/*
 * rtc.c
 *
 *  Created on: Oct 16, 2024
 *      Author: true
 */


#include <ch32v20x.h>
#include <stdint.h>

#include "periph/rtc.h"



#define RTC_INIT_PATTERN    0x1337



static const uint8_t days_per_mon[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};



uint8_t rtc_state;



void rtc_set_state(uint16_t state)
{
    rtc_state = state;
}

/*
 * @fn      rtc_is_leapyear
 * @brief   Returns true if year is a leap year.
 *
 * @param   year
 *
 * @return  1 - Yes
 *          0 - No
 */
uint8_t rtc_is_leapyear(u16 year)
{
    if (year % 4 == 0) {
        if (year % 100 == 0) {
            if (year % 400 == 0) {
                return 1;
            } else {
                return 0;
            }
        }
        else return 1;
    }
    else return 0;
}

/*
 * @fn      rtc_set_clock
 * @brief   Set Time.
 *
 * @param   Struct of RTClock
 *
 * @return  1 - error
 *          0 - success
 */
int8_t rtc_set_clock(struct RTClock *c)
{
    uint16_t x;
    uint8_t m;
    uint32_t count = 0;

    if(c->year < 1970 || c->year > 2099)
        return -1;

    for(x = 1970; x < c->year; x++) {
        if (rtc_is_leapyear(x))
            count += 31622400;
        else
            count += 31536000;
    }

    m = c->mon - 1;
    for(x = 0; x < m; x++){
        count += (u32)days_per_mon[x] * 86400;
        if(rtc_is_leapyear(c->year) && x == 1)
            count += 86400;
    }

    count += (u32)(c->day - 1) * 86400;
    count += (u32)c->h * 3600;
    count += (u32)c->m * 60;
    count += c->s;

    PWR_BackupAccessCmd(ENABLE);
    RTC_SetCounter(count);
    RTC_WaitForLastTask();

    return 0;
}

int8_t rtc_init()
{
    uint32_t timeout;
    static const struct RTClock clock = {
            .year = 2024,
            .mon  = 11,
            .day  = 1,
            .h    = 8,
            .m    = 0,
            .s    = 0
    };

    // enable access to RTC registers
    PWR_BackupAccessCmd(ENABLE);

    // get RTC state
    // if things aren't configured it'll be initialized in a moment
    rtc_state = BKP_ReadBackupRegister(RTC_STATE_DR);
    RTC_WaitForLastTask();

    // is RTC already configured?
    if (BKP_ReadBackupRegister(RTC_INIT_DR) != RTC_INIT_PATTERN) {
        // must not be. initialize rtc
        BKP_DeInit();

        RCC_LSEConfig(RCC_LSE_ON);

        timeout = SystemCoreClock / 2;
        while(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET && timeout--);

        // if crystal didn't start in time, let the application know
        if (!timeout) return -1;

        // use crystal for RTC and enable it
        RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);
        RCC_RTCCLKCmd(ENABLE);
        RTC_WaitForLastTask();
        RTC_WaitForSynchro();
        //      RTC_ITConfig(RTC_IT_ALR, ENABLE);
        //      RTC_ITConfig(RTC_IT_SEC, ENABLE);
        //      RTC_WaitForLastTask();

        RTC_EnterConfigMode();
        RTC_SetPrescaler(32767);
        RTC_WaitForLastTask();

        // set an initial time

        rtc_set_clock((struct RTClock *)&clock);
        RTC_ExitConfigMode();

        rtc_state = RTC_STATE_CLOCK_NOT_SET;
        BKP_WriteBackupRegister(RTC_STATE_DR, rtc_state);
        RTC_WaitForLastTask();
        BKP_WriteBackupRegister(RTC_INIT_DR,  RTC_INIT_PATTERN);

        // RTC_NVIC_Config();
        // RTC_Get();
    }

    RTC_WaitForLastTask();

    return 0;
}