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

#include <WiFi.h>
#include <PubSubClient.h>
#include <LiquidCrystal_I2C.h>

WiFiClient WIFI_CLIENT;
PubSubClient MQTT_CLIENT(WIFI_CLIENT); // uprava 
LiquidCrystal_I2C lcd(0x27, 20, 4);

long buducnost = 0;

void callback(char* topic, byte* payload, unsigned int length) // nove
{
  Serial.print("Prijata sprava: ");

  String message;
  for (int i = 0; i < length; i++) 
  {
    message += (char)payload[i];
  }
  Serial.println(message);

  lcd.clear();                   
  lcd.print(message);  
}

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

void setup() {

  lcd.init();
  lcd.backlight();  
   
  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

  lcd.setCursor(0, 0);
  lcd.print("MQTT Receiver");
  lcd.setCursor(0, 1);
  lcd.print("Waiting for msg...");
  delay(1000);
  lcd.clear();
}

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

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