// SMART ROOM SYSTEM - Wokwi Compatible Code
// EC8020 Design Task 2

#include <Servo.h>
#include <Keypad.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// ===== LCD SETUP =====
LiquidCrystal_I2C lcd(0x27, 20, 4); // I2C address 0x27 (common for LCD2004)

// ===== PIN DEFINITIONS =====
// Door Lock System
#define SERVO_PIN 9
#define LED_LOCKED 10
#define LED_UNLOCKED 11
#define BUZZER_LOCK 12

// Lighting System
#define PIR_SENSOR 8
#define LIGHT_RELAY 7

// Smoke Detection System
#define SMOKE_SENSOR A0
#define ALARM_BUZZER 6
#define ALARM_LED 5

// ===== KEYPAD SETUP =====
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {A1, A2, A3, A4};  // Keypad rows
byte colPins[COLS] = {2, 3, 4, 13};     // Keypad columns

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// ===== GLOBAL VARIABLES =====
// Door Lock
Servo doorServo;
String password = "1234";  // Default password
String enteredPassword = "";
bool doorLocked = true;
unsigned long unlockTime = 0;
const unsigned long AUTO_LOCK_TIME = 10000; // 10 seconds

// Lighting System
unsigned long lastMotionTime = 0;
bool lightOn = false;
const unsigned long LIGHT_TIMEOUT = 30000; // 30 seconds

// Smoke Detection
const int SMOKE_THRESHOLD = 910;  // Adjust based on sensor calibration
bool alarmActive = false;

// ===== SETUP =====
void setup() {
  Serial.begin(9600);

  // LCD Setup
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0, 1); lcd.print("Enter Password: ");
  lcd.setCursor(0, 2); lcd.print("Door: LOCKED");
  lcd.setCursor(0, 3); lcd.print("Light: OFF");
  
  // Door Lock Setup
  doorServo.attach(SERVO_PIN);
  pinMode(LED_LOCKED, OUTPUT);
  pinMode(LED_UNLOCKED, OUTPUT);
  pinMode(BUZZER_LOCK, OUTPUT);
  lockDoor();  // Start in locked state
  
  // Lighting System Setup
  pinMode(PIR_SENSOR, INPUT);
  pinMode(LIGHT_RELAY, OUTPUT);
  digitalWrite(LIGHT_RELAY, LOW);  // Light off
  
  // Smoke Detection Setup
  pinMode(ALARM_BUZZER, OUTPUT);
  pinMode(ALARM_LED, OUTPUT);
  digitalWrite(ALARM_BUZZER, LOW);
  digitalWrite(ALARM_LED, LOW);
  
}

// ===== MAIN LOOP =====
void loop() {
  handleDoorLock();
  handleLighting();
  handleSmokeDetection();
  delay(50);  // Small delay for stability
}

// ===== DOOR LOCK FUNCTIONS =====
void handleDoorLock() {
  // Check for keypad input
  char key = keypad.getKey();
  
  if (key) {
    
    if (key == '#') {  // Submit password
      checkPassword();
    } else if (key == '*') {  // Clear password
      enteredPassword = "";
      lcd.setCursor(0, 1); lcd.print("Enter Password:    ");
    } else if (enteredPassword.length() < 4) {
      enteredPassword += key;
      displayEnteredPassword();
      
      // Auto-submit when 4 digits entered
      if (enteredPassword.length() == 4) {
        checkPassword();
      }
    }
  }
  
  // Auto-lock after timeout
  if (!doorLocked && millis() - unlockTime > AUTO_LOCK_TIME) {
    lockDoor();
    // Reset LCD layout
    lcd.clear();
    lcd.setCursor(0, 1); lcd.print("Enter Password:   ");
    lcd.setCursor(0, 2); lcd.print("Door: LOCKED   ");
    lcd.setCursor(0, 3); lcd.print(lightOn ? "Light: ON " : "Light: OFF");
  
    Serial.println(">> Auto-locking door (timeout)");
  }
}

void displayEnteredPassword() {
  lcd.setCursor(0, 1); 
  lcd.print("Password: ");
  for (int i = 0; i < enteredPassword.length(); i++) {
    lcd.print("*");
  }
  lcd.print("    "); // Clear leftover chars
}

void checkPassword() {
  Serial.println("----------------------------");
  Serial.print("Verifying password: ");
  for (int i = 0; i < enteredPassword.length(); i++) {
    Serial.print("*");
  }
  Serial.println();
  
  if (enteredPassword == password) {
    unlockDoor();
    lcd.setCursor(0, 2);
    lcd.print("Door: UNLOCKED    ");
    Serial.println("✓ ACCESS GRANTED - Door Unlocked");
  } else {
    Serial.println("✗ ACCESS DENIED - Wrong Password");
    wrongPasswordAlert();
    lcd.setCursor(0, 2);
    lcd.print("ACCESS DENIED     ");
    delay(2000);

