#include <Keypad.h>
#include <string.h>

const byte rows = 4;
const byte cols = 3;

char keys[rows][cols] = {
  {'1', '2', '3'}, {'4', '5', '6'},
  {'7', '8', '9'}, {'*', '0', '#'},
};

byte rowPins[rows] = {14, 15, 16, 17};
byte colPins[cols] = {18, 19, 20};
byte buzzerPin = 21;

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, rows, cols);

char combination[5] = "EEEE"; // Set to default combination
char correctCombination[5] = "1234"; // Correct combination
byte pointer = 0;

void setup() {
  Serial.begin(9600);
}

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

  if (key) {
    combination[pointer] = key;
    pointer++;

    Serial.println(pointer);

    if (pointer >= 4) {
      combination[pointer] = '\0';

      if (strcmp(combination, correctCombination) == 0) {
        tone(buzzerPin, 1500);
      } else {
        tone(buzzerPin, 1000);
      }

      Serial.println(combination);
      Serial.println(strcmp(combination, correctCombination) == 0 ? "Correct" : "Wrong");
      delay(700);
      noTone(buzzerPin);

      // Reset combination
      memset(combination, 'E', sizeof(combination) - 1); // Reset to "EEEE"
      combination[4] = '\0'; // Ensure null-termination
      pointer = 0;
    }
  }
}