// Código: ESP32 -> DHT11 + LDR -> MQTT, com timestamp NTP
#include <WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>
#include <NTPClient.h>
#include <WiFiUdp.h>

// ========== CONFIG ==========
const char* ssid     = "SEU_SSID";
const char* password = "SUA_SENHA_WIFI";

const char* mqtt_server = "test.mosquitto.org"; // broker público para testes
const uint16_t mqtt_port = 1883;
const char* mqtt_user = NULL; // se houver usuário
const char* mqtt_pass = NULL; // se houver senha

const char* deviceId = "esp32_001";
String topicTelem = String("esp32/sensores/") + deviceId + "/telemetry";
String topicCmd   = String("esp32/sensores/") + deviceId + "/commands";
String topicStatus= String("esp32/sensores/") + deviceId + "/status";

// Pins
#define DHTPIN 15
#define DHTTYPE DHT11
#define LDR_PIN 35
#define LED_PIN 

// Intervalos
const unsigned long publishInterval = 15000; // 15s

DHT dht(DHTPIN, DHTTYPE);
WiFiClient espClient;
PubSubClient client(espClient);

// NTP
WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP, "pool.ntp.org", 0, 60000); // 0 = UTC, ajuste se quiser offset

unsigned long lastPublish = 0;

void setup_wifi() {
  delay(10);
  Serial.println();
  Serial.print("Conectando a ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);
  int tries = 0;
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    tries++;
    if (tries > 40) { // timeout
      Serial.println("\nFalha ao conectar WiFi — reiniciando...");
      ESP.restart();
    }
  }

  Serial.println("");
  Serial.println("WiFi conectado");
  Serial.print("IP: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  // Recebe comandos do MyMQTT
  String msg;
  for (unsigned int i = 0; i < length; i++) msg += (char)payload[i];
  Serial.print("Recebido em [");
  Serial.print(topic);
  Serial.print("] -> ");
  Serial.println(msg);

  // exemplo: {"cmd":"led","state":"on"}
  if (String(topic) == topicCmd) {
    if (msg.indexOf("led") >= 0) {
      if (msg.indexOf("on") >= 0) {
        digitalWrite(LED_PIN, HIGH);
        client.publish(topicStatus.c_str(), "{\"led\":\"on\"}");
      } else if (msg.indexOf("off") >= 0) {
        digitalWrite(LED_PIN, LOW);
        client.publish(topicStatus.c_str(), "{\"led\":\"off\"}");
      }
    }
    // pode adicionar mais comandos aqui
  }
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Conectando MQTT...");
    String clientId = String("ESP32Client-") + String(random(0xffff), HEX);
    if (client.connect(clientId.c_str(), mqtt_user, mqtt_pass)) {
      Serial.println("Conectado");
      // subscribe
      client.subscribe(topicCmd.c_str());
      // publicar status inicial
      client.publish(topicStatus.c_str(), "{\"status\":\"online\"}");
    } else {
      Serial.print("falha, rc=");
      Serial.print(client.state());
      Serial.println(" tentando novamente em 5s");
      delay(5000);
    }
  }
}

String iso8601Time() {
  timeClient.update();
  unsigned long epoch = timeClient.getEpochTime();
  // Converte epoch para string ISO (UTC)
  char buf[30];
  struct tm *ptm = gmtime((time_t*)&epoch);
  sprintf(buf, "%04d-%02d-%02dT%02d:%02d:%02dZ",
          ptm->tm_year + 1900, ptm->tm_mon + 1, ptm->tm_mday,
          ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
  return String(buf);
}

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);

  dht.begin();
  setup_wifi();

  timeClient.begin();
  timeClient.update();

  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(callback);
}

float readLuminosityPercent() {
  int raw = analogRead(LDR_PIN); // 0..4095
  // em algumas placas ESP32 a resolução default é 12 bits (0..4095)
  // Ajuste o mapeamento conforme seu divisor (LDR + 10k)
  // Consideramos raw-> 0 (escuro) .. 4095 (claro)
  float perc = ( (float)raw / 4095.0 ) * 100.0;
  return perc;
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) {
    setup_wifi();
  }

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

  unsigned long now = millis();
  if (now - lastPublish >= publishInterval) {
    lastPublish = now;

    float h = dht.readHumidity();
    float t = dht.readTemperature(); // Celsius
    float lum = readLuminosityPercent();

    // verificar leitura válida
    if (isnan(h) || isnan(t)) {
      Serial.println("Falha ao ler DHT11!");
    } else {
      String timestamp = iso8601Time();
      // montar json simples
      String payload = "{";
      payload += "\"temperature\":" + String(t,1) + ",";
      payload += "\"humidity\":" + String(h,1) + ",";
      payload += "\"luminosity\":" + String(lum,0) + ",";
      payload += "\"timestamp\":\"" + timestamp + "\"";
      payload += "}";

      Serial.print("Publicando em ");
      Serial.print(topicTelem);
      Serial.print(" -> ");
      Serial.println(payload);

      client.publish(topicTelem.c_str(), payload.c_str());
    }
  }
}