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

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

// MQTT Broker settings
const char* mqtt_server = "broker.hivemq.com";
const char* topic = "Esp-project";

// Create WiFi and MQTT client objects
WiFiClient espClient;
PubSubClient client(espClient);

// DHT Sensor settings
#define DHTPIN 12  // Pin connected to DHT22
#define DHTTYPE DHT22  // DHT 22 (AM2302)
DHT dht(DHTPIN, DHTTYPE);

// Reconnection settings
unsigned long lastReconnectAttempt = 0;
unsigned long reconnectInterval = 5000;  // Start with 5 seconds between attempts
const unsigned long maxReconnectInterval = 60000;  // Max delay of 1 minute

void setup_wifi() {
  delay(10);
  Serial.print("Connecting to ");
  Serial.println(ssid);

  // Start WiFi connection
  WiFi.begin(ssid, password);

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

// MQTT reconnect logic with exponential backoff
bool reconnect() {
  if (client.connect("Esp_project")) {
    Serial.println("MQTT connected");
    reconnectInterval = 5000;  // Reset the interval on success
    return true;
  } else {
    Serial.print("Failed to connect, rc=");
    Serial.print(client.state());
    Serial.println(". Trying again in " + String(reconnectInterval / 1000) + " seconds.");
    return false;
  }
}

void setup() {
  // Initialize Serial
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");

  // Initialize DHT sensor
  dht.begin();

  // Start WiFi connection
  setup_wifi();

  // Set MQTT server and callback
  client.setServer(mqtt_server, 1883);
}

void loop() {
  // Check if connected to MQTT, otherwise try to reconnect
  if (!client.connected()) {
    unsigned long now = millis();
    if (now - lastReconnectAttempt > reconnectInterval) {
      lastReconnectAttempt = now;
      if (reconnect()) {
        lastReconnectAttempt = 0;
      } else {
        reconnectInterval = min(reconnectInterval * 2, maxReconnectInterval);  // Exponential backoff
      }
    }
  } else {
    // MQTT client loop to maintain connection
    client.loop();

    // Read data from DHT22
    float humidity = dht.readHumidity();
    float temperature = dht.readTemperature();

    // Check if readings are valid
    if (isnan(humidity) || isnan(temperature)) {
      Serial.println("Failed to read from DHT sensor!");
      return;
    }

    // Print temperature and humidity
    Serial.print("Humidity: ");
    Serial.print(humidity);
    Serial.print("%  Temperature: ");
    Serial.print(temperature);
    Serial.println("°C");

    // Create a JSON-like string to send over MQTT
    String payload = "{\"temperature\": ";
    payload += String(temperature);
    payload += ", \"humidity\": ";
    payload += String(humidity);
    payload += "}";

    // Publish the payload to the MQTT broker
    client.publish(topic, payload.c_str());
    Serial.println("Published to MQTT: " + payload);

    // Wait 2 seconds before next reading
    delay(2000);
  }
}