#include <WiFi.h>

#include <PubSubClient.h>
#include <math.h>

// ======================================
// WiFi Details
// ======================================

const char* ssid = "Wokwi-GUEST";

const char* password = "";

// ======================================
// MQTT Broker
// ======================================

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

// ======================================
// ESP32 Pins
// ======================================

#define VOLTAGE_PIN 34

#define CURRENT_PIN 35

#define TEMP_PIN 32

WiFiClient espClient;

PubSubClient client(espClient);

// ======================================
// MQTT Reconnect
// ======================================

void reconnect()
{
  while (!client.connected())
  {
    Serial.println("Connecting MQTT...");

    String clientId =
      "ESP32Client-" +
      String(random(1000));

    if (client.connect(clientId.c_str()))
    {
      Serial.println("✅ MQTT Connected");
    }

    else
    {
      Serial.print("❌ MQTT Failed : ");

      Serial.println(client.state());

      delay(2000);
    }
  }
}

// ======================================
// Setup
// ======================================

void setup()
{
  Serial.begin(115200);

  // ----------------------------------
  // Connect WiFi
  // ----------------------------------

  Serial.println("Connecting WiFi");

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);

    Serial.print(".");
  }

  Serial.println("\n✅ WiFi Connected");

  // ----------------------------------
  // MQTT Server
  // ----------------------------------

  client.setServer(
      mqtt_server,
      1883
  );
}

// ======================================
// Loop
// ======================================

void loop()
{
  // ----------------------------------
  // MQTT Reconnect
  // ----------------------------------

  if (!client.connected())
  {
    reconnect();
  }

  client.loop();

  // ==================================
  // Read Voltage Pot
  // ==================================

  int voltageADC =
      analogRead(VOLTAGE_PIN);

  float voltage =
      map(
        voltageADC,
        0,
        4095,
        150,
        260
      );

  // ==================================
  // Read Current Pot
  // ==================================

  int currentADC =
      analogRead(CURRENT_PIN);

  float current =
      map(
        currentADC,
        0,
        4095,
        0,
        25
      );

  // ==================================
  // Read NTC Sensor
  // ==================================

  int tempADC = analogRead(TEMP_PIN);

// Convert ADC to Voltage
float voltageNTC =
    tempADC * (3.3 / 4095.0);

// Thermistor Parameters
const float BETA = 3950;

float resistance =
    10000 * (
      voltageNTC /
      (3.3 - voltageNTC)
    );

// Steinhart-Hart Equation
float temperature =
    1 / (
      log(resistance / 10000) / BETA +
      1.0 / 298.15
    ) - 273.15;

  // ==================================
  // Create CSV Data
  // ==================================

  String data =
      String(voltage) + "," +
      String(current) + "," +
      String(temperature);

  // ==================================
  // Publish MQTT
  // ==================================

  client.publish(
      "power/system",
      data.c_str()
  );

  // ==================================
  // Serial Monitor Output
  // ==================================

  Serial.println("--------------------------------");

  Serial.print("Voltage : ");

  Serial.print(voltage);

  Serial.println(" V");

  Serial.print("Current : ");

  Serial.print(current);

  Serial.println(" A");

  Serial.print("Temperature : ");

  Serial.print(temperature);

  Serial.println(" C");

  Serial.print("MQTT Data : ");

  Serial.println(data);

  Serial.println("✅ MQTT Published");

  // ==================================
  // Delay
  // ==================================

  delay(5000);
}