#include "rtc.h"
#include <ch.h>

static bool time_valid = false;
static rtc_t current_time = {2000,1,1,0,0,0};
static VirtualTimer rtc_timer;

void rtc_set(const rtc_t *time)
{
    chSysLock();
    current_time = *time;
    time_valid = true;
    chSysUnlock();
}

bool rtc_get(rtc_t *time)
{
    if (!time_valid)
        return false;
    
    chSysLock();
    *time = current_time;
    chSysUnlock();
    return true;
}

static char get_days_in_month(const rtc_t *time)
{
    switch (time->month)
    {
        case 4:
        case 6:
        case 9:
        case 11:
            return 30;
        
        case 2:
            if (time->year % 4 == 0 && (time->year % 100 != 0 || time->year % 400 == 0))
                return 29;
            else
                return 28;
        
        default:
            return 31;
    }
}

static void rtc_increment(void *arg) __attribute__((optimize("O3")));
static void rtc_increment(void *arg) 
{
    chSysLockFromIsr();
    
    if (time_valid)
    {
        current_time.second++;
        if (current_time.second == 60)
        {
            current_time.second = 0;
            current_time.minute++;
            if (current_time.minute == 60)
            {
                current_time.minute = 0;
                current_time.hour++;
                if (current_time.hour == 24)
                {
                    current_time.hour = 0;
                    current_time.day++;
                    
                    if (current_time.day > get_days_in_month(&current_time))
                    {
                        current_time.day = 1;
                        current_time.month++;
                        
                        if (current_time.month > 12)
                        {
                            current_time.month = 1;
                            current_time.year++;
                        }
                    }
                }
            }
        }
    }
    
    chVTSetI(&rtc_timer, S2ST(1), &rtc_increment, NULL);
    chSysUnlockFromIsr();
}

void rtc_start()
{
    chSysLock();
    chVTSetI(&rtc_timer, S2ST(1), &rtc_increment, NULL);
    chSysUnlock();
}