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


LiquidCrystal_I2C lcd(0x27, 16, 2);

WiFiClient WIFI_CLIENT;
PubSubClient MQTT_CLIENT(WIFI_CLIENT);


void callback(char* topic, byte* payload, unsigned int length) 
{
  Serial.print("Prijata sprava z temy [");
  Serial.print(topic);
  Serial.print("]: ");

  // Správa sa vypíše ako text
  String message;
  for (int i = 0; i < length; i++) 
  {
    message += (char)payload[i];
  }
  Serial.println(message);


  lcd.clear();             
  lcd.setCursor(0, 0);  
  lcd.print("Sprava:");        
  lcd.setCursor(0, 1);        
  lcd.print(message);       


  int receivedValue = message.toInt();
  Serial.print("Spracovana hodnota: ");
  Serial.println(receivedValue);
}

void reconnect() 
{
  while (!MQTT_CLIENT.connected()) 
  {
    Serial.println("Pripajanie sa ku MQTT brokeru...");
    if (MQTT_CLIENT.connect("ReceiverClient")) 
    {
      Serial.println("Pripojene...");
      MQTT_CLIENT.subscribe("ahoj"); 
      Serial.println("Prihlaseny na temu: ahoj");
    } 
    else 
    {
      Serial.print("Nepripojene (3sek)... ");
      delay(3000);
    }
  }
}

void setup() 
{  

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

  WiFi.mode(WIFI_STA);

  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);
  MQTT_CLIENT.setCallback(callback);


  lcd.setCursor(0, 0);
  lcd.print("MQTT Receiver");
  lcd.setCursor(0, 1);
  lcd.print("Waiting for msg...");
  delay(2000);
  lcd.clear();
}

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

  MQTT_CLIENT.loop();
}