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

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

//***Set server***
const char* mqttServer = "test.mosquitto.org"; 
int port = 1883;

WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);

void wifiConnect() {
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println(" Connected!");
}

void mqttConnect() {
  while(!mqttClient.connected()) {
    Serial.println("Attemping MQTT connection...");
    String clientId = "ESP32Client-";
    clientId += String(random(0xffff), HEX);
    if(mqttClient.connect(clientId.c_str())) {
      Serial.println("connected");

      //***Subscribe all topic you need***
      mqttClient.subscribe("DuongAn21127209/led");
    }
    else {
      Serial.println("try again in 5 seconds");
      delay(5000);
    }
  }
}

//MQTT Receiver
void callback(char* topic, byte* message, unsigned int length) {
  Serial.println(topic);
  String strMsg;
  for(int i=0; i<length; i++) {
    strMsg += (char)message[i];
  }
  Serial.println(strMsg);

  //***Code here to process the received package***
  
}

void setup() {
  Serial.begin(9600);
  Serial.print("Connecting to WiFi");

  wifiConnect();
  mqttClient.setServer(mqttServer, port);
  mqttClient.setCallback(callback);
  mqttClient.setKeepAlive( 90 );
}


void loop() {
  if(!mqttClient.connected()) {
    mqttConnect();
  }
  mqttClient.loop();

  //***Publish data to MQTT Server***
  int temp = random(0,100);
  char buffer[50];
  sprintf(buffer, "%d", temp);
  mqttClient.publish("21127209/temperature", buffer);

  delay(5000);
}