#include <SPI.h>
#include <MFRC522.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// --- Hardware Pins ---
#define SS_PIN 10
#define RST_PIN 9
#define RELAY_PIN 8
#define GREEN_LED 7
#define RED_LED 6
#define BUZZER_PIN 5
#define PIR_PIN 4

// --- Display Setup ---
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// --- RFID Setup ---
MFRC522 rfid(SS_PIN, RST_PIN);

void setup() {
  Serial.begin(115200);
  SPI.begin();           
  rfid.PCD_Init();       

  pinMode(RELAY_PIN, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(PIR_PIN, INPUT);
  
  digitalWrite(RELAY_PIN, LOW); // Ensure relay starts OFF

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    for(;;);
  }

  showStandby();
  Serial.println("System Active. Scan ANY card to open...");
}

void loop() {
  // 1. Check for Motion (PIR Sensor)
  if (digitalRead(PIR_PIN) == HIGH) {
    securityAlert();
    showStandby(); 
  }

  // 2. Check for RFID Cards
  // If no card is present, the code just keeps looping
  if (!rfid.PICC_IsNewCardPresent()) return;
  if (!rfid.PICC_ReadCardSerial()) return;

  // 3. Logic: ANY card detected will trigger access
  Serial.println("Card detected! Opening relay...");
  grantAccess();
  
  // Finish reading and return to standby
  rfid.PICC_HaltA();
  showStandby(); 
}

void showStandby() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(20, 15);
  display.println("SECURE TERMINAL");
  display.setCursor(25, 40);
  display.println("TAP ANY CARD");
  display.display();
}

void grantAccess() {
  display.clearDisplay();
  display.setCursor(25, 20);
  display.setTextSize(2);
  display.println("GRANTED");
  display.display();

  digitalWrite(GREEN_LED, HIGH);
  digitalWrite(RELAY_PIN, HIGH); // <--- RELAY TURNS ON HERE
  tone(BUZZER_PIN, 1500, 500);   
  
  delay(5000); // Keep relay on for 5 seconds
  
  digitalWrite(RELAY_PIN, LOW);  // <--- RELAY TURNS OFF HERE
  digitalWrite(GREEN_LED, LOW);
}

void securityAlert() {
  display.clearDisplay();
  display.setCursor(15, 20);
  display.setTextSize(2);
  display.println("WARNING!");
  display.setCursor(20, 45);
  display.setTextSize(1);
  display.println("Motion Detected");
  display.display();
  
  digitalWrite(RED_LED, HIGH);
  tone(BUZZER_PIN, 2000, 100); 
  delay(500);
  digitalWrite(RED_LED, LOW);
}