#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 10, 9, 8, 7);

unsigned long startTime = 0;
unsigned long elapsedTime = 0;
boolean timerRunning = false;
boolean stopped = false;
boolean buttonPressed = false;

const int startButtonPin = 2; // Pin for the "Press Start" button
const int stopButtonPin = 3;  // Pin for the "Stop" button
const int resetButtonPin = 4; // Pin for the "Reset" button

void setup() {
  lcd.begin(16, 2);
  lcd.print("Press to start");
  pinMode(startButtonPin, INPUT);
  pinMode(stopButtonPin, INPUT);
  pinMode(resetButtonPin, INPUT);
}

void loop() {
  // Check if the "Press Start" button is pressed to start or resume the timer
  if (digitalRead(startButtonPin) == HIGH && !timerRunning && !stopped && !buttonPressed) {
    startTime = millis() - elapsedTime;
    timerRunning = true;
    buttonPressed = true;
  }

  // Check if the "Stop" button is pressed to pause or resume the timer
  if (digitalRead(stopButtonPin) == HIGH) {
    if (!buttonPressed) {
      buttonPressed = true;
      if (timerRunning) {
        elapsedTime = millis() - startTime;
        timerRunning = false;
        stopped = true;
        lcd.setCursor(0, 1);
        lcd.print("      STOP");
        delay(1000); // Pause for 1 second
      } else if (!timerRunning && stopped) {
        startTime = millis() - elapsedTime;
        timerRunning = true;
        stopped = false;
        lcd.setCursor(0, 1);
        lcd.print("             "); // Clear the "STOP" message
      }
    }
  } else {
    buttonPressed = false;
  }

  // Check if the "Reset" button is pressed to clear everything and start over
  if (digitalRead(resetButtonPin) == HIGH) {
    startTime = 0;
    elapsedTime = 0;
    timerRunning = false;
    stopped = false;
    lcd.clear();
    lcd.print("Press to start");
  }
  
  // Calculate and display the elapsed time if the timer is running
  if (timerRunning) {
    elapsedTime = millis() - startTime;

    // Display the elapsed time on the LCD
    if (elapsedTime % 1000 == 0) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Elapsed Time:");
      lcd.setCursor(0, 1);
      lcd.print(elapsedTime / 1000); // Display elapsed time in seconds
      lcd.print("s");
    }
  }
}