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

const uint8_t ROWS = 4;
const uint8_t COLS = 4;

#define I2C_ADDR        0x27
#define LCD_COLUMNS     16
#define LCD_LINES       2
#define SERVO_LOCK_POS  20
#define SERVO_UNLOCK_POS 90
#define red 13
#define green 12

// Creating Servo object
Servo servo;

// Defining keypad keys
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

// Defining pins for the keypad
uint8_t colPins[COLS] = {5, 4, 3, 2};
uint8_t rowPins[ROWS] = {9, 8, 7, 6};

// Creating Keypad object
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Creating LiquidCrystal_I2C object
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

// Defining delays for code checking and message display
const int CHECK_DELAY = 500;  // Adjust delay based on typing speed
const int MESSAGE_DELAY = 2000;  // Adjust delay for message display

// Strings to store entered code and message
String phrase = "";
String message = "";

// Function to unlock the servo
void unlock() {
  servo.write(SERVO_LOCK_POS);
}

// Function to lock the servo
void lock() {
  servo.write(SERVO_UNLOCK_POS);
}

void setup() {
  // Initializing the LCD screen and turning on the backlight
  lcd.init();
  lcd.backlight();

  // Attaching the servo to pin 10
  servo.attach(10);

  // Initializing serial communication
  Serial.begin(115200);

  // Configuring pins for LEDs (red and green)
  pinMode(red, OUTPUT);
  pinMode(green , OUTPUT);
}

void loop() {
  // Introducing a delay at the beginning of each loop iteration
  delay(50);

  // Getting the pressed key on the keypad
  char key = keypad.getKey();

  // If a key is pressed
  if (key != NO_KEY) {
    // Adding the key to the phrase string
    phrase += key;

    // Clearing the LCD screen
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print(phrase);

    // If the length of the phrase exceeds the first line of the LCD
    if (phrase.length() > LCD_COLUMNS) {
      lcd.setCursor(0, 1);
      lcd.print(phrase.substring(LCD_COLUMNS, 2 * LCD_COLUMNS));
    }

    // If the length of the phrase reaches 4 characters
    if (phrase.length() == 4) {
      // Introducing a delay for code checking
      delay(CHECK_DELAY);

      // Checking the entered code
      if (phrase == "0000") {
        // If the code is correct, display a welcome message, unlock the servo, and turn on the green LED
        message = "Welcome!";
        unlock();
        digitalWrite(green, HIGH);
        digitalWrite(red, LOW);
      } else {
        // If the code is incorrect, display an error message, lock the servo, and turn on the red LED
        message = "Incorrect code";
        lock();
        digitalWrite(green, LOW);
        digitalWrite(red, HIGH);
      }

      // Introducing a delay before clearing the phrase and message
      delay(MESSAGE_DELAY);

      // Clearing the phrase and message
      phrase = "";
      message = "";

      // Clearing the LCD screen
      lcd.clear();
    }
  }

  // If a message is ready to be displayed
  if (message.length() > 0) {
    // Displaying the message on the second line of the LCD
    lcd.setCursor(0, 1);
    lcd.print(message);

    // Introducing a delay for message display
    delay(MESSAGE_DELAY);

    // Clearing the phrase and message
    phrase = "";
    message = "";

    // Clearing the LCD screen
    lcd.clear();
  }
}