#include <Keypad.h>

#define ROW_NUM 4
#define COL_NUM 4

char key = '\0';
String inp = "";
String pass = "";

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

byte rowPins[ROW_NUM] = {19, 18, 5, 17};
byte colPins[COL_NUM] = {16, 4, 2, 15};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROW_NUM, COL_NUM);

void setup() {
  Serial.begin(9600);
  Serial.println("Welcome to your personal lock services!");
  delay(1000);

  Serial.println("Press # to set a new password.");
  Serial.println(key);
  while (true) {
    key = keypad.getKey();
    if (key == '#') break;
    delay(50);
  }

  newPass();
  checkPass();
}

void loop() {
  delay(10000);
}

void newPass() {
  Serial.println("Enter a new password. Press # when password set.");
  while (true) {
    key = keypad.getKey();
    if (key) {
      if (key == '#') {
        Serial.println("\nPassword has been set!\n");
        break;
      }
      else if (key == '*') {
        pass = "";
        Serial.println("\nInput cleared. Enter your new password again.");
      }
      else {
        pass.concat(key);
        Serial.print('@');
      }
    }
    delay(50);
  }
  delay(1000);
}

void checkPass() {
  Serial.println("Enter Password. Press # when password entered: ");
  while (true) {
    key = keypad.getKey();
    if (key) {
      if (key == '#') {
        if (inp == pass) {
          Serial.println("\nAccess granted!");
          break;
        }
        else {
          Serial.println("\nAccess denied, try again.");
          inp = "";
        }
      }
      else if (key == '*') {
        inp = "";
        Serial.println("\nInput cleared. Enter your password again.");
      }
      else {
        inp.concat(key);
        Serial.print('@');
      }
    }
    delay(50);
  }
}