#include <WiFi.h>
#include <PubSubClient.h>

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

// MQTT Broker Settings
const char* mqtt_server = "test.mosquitto.org"; // Example public broker
const char* mqtt_topic = "esp32/test/topic14";   // Topic to subscribe to

WiFiClient espClient;
PubSubClient client(espClient);

// Function to connect to Wi-Fi
void connectWiFi() {
  // Serial.println("Connecting to WiFi...");
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("WiFi Connected");
}

// Function to connect to the MQTT broker
void connectMQTT() {
  while (!client.connected()) {
    Serial.println("Attempting MQTT connection...");

    // Create a unique client ID
    String clientId = "ESP32Client-" + String(random(0xffff), HEX);

    if (client.connect(clientId.c_str())) {
      Serial.println("Connected to MQTT broker");

      // Subscribe to the topic
      client.subscribe(mqtt_topic);
    } else {
      Serial.print("Failed to connect, state: ");
      Serial.println(client.state());
      delay(5000);  // Retry after 5 seconds
    }
  }
}

// MQTT Callback to handle incoming messages
void callback(char* topic, byte* payload, unsigned int length) {
  String message = "";
  for (int i = 0; i < length; i++) {
    message += (char)payload[i];
  }

  Serial.print("Received message: ");
  Serial.println(message);
}

void setup() {
  Serial.begin(115200);  // Initialize Serial Monitor
  connectWiFi();         // Connect to Wi-Fi

  client.setServer(mqtt_server, 1883);  // Set MQTT broker address and port
  client.setCallback(callback);         // Set the callback function to handle messages

  connectMQTT();  // Ensure MQTT connection is established
}

void loop() {
  if (!client.connected()) {
    connectMQTT();  // Reconnect if the connection is lost
  }
  client.loop();  // Keep the connection alive and listen for messages
  delay(100);     // Small delay for stability
}