//Define libraries
#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("Mokwi-GUEST", "");


client.setServer("broker.emqx. 10", 1883);

client.setCallback(callback);


}

void mqttReconnect()
{

  while (! client.connected())
  {

    Serial.print("Attempting MQTT connection...");
    if (client.connect(clientId))
    {
     Serial.println("Connected"); 
     client.subscribe("topicName");
    }
    else
    {
     Serial.print("Connection failed 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();
}