String apiKey = "TEFKPUX88K03CLTT";  // Enter your Write API key from ThingSpeak

const char* ssid = "Wokwi-GUEST";     // your WiFi SSID
const char* pass = "";                // your WiFi password
const char* server = "api.thingspeak.com";  // ThingSpeak server

const int gasSensorPin = 34;  // GPIO for Gas Sensor
const int ledPin = 22;        // GPIO for Red LED
const int LED_wifi = 2;       // GPIO for WiFi status LED (can use onboard LED)

WiFiClient client;

void setup() {
  Serial.begin(115200);
  pinMode(gasSensorPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(LED_wifi, OUTPUT);

  Serial.println("Connecting to WiFi...");
  WiFi.begin(ssid, pass);

  while (WiFi.status() != WL_CONNECTED) {
    digitalWrite(LED_wifi, HIGH);
    delay(500);
    Serial.print(".");
    digitalWrite(LED_wifi, LOW);
    delay(500);
  }

  Serial.println("");
  Serial.println("WiFi connected");
  digitalWrite(LED_wifi, HIGH);
}

void loop() {
  // Read gas sensor value
  int gasSensorValue = analogRead(gasSensorPin);

  // Control LED based on gas sensor reading
  if (gasSensorValue > 500) {
    digitalWrite(ledPin, HIGH);  // Turn on LED if gas value exceeds 500
  } else {
    digitalWrite(ledPin, LOW);   // Turn off LED otherwise
  }

  // Send data to ThingSpeak
  sendDataToThingSpeak(gasSensorValue);

  // Delay for 20 seconds before sending data again
  delay(5000);
}

void sendDataToThingSpeak(int gasSensorValue) {
  if (client.connect(server, 80)) {  // Connect to ThingSpeak server
    String postStr = apiKey;
    postStr += "&field1=";
    postStr += String(gasSensorValue);
    postStr += "\r\n\r\n";

    client.print("POST /update HTTP/1.1\n");
    client.print("Host: api.thingspeak.com\n");
    client.print("Connection: close\n");
    client.print("X-THINGSPEAKAPIKEY: " + apiKey + "\n");
    client.print("Content-Type: application/x-www-form-urlencoded\n");
    client.print("Content-Length: " + String(postStr.length()) + "\n\n");
    client.print(postStr);

    Serial.print("Gas Sensor value: ");
    Serial.println(gasSensorValue);

    client.stop();  // Close the connection
    Serial.println("Waiting for next update...");
  } else {
    Serial.println("Connection to ThingSpeak failed");
  }
}