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

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

// MQTT Broker settings
const char* mqtt_server = "broker.emqx.io";
const int mqtt_port = 1883;
const char* mqtt_topic = "esp32/led";

// Pin definition
const int ledPin = 2;

WiFiClient espClient;
PubSubClient client(espClient);

void setup_wifi() {
  delay(10);
  Serial.println("Connecting to WiFi");
  WiFi.begin(ssid, password);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  // Create a buffer for the JSON document
  StaticJsonDocument<200> doc;
  
  // Create a character array to store the message
  char message[length + 1];
  for (int i = 0; i < length; i++) {
    message[i] = (char)payload[i];
  }
  message[length] = '\0';
  
  Serial.print("Message received: ");
  Serial.println(message);

  // Parse JSON
  DeserializationError error = deserializeJson(doc, message);
  
  if (error) {
    Serial.print("deserializeJson() failed: ");
    Serial.println(error.c_str());
    return;
  }

  // Get the "msg" value from JSON
  const char* msg = doc["msg"];
  
  if (msg != nullptr) {
    if (strcmp(msg, "on") == 0) {
      digitalWrite(ledPin, HIGH);
      Serial.println("LED ON");
    } else if (strcmp(msg, "off") == 0) {
      digitalWrite(ledPin, LOW);
      Serial.println("LED OFF");
    }
  }
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    String clientId = "ESP32Client-";
    clientId += String(random(0xffff), HEX);
    
    if (client.connect(clientId.c_str())) {
      Serial.println("connected");
      client.subscribe(mqtt_topic);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" retrying in 5 seconds");
      delay(5000);
    }
  }
}

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(callback);
}

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