#include <Arduino.h>
#include <U8g2lib.h>

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);

int timer = 0;
int prevTimer =00;
bool pinstate = 0;
unsigned long previousMillis = 0;    // stores last time the counter was updated
const long interval = 1000;          // interval for the counter update (1 second)
unsigned long displaySleepMillis = 0;  // stores last time the display was active
const long displaySleepInterval = 10000; // display sleep interval (5 minutes)
  bool isTimerSet = true;  // Flag to track if prevTimer has been set


void setup(void) {
  u8g2.begin();   // initialise display
  u8g2.setContrast(127);
  pinMode(2, INPUT);
  u8g2.setFont(u8g2_font_logisoso50_tn);  // set font
  u8g2.setCursor(30 , 64);
  u8g2.print("00");
  u8g2.sendBuffer();
  displaySleepMillis = millis();  // set initial display activity time
  oldTime();

}


void loop() {
  unsigned long currentMillis = millis();  // Get the current time

  int pinstate = digitalRead(2);
  if (pinstate == 1) {
      oldTime();    //update old time only atstart of new time

    // if the pin is high, update the counter
    if (currentMillis - previousMillis >= interval) {
      previousMillis = currentMillis;
      count();
    }
    displaySleepMillis = currentMillis;  // reset display activity time
    isTimerSet = false;  // Reset the flag when pinstate is high

  } else {
    if (!isTimerSet) {
      prevTimer = timer-1;
      isTimerSet = true;  // Set the flag to true after setting prevTimer
    }
    timer = 0;
  }


  // check if the display should sleep
  if (currentMillis - displaySleepMillis >= displaySleepInterval) {
    u8g2.setPowerSave(1);  // put display to sleep
  } else {
    u8g2.setPowerSave(0);  // wake up display if it's active
  }
}

void count() {
  u8g2.clearBuffer();   // clear display
  u8g2.setCursor(30, 64);
  if (timer < 10) {
    u8g2.print("0");
  }
  u8g2.print(timer);    // draw string
  oldTime();

  u8g2.sendBuffer();    // move from mem onto display
  timer++;
  if (timer > 99) {     // reset timer after 99 seconds
    timer = 0;
  }
}

void oldTime(){
u8g2.setFont(u8g2_font_profont11_mn);
u8g2.setCursor(60,10);
if(prevTimer<10){
  u8g2.print("0");
}

u8g2.print(prevTimer);
u8g2.sendBuffer();
u8g2.setFont(u8g2_font_logisoso50_tn);  // set back font

}