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

// Define I2C LCD address and dimensions
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define GPIO pins
#define TRIG_PIN 12  // GPIO pin connected to the Trig pin of the ultrasonic sensor
#define ECHO_PIN 13  // GPIO pin connected to the Echo pin of the ultrasonic sensor
#define RED_LED_PIN 14   // GPIO pin connected to the red LED
#define GREEN_LED_PIN 15 // GPIO pin connected to the green LED
#define BUTTON_PIN 26    // GPIO pin for the submit button
#define BUZZER_PIN 25

// Correct PIN
const String correctPin = "123456";

// Keypad setup
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {5, 4, 0, 2}; // Connect to the row pinouts of the keypad
byte colPins[COLS] = {16, 17, 18, 19}; // Connect to the column pinouts of the keypad
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

String enteredPin = "";

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Set up pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);

  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Welcome");
}

// Function to measure distance
float measureDistance() {
  // Send a 10us pulse to trigger the ultrasonic sensor
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Measure the duration of the echo pulse
  long duration = pulseIn(ECHO_PIN, HIGH);

  // Calculate distance in cm
  float distance = (duration * 0.0343) / 2;  // Speed of sound = 343 m/s or 0.0343 cm/us
  return distance;
}

void loop() {
  float distance = measureDistance();
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance <= 10 && distance > 0) {
    // Object detected within range
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Enter Pin:");
    digitalWrite(RED_LED_PIN, HIGH); // Turn on red LED

    char key = keypad.getKey();
    if (key) {
      if (key == '*') {
        // Clear entered PIN
        enteredPin = "";
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Enter Pin:");
      } else if (key == '#') {
        // Submit PIN
        if (enteredPin == correctPin) {
          lcd.clear();
          lcd.setCursor(0, 0);
          lcd.print("Thank You");
          digitalWrite(RED_LED_PIN, LOW);
          digitalWrite(GREEN_LED_PIN, HIGH); // Turn on green LED
          delay(2000); // Show message for 2 seconds
          lcd.clear();
          lcd.setCursor(0, 0);
          lcd.print("Welcome");
          enteredPin = "";
        } else {
          lcd.clear();
          lcd.setCursor(0, 0);
          lcd.print("Pin Wrong");
          digitalWrite(RED_LED_PIN, HIGH);
          digitalWrite(GREEN_LED_PIN, LOW);
          delay(2000); // Show message for 2 seconds
          lcd.clear();
          lcd.setCursor(0, 0);
          lcd.print("Enter Pin:");
          enteredPin = "";
        }
      } else {
        // Add digit to entered PIN
        if (enteredPin.length() < 6) {
          enteredPin += key;
          lcd.setCursor(0, 1);
          lcd.print(enteredPin);
        }
      }
    }

  } else {
    // No object detected
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Welcome");
    digitalWrite(RED_LED_PIN, LOW); // Turn off red LED
    digitalWrite(GREEN_LED_PIN, LOW); // Turn off green LED
  }

  delay(100); // Small delay to prevent rapid re-triggering
}