#include <Adafruit_Sensor.h>
#include <DHT_U.h>  // DHT sensor library

// Pin Definitions
#define DHTPIN 12         // Pin where DHT22 is connected
#define GAS_SENSOR_PIN 36 // Analog pin for potentiometer (simulated gas sensor)
#define COOLING_FAN_PIN 26 // Pin for cooling fan (simulated by an LED)
#define EXHAUST_FAN_PIN 14 // Pin for exhaust fan (simulated by an LED)

// DHT parameters
#define DHTTYPE DHT22  // DHT 22 (AM2302)
DHT_Unified dht(DHTPIN, DHTTYPE);

float temp;
const float tempThreshold = 35.0;   // Temperature threshold for cooling fan
const int gasThreshold = 400;       // Gas detection threshold (analog value)

// Setup function
void setup() {
  Serial.begin(115200);
  
  // Initialize DHT sensor
  dht.begin();
  
  // Setup pins as output
  pinMode(COOLING_FAN_PIN, OUTPUT);
  pinMode(EXHAUST_FAN_PIN, OUTPUT);
  
  // Initially turn off both fans
  digitalWrite(COOLING_FAN_PIN, LOW); 
  digitalWrite(EXHAUST_FAN_PIN, LOW); 

  Serial.println("Temperature and Gas monitoring system started...");
}

void loop() {
  // --- Temperature Monitoring ---
  sensors_event_t event;
  dht.temperature().getEvent(&event);

  // Check if the sensor is reading temperature correctly
  if (isnan(event.temperature)) {
    Serial.println(F("Error reading temperature!"));
  } else {
    temp = event.temperature;
    Serial.print(F("Temperature: "));
    Serial.print(temp);
    Serial.println(F("°C"));
    
    // Check if temperature exceeds threshold for cooling fan
    if (temp > tempThreshold) {
      Serial.println("Temperature exceeded threshold! Turning on cooling fan...");
      digitalWrite(COOLING_FAN_PIN, HIGH);  // Turn on cooling fan
    } else {
      Serial.println("Temperature below threshold. Cooling fan is off.");
      digitalWrite(COOLING_FAN_PIN, LOW);   // Turn off cooling fan
    }
  }
  
  // --- Gas Monitoring ---
  int gasValue = analogRead(GAS_SENSOR_PIN);  // Read gas sensor (simulated by potentiometer)
  Serial.print("Gas Sensor Value: ");
  Serial.println(gasValue);
  
  // Check if gas sensor value exceeds threshold for exhaust fan
  if (gasValue > gasThreshold) {
    Serial.println("Gas detected! Turning on exhaust fan...");
    digitalWrite(EXHAUST_FAN_PIN, HIGH);  // Turn on exhaust fan
  } else {
    Serial.println("No gas detected. Exhaust fan is off.");
    digitalWrite(EXHAUST_FAN_PIN, LOW);   // Turn off exhaust fan
  }
  
  delay(1000);  // Wait 1 second before next reading
}