Panduan Instruktur & Menyiapkan Lab Server di Windows

/*
 * ================================================================
 *  KIT IoT PELATIHAN - firmware tunggal v3 (MQTT + HTTP)
 *  BEST Lab - Politeknik Negeri Semarang
 * ================================================================
 *  Peserta TIDAK perlu mengubah kode ini. Semua pengaturan lewat HP/laptop:
 *   1. Nyalakan kit -> muncul WiFi "KIT-IOT-xxxx" (password: kitiot123)
 *   2. Sambungkan HP ke WiFi tersebut -> halaman pengaturan terbuka otomatis
 *      (jika tidak, buka http://192.168.4.1)
 *   3. Isi WiFi lab, IP Lab Server, nama & password instance, ID kit -> Simpan
 *   4. Buka http://<IP kit>/ untuk melihat data, kendali LED, uji koneksi
 *
 *  Protokol (MQTT atau HTTP) TIDAK diatur di kit, melainkan di halaman instance
 *  pada Lab Server. Kit membaca pengaturan itu setiap 30 detik lalu menyesuaikan.
 *
 *  Reset pengaturan: tahan tombol BOOT 5 detik saat kit menyala.
 *  Komponen: DHT11 (DATA) -> GPIO4 | LED (+ resistor 220 ohm ke GND) -> GPIO26
 *            Tombol BOOT (GPIO0) | LED bawaan (GPIO2) ikut menyala bersama LED
 *  Modul DHT11 3 kaki: VCC -> 3V3, DATA -> GPIO4, GND -> GND (resistor pull-up sudah ada di modul)
 *  Library: PubSubClient (Nick O'Leary), DHT sensor library (Adafruit), Adafruit Unified Sensor
 *  Board  : "ESP32 Dev Module"
 * ================================================================
 */
#include <WiFi.h>
#include <WiFiUdp.h>
#include <WebServer.h>
#include <DNSServer.h>
#include <Preferences.h>
#include <HTTPClient.h>
#include <PubSubClient.h>
#include <DHT.h>

#define FW_VERSION "3.1.0"

// ---------------- PIN ----------------
#define PIN_DHT    4
#define PIN_LED    26     // LED yang dikendalikan dari aplikasi
#define PIN_BTN    0      // tombol BOOT
#define PIN_ONBOARD 2     // LED bawaan papan
#define DHTTYPE    DHT11

const char* AP_PASS = "kitiot123";
const uint16_t MQTT_PORT = 1883;
const uint16_t HTTP_PORT = 8080;
const uint16_t ECHO_PORT = 5005;
const uint16_t TP_PORT   = 5006;

// ---------------- PENGATURAN (disimpan di flash) ----------------
struct Config { String ssid, pass, server, inst, ipass, kitId; } cfg;

Preferences prefs;
WebServer web(80);
DNSServer dns;
WiFiClient net;          // untuk MQTT
WiFiClient httpNet;      // untuk HTTP
PubSubClient mqtt(net);
DHT dht(PIN_DHT, DHTTYPE);

bool portalOnly = false, apActive = false;
String apName;
char clientId[72];
char tStatus[96], tTele[96], tHealth[96], tSet[96], tState[96], tTest[96];

// pengaturan dari Lab Server
String proto = "mqtt";
uint32_t intervalMs = 5000, pollMs = 2000;

// ---------------- DATA & METRIK ----------------
float tempC = NAN, humid = NAN;
bool ledOn = false;
uint32_t seq = 0, dhtOk = 0, dhtFail = 0, pubOk = 0, pubFail = 0;
uint32_t mqttReconnects = 0, wifiDrops = 0, cmdRx = 0, loopMaxUs = 0;
unsigned long upMs = 0, lastAcc = 0, wifiLostAt = 0, lastHttpOk = 0;
unsigned long tSensor = 0, tTele0 = 0, tHealth0 = 0, tMqttTry = 0, tLog = 0, tCfg = 0, tPoll = 0, btnDownAt = 0;
bool wasConnected = false, cfgLoaded = false;

struct Sample { uint32_t up; int16_t rssi; uint32_t heap; float t, h; uint8_t led; float dhtRate; uint32_t pubFail, drops; char p; };
const int LOG_N = 120;
Sample logBuf[LOG_N];
int logHead = 0, logCount = 0;

