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

// WiFi Credentials
const char* ssid = "Wokwi-GUEST";
const char* password = "";

const char* mqttServer = "test.mosquitto.org";
const int mqttPort = 1883;
const char* mqttUser = "aaaa";
const char* mqttPassword = "aaaa";

int ValueToSend;
#define ADCpin 36   //pin for potensiometer
#define LED 26    //built-in LED_BUILTIN

WiFiClient espClient;
PubSubClient client(espClient);


void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) 
  {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");

  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);

  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
    
    if (client.connect("userid")) {      //user id must be unique in case of many users under one topic to avoid conflict/crosstalk information
      Serial.println("Connected to MQTT");
      client.subscribe("LED");            //SUBSCRIBE TOPIC
    } else {
      Serial.print("Failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }
  
  pinMode(LED, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  //delay(10); // this speeds up the simulation
  int ADC = analogRead(ADCpin);
  //ValueToSend = map(ADC,0,4095,0,100);
  int ValueToSend = 1000*ADC*5/4095;
  Serial.println(ValueToSend);
  char payload[10]; // buffer array size is proportional to message that wanted to be sent
  snprintf(payload, sizeof(payload), "%d", ValueToSend);
  client.publish("pubtopic", payload);    //PUBLISH TOPIC
  
  // Printing message value on Serial Monitor and waiting
  client.loop();
  Serial.println();
  delay(1000);   //adjust interval
}

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

  if (topic == "LED"){
    for (int i = 0; i < length; i++) {
      //Serial.print((char)payload[i]);
      msg += (char)payload[i];
    }
    Serial.println(msg);
    Serial.print("LED status: ");
    if (msg == "ON"){ 
      digitalWrite(LED, HIGH);
      Serial.println("ON"); 
    }
    else if (msg == "OFF"){ 
      digitalWrite(LED, LOW);
      Serial.println("OFF");
    }
  }
  Serial.println();
  delay(1000);   //adjust interval
}