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

WiFiClient wifiClient;    
PubSubClient mqttClient(wifiClient); 

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

char *mqttServer = "broker.emqx.io";
int mqttPort = 1883;

#define ECHO_PIN 26
#define TRIG_PIN 27

float distance_cm, duration_us;


void callback(char* topic, byte* message, unsigned int length) {
  Serial.print("Callback - ");
  Serial.print("Message:");
  for (int i = 0; i < length; i++) {
    Serial.print((char)message[i]);
  }
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT); 
  
  WiFi.begin(ssid, password);   

  while (WiFi.status() != WL_CONNECTED) {
      delay(500);
      Serial.print(".");
    } 
    Serial.println("");
     Serial.println("Connected to Wi-Fi");

  mqttClient.setServer(mqttServer, mqttPort); 
  mqttClient.setCallback(callback); 
}

void loop() {

  if (!mqttClient.connected())
   { Serial.println("Connecting to MQTT Broker...");
     while (!mqttClient.connected()) {
     Serial.println("Reconnecting to MQTT Broker..");
     String clientId = "ESP32Client-";
     clientId += String(random(0xffff), HEX);
      
     if (mqttClient.connect(clientId.c_str())) {
       Serial.println("Connected.");
     }      
    } 
   }  else {
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  duration_us = pulseIn(ECHO_PIN, HIGH);
  distance_cm = 0.017 * duration_us;

  Serial.print("distance: ");
  Serial.print(distance_cm);
  Serial.println(" cm");
  
  mqttClient.publish("servoafnan", String(distance_cm).c_str());

  delay(2000); 
  }
}