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

// === WiFi and ThingSpeak Configuration ===
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const String apiKey = "129XW35TOMI41Q8P";  // Replace with your actual API key
const String server = "http://api.thingspeak.com/update";

// === Pin Definitions ===
#define DHTPIN 15            // DHT22 data pin
#define DHTTYPE DHT 22        // Sensor type
#define MQ135_PIN 34         // Analog pin for gas sensor simulation
#define LDR_PIN 35           // Analog pin for light sensor (LDR)
#define LED_PIN 2            // LED for air quality status
#define BUZZER_PIN 4         // Buzzer pin for alerts

DHT dht(DHTPIN, DHTTYPE);    // DHT sensor object

void setup() {
  Serial.begin(115200);
  delay(1000);

  // Initialize sensors and actuators
  dht.begin();
  pinMode(MQ135_PIN, INPUT);
  pinMode(LDR_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  Serial.println("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }
  Serial.println("\nWiFi connected.");
}

void loop() {
  Serial.println("WiFi connected.");
  // === Sensor Readings ===
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();
  int airQuality = analogRead(MQ135_PIN);
  int lightLevel = analogRead(LDR_PIN); // Simulated light intensity

  // Validate DHT sensor readings
  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("Failed to read from DHT sensor!");
    delay(2000);
    return;
  }

  // === Print to Serial Monitor ===
  Serial.print("Temp: ");
  Serial.print(temperature);
  Serial.print("°C, Humidity: ");
  Serial.print(humidity);
  Serial.print("%, Air Quality: ");
  Serial.print(airQuality);
  Serial.print(", Light Level: ");
  Serial.println(lightLevel);

  // === Alert and Indication Based on Air Quality ===
  bool poorAir = airQuality > 2000;
  digitalWrite(LED_PIN, poorAir ? HIGH : LOW);       // LED warning
  digitalWrite(BUZZER_PIN, poorAir ? HIGH : LOW);    // Buzzer warning

  // === Send Data to ThingSpeak ===
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;

    String url = server + "?api_key=" + apiKey +
                 "&field1=" + String(temperature) +
                 "&field2=" + String(humidity) +
                 "&field3=" + String(airQuality) +
                 "&field4=" + String(lightLevel);

    http.begin(url);                   // Start HTTP request
    int httpResponseCode = http.GET(); // Send GET

    if (httpResponseCode > 0) {
      Serial.print("Data sent. Response code: ");
      Serial.println(httpResponseCode);
    } else {
      Serial.print("Error sending data. Code: ");
      Serial.println(httpResponseCode);
    }

    http.end(); // Close HTTP connection
  } else {
    Serial.println("WiFi not connected.");
  }

  delay(15000); // Wait 15 seconds (ThingSpeak limit)
}