#include <Servo.h>
#include <SPI.h>
#include <MFRC522.h>

#define RST_PIN         9   // Configurable, pin connected to RST of MFRC522
#define SS_PIN          10  // Configurable, pin connected to SDA of MFRC522
#define SERVO_PIN       3   // Servo control pin

MFRC522 mfrc522(SS_PIN, RST_PIN);  // Create MFRC522 instance
Servo myServo;                     // Create Servo object

// Define a known RFID UID (you can find your RFID tag's UID using the serial monitor)
byte knownUID[] = {0xDE, 0xAD, 0xBE, 0xEF}; // Replace with your card's UID

void setup() {
  Serial.begin(9600);           // Initialize serial communications
  SPI.begin();                  // Init SPI bus
  mfrc522.PCD_Init();           // Init MFRC522
  myServo.attach(SERVO_PIN);    // Attach the servo to pin
  myServo.write(0);             // Initialize servo to 0 degrees
  Serial.println("Place your RFID card near the reader...");
}

void loop() {
  // Look for a card
  if (!mfrc522.PICC_IsNewCardPresent()) {
    return;
  }
  
  // Select one of the cards
  if (!mfrc522.PICC_ReadCardSerial()) {
    return;
  }

  // Show UID on serial monitor
  Serial.print("Card UID: ");
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
  }
  Serial.println();

  // Check if the card UID matches the known UID
  if (compareUID(mfrc522.uid.uidByte, knownUID, mfrc522.uid.size)) {
    Serial.println("Access granted!");
    myServo.write(90);   // Rotate servo to 90 degrees (open door)
    delay(3000);         // Hold for 3 seconds
    myServo.write(0);    // Rotate servo back to 0 degrees (close door)
  } else {
    Serial.println("Access denied!");
  }
  
  // Halt PICC to stop further communication
  mfrc522.PICC_HaltA();
}

// Function to compare two UIDs
bool compareUID(byte *uid1, byte *uid2, byte size) {
  for (byte i = 0; i < size; i++) {
    if (uid1[i] != uid2[i]) {
      return false;
    }
  }
  return true;
}