#include "WiFi.h"
#include "PubSubClient.h"
int led_pin = 5;
char clientID[50];
WiFiClient espClient;
PubSubClient client(espClient);
void setup(){
  Serial.begin(115200);
  pinMode(led_pin, OUTPUT);
  WiFi.mode(WIFI_STA);
  WiFi.begin("Wokwi-GUEST", "");
  client.setServer("broker.emqx.io", 1883);
  client.setCallback(callback);
}

void mqttReconnect(){
  while(!client.connected()){
    Serial.print("Attempting MQTT connection...");
    if(client.connect(clientID)){
      Serial.print("Connected");
      client.subscribe("topicName");
    }
    else{
      Serial.print("Connection failed. Please try again in 5 seconds.");
      delay(5000);
    }
  }
}

void callback(char* topic, byte* message, unsigned int length){
  String stMessage;
  for(int i = 0; i < length; i++){
    stMessage += (char)message[i];
  }
  if(stMessage == "off"){
    digitalWrite(led_pin, LOW);
    Serial.print("Light off.");
  }
  else if(stMessage == "on"){
    digitalWrite(led_pin, HIGH);
    Serial.print("Light on.");
  }
  else{
    Serial.print("Invalid command.");
  }
}

void loop(){
  delay(10000);
  if(!client.connected()){
    mqttReconnect();
  }
  client.loop();
}