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

// ---------------- WIFI ----------------
const char* ssid = "Wokwi-GUEST";   // Change if using real WiFi
const char* password = "";

// ---------------- MQTT ----------------
const char* mqttServer = "broker.hivemq.com";
const int mqttPort = 1883;
const char* subscribeTopic = "esp32/wokwi/MQTT";

// Clients
WiFiClient espClient;
PubSubClient client(espClient);

// --------------- CALLBACK ---------------
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.println("\n----- Message Received -----");

  Serial.print("Topic: ");
  Serial.println(topic);

  Serial.print("Message: ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }

  Serial.println("\n----------------------------");
}

// --------------- WIFI CONNECT ---------------
void connectWiFi() {
  Serial.print("Connecting to WiFi");
  WiFi.begin(ssid, password);

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

  Serial.println("\nWiFi Connected!");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

// --------------- MQTT RECONNECT ---------------
void reconnectMQTT() {
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");

    // Create unique client ID
    String clientId = "ESP32Client-";
    clientId += String(random(1000, 9999));

    if (client.connect(clientId.c_str())) {
      Serial.println("Connected!");
      client.subscribe(subscribeTopic);
      Serial.print("Subscribed to: ");
      Serial.println(subscribeTopic);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" retrying in 5 seconds...");
      delay(5000);
    }
  }
}

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

  randomSeed(micros());   // For unique client ID

  connectWiFi();

  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);
  client.setBufferSize(512);
}

// --------------- LOOP ---------------
void loop() {
  if (!client.connected()) {
    reconnectMQTT();
  }

  client.loop();
}