#include <Wire.h>                 // For I2C communication
#include <LiquidCrystal_I2C.h>    // For I2C LCD
#include <OneWire.h>              // For DS18B20
#include <DallasTemperature.h>    // For DS18B20

// Pin configuration
#define TEMP_PIN 15             // GPIO15 for DS18B20
#define SMOKE_PIN 4             // GPIO4 for MQ-135 Analog Output
#define LED_PIN 2               // GPIO2 for onboard LED
#define BUZZER_PIN 5            // GPIO5 for buzzer
#define RELAY_PIN 16            // GPIO16 for relay controlling external LED

// Thresholds
#define TEMP_THRESHOLD 60       // Temperature threshold in °C
#define SMOKE_THRESHOLD 512     // Smoke level threshold (mapped value)

// Initialize DS18B20
OneWire oneWire(TEMP_PIN);
DallasTemperature sensors(&oneWire);

// Initialize I2C LCD (address: 0x27, 16x2 display)
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(115200);
  sensors.begin();  // Initialize DS18B20 sensor
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(SMOKE_PIN, INPUT);
  pinMode(RELAY_PIN, OUTPUT);  // Initialize relay pin

  digitalWrite(LED_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(RELAY_PIN, HIGH); // Relay off initially (assuming active-low relay)

  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("System Init...");
  delay(2000);
  lcd.clear();

  Serial.println("System Initialized");
}

void displayOnLCD(float temp, int mappedPPM, bool tempAlert, bool smokeAlert, bool buzzerActive) {
  lcd.clear();
  lcd.setCursor(0, 0);

  lcd.print("Temp: ");
  lcd.print(temp);
  lcd.print("C");

  lcd.setCursor(0, 1);
  lcd.print("Smoke: ");
  lcd.print(mappedPPM);

  // Display alerts
  if (tempAlert) {
    lcd.setCursor(0, 1);
    lcd.print("ALERT: Temp High!");
  } else if (smokeAlert) {
    lcd.setCursor(0, 1);
    lcd.print("ALERT: Smoke High!");
  }

  // Display buzzer status
  if (buzzerActive) {
    lcd.setCursor(0, 1);
    lcd.print("Buzzer ON");
  }
}

void soundBuzzer() {
  digitalWrite(BUZZER_PIN, HIGH);
  delay(500);
  digitalWrite(BUZZER_PIN, LOW);
  delay(500);
}

void loop() {
  // Read temperature from DS18B20
  sensors.requestTemperatures();
  float temp = sensors.getTempCByIndex(0);

  if (temp == DEVICE_DISCONNECTED_C) {
    Serial.println("Failed to read temperature from DS18B20");
    delay(2000);
    return;
  }

  // Read smoke sensor value
  int rawPPMValue = analogRead(SMOKE_PIN);
  int mappedPPMValue = rawPPMValue / 4.095; // Map ADC value to 0-1000 scale for PPM

  // Check thresholds
  bool tempAlert = temp > TEMP_THRESHOLD;
  bool smokeAlert = mappedPPMValue > SMOKE_THRESHOLD;

  // Print values to Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temp);
  Serial.println(" °C");
  Serial.print("Mapped PPM: ");
  Serial.println(mappedPPMValue);

  bool buzzerActive = false;

  // Handle alerts for high temperature or high smoke level
  if (tempAlert || smokeAlert) {
    digitalWrite(LED_PIN, HIGH);  // Turn on onboard LED
    digitalWrite(RELAY_PIN, LOW); // Turn off external LED (disconnect from battery)
    soundBuzzer();               // Activate buzzer
    buzzerActive = true;         // Indicate buzzer is active
    displayOnLCD(temp, mappedPPMValue, tempAlert, smokeAlert, buzzerActive);
    if (tempAlert) Serial.println("ALERT: High Temperature!");
    if (smokeAlert) Serial.println("ALERT: High Smoke Level!");
  } else {
    digitalWrite(LED_PIN, LOW);   // Turn off onboard LED
    digitalWrite(RELAY_PIN, HIGH); // Turn ON external LED (connect to battery)
    displayOnLCD(temp, mappedPPMValue, false, false, buzzerActive);
  }

  delay(2000); // Delay for next reading
}