/** mbed Microcontroller Library
 ******************************************************************************
 * @file	rtc_api.c
 * @author 
 * @version V1.0.0
 * @date	2016-08-01
 * @brief	This file provides mbed API for RTC.
 ******************************************************************************
 * @attention
 *
 * This module is a confidential and proprietary property of RealTek and
 * possession or use of this module requires written permission of RealTek.
 *
 * Copyright(c) 2016, Realtek Semiconductor Corporation. All rights reserved.
 ****************************************************************************** 
 */

#include "rtc_api.h"

#include <time.h>
#include "timer_api.h"

static struct tm rtc_timeinfo;
static int rtc_en = 0;
static alarm_irq_handler rtc_alarm_handler;

const static u8 dim[12] = { 
	31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

/**
  * @brief  This function is used to tell a year is a leap year or not.
  * @param  year: The year need to be told.
  * @retval value: 
  *             - 1: This year is leap year.
  *             - 0: This year is not leap year.
  */
static inline bool is_leap_year(unsigned int year)
{
	u32 full_year = year + 1900;
	return (!(full_year % 4) && (full_year % 100)) || !(full_year % 400);
}


/**
  * @brief  This function tells how many days in a month of a year.
  * @param  year: Specified year
  * @param  month: Specified month
  * @retval value: Number of days in the month.
  */
static u8 days_in_month (u8 month, u8 year)
{
	u8 ret = dim[month];
	if (ret == 0)
		ret = is_leap_year (year) ? 29 : 28;
	return ret;
}

/**
  * @brief  This function is used to calculate month and day of month according to year and day of the year.
  * @param  year: years since 1900.
  * @param  yday: day of the year.
  * @param  mon: pointer to the variable which stores month,  the value can be 0-11
  * @param  mday: pointer to the variable which stores day of month, the value can be 1-31
  * @retval value: none
  */
static void rtc_calculate_mday(int year, int yday, int* mon, int* mday)
{
	int t_mon = -1, t_yday = yday + 1;

	while(t_yday > 0){
		t_mon ++;
		t_yday -= days_in_month(t_mon, year);
	}

	*mon = t_mon;
	*mday = t_yday + days_in_month(t_mon, year);
}

/**
  * @brief  This function is used to calculate day of week according to date.
  * @param  year: years since 1900.
  * @param  mon: which month of the year
  * @param  mday: pointer to the variable which store day of month
  * @param  wday: pointer to the variable which store day of week, the value can be 0-6, and 0 means Sunday
  * @retval value: none
  */
static void rtc_calculate_wday(int year, int mon, int mday, int* wday)
{
	int t_year = year + 1900, t_mon = mon + 1;

	if(t_mon == 1 || t_mon == 2){
		t_year --;
		t_mon += 12;
	}

	int c = t_year / 100;
	int y = t_year % 100;
	int week = (c / 4) - 2 * c + (y + y / 4) + (26 * (t_mon + 1) / 10) + mday -1;
	
	while(week < 0){
		week += 7;
	}
	week %= 7;
	
	*wday = week;
}

/**
  * @brief  This function is used to restore rtc_timeinfo global variable whose value is lost after system reset.
  * @param  none
  * @retval value: none
  */
static void rtc_restore_timeinfo(void)
{
	u32 value, days_in_year;

	RTC_TimeTypeDef RTC_TimeStruct;
        RTC_GetTime(RTC_Format_BIN, &RTC_TimeStruct);
	rtc_timeinfo.tm_sec = RTC_TimeStruct.RTC_Seconds;
	rtc_timeinfo.tm_min = RTC_TimeStruct.RTC_Minutes;
	rtc_timeinfo.tm_hour = RTC_TimeStruct.RTC_Hours;
	rtc_timeinfo.tm_yday = RTC_TimeStruct.RTC_Days;

	value = BKUP_Read(0);
	rtc_timeinfo.tm_year = (value & BIT_RTC_BACKUP) >> 8;

	days_in_year =  (is_leap_year(rtc_timeinfo.tm_year) ? 366 : 365);
	if(rtc_timeinfo.tm_yday > days_in_year - 1){
		rtc_timeinfo.tm_year ++;
		rtc_timeinfo.tm_yday -= days_in_year;

