dt).hour, (dt).min, (dt).sec

#define DT_FORMAT_DATE_WK   DT_FORMAT_WK " " DT_FORMAT_DATE
#define DT_SUBS_DATE_WK(dt) DT_SUBS_WK(dt), DT_SUBS_DATE(dt)

#define DT_FORMAT_WK   "%s"
#define DT_SUBS_WK(dt) DT_WKDAY_NAMES[(dt).wkday]

#define DT_FORMAT_DATE_TIME   DT_FORMAT_DATE " " DT_FORMAT_TIME
#define DT_SUBS_DATE_TIME(dt) DT_SUBS_DATE(dt), DT_SUBS_TIME(dt)

#define DT_FORMAT   DT_FORMAT_DATE_WK " " DT_FORMAT_TIME
#define DT_SUBS(dt) DT_SUBS_DATE_WK(dt), DT_SUBS_TIME(dt)

// base century for two-digit year conversions
#define DT_CENTURY 2000
// start year for weekday computation
#define DT_START_YEAR 2019
// January 1st weekday of DT_START_YEAR
#define DT_START_WKDAY TUESDAY
// max date supported by 2-digit year RTC counters (it can't check Y%400==0 with only two digits)
#define DT_END_YEAR 2399

typedef union __attribute__((packed)) {
    struct __attribute__((packed)) {
        uint8_t ones : 4;
        uint8_t tens : 4;
    };
    uint8_t byte;
} bcd_t;
_Static_assert(sizeof(bcd_t) == 1, "Bad bcd_t len");

/** Check if a year is leap */
static inline bool is_leap_year(int year)
{
    return year % 400 == 0 || (year % 4 == 0 && year % 100 != 0);
}

/**
 * Check if a datetime could be valid (ignores leap years)
 *
 * @param[in] dt
 * @return basic validations passed
 */
bool datetime_is_valid(const datetime_t *dt);

/**
 * Set weekday based on a date in a given datetime
 *
 * @param[in,out] dt
 * @return success
 */
bool datetime_set_weekday(datetime_t *dt);

/**
 * Get weekday for given a date
 *
 * @param year - year number
 * @param month - 1-based month number
 * @param day - 1-based day number
 * @return weekday
 */
enum weekday date_weekday(uint16_t year, enum month month, uint8_t day);


#endif //CSPEMU_DATETIME_H