#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Keypad.h>
#include <Servo.h>


/* --------- LCD --------- */
LiquidCrystal_I2C lcd(0x27, 16, 2);

/* --------- KEYPAD --------- */
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {32, 33, 25, 26}; // Connect to ROW0-ROW3
byte colPins[COLS] = {27, 14, 12, 13}; // Connect to COL0-COL3
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

/* --------- SERVO --------- */
Servo doorServo;
#define SERVO_PIN 23

/* --------- LED & BUZZER --------- */
#define GREEN_LED 2
#define RED_LED 15
#define BUZZER 4

/* --------- PASSWORD --------- */
String password = "1234";
String inputPassword = "";

void setup() {
  Serial.begin(115200);

  // LCD init
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Door Lock System");

  // Pins
  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  // Servo init
  doorServo.attach(SERVO_PIN);
  doorServo.write(0); // Locked
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    if (key == '#') { // Enter
      checkPassword();
      inputPassword = ""; // reset
    } else if (key == '*') { // Clear
      inputPassword = "";
      lcd.setCursor(0,1);
      lcd.print("                "); // clear line
    } else {
      inputPassword += key;
      lcd.setCursor(0,1);
      lcd.print(inputPassword);
    }
  }
}

void checkPassword() {
  if (inputPassword == password) {
    lcd.setCursor(0,1);
    lcd.print("ACCESS GRANTED");
    digitalWrite(GREEN_LED, HIGH);
    digitalWrite(RED_LED, LOW);
    tone(BUZZER, 1000, 200); // beep
    doorServo.write(90); // unlock door
    delay(3000);
    doorServo.write(0); // lock door
    digitalWrite(GREEN_LED, LOW);
    lcd.setCursor(0,1);
    lcd.print("                ");
  } else {
    lcd.setCursor(0,1);
    lcd.print("ACCESS DENIED ");
    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
    tone(BUZZER, 500, 500); // long beep
    delay(2000);
    digitalWrite(RED_LED, LOW);
    lcd.setCursor(0,1);
    lcd.print("                ");
  }
}