		/* over one year, update days in RTC_TR */
		RTC_TimeStruct.RTC_Days = rtc_timeinfo.tm_yday;
		RTC_SetTime(RTC_Format_BIN, &RTC_TimeStruct);
	}

	rtc_calculate_mday(rtc_timeinfo.tm_year, rtc_timeinfo.tm_yday, &rtc_timeinfo.tm_mon, &rtc_timeinfo.tm_mday);
	rtc_calculate_wday(rtc_timeinfo.tm_year, rtc_timeinfo.tm_mon, rtc_timeinfo.tm_mday, &rtc_timeinfo.tm_wday);
}

/**
  * @brief  This function is used to backup tm_year parameter in rtc_timeinfo global variable before system reset.
  * @param  none
  * @retval value: none
  */
void rtc_backup_timeinfo(void)
{
	u32 value = BKUP_Read(0);
	value = (value & ~BIT_RTC_BACKUP) | (rtc_timeinfo.tm_year << 8);

	BKUP_Write(0, value);
	
	BKUP_Set(0, BIT_RTC_RESTORE);
}

/**
  * @brief  Initializes the RTC device, include clock, RTC registers and function.
  * @param  none
  * @retval  none
  */
void rtc_init(void)
{
	RTC_InitTypeDef RTC_InitStruct;

	RTC_ClokSource(0);

	RTC_StructInit(&RTC_InitStruct);
	RTC_InitStruct.RTC_HourFormat = RTC_HourFormat_24;
	
	RTC_Init(&RTC_InitStruct);

	/* 32760 need add need add 15 cycles (256Hz) every 4 min*/
	//RTC_SmoothCalibConfig(RTC_CalibSign_Positive, 15,
	//	RTC_CalibPeriod_4MIN, RTC_Calib_Enable);

	rtc_en = 1;
}

/**
  * @brief  Deinitializes the RTC device.
  * @param  none
  * @retval  none
  */
void rtc_free(void)
{
	rtc_en = 0;
	rtc_alarm_handler = NULL;
}

/**
  * @brief  This function tells whether RTC is enabled or not.
  * @param  none
  * @retval  status: 
  *              - 1: RTC is enable.
  *              - 0: RTC is disable.
  */
int rtc_isenabled(void)
{
	return rtc_en;
}

/**
  * @brief  Set the specified timestamp in seconds to RTC.
  * @param  t: Seconds from 1970.1.1 00:00:00 to specified data and time
  *              which is to be set.
  * @retval  none
  */
void rtc_write(time_t t)
{	
	/* Convert the time in to a tm*/
	struct tm *timeinfo = localtime(&t);

	RTC_TimeTypeDef RTC_TimeStruct;
	
	/*set time in RTC */
	RTC_TimeStruct.RTC_H12_PMAM = RTC_H12_AM;
	RTC_TimeStruct.RTC_Days = timeinfo->tm_yday;
	RTC_TimeStruct.RTC_Hours = timeinfo->tm_hour;
	RTC_TimeStruct.RTC_Minutes = timeinfo->tm_min;
	RTC_TimeStruct.RTC_Seconds = timeinfo->tm_sec;
	RTC_SetTime(RTC_Format_BIN, &RTC_TimeStruct);

	/* Set rtc_timeinfo*/
	_memcpy((void*)&rtc_timeinfo, (void*)timeinfo, sizeof(struct tm));
}

/**
  * @brief  Get current timestamp in seconds from RTC.
  * @param  none
  * @retval   value: The current timestamp in seconds which is calculated from 
  *              1970.1.1 00:00:00.
  */
time_t rtc_read(void)
{
	time_t t;
	struct tm tm_temp;
	RTC_TimeTypeDef RTC_TimeStruct;
	u32 delta_days = 0;

	if(BKUP_Read(0) & BIT_RTC_RESTORE){
		rtc_restore_timeinfo();
		BKUP_Clear(0, BIT_RTC_RESTORE);
	}

	_memcpy((void*)&tm_temp, (void*)&rtc_timeinfo, sizeof(struct tm));

	/*hour, min, sec get from RTC*/
	RTC_GetTime(RTC_Format_BIN, &RTC_TimeStruct);
	tm_temp.tm_sec = RTC_TimeStruct.RTC_Seconds;
	tm_temp.tm_min = RTC_TimeStruct.RTC_Minutes;
	tm_temp.tm_hour = RTC_TimeStruct.RTC_Hours;