// ================================================================
//  UTIL
// ================================================================
void setLed(bool on) {
  ledOn = on;
  digitalWrite(PIN_LED, on ? HIGH : LOW);
  digitalWrite(PIN_ONBOARD, on ? HIGH : LOW);
}
String num(float v, int d = 1) { return isnan(v) ? String("null") : String(v, d); }
float dhtRate() { uint32_t n = dhtOk + dhtFail; return n ? 100.0f * dhtOk / n : 0; }
float availPct() { unsigned long up = millis(); return up ? 100.0f * upMs / up : 0; }
bool serverOk() { return proto == "mqtt" ? mqtt.connected() : (lastHttpOk && millis() - lastHttpOk < 2 * intervalMs + 3000); }

String htmlEscape(const String& s) {
  String o; o.reserve(s.length());
  for (char c : s) {
    if (c == '<') o += "&lt;"; else if (c == '>') o += "&gt;";
    else if (c == '"') o += "&quot;"; else if (c == '&') o += "&amp;"; else o += c;
  }
  return o;
}

// ambil nilai teks / angka dari JSON sederhana, contoh: "protocol": "http"
String jsonStr(const String& js, const char* key) {
  int k = js.indexOf(String("\"") + key + "\"");
  if (k < 0) return "";
  int c = js.indexOf(':', k); if (c < 0) return "";
  int q1 = js.indexOf('"', c + 1); if (q1 < 0) return "";
  int q2 = js.indexOf('"', q1 + 1); if (q2 < 0) return "";
  return js.substring(q1 + 1, q2);
}
long jsonNum(const String& js, const char* key, long def) {
  int k = js.indexOf(String("\"") + key + "\"");
  if (k < 0) return def;
  int c = js.indexOf(':', k); if (c < 0) return def;
  return atol(js.c_str() + c + 1);
}

// ================================================================
//  PENYIMPANAN PENGATURAN
// ================================================================
void loadConfig() {
  prefs.begin("kit", true);
  cfg.ssid  = prefs.getString("ssid", "");
  cfg.pass  = prefs.getString("pass", "");
  cfg.server = prefs.getString("server", "");
  cfg.inst  = prefs.getString("inst", "");
  cfg.ipass = prefs.getString("ipass", "");
  cfg.kitId = prefs.getString("kit", "");
  prefs.end();
  if (cfg.kitId == "") cfg.kitId = "kit-01";
}

void saveConfig() {
  prefs.begin("kit", false);
  prefs.putString("ssid", cfg.ssid);   prefs.putString("pass", cfg.pass);
  prefs.putString("server", cfg.server); prefs.putString("inst", cfg.inst);
  prefs.putString("ipass", cfg.ipass); prefs.putString("kit", cfg.kitId);
  prefs.end();
}

void factoryReset() {
  prefs.begin("kit", false); prefs.clear(); prefs.end();
  delay(300); ESP.restart();
}

// ================================================================
//  HTTP KE LAB SERVER
// ================================================================
int httpReq(bool post, const String& path, const String& body, String* resp) {
  if (cfg.server == "" || WiFi.status() != WL_CONNECTED) return -1;
  HTTPClient http;
  http.setTimeout(3000);
  String url = "http://" + cfg.server + ":" + String(HTTP_PORT) + "/api/i/" + cfg.inst + path +
               (path.indexOf('?') >= 0 ? "&" : "?") + "key=" + cfg.ipass;
  if (!http.begin(httpNet, url)) return -1;
  int code;
  if (post) { http.addHeader("Content-Type", "application/json"); code = http.POST(body); }
  else code = http.GET();
  if (resp && code > 0) *resp = http.getString();
  http.end();
  if (code >= 200 && code < 300) lastHttpOk = millis();
  return code;
}

