#include <Keypad.h>
#include <Servo.h>

#define ROW_NUM    4  // four rows
#define COLUMN_NUM 4  // four columns
#define SERVO_PIN  A0 // // the Arduino pin, which connects to the servo motor

Servo servo; // servo motor

char keys[ROW_NUM][COLUMN_NUM] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte pin_rows[ROW_NUM] = {9, 8, 7, 6}; //connect to the row pinouts of the keypad
byte pin_column[COLUMN_NUM] = {5, 4, 3, 2}; //connect to the column pinouts of the keypad

Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );

const String password_1 = "ABC1234"; // change your password here
const String password_2 = "5642B";   // change your password here
const String password_3 = "9765";    // change your password here
String input_password;

int angle = 0; // the current angle of servo motor
unsigned long lastTime;

void setup() {
  Serial.begin(9600);
  input_password.reserve(32); // maximum password size is 32, change if needed

  servo.attach(SERVO_PIN);
  servo.write(0); // rotate servo motor to 0°
  lastTime = millis();
}

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

  if (key) {
    Serial.println(key);

    if (key == '*') {
      input_password = ""; // reset the input password
    } else if (key == '#') {
      if (input_password == password_1 || input_password == password_2 || input_password == password_3) {
        Serial.println("The password is correct, rotating Servo Motor to 90°");
        angle = 90;
        servo.write(angle);
        lastTime = millis();
      } else {
        Serial.println("The password is incorrect, try again");
      }

      input_password = ""; // reset the input password
    } else {
      input_password += key; // append new character to input password string
    }
  }

  if (angle == 90 && (millis() - lastTime) > 5000) { // 5 seconds
    angle = 0;
    servo.write(angle);
    Serial.println("Rotating Servo Motor to 0°");
  }
}