#include <SPI.h>
#include <MFRC522.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define SS_PIN 10
#define RST_PIN 9

#define GREEN_LED 7
#define RED_LED 6
#define BUZZER 8

MFRC522 rfid(SS_PIN, RST_PIN);
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Authorized RFID UID
String authorizedUID = "55 66 77 88";

void setup() {

  Serial.begin(9600);

  SPI.begin();
  rfid.PCD_Init();

  lcd.init();
  lcd.backlight();

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

  lcd.setCursor(0, 0);
  lcd.print("Smart Attendance");
  lcd.setCursor(0, 1);
  lcd.print("Scan Your Card");

  Serial.println("System Ready");
}

void loop() {

  // Wait for RFID card
  if (!rfid.PICC_IsNewCardPresent()) {
    return;
  }

  if (!rfid.PICC_ReadCardSerial()) {
    return;
  }

  String cardUID = "";

  // Read UID
  for (byte i = 0; i < rfid.uid.size; i++) {
    cardUID += String(rfid.uid.uidByte[i] < 0x10 ? " 0" : " ");
    cardUID += String(rfid.uid.uidByte[i], HEX);
  }

  cardUID.toUpperCase();
  cardUID.trim(); //Clean fix: removes any accidental trailing spaces

  Serial.print("Card UID:");
  Serial.println(cardUID);

  // Authorized Card
  if (cardUID == authorizedUID)
 {

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Welcome Jessica");

    lcd.setCursor(0,1);
    lcd.print("Attendance OK");
    digitalWrite(RED_LED, LOW);
    digitalWrite(GREEN_LED,HIGH);
    tone(BUZZER, 1000);
    Serial.println("Jessica Present");
    delay(2000);

    digitalWrite(GREEN_LED,LOW);
    noTone(BUZZER);

    
}
else {
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Access Denied");
  digitalWrite(RED_LED,HIGH);

  tone(BUZZER, 500);
  Serial.println("Unauthorized Access");
  delay(2000);
  digitalWrite(GREEN_LED,LOW);
  digitalWrite(RED_LED,HIGH);// Turn RED OFF after delay

  noTone(BUZZER);
}
//reset the screen back to the standard idle state
lcd.clear();

lcd.setCursor(0,0);
lcd.print("Scan Your Card");
rfid.PICC_HaltA();

}