#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

const int button1 = A0;
const int button2 = A1;
const int resetButton = A2;
const int stopButton = A3;
const int outputPin = 7;

unsigned long countDownTime = 0;  // in seconds
unsigned long remainingTime = 0;  // in seconds

bool isCountingDown = false;
bool isResetting = false;

void setup() {
  lcd.begin(16, 2);
  pinMode(button1, INPUT_PULLUP);
  pinMode(button2, INPUT_PULLUP);
  pinMode(resetButton, INPUT_PULLUP);
  pinMode(stopButton, INPUT_PULLUP);
  pinMode(outputPin, OUTPUT);

  lcd.print("Press button 1");
  lcd.setCursor(0, 1);
  lcd.print("add 10s of time");
}

void loop() {
  // check if button 1 is pressed
  if (digitalRead(button1) == LOW && !isCountingDown && !isResetting) {
    countDownTime += 10;
    lcd.clear();
    lcd.print("Added 10s.");
    lcd.setCursor(0, 1);
    lcd.print("Total: ");
    lcd.print(countDownTime);
    lcd.print("s");
    delay(500);
  }

  // check if button 2 is pressed
  if (digitalRead(button2) == LOW && !isCountingDown && !isResetting && countDownTime > 0) {
    remainingTime = countDownTime;
    isCountingDown = true;
    digitalWrite(outputPin, HIGH);
    lcd.clear();
    lcd.print("Countdown started");
    lcd.setCursor(0, 1);
    lcd.print("Remaining: ");
    lcd.print(remainingTime);
    lcd.print("s");
    delay(500);
  }

  // check if reset button is pressed
  if (digitalRead(resetButton) == LOW && !isCountingDown && !isResetting) {
    countDownTime = 0;
    lcd.clear();
    lcd.print("Time reset to 0s");
    delay(500);
  }
  
  // check if stop button is pressed
  if (digitalRead(stopButton) == LOW && isCountingDown) {
    isCountingDown = false;
    digitalWrite(outputPin, LOW);
    lcd.clear();
    lcd.print("Countdown stopped");
    lcd.setCursor(0, 1);
    lcd.print("Remaining: ");
    lcd.print(remainingTime);
    lcd.print("s");
    delay(500);
  }

  // update remaining time if counting down
  if (isCountingDown) {
    lcd.clear();
    lcd.print("Counting down...");
    lcd.setCursor(0, 1);
    lcd.print("Remaining: ");
    lcd.print(remainingTime);
    lcd.print("s");
    delay(1000);

    if (remainingTime > 0) {
      remainingTime--;
    } else {
      isCountingDown = false;
      digitalWrite(outputPin, LOW);
      lcd.clear();
      lcd.print("Countdown finished");
      lcd.setCursor(0, 1);
      lcd.print("Set the time");
      delay(2000);
      remainingTime = 0;
      countDownTime = 0;
    }
  }
}