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

long previousMillisA = 0; // will store last time LED
int intervalA = 500; // interval at which to blink (milliseconds)

int GLED = 18;

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

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

WiFiClient espClient;
PubSubClient client(espClient);
const char* espClientName = "esp32Clientsph26789"; // 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];
  }


/// Handle your topics and payload here

// Example

 

  if (topic == "studentName/room/ADC")

  {

    Serial.print("Temp: ");

    Serial.println( messageTemp );

  }

}

 

void MQTTSubscribe()

{

  // Subsccribe to your topics here

  client.subscribe("studentName/room/ADC");  // example

 

}

 

void setup_MQTT()

{

  client.setServer(hostname, PORTNUM);

  client.setCallback(callback);

 

}

 

void setup()

{

  Serial.begin(9600);

  delay(5000);

 

  pinMode(GLED, OUTPUT);

  digitalWrite(GLED, LOW);

 

  setup_wifi();

  setup_MQTT();

}

 

void loop()

{

  if ( !client.connected() )

  {

    connectMQTT();

  }

  client.loop();

 

/// You can publish your codes here

/// Use non-block codes like millis()

  long currentMillisA = millis(); 

  if (currentMillisA - previousMillisA >= intervalA)

  {

    previousMillisA = currentMillisA;

   

    int adcRes = analogRead(A5);

    Serial.print("Local: ");

    Serial.println( adcRes );

   

    char str[4];

    sprintf(str, "%d", adcRes);

   

    client.publish("studentName/room/ADC", str);

  }

 

}