#include <ESP8266WiFi.h>
#include <PubSubClient.h>
const char* ssid = "WIFI-NAME";
const char* password = "WIFI-PASSWORD";
const char* mqtt_server = "test.mosquitto.org";
const char* device_id = "esp8266";
WiFiClient espClient;
PubSubClient client(espClient);
//======================================
// CALLBACK FUNCTION
//=======================================
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");Serial.print(topic);Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
  if ((char)payload[0] == '1') {
    digitalWrite(D1, HIGH);
	} 
	else{
    digitalWrite(D1, LOW);  // Turn the LED off by making the voltage HIGH
	}
}
//======================================
// RECONNECT FUNCTION
//=======================================
void reconnect() {
 while (!client.connected())
  {
    Serial.print("Attempting MQTT connection...");
    if (client.connect(device_id))
    { 
    Serial.println("connected");
    client.subscribe("esp8266/light/gemlabs");
    }                                                                              
  }
}
//======================================
// SETUP FUNCTION
//=======================================
void setup() {
  Serial.begin(9600);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("WiFi connected");Serial.println("IP address: ");Serial.println(WiFi.localIP());
  pinMode(D1, OUTPUT);
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}
//======================================
// LOOP FUNCTION
//=======================================
void loop() {

  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}