/* ESP32 MQTT Subscriber / Logger
   Subscribes to sensors/telemetry and logs received payloads to Serial
*/

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

const char* ssid = "Wokwi-GUEST";
const char* pass = "";

const char* mqtt_server = "test.mosquitto.org";
const uint16_t mqtt_port = 1883;

WiFiClient espClient;
PubSubClient mqtt(espClient);

void setup_wifi() {
  Serial.begin(115200);
  delay(10);
  Serial.println();
  Serial.print("Connecting to WiFi ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, pass);

  unsigned long start = millis();
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(500);
    if (millis() - start > 10000) {
      Serial.println("\nStill trying to connect WiFi in sim (Wokwi may auto-connect). Continuing...");
      break;
    }
  }
  Serial.println("");
  Serial.print("WiFi IP: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("[RECV] topic: ");
  Serial.println(topic);

  // print payload preview (first 400 chars)
  unsigned int previewLen = min(length, 400u);
  String s = "";
  for (unsigned int i = 0; i < previewLen; i++) s += (char)payload[i];
  Serial.printf("payload_len=%u preview=\"%s\"\n", length, s.c_str());

  // simple detection: look for the words "password" or "username"
  String payloadStr = "";
  for (unsigned int i=0;i<length;i++) payloadStr += (char)payload[i];
  if (payloadStr.indexOf("password") >= 0 || payloadStr.indexOf("username") >= 0) {
    Serial.println("!!! SUSPICIOUS: possible credential leak detected !!!");
  }
}

void reconnect() {
  while (!mqtt.connected()) {
    Serial.print("Connecting to MQTT...");
    if (mqtt.connect("esp32_subscriber_sim")) {
      Serial.println("connected");
      mqtt.subscribe("sensors/telemetry");
      Serial.println("Subscribed to sensors/telemetry");
    } else {
      Serial.print("failed, rc=");
      Serial.print(mqtt.state());
      Serial.println(" try again in 2s");
      delay(2000);
    }
  }
}

void setup() {
  setup_wifi();
  mqtt.setServer(mqtt_server, mqtt_port);
  mqtt.setCallback(callback);
}

void loop() {
  if (!mqtt.connected()) reconnect();
  mqtt.loop();
  delay(10);
}