#include "DHT.h"
#include <WiFi.h>
#include <HTTPClient.h>

#define DHTPIN 4         // DHT sensor connected to GPIO 4
#define DHTTYPE DHT22    // DHT22 sensor type
#define RELAY_PIN 19     // Relay module pin connected to the fan
#define POT_PIN 35       // Potentiometer pin to set threshold

// Wi-Fi credentials
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// ThingSpeak API
const char* server = "http://api.thingspeak.com/update";
const char* apiKey = "YD85BTR7JJQGHH2X";

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin();
  
  pinMode(RELAY_PIN, OUTPUT);   // Relay pin setup
  pinMode(POT_PIN, INPUT);      // Potentiometer setup

  // Start Wi-Fi
  WiFi.begin(ssid, password);
  Serial.print("Connecting to Wi-Fi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWi-Fi Connected!");
}

void loop() {
  // Read sensor data
  float temperature = readTemperature();
  float humidity = readHumidity();

  // Calculate heat index
  float heatIndex = computeHeatIndex(temperature, humidity);

  // Calculate threshold from potentiometer
  float threshold = calculateThreshold();

  // Control fan based on heat index and threshold
  controlFan(heatIndex, threshold);

  // Send data to ThingSpeak
  sendDataToThingSpeak(temperature, humidity, heatIndex, threshold);

  // Wait 1 minute before next measurement
  delay(6000);
}

// Function to read temperature
float readTemperature() {
  float temp = dht.readTemperature();
  if (isnan(temp)) {
    Serial.println("Failed to read temperature!");
    return -1;  // Return an invalid value
  }
  return temp;
}

// Function to read humidity
float readHumidity() {
  float hum = dht.readHumidity();
  if (isnan(hum)) {
    Serial.println("Failed to read humidity!");
    return -1;  // Return an invalid value
  }
  return hum;
}

// Simple computeHeatIndex function
float computeHeatIndex(float temp, float humidity) {
  // Approximation formula for heat index
  return temp + (0.55 * (0.55 - humidity / 100) * (temp - 14.5));
}

// Function to calculate threshold using rule of three
float calculateThreshold() {
  int potValue = analogRead(POT_PIN);
  return (potValue * 20.0 / 4095.0) + 20.0;  // Map potentiometer (0-4095) to range (20-40)
}

// Function to control the fan
void controlFan(float heatIndex, float threshold) {
  if (heatIndex > threshold) {
    digitalWrite(RELAY_PIN, HIGH);  // Turn fan ON
    Serial.println("Fan ON");
  } else {
    digitalWrite(RELAY_PIN, LOW);   // Turn fan OFF
    Serial.println("Fan OFF");
  }
}

// Function to send data to ThingSpeak
void sendDataToThingSpeak(float temperature, float humidity, float heatIndex, float threshold) {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    String url = String(server) + "?api_key=" + apiKey +
                 "&field1=" + String(temperature) +
                 "&field2=" + String(humidity) +
                 "&field3=" + String(heatIndex) +
                 "&field4=" + String(threshold);
    http.begin(url);
    int httpResponseCode = http.GET();

    if (httpResponseCode > 0) {
      Serial.println("Data sent to ThingSpeak successfully.");
    } else {
      Serial.println("Failed to send data to ThingSpeak.");
    }
    http.end();
  } else {
    Serial.println("Wi-Fi not connected.");
  }
}