/*
  RTC_com.cpp

  MIT License
  Copyright (c) 2023 hdrlux
*/

#include <Arduino.h>    // for all the 'standard' Arduino stuff
#include <DS3232RTC.h>  // https://github.com/JChristensen/DS3232RTC
#include <TimeLib.h>    // https://github.com/PaulStoffregen/Time [valid until year 2099, no 2038 bug]
#include "GPS_RTC_Clock.h"
#include "RTC_com.h"

#define cfg_pin_RTC_SQW 3;
#ifndef DEBUG_PORT
#define DEBUG_PORT Serial
#endif

// add the static modifier to limit visibility of these variables to just this file
//static int ledPin_PPS = A6;      // Pin for RTC PseudoPPS LED [analog PIN used as digital PIN]
//static int ledPin_Sync = A7;     // Pin for valid RTC Sync
static byte RTC_1HZ_PIN = cfg_pin_RTC_SQW;     // Pin 3 = NANO INT1, RTC provides a 1Hz interrupt signal on this Pin
static time_t last_sync_t = 0;   // last sync
static byte sync_err_hours = 4;  // set to 4 for DS3231M, may be set to 8 for DS3231SN. Warning if no GPS sync after n hours, possible 0.1 sec error.
static bool RTCcolon = false;
bool SyncErr = true;

#include <DS3232RTC.h>
DS3232RTC myRTC(0x68); // cfg_
volatile bool RTC_sec = false;   // flag for PseudoPPS
volatile bool RTC_sync = false;  // flag for RTC sync
unsigned long RTCMicros;  // blinking timer

void rtc_interrupt() {
  //Serial.print("DEBUG[INT] RTC interrupt "); Serial.println(micros());
  RTCMicros = micros();
  RTC_sec = true;
}

void RTC_LED_setup() {
  //pinMode(ledPin_PPS, OUTPUT);
  //pinMode(ledPin_Sync, OUTPUT);
  //digitalWrite(ledPin_PPS, LOW);   // LED off
  //digitalWrite(ledPin_Sync, LOW);  // LED off
}

void RTC_setup() {
  pinMode(RTC_1HZ_PIN, INPUT_PULLUP);                                           // enable pullup on interrupt pin (RTC SQW pin is open drain)
  attachInterrupt(digitalPinToInterrupt(RTC_1HZ_PIN), rtc_interrupt, FALLING);  // HIGH 500ms after start of second
  myRTC.begin();
  myRTC.squareWave(DS3232RTC::SQWAVE_1_HZ);  // 1 Hz square wave
  RTC_sec = false;
}

void RTC_loop() {
  if (RTC_sec) {                    // do after RTC PseudoPPS interrupt, without interrupt NO time/date to display
    //DEBUG_PORT.println("DEBUG[RTC_loop()] RTC_sec: " + String(RTC_sec));
    //DEBUG_PORT.println("DEBUG[RTC_loop()] RTCMicros: " + String(RTCMicros));
    //DEBUG_PORT.println("DEBUG[RTC_loop()] millis: " + String(millis()));
    
    lcd.setCursor(13, 0);
    lcd.print(":");

    RTCcolon = true;
    RTC_sec = false;                // clear flag

    int32_t drift = (int32_t)(GPSMicros - RTCMicros); // % (4294967295UL);

    // Корректировка переполнения (wrap-around)
    if (drift > 900000)       // Если разница > 0.9 сек
      drift -= 1000000;       // Корректируем на -1 сек
    else if (drift < -900000) // Если разница < -0.9 сек
      drift += 1000000;       // Корректируем на +1 сек
    
    // Отображение дрейфа в правом нижнем углу LCD (16x2)
    String driftStr = String(drift);
    // Вычисляем позицию для выравнивания справа: 16 - длина строки
    lcd.setCursor(16 - driftStr.length(), 1);
    lcd.print(driftStr);
    
    DEBUG_PORT.println("SQW: " + String(RTCMicros) + "; drift: " + String(drift) + "; newSec: " + String(NewSec));
    
    if (abs(drift) > 20000 && !gps_on) RTC_sync = true;
    //digitalWrite(ledPin_PPS, LOW);  // LED off
    time_t now_t = myRTC.get();
    if ((last_sync_t + (sync_err_hours * 3600)) < now_t) {
      SyncErr = true;
      //digitalWrite(ledPin_Sync, LOW);  // LED off
      lcd.setCursor(0, 0);
      lcd.print("r");
    }
    Sec_Flip(now_t);  // pass current datetime from RTC in UTC
  }
  else if (micros() - RTCMicros >= 500000 && RTCcolon) {
    lcd.setCursor(13, 0);
    lcd.print(" ");
    RTCcolon = false;
    NewSec = false;
  }
  else {
    NewSec = false;
  }
  /*if (millis() > (RTCMicros + 100)) {  // do 100ms after PseudoPPS interrupt
    digitalWrite(ledPin_PPS, HIGH);    // LED on
  }*/
}

void SetRTC(time_t t) {
  myRTC.set(t + 1);  // the GPS NMEA output is 1 second behind at PPS !!
  last_sync_t = t;
  SyncErr = false;
  //digitalWrite(ledPin_Sync, HIGH);   // LED on
  DEBUG_PORT.println("RTC set by GPS");  // debug
  lcd.setCursor(0, 0);
  lcd.print("R");
  
  char segment[9];
  snprintf(segment, sizeof(segment),"%.2u:%.2u:%.2u", hour(t), minute(t), second(t));
  lcd.setCursor(0, 1);
  lcd.print(segment);
}

//End