	/* calculate how many days later from last time update rtc_timeinfo */
	delta_days = RTC_TimeStruct.RTC_Days - tm_temp.tm_yday;

	/* calculate  wday, mday, yday, mon, year*/
	tm_temp.tm_wday += delta_days;
	if(tm_temp.tm_wday >= 7){
		tm_temp.tm_wday = tm_temp.tm_wday % 7;
	}
	
	tm_temp.tm_yday += delta_days;
	tm_temp.tm_mday += delta_days;
	
	while(tm_temp.tm_mday > days_in_month(tm_temp.tm_mon, tm_temp.tm_year)){
		tm_temp.tm_mday -= days_in_month(tm_temp.tm_mon, tm_temp.tm_year);
		tm_temp.tm_mon++;

		if(tm_temp.tm_mon >= 12){
			tm_temp.tm_mon -= 12;
			tm_temp.tm_yday -= is_leap_year(tm_temp.tm_year) ? 366 : 365;
			tm_temp.tm_year ++;

			/* over one year, update days in RTC_TR */
			RTC_TimeStruct.RTC_Days = tm_temp.tm_yday;
			RTC_SetTime(RTC_Format_BIN, &RTC_TimeStruct);

			/* update rtc_timeinfo */
			_memcpy((void*)&rtc_timeinfo, (void*)&tm_temp, sizeof(struct tm));
		}
	}
	
	/* Convert to timestamp(seconds from 1970.1.1 00:00:00)*/
	t = mktime(&tm_temp);

	return t;
}

/**
  * @brief  RTC alarm interrupt handler function.
  * @param  data: RTC IRQ callback data
  * @retval   none
  */
void rtc_alarm_intr_handler(u32 data)
{
	alarm_irq_handler hdl;
	
	/*clear alarm flag*/
	RTC_AlarmClear();

	/* execute user handler*/
	if(rtc_alarm_handler != NULL){
		hdl = (alarm_irq_handler)rtc_alarm_handler;
		hdl();
	}

	/*disable alarm*/
	rtc_disable_alarm();
}

/**
  * @brief  Set the specified RTC Alarm and interrupt.
  * @param  alarm: alarm object define in application software.
  * @param  alarmHandler:  alarm interrupt callback function.
  * @retval   status:
  *            - 1: success
  *            - Others: failure
  */
u32 rtc_set_alarm(alarm_t *alrm, alarm_irq_handler alarmHandler)
{
	RTC_AlarmTypeDef RTC_AlarmStruct_temp;

	rtc_alarm_handler = alarmHandler;
	
	/* set alarm */
	RTC_AlarmStructInit(&RTC_AlarmStruct_temp);
	RTC_AlarmStruct_temp.RTC_AlarmTime.RTC_H12_PMAM = RTC_H12_AM;
	RTC_AlarmStruct_temp.RTC_AlarmTime.RTC_Days = alrm->yday;
	RTC_AlarmStruct_temp.RTC_AlarmTime.RTC_Hours = alrm->hour;
	RTC_AlarmStruct_temp.RTC_AlarmTime.RTC_Minutes = alrm->min;
	RTC_AlarmStruct_temp.RTC_AlarmTime.RTC_Seconds = alrm->sec;

	RTC_AlarmStruct_temp.RTC_AlarmMask = RTC_AlarmMask_None;
	RTC_AlarmStruct_temp.RTC_Alarm2Mask = RTC_Alarm2Mask_None;

	RTC_SetAlarm(RTC_Format_BIN, &RTC_AlarmStruct_temp);

	RTC_AlarmCmd(ENABLE);
	InterruptRegister((IRQ_FUN)rtc_alarm_intr_handler, RTC_IRQ, (u32)alrm, 4);
	InterruptEn(RTC_IRQ, 4);

	return _TRUE;
}

/**
  * @brief  Disable RTC Alarm and function.
  * @param  none
  * @retval   none
  */
void rtc_disable_alarm(void)
{
	InterruptDis(RTC_IRQ);
	InterruptUnRegister(RTC_IRQ);
	RTC_AlarmCmd(DISABLE);

	rtc_alarm_handler = NULL;
}