//http://hivemq.com/demos/websocket-client/ 

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

WiFiClient WIFI_CLIENT;
PubSubClient MQTT_CLIENT(WIFI_CLIENT); // uprava 

long buducnost = 0;

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

void reconnect() // uprava
{
  while (!MQTT_CLIENT.connected()) 
   {
      Serial.println("Pripajanie sa ku MQTT brokeru...");
      if (MQTT_CLIENT.connect("UCITEL")) 
      {
        Serial.println("pripojene...");
        MQTT_CLIENT.subscribe("SPSKNM/TOPIC");
      } 
      else 
      {
        Serial.print("nepripojene (3sek)...");
        delay(3000);
      }
  }
}

void setup() 
{  
  WiFi.mode(WIFI_STA); // nove

  Serial.begin(9600);
  WiFi.begin("Wokwi-GUEST", "", 6);
  while (WiFi.status() != WL_CONNECTED) 
  {
    delay(250);
    Serial.print(".");
  }
  Serial.print("WIFI uspesne pripojena: ");
  Serial.println(WiFi.localIP());

  MQTT_CLIENT.setServer("broker.hivemq.com", 1883); // uprava
  MQTT_CLIENT.setCallback(callback); // nove
}

void loop() 
{
  if (!MQTT_CLIENT.connected()) 
    reconnect();

  MQTT_CLIENT.loop(); // snaha o co najcastejsie volanie obsluhy MQTT

  if (millis() > buducnost) // nesmie sa pouzit velky delay 
  {
    char udaj[3];
    String( random(20,31) ).toCharArray(udaj,3);
    MQTT_CLIENT.publish("SPSKNM/TOPIC", udaj);
   
    buducnost = millis() + 3000;
  }
}