#include <Keypad.h>
#include <LiquidCrystal.h>

#define BUZZER_PIN 7
#define PASSWORD "1234"  // Set your desired password here

// Define LCD pins and initialize the LCD
LiquidCrystal lcd(2, 3, 4, 6);

// Define keypad configuration
const byte ROWS = 4; // four rows
const byte COLS = 4; // four columns
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6}; // Connect to the row pinouts of the keypad
byte colPins[COLS] = {5, 4, 3, 2}; // Connect to the column pinouts of the keypad

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

unsigned long startTime = 0;
unsigned long elapsedTime = 0;
bool running = false;
bool alertActive = false;
String inputPassword = "";

// Function to start the stopwatch
void startStopwatch() {
  startTime = millis();
  running = true;
  alertActive = false;
  inputPassword = ""; // Reset password entry
  lcd.clear();
  lcd.print("Stopwatch Started");
}

// Function to stop the stopwatch
void stopStopwatch() {
  running = false;
  lcd.clear();
  lcd.print("Stopwatch Stopped");
  delay(1000);
}

// Function to reset the stopwatch
void resetStopwatch() {
  startTime = millis();
  lcd.clear();
  lcd.print("Reset Stopwatch");
  delay(1000);
  lcd.clear();
}

void setup() {
  lcd.begin(16, 2); // Initialize 16x2 LCD
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);
  lcd.print("Press A to Start");
}

void loop() {
  char key = keypad.getKey();

  if (key) {
    if (key == 'A' && !running) {
      startStopwatch();
    } else if (key == 'B' && running) {
      stopStopwatch();
    } else if (key == 'C' && !running) {
      resetStopwatch();
    } else if (key == '#') {
      inputPassword = ""; // Clear input if '#' is pressed
    } else if (isdigit(key)) {
      inputPassword += key;
      
      // Check if password is correct
      if (inputPassword == PASSWORD) {
        lcd.clear();
        lcd.print("Password Correct");
        delay(1000);
        inputPassword = "";
        alertActive = false;
        digitalWrite(BUZZER_PIN, LOW); // Stop buzzer if correct password is entered
      } else if (inputPassword.length() >= 4) {
        lcd.clear();
        lcd.print("Wrong Password");
        delay(1000);
        inputPassword = ""; // Reset on incorrect password
      }
    }
  }

  if (running) {
    elapsedTime = (millis() - startTime) / 1000;
    lcd.setCursor(0, 1);
    lcd.print("Time: ");
    lcd.print(elapsedTime);
    lcd.print(" s");

    // Activate buzzer if stopwatch runs for more than 30 seconds
    if (elapsedTime > 30 && !alertActive) {
      digitalWrite(BUZZER_PIN, HIGH);
      alertActive = true;
    }
  }
}