#include                // MFRC522 RFID library
#include                 // I2C communication library
#include    // I2C LCD library
#include                // Servo motor library

#define ID_LEN 4                 // Length of the RFID UID in bytes

// ———— Global objects & pins ————
RFID1               rfid;                // RFID reader object
LiquidCrystal_I2C  lcd(0x27, 16, 2);     // LCD at I2C address 0x27, 16×2 chars
Servo               myServo;             // Servo motor object

const int buzPin   = 10;   // Buzzer output pin
const int servoPin = 11;   // Servo control pin

// Authorized card UID (change to your card’s UID)
uchar userId[ID_LEN]     = { 0x36, 0xE2, 0xC4, 0xF7 };
// Buffer to store the UID read from a card
uchar userIdRead[ID_LEN];

// ———— Setup runs once ————
void setup() {
  Serial.begin(9600);            // Start serial monitor for debugging

  // Initialize RFID reader (SS, RST, MISO, MOSI, SCK, IRQ)
  rfid.begin(7, 5, 4, 3, 6, 2);
  rfid.init();                   // Power up and reset RFID module

  pinMode(buzPin, OUTPUT);       // Configure buzzer pin as output

  // Attach servo and move it to 90° (door closed)
  myServo.attach(servoPin);
  myServo.write(90);
  delay(500);                    // Wait for servo to reach position

  lcd.init();                    // Initialize the LCD
  lcd.backlight();               // Turn on LCD backlight

  showWelcome();                 // Display the welcome screen
}

// ———— Main loop repeats forever ————
void loop() {
  uchar status, str[MAX_LEN];

  // Ask RFID module if a card is in range
  status = rfid.request(PICC_REQIDL, str);
  if (status == MI_OK) {
    getId();                // Read the card’s UID into buffer
    scanningAnimation();    // Show “Scanning……” with dots

    // Check if the read UID matches authorized UID
    if (idVerify()) {
      handleSuccess();      // If match, open door
    } else {
      handleFailure();      // If no match, show error
    }

    delay(500);             // Short pause before resetting screen
    showWelcome();          // Return to welcome message

    // Clear the UID buffer for next read
    for (int i = 0; i < ID_LEN; i++) {
      userIdRead[i] = 0;
    }
  }
}

// ———— Display initial welcome screen ————
void showWelcome() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Welcome!");         // Top line
  lcd.setCursor(0, 1);
  lcd.print("Place your card");  // Bottom line
}

// ———— Show scanning animation ————
void scanningAnimation() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Scanning");         // Print text
  // Add six dots one by one
  for (int i = 0; i < 6; i++) {
    lcd.print(".");
    delay(500);                  // Wait half a second per dot
  }
}

// ———— Read UID from the card ————
void getId() {
  uchar status, str[MAX_LEN];
  status = rfid.anticoll(str);   // Anti-collision to get full UID
  if (status == MI_OK) {
    Serial.print("Card ID: ");
    // Copy each byte into our buffer and print it for debug
    for (int i = 0; i < ID_LEN; i++) {
      userIdRead[i] = str[i];
      Serial.print("0x");
      Serial.print(str[i], HEX);
      Serial.print(" ");
    }
    Serial.println();
    rfid.halt();                 // Halt further readings until next loop
  }
}

// ———— Compare read UID with authorized UID ————
bool idVerify() {
  for (int i = 0; i < ID_LEN; i++) {
    if (userIdRead[i] != userId[i]) {
      verifyPrint(false);        // Mismatch: indicate failure
      return false;
    }
  }
  verifyPrint(true);             // Match: indicate success
  return true;
}

// ———— Sound buzzer for pass/fail feedback ————
void verifyPrint(bool result) {
  if (result) {
    beep(100, 3);                // Three short beeps for success
    delay(400);                  // Pause before next action
  } else {
    beep(500, 1);                // One long beep for error
    delay(400);
  }
}

// duration: length of one beep in ms; frequency: number of beeps
void beep(int duration, int frequency) {
  for (int i = 0; i < frequency; i++) {
    tone(buzPin, 1000);          // Play 1 kHz tone
    delay(duration);             // Keep tone on
    noTone(buzPin);              // Stop tone
    delay(100);                  // Short gap between beeps
  }
}

// ———— Actions when card is valid ————
void handleSuccess() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Card success!");
  lcd.setCursor(0, 1);
  lcd.print("Welcome home");

  delay(500);                     // Let user read the message
  myServo.write(0);               // Move servo to 0° (open door)
  delay(2000);                    // Door stays open for 2 seconds
  myServo.write(90);              // Return servo to 90° (close door)
}

// ———— Actions when card is invalid ————
void handleFailure() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Card error!");       // Show error message
  delay(1000);                    // Pause so user sees the error
}