#include "py/obj.h"

#include "shared/timeutils/timeutils.h"

#define LEAPOCH ((31 + 29) * 86400)

#define DAYS_PER_400Y (365 * 400 + 97)

#define DAYS_PER_100Y (365 * 100 + 24)

#define DAYS_PER_4Y (365 * 4 + 1)

STATIC const uint16_t days_since_jan1[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };

bool timeutils_is_leap_year(mp_uint_t year) {

return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;

}

mp_uint_t timeutils_days_in_month(mp_uint_t year, mp_uint_t month) {

mp_uint_t mdays = days_since_jan1[month] - days_since_jan1[month - 1];

if (month == 2 && timeutils_is_leap_year(year)) {

mdays++;

}

return mdays;

}

mp_uint_t timeutils_year_day(mp_uint_t year, mp_uint_t month, mp_uint_t date) {

mp_uint_t yday = days_since_jan1[month - 1] + date;

if (month >= 3 && timeutils_is_leap_year(year)) {

yday += 1;

}

return yday;

}

void timeutils_seconds_since_2000_to_struct_time(mp_uint_t t, timeutils_struct_time_t *tm) {

// The following algorithm was adapted from musl's __secs_to_tm and adapted

// for differences in MicroPython's timebase.

mp_int_t seconds = t - LEAPOCH;

mp_int_t days = seconds / 86400;

seconds %= 86400;

if (seconds < 0) {

seconds += 86400;

days -= 1;

}

tm->tm_hour = seconds / 3600;

tm->tm_min = seconds / 60 % 60;

tm->tm_sec = seconds % 60;

mp_int_t wday = (days + 2) % 7; // Mar 1, 2000 was a Wednesday (2)

if (wday < 0) {

wday += 7;

}

tm->tm_wday = wday;

mp_int_t qc_cycles = days / DAYS_PER_400Y;

days %= DAYS_PER_400Y;

if (days < 0) {

days += DAYS_PER_400Y;

qc_cycles--;

}

mp_int_t c_cycles = days / DAYS_PER_100Y;

if (c_cycles == 4) {

c_cycles--;

}

days -= (c_cycles * DAYS_PER_100Y);

mp_int_t q_cycles = days / DAYS_PER_4Y;

if (q_cycles == 25) {

q_cycles--;

}

days -= q_cycles * DAYS_PER_4Y;

mp_int_t years = days / 365;

if (years == 4) {

years--;

}

days -= (years * 365);

/* We will compute tm_yday at the very end

tm->tm_year = 2000 + years + 4 * q_cycles + 100 * c_cycles + 400 * qc_cycles;

// Note: days_in_month[0] corresponds to March

STATIC const int8_t days_in_month[] = {31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31, 29};

mp_int_t month;

for (month = 0; days_in_month[month] <= days; month++) {

days -= days_in_month[month];

}

tm->tm_mon = month + 2;

if (tm->tm_mon >= 12) {

tm->tm_mon -= 12;

tm->tm_year++;

}

tm->tm_mday = days + 1; // Make one based

tm->tm_mon++; // Make one based

tm->tm_yday = timeutils_year_day(tm->tm_year, tm->tm_mon, tm->tm_mday);

}

mp_uint_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month,

mp_uint_t date, mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {

return

second

+ minute * 60

+ hour * 3600

+ (timeutils_year_day(year, month, date) - 1

+ ((year - 2000 + 3) / 4) // add a day each 4 years starting with 2001

- ((year - 2000 + 99) / 100) // subtract a day each 100 years starting with 2001

+ ((year - 2000 + 399) / 400) // add a day each 400 years starting with 2001

) * 86400

+ (year - 2000) * 31536000;

}

mp_uint_t timeutils_mktime_2000(mp_uint_t year, mp_int_t month, mp_int_t mday,

mp_int_t hours, mp_int_t minutes, mp_int_t seconds) {

// Normalize the tuple. This allows things like:

//

// tm_tomorrow = list(time.localtime())

// tm_tomorrow[2] += 1 # Adds 1 to mday

// tomorrow = time.mktime(tm_tomorrow)

//

// And not have to worry about all the weird overflows.

//

// You can subtract dates/times this way as well.

minutes += seconds / 60;

if ((seconds = seconds % 60) < 0) {

seconds += 60;

minutes--;

}

hours += minutes / 60;

if ((minutes = minutes % 60) < 0) {

minutes += 60;

hours--;

}

mday += hours / 24;

if ((hours = hours % 24) < 0) {

hours += 24;

mday--;

}

month--; // make month zero based

year += month / 12;

if ((month = month % 12) < 0) {

month += 12;

year--;

}

month++; // back to one based

while (mday < 1) {

if (--month == 0) {

month = 12;

year--;

}

mday += timeutils_days_in_month(year, month);

}

while ((mp_uint_t)mday > timeutils_days_in_month(year, month)) {

mday -= timeutils_days_in_month(year, month);

if (++month == 13) {

month = 1;

year++;

}

}

return timeutils_seconds_since_2000(year, month, mday, hours, minutes, seconds);

}

int timeutils_calc_weekday(int y, int m, int d) {

return ((d += m < 3 ? y-- : y - 2, 23 * m / 9 + d + 4 + y / 4 - y / 100 + y / 400) + 6) % 7;

}