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

const char* ssid = "Wokwi-GUEST";
const char* password = "";

const char* mqtt_server = "broker.hivemq.com";
const int mqtt_port = 1883;

const char* pub_topic = "wcoe/iot/esp32/publish";
const char* sub_topic = "wcoe/iot/esp32/subscribe";

WiFiClient espClient;
PubSubClient client(espClient);

unsigned long lastMsg = 0;
int counter = 1;

void setup_wifi() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("\nWiFi connected");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived: ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");
    if (client.connect("ESP32Client")) {
      Serial.println("connected");
      client.subscribe(sub_topic);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      delay(2000);
    }
  }
}

void setup() {
  setup_wifi();
  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(callback);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }

  client.loop();

  unsigned long now = millis();
  if (now - lastMsg > 5000) {
    lastMsg = now;

    String msg = "Hello from ESP32 #" + String(counter++);
    client.publish(pub_topic, msg.c_str());

    Serial.println("Published: " + msg);
  }
}