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

char red_led = 23;
char gre_led = 19;
char yel_led = 18;

char red_led_state = LOW;
long red_led_previous_millis = 0;
int red_led_interval = 1000;

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

const char* hostname = "broker.hivemq.com";

WiFiClient espClient;
PubSubClient client(espClient);
const char* espClientName = "esp32Client_Win"; // yourStudentID must be unique
int PORTNUM = 1883;

void setup_wifi()
{
  WiFi.begin(ssid, password);
  while(WiFi.status() != WL_CONNECTED )
  {
    delay(1000);
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("Given IP by the router to ESP32 is ");
  Serial.println(WiFi.localIP());
}

void connectMQTT()
{
  while(!client.connected() )
  {
    Serial.println("Connecting to MQTT ...");
    if (client.connect(espClientName) ) //, mqttUser, mqttPassword) )
    {
      Serial.println("Connected");
      MQTTSubscribe();
    }
    else
    {
      Serial.print("Failed with state ");
      Serial.print(client.state() );
      delay(2000);
    }
  }
}

void callback(String topic, byte* payload, unsigned int length)
{
  String messageTemp;
  Serial.print("Message received in topic: ");
  Serial.print(topic);
  Serial.print(" length is: ");
  Serial.println(length);

  Serial.print("Data received from broker: ");
  for (int i = 0; i<length; i++)
  {
    Serial.print( (char)payload[i] );
    messageTemp += (char)payload[i];
  }
}

void MQTTSubscribe() 
{
 
}

void setup_MQTT() 
{
  client.setServer(hostname, PORTNUM);
  client.setCallback(callback); 
}

void setup() 
{
  Serial.begin(9600);
  delay(5000);
 
  pinMode(red_led, OUTPUT);
  pinMode(yel_led, OUTPUT);
  pinMode(gre_led, OUTPUT);

  setup_wifi();
  setup_MQTT();
}

void loop() 
{
  if ( !client.connected() )
  {
    connectMQTT();
  }
  client.loop();

  
  long current_millis = millis();
  if (current_millis - red_led_previous_millis >= red_led_interval)
  {
    red_led_previous_millis = current_millis;

    //now reversethe led 's state
    if (red_led_state == LOW)
      red_led_state = HIGH;
    else
      red_led_state = LOW;

    digitalWrite(red_led, red_led_state);
  }
    
}