#include <Keypad.h>

#define PASS_LENGTH 8
char password[PASS_LENGTH] = {'1', '2', '3', '4', '5', '6', '7', '8'};
char passwordInput[PASS_LENGTH];
bool match;

const byte ROWS = 4;
const byte COLS = 4;
char hexaKeys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6};
byte colPins[COLS] = {5, 4, 3, 2};
Keypad keypad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);

#define buzzer_pin 10
void setup() 
{
  Serial.begin(9600);
  pinMode(buzzer_pin, OUTPUT);
}

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

  if (key != NO_KEY) 
  {
    for (int i = 0; i < PASS_LENGTH - 1; i++) 
    {
      passwordInput[i] = passwordInput[i + 1];
    }

    passwordInput[PASS_LENGTH - 1] = key;

    for (int i = 0; i < PASS_LENGTH; i++) 
    {
      Serial.print(passwordInput[i]);
    }
    Serial.println();

    match = true;
    for (int i = 0; i < PASS_LENGTH - 1; i++) 
    {
      if (passwordInput[i] != password[i]) 
      {
        match = false;
        break;
      }
    }

    if (match) 
    {
      Serial.println("Password matched!");
      for(int i = 0; i < 3;i++)
      {
        beep(50);
        delay(200);
        beep(0);
        delay(200);
      }
      
    }
  }
}

void beep(unsigned char delayms)
{
  analogWrite(buzzer_pin, 200);
  delay(delayms);
  analogWrite(buzzer_pin, 0);
  delay(delayms);
}