    // Reset LCD for next try
    lcd.setCursor(0, 1); lcd.print("Enter Password:   ");
    lcd.setCursor(0, 2); lcd.print("Status: LOCKED    ");
  }
  Serial.println("----------------------------");
  
  enteredPassword = "";  // Clear for next attempt
}

void unlockDoor() {
  doorLocked = false;
  doorServo.write(90);  // Unlock position (90 degrees)
  digitalWrite(LED_UNLOCKED, HIGH);
  digitalWrite(LED_LOCKED, LOW);
  unlockTime = millis();
  
  // Success beep
  tone(BUZZER_LOCK, 1000, 200);
  delay(250);
  tone(BUZZER_LOCK, 1200, 200);
}

void lockDoor() {
  doorLocked = true;
  doorServo.write(0);  // Lock position (0 degrees)
  digitalWrite(LED_LOCKED, HIGH);
  digitalWrite(LED_UNLOCKED, LOW);
  
  // Lock beep
  tone(BUZZER_LOCK, 800, 150);
}

void wrongPasswordAlert() {
  // Blink red LED and sound buzzer 3 times
  for (int i = 0; i < 3; i++) {
    digitalWrite(LED_LOCKED, LOW);
    tone(BUZZER_LOCK, 2000, 200);
    delay(250);
    digitalWrite(LED_LOCKED, HIGH);
    delay(250);
  }
}

// ===== LIGHTING SYSTEM FUNCTIONS =====
void handleLighting() {
  int motionDetected = digitalRead(PIR_SENSOR);
  
  if (motionDetected == HIGH) {
    // Motion detected
    if (!lightOn) {
      turnLightOn();
    }
    lastMotionTime = millis();  // Reset timer
  } else {
    // No motion
    if (lightOn && (millis() - lastMotionTime > LIGHT_TIMEOUT)) {
      turnLightOff();
    }
  }
}


void turnLightOn() {
  digitalWrite(LIGHT_RELAY, HIGH);
  lightOn = true;
  lcd.setCursor(0, 3);
  lcd.print("Light: ON         ");
  Serial.println(">> Light ON - Motion detected");
}

void turnLightOff() {
  digitalWrite(LIGHT_RELAY, LOW);
  lightOn = false;
  lcd.setCursor(0, 3);
  lcd.print("Light: OFF        ");
  Serial.println(">> Light OFF - No motion (timeout)");
}

// ===== SMOKE DETECTION FUNCTIONS =====
void handleSmokeDetection() {
  int smokeLevel = analogRead(SMOKE_SENSOR);

  // Always display smoke level on LCD line 0
  lcd.setCursor(0, 0);
  lcd.print("Smoke Level: ");
  lcd.print(smokeLevel);
  lcd.print("    "); // Clear extra chars
  
  if (smokeLevel > SMOKE_THRESHOLD) {
    // Smoke detected above threshold
    if (!alarmActive) {
      activateAlarm();
    }
    // Keep alarm sounding while smoke is present
    static unsigned long lastBeep = 0;
    if (millis() - lastBeep > 500) {
      tone(ALARM_BUZZER, 3000, 400);
      lastBeep = millis();
    }
    // Overwrite with ALERT if danger
    lcd.setCursor(0, 0);
    lcd.print("!!! SMOKE ALERT !!!");
  } else {
    // No dangerous smoke level
    if (alarmActive) {
      deactivateAlarm();
    }
  }
}

void activateAlarm() {
  alarmActive = true;
  digitalWrite(ALARM_LED, HIGH);
  Serial.println("⚠⚠⚠ ALARM ACTIVATED ⚠⚠⚠");
  Serial.println("SMOKE/GAS DETECTED!");
  Serial.println("⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠");
}

void deactivateAlarm() {
  alarmActive = false;
  digitalWrite(ALARM_LED, LOW);
  noTone(ALARM_BUZZER);
  Serial.println(">> Alarm deactivated - Air quality normal");
}

// ===== UTILITY FUNCTIONS (for testing) =====
void printStatus() {
  Serial.println("\n===== SYSTEM STATUS =====");
  Serial.print("Door: ");
  Serial.println(doorLocked ? "LOCKED" : "UNLOCKED");
  Serial.print("Light: ");
  Serial.println(lightOn ? "ON" : "OFF");
  Serial.print("Alarm: ");
  Serial.println(alarmActive ? "ACTIVE" : "INACTIVE");
  Serial.println("========================\n");
}