#include <WiFi.h>
#include <PubSubClient.h>
 
#define LedPin 14                    // ESP32 in-board led pin
 
const char* ssid = "Wokwi-GUEST";        // Change this to your Wifi SSID
const char* password = "";              // Change this to your Wifi Password
const char* mqtt_server = "test.mosquitto.org"; // Mosquitto Server URL
 
WiFiClient espClient;
PubSubClient client(espClient);
 
void setup_wifi()
{
    delay(10);
    Serial.println();
    Serial.print("Connecting to ");
    Serial.print(ssid);
    WiFi.begin(ssid, password);
    while(WiFi.status() != WL_CONNECTED)
    {
        delay(500);
        Serial.print(".");
    }
    Serial.println("");
    Serial.println("WiFi connected");
    Serial.print("IP address: ");
    Serial.println(WiFi.localIP());
}
 
void callback(char* topic, byte* payload, unsigned int length)
{
    char msg = 0;
    Serial.print("Message arrived [");
    Serial.print(topic);
    Serial.print("]: ");
 
    for(int i = 0 ; i < length; i++)
    {
      msg = (char)payload[i];
     }
    Serial.println(msg);
    if('0' == msg){ digitalWrite(LedPin, HIGH); }
    else if('1' == msg){ digitalWrite(LedPin, LOW); }
}
 
void reconnect()
{
  while(!client.connected())
  {
      Serial.println("Attempting MQTT connection...");
 
      if(client.connect("ESPClient"))
      {
          Serial.println("Connected");
          client.subscribe("/iot/led");
      }
      else
      {
          Serial.print("Failed, rc=");
          Serial.print(client.state());
          Serial.println(" try again in 5 seconds");
          delay(5000);
      }
    }
}
 
void setup()
{    
    Serial.begin(115200);
    pinMode(LedPin, OUTPUT);
    setup_wifi();
    client.setServer(mqtt_server, 1883);
    client.setCallback(callback);
}
void loop()
{
    if(!client.connected()) { reconnect(); }
    client.loop();
}