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

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

// MQTT broker info
const char* mqtt_server = "test.mosquitto.org";
const int mqtt_port = 1883;

// MQTT topics for NTC sensor
const char* ntc_temp_topic = "esp32/ntc/temperature";
// MQTT topics for DHT22 sensor
const char* dht_temp_topic = "esp32/dht22/temperature";
const char* dht_hum_topic = "esp32/dht22/humidity";

// Analog temperature sensor pin (NTC)
const int ntc_tempPin = 34; // Use GPIO34 (ADC1_CH6) for analog input

// NTC Thermistor parameters (adjust these based on your specific NTC)
const float ntc_nominalResistance = 10000.0;     // Resistance at 25°C (10k Ohm typical)
const float ntc_nominalTemperature = 25.0 + 273.15; // Temperature at nominal resistance (in Kelvin)
const float ntc_bCoefficient = 3950.0;          // Beta value of the thermistor (check datasheet)
const float ntc_seriesResistance = 10000.0;      // Resistance of the series resistor in the voltage divider

// DHT setup
#define DHTPIN 4
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

// WiFi and MQTT clients
WiFiClient espClient;
PubSubClient client(espClient);

// Connect to WiFi
void setup_wifi() {
  Serial.print("Connecting to WiFi");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println(" connected");
}

// Reconnect to MQTT broker
void reconnect_mqtt() {
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");
    if (client.connect("ESP32Client_MultiSensor")) { // More descriptive client ID
      Serial.println("connected");
    } else {
      Serial.print(" failed, rc=");
      Serial.print(client.state());
      delay(2000);
    }
  }
}

// Read analog value and convert to temperature (for NTC thermistor)
float readTemperatureNTC() {
  int analogValue = analogRead(ntc_tempPin);
  // Convert analog reading to resistance of the thermistor
  // Assuming a simple voltage divider circuit: Vout = Vin * (R_thermistor / (R_thermistor + R_series))
  float voltage = analogValue * (3.3 / 4095.0);
  float thermistorResistance = ntc_seriesResistance / ((3.3 / voltage) - 1);

  // Apply the Steinhart-Hart equation (simplified using Beta coefficient)
  float steinhart;
  steinhart = thermistorResistance / ntc_nominalResistance; // (R/Ro)
  steinhart = log(steinhart);                             // ln(R/Ro)
  steinhart /= ntc_bCoefficient;                          // 1/B * ln(R/Ro)
  steinhart += 1.0 / ntc_nominalTemperature;              // 1/T0 + 1/B * ln(R/Ro)
  steinhart = 1.0 / steinhart;                             // T in Kelvin
  steinhart -= 273.15;                                     // Convert to Celsius

  return steinhart;
}

void setup() {
  Serial.begin(115200);
  dht.begin();
  setup_wifi();
  client.setServer(mqtt_server, mqtt_port);
}

void loop() {
  if (!client.connected()) {
    reconnect_mqtt();
  }
  client.loop();

  // Read and publish NTC temperature
  float ntcTemperature = readTemperatureNTC();
  Serial.print("NTC Temperature: ");
  Serial.print(ntcTemperature);
  Serial.println(" °C");
  client.publish(ntc_temp_topic, String(ntcTemperature).c_str());

  // Read and publish DHT22 data
  float dhtTemperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  if (isnan(dhtTemperature) || isnan(humidity)) {
    Serial.println("Failed to read from DHT22 sensor!");
  } else {
    Serial.print("DHT Temperature: ");
    Serial.print(dhtTemperature);
    Serial.print(" °C | Humidity: ");
    Serial.print(humidity);
    Serial.println(" %");

    client.publish(dht_temp_topic, String(dhtTemperature).c_str());
    client.publish(dht_hum_topic, String(humidity).c_str());
  }

  delay(2000); // Reduced delay to accommodate both sensors
}