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

// WiFi & MQTT Settings
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqtt_server = "broker.emqx.io";

// Topics
const char* publish_topic = "np/std1/sensor/DHT22";
const char* subscribe_topic = "sph2/room/LED";

// Pins
const int DHT_PIN = 15;
const int LED_PIN = 23;

WiFiClient espClient;
PubSubClient client(espClient);
DHTesp dhtSensor;
unsigned long lastMsg = 0;

// This function runs when a message arrives from the broker
void callback(char* topic, byte* payload, unsigned length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  
  String message;
  for (int i = 0; i < length; i++) {
    message += (char)payload[i];
  }
  Serial.println(message);

  // Check the payload
  if (string(topic) == "sph2/room/LED"){
  if (message == "On") {
    digitalWrite(LED_PIN, HIGH);
    Serial.println("LED is ON");
  } else if (message == "Off") {
    digitalWrite(LED_PIN, LOW);
    Serial.println("LED is OFF");
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  dhtSensor.setup(DHT_PIN, DHTesp::DHT22);
  
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }
  
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback); // Set the function to handle incoming messages
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");
    if (client.connect("ESP32_Client_Room1")) {
      Serial.println("connected");
      // Subscribe to the LED topic after connecting
      client.subscribe(subscribe_topic);
    } else {
      delay(5000);
    }
  }
}

void loop() {
  if (!client.connected()) reconnect();
  client.loop(); // Essential for receiving messages

  unsigned long now = millis();
  if (now - lastMsg > 2000) {
    lastMsg = now;
    TempAndHumidity data = dhtSensor.getTempAndHumidity();
    if (!isnan(data.temperature)) {
      String msg = "{\"temp\":" + String(data.temperature, 1) + "}";
      client.publish(publish_topic, msg.c_str());
    }
  }
}