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

// --- Pin Definitions Based on Diagram ---
#define RST_PIN     9
#define SS_PIN      10
#define BUZZER_PIN  3
#define LED_GREEN   2
#define LED_RED     4

// Initialize LCD (Address 0x27 is standard for 16x2 I2C displays)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Initialize RFID Reader
MFRC522 mfrc522(SS_PIN, RST_PIN);

// Example authorized UID (This matches the default Wokwi custom card UID format)
byte authorizedUID[] = {0x11, 0x22, 0x33, 0x44}; 

void setup() {
  Serial.begin(9600);
  SPI.begin();           // Init SPI bus
  mfrc522.PCD_Init();    // Init MFRC522 card

  // Initialize LCD
  lcd.init();
  lcd.backlight();
  displayIdleMessage();

  // Initialize Indicators
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_RED, OUTPUT);
  
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_RED, LOW);
}

void loop() {
  // Reset look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent()) {
    return;
  }

  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) {
    return;
  }

  // Check UID match against authorizedUID array
  bool accessGranted = true;
  
  // Verify that the scanned card size matches your target key size (typically 4 bytes)
  if (mfrc522.uid.size == sizeof(authorizedUID)) {
    for (byte i = 0; i < mfrc522.uid.size; i++) {
      if (mfrc522.uid.uidByte[i] != authorizedUID[i]) {
        accessGranted = false; // A byte doesn't match, deny access
        break; 
      }
    }
  } else {
    accessGranted = false; // Card format mismatch
  }

  if (accessGranted) {
    grantAccess();
  } else {
    denyAccess();
  }

  mfrc522.PICC_HaltA();
  displayIdleMessage();
}

void displayIdleMessage() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("   ASTRO PASS    ");
  lcd.setCursor(0, 1);
  lcd.print("    SMART RFID  ");
}

void grantAccess() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("ACCESS GRANTED ");
  lcd.setCursor(0, 1);
  lcd.print(" WELCOME ABOARD ");

  digitalWrite(LED_GREEN, HIGH);
  
  // Successful access chirp
  digitalWrite(BUZZER_PIN, HIGH);
  delay(150);
  digitalWrite(BUZZER_PIN, LOW);
  delay(100);
  digitalWrite(BUZZER_PIN, HIGH);
  delay(150);
  digitalWrite(BUZZER_PIN, LOW);

  delay(2000); // Leave gate simulated open
  digitalWrite(LED_GREEN, LOW);
}

void denyAccess() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(" ACCESS DENIED  ");
  lcd.setCursor(0, 1);
  lcd.print("INVALID BADGE ID");

  digitalWrite(LED_RED, HIGH);
  
  // Long rejection beep
  digitalWrite(BUZZER_PIN, HIGH);
  delay(800);
  digitalWrite(BUZZER_PIN, LOW);

  delay(1500);
  digitalWrite(LED_RED, LOW);
}