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

/* ========= WiFi Credentials ========= */
const char* ssidName = "Wokwi-GUEST";
const char* ssidPass = "";

/* ========= MQTT Broker Details ========= */
const char* brokerAddress = "broker.hivemq.com";
const int   brokerPort    = 1883;

const char* topicTemp   = "vit/iot/temp";
const char* topicStatus = "vit/iot/status";

/* ========= Hardware Configuration ========= */
const int sensorPin = 34;
const int ledPin    = 23;

/* ========= Objects ========= */
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);

/* ========= Timing Control ========= */
unsigned long lastSentTime = 0;
const unsigned long sendInterval = 5000;

/* ========= Data Variables ========= */
float temperatureValue = 0.0;
int messageCount = 0;

/* ========= WiFi Connection ========= */
void startWiFi() {
  Serial.print("Joining WiFi");

  WiFi.begin(ssidName, ssidPass);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print("*");
  }

  Serial.println("\nWiFi connected successfully");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

/* ========= MQTT Connection ========= */
void connectBroker() {

  while (!mqttClient.connected()) {

    Serial.print("Connecting to MQTT Broker... ");

    String clientID = "ESP32_Client_";
    clientID += String(random(1000, 9999));

    if (mqttClient.connect(clientID.c_str())) {

      Serial.println("Connected!");

      String onlineMsg = "{\"device\":\"ESP32\",\"state\":\"active\"}";
      mqttClient.publish(topicStatus, onlineMsg.c_str());

      // Blink LED to indicate successful connection
      for (int i = 0; i < 3; i++) {
        digitalWrite(ledPin, HIGH);
        delay(120);
        digitalWrite(ledPin, LOW);
        delay(120);
      }

    } else {
      Serial.print("Failed, rc=");
      Serial.print(mqttClient.state());
      Serial.println(" retrying in 5 sec...");
      delay(5000);
    }
  }
}

/* ========= Setup ========= */
void setup() {

  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);

  startWiFi();

  mqttClient.setServer(brokerAddress, brokerPort);
}

/* ========= Main Program Loop ========= */
void loop() {

  if (!mqttClient.connected()) {
    connectBroker();
  }

  mqttClient.loop();

  // Read potentiometer
  int adcValue = analogRead(sensorPin);

  // Convert to temperature range (0 to 50 °C)
  temperatureValue = (adcValue / 4095.0) * 50.0;

  Serial.print("Temperature Reading: ");
  Serial.print(temperatureValue, 1);
  Serial.println(" °C");

  unsigned long currentMillis = millis();

  if (currentMillis - lastSentTime >= sendInterval) {

    lastSentTime = currentMillis;
    messageCount++;

    String payload = "{";
    payload += "\"temperature\":" + String(temperatureValue, 1) + ",";
    payload += "\"messages\":" + String(messageCount) + ",";
    payload += "\"millis\":" + String(currentMillis);
    payload += "}";

    Serial.println("Publishing Data...");
    Serial.println(payload);

    if (mqttClient.publish(topicTemp, payload.c_str())) {

      Serial.println("Publish Success");

      digitalWrite(ledPin, HIGH);
      delay(100);
      digitalWrite(ledPin, LOW);

    } else {
      Serial.println("Publish Error");
    }

    Serial.println("=============================");
  }

  delay(1000);
}