#include 
#include 
#include 
#include 

#define ID_LEN 4    // Length of RFID UID

// Pin definitions
const int servoPin  = 9;    // Servo motor for door
const int buzzerPin = 10;   // Buzzer
const int flamePin  = 11;   // Flame sensor (digital)
const int smokePin  = A0;   // Smoke sensor (analog)

// Objects
RFID1 rfid;
Servo myServo;
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Authorized RFID card UID
uchar userId[ID_LEN] = {0x36, 0xE2, 0xC4, 0xF7};
uchar userIdRead[ID_LEN];

// Servo movement control
int targetPos  = 0;   // Target angle
int currentPos = 0;   // Current angle

// Door state after valid card
bool cardAction = false;
unsigned long cardTimer = 0;

// Emergency control flags
bool emergencyAlert = false;
bool emergencyRecovering = false;
unsigned long emergencyRecoverStart = 0;

// Smoke sensor threshold
int smokeValue = 0;
const int smokeThreshold = 200;

// System states for LCD display
enum SystemState {
  STATE_BOOT,
  STATE_IDLE,
  STATE_ACCESS_GRANTED,
  STATE_ACCESS_DENIED,
  STATE_EMERGENCY
};

SystemState currentState = STATE_BOOT;
SystemState lastState    = STATE_IDLE;

// Emergency type for LCD message
enum EmergencyType {
  EM_NONE,
  EM_SMOKE,
  EM_FIRE,
  EM_BOTH
};

EmergencyType emergencyType = EM_NONE;

// Set servo target angle (0–90 degrees)
void setServoAngle(int angle) {
  targetPos = constrain(angle, 0, 90);
}

// Move servo smoothly without blocking the program
void servoSmoothRun() {
  static unsigned long lastStep = 0;

  if (millis() - lastStep >= 15) {
    lastStep = millis();

    if (currentPos < targetPos) currentPos++;
    else if (currentPos > targetPos) currentPos--;

    myServo.write(currentPos);
  }
}

// Short beep for authorized card
void beepShort() {
  tone(buzzerPin, 2000);
  delay(80);
  noTone(buzzerPin);
}

// Beep pattern for denied card (blocking)
void beepDenied() {
  for (int i = 0; i < 4; i++) {
    tone(buzzerPin, 1600);
    delay(100);
    noTone(buzzerPin);
    delay(100);
  }
}

// Alarm sound for emergency (non-blocking)
void beepAlarmNonBlock() {
  static unsigned long t = 0;
  static bool buz = false;

  if (millis() - t > 120) {
    t = millis();
    buz = !buz;
    if (buz) tone(buzzerPin, 1500);
    else noTone(buzzerPin);
  }
}

// Read RFID card UID
void getId() {
  uchar status, str[MAX_LEN];
  status = rfid.anticoll(str);

  if (status == MI_OK) {
    for (int i = 0; i < ID_LEN; i++) {
      userIdRead[i] = str[i];
    }
    rfid.halt();
  }
}

// Compare scanned UID with authorized UID
bool idVerify() {
  for (int i = 0; i < ID_LEN; i++) {
    if (userIdRead[i] != userId[i]) return false;
  }
  return true;
}

// Clear UID buffer after each scan
void clearBuffer() {
  for (int i = 0; i < ID_LEN; i++) {
    userIdRead[i] = 0;
  }
}

// Update LCD only when system state changes
void updateLCD() {
  if (currentState == lastState) return;

  lcd.clear();

  switch (currentState) {
    case STATE_BOOT:
      lcd.print("System Booting");
      break;

    case STATE_IDLE:
      lcd.print("System Ready");
      lcd.setCursor(0, 1);
      lcd.print("Scan Your Card");
      break;

    case STATE_ACCESS_GRANTED:
      lcd.print("Access Granted");
      lcd.setCursor(0, 1);
      lcd.print("Door Opening");
      break;

    case STATE_ACCESS_DENIED:
      lcd.print("Access Denied");
      lcd.setCursor(0, 1);
      lcd.print("Try Again");
      break;

    case STATE_EMERGENCY:
      lcd.print("Emergency");
      lcd.setCursor(0, 1);
      if (emergencyType == EM_FIRE)       lcd.print("Fire Detected!");
      else if (emergencyType == EM_SMOKE) lcd.print("Smoke Detected!");
      else if (emergencyType == EM_BOTH)  lcd.print("Fire & Smoke!");
      break;
  }

  lastState = currentState;
}

void setup() {
  Wire.begin();
  lcd.init();
  lcd.backlight();

  currentState = STATE_BOOT;
  updateLCD();
  delay(1000);

  currentState = STATE_IDLE;
  updateLCD();

  rfid.begin(7, 5, 4, 3, 6, 2);
  rfid.init();

  pinMode(buzzerPin, OUTPUT);
  pinMode(flamePin, INPUT);

  myServo.attach(servoPin);
  myServo.write(0);
}

void loop() {
  smokeValue = analogRead(smokePin);
  bool flameDetected = (digitalRead(flamePin) == LOW);

  // Determine emergency type
  if (smokeValue > smokeThreshold && flameDetected)
    emergencyType = EM_BOTH;
  else if (smokeValue > smokeThreshold)
    emergencyType = EM_SMOKE;
  else if (flameDetected)
    emergencyType = EM_FIRE;
  else
    emergencyType = EM_NONE;

  bool emergencyDetected = (emergencyType != EM_NONE);
  bool allowRFID = true;

  // Emergency handling
  if (emergencyDetected) {
    emergencyAlert = true;
    emergencyRecovering = false;

    setServoAngle(90);              // Force door open
    beepAlarmNonBlock();
    allowRFID = false;
    currentState = STATE_EMERGENCY;
  }
  else if (emergencyAlert) {
    if (!emergencyRecovering) {
      emergencyRecovering = true;
      emergencyRecoverStart = millis();
    }

    if (millis() - emergencyRecoverStart < 1500) {
      beepAlarmNonBlock();
      allowRFID = false;
    }
    else {
      emergencyAlert = false;
      emergencyRecovering = false;
      emergencyType = EM_NONE;

      setServoAngle(0);             // Start closing door
      noTone(buzzerPin);
    }
  }

  // RFID access control
  if (allowRFID && !cardAction) {
    uchar status, str[MAX_LEN];
    status = rfid.request(PICC_REQIDL, str);

    if (status == MI_OK) {
      getId();

      if (idVerify()) {
        beepShort();
        setServoAngle(90);
        cardAction = true;
        cardTimer = 0;
        currentState = STATE_ACCESS_GRANTED;
      }
      else {
        currentState = STATE_ACCESS_DENIED;
        updateLCD();                // Show message immediately
        beepDenied();               // Then beep
      }

      clearBuffer();
    }
  }

  // Auto close door after valid card
  if (cardAction) {
    if (currentPos >= 90) {
      if (cardTimer == 0) cardTimer = millis();
      if (millis() - cardTimer >= 1500) {
        setServoAngle(0);
      }
    }

    if (currentPos <= 3 && targetPos == 0) {
      cardAction = false;
      cardTimer = 0;
      currentState = STATE_IDLE;
    }
  }

  // Change LCD back to idle only after door fully closes
  if (!emergencyDetected &&
      !emergencyAlert &&
      targetPos == 0 &&
      currentPos <= 3 &&
      currentState == STATE_EMERGENCY) {

    currentState = STATE_IDLE;
  }

  servoSmoothRun();
  updateLCD();
}