#include <WiFi.h>            // Include the WiFi library
#include <PubSubClient.h>    // Include the MQTT library

//  network credentials
const char* ssid = "iPhone Ernesto (2)";
const char* password = "****";

//  MQTT broker IP address or hostname
const char* mqtt_server = "broker.hivemq.com";

WiFiClient espClient;       // Create a WiFi client instance
PubSubClient client(espClient);  // Create a MQTT client instance

void setup() {
  Serial.begin(115200);     // Start the serial communication
  delay(10);

  // Connect to Wi-Fi
  WiFi.begin(ssid, password);   // Connect to WiFi network
  while (WiFi.status() != WL_CONNECTED) {  // Wait for WiFi connection
    delay(500);
    Serial.print(".");
  }
  Serial.println("WiFi connected");

  // Connect to MQTT Broker
  client.setServer(mqtt_server, 1883);   // Set the MQTT broker server and port
  client.setCallback(callback);   // Set callback function to handle incoming messages
  
  while (!client.connected()) {   // Attempt to connect to MQTT broker
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32C3Client")) {   // Client ID for MQTT connection
      Serial.println("connected");
      client.subscribe("arduino/uno");  // Subscribe to the topic "arduino/uno"
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());   // Print connection status
      Serial.println(" try again in 5 seconds");
      delay(5000);   // Wait 5 seconds before retrying
    }
  }
}

void loop() {
  client.loop();    // Maintain MQTT connection and handle incoming messages
}

// MQTT callback function to handle incoming messages
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);   // Print the topic of the incoming message
  Serial.print("] ");
  
  // Print the incoming message
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}