void fetchConfig() {
  String r;
  int code = httpReq(false, "/config?kit=" + cfg.kitId, "", &r);
  if (code != 200) return;
  String p = jsonStr(r, "protocol");
  long iv = jsonNum(r, "interval_s", 5), pl = jsonNum(r, "poll_s", 2);
  if (iv >= 1) intervalMs = iv * 1000UL;
  if (pl >= 1) pollMs = pl * 1000UL;
  if ((p == "mqtt" || p == "http") && p != proto) {
    if (proto == "mqtt" && mqtt.connected()) { mqtt.publish(tStatus, "offline", true); mqtt.disconnect(); }
    proto = p;
    Serial.printf("Protokol diganti oleh server: %s\n", proto.c_str());
  }
  cfgLoaded = true;
}

// kirim satu jenis data lewat protokol yang aktif
bool sendKind(const char* kind, const String& body, bool retained = false) {
  bool ok;
  if (proto == "mqtt") {
    char topic[96]; snprintf(topic, sizeof(topic), "lab/%s/%s/%s", cfg.inst.c_str(), cfg.kitId.c_str(), kind);
    ok = mqtt.connected() && mqtt.publish(topic, body.c_str(), retained);
  } else {
    String k = String(kind); if (k == "led/state") k = "ack";
    int code = httpReq(true, "/k/" + cfg.kitId + "/" + k, body, nullptr);
    ok = code >= 200 && code < 300;
  }
  if (ok) pubOk++; else pubFail++;
  return ok;
}

void publishState(long id, const char* src) {
  char b[80]; snprintf(b, sizeof(b), "{\"v\":%d,\"id\":%ld,\"src\":\"%s\"}", ledOn ? 1 : 0, id, src);
  sendKind("led/state", String(b), true);
}

// perintah: "1"/"0"/"ON"/"OFF" atau {"v":1,"id":123}
void applyCommand(const char* msg) {
  cmdRx++;
  int v = -1; long id = 0;
  const char* pv = strstr(msg, "\"v\"");
  if (pv) {
    pv = strchr(pv, ':'); if (pv) v = atoi(pv + 1);
    const char* pid = strstr(msg, "\"id\""); if (pid && (pid = strchr(pid, ':'))) id = atol(pid + 1);
  } else if (!strcmp(msg, "1") || !strcasecmp(msg, "ON")) v = 1;
  else if (!strcmp(msg, "0") || !strcasecmp(msg, "OFF")) v = 0;
  if (v == 0 || v == 1) { setLed(v == 1); publishState(id, proto.c_str()); }
}

void pollCommand() {
  String r;
  int code = httpReq(false, "/k/" + cfg.kitId + "/command", "", &r);
  if (code == 200 && r.length()) applyCommand(r.c_str());
}

// ================================================================
//  MQTT
// ================================================================
void onMessage(char* topic, byte* payload, unsigned int len) {
  if (strcmp(topic, tSet) != 0) return;
  char msg[96]; unsigned int n = len < sizeof(msg) - 1 ? len : sizeof(msg) - 1;
  memcpy(msg, payload, n); msg[n] = '\0';
  applyCommand(msg);
}

void connectMqtt() {
  if (cfg.server == "") return;
  if (mqtt.connect(clientId, cfg.inst.c_str(), cfg.ipass.c_str(), tStatus, 1, true, "offline")) {
    mqtt.publish(tStatus, "online", true);
    mqtt.subscribe(tSet, 1);
    publishState(0, "boot");
  }
}

// ================================================================
//  HALAMAN WEB KIT
// ================================================================
const char CSS[] PROGMEM = R"CSS(
<style>
*{box-sizing:border-box}body{font-family:Segoe UI,Arial,sans-serif;margin:0;background:#f4f7f6;color:#222;font-size:18px}
header{background:#004280;color:#fff;padding:14px 18px;font-weight:700;font-size:20px}
header small{display:block;font-weight:400;font-size:14px;opacity:.85}
main{max-width:640px;margin:auto;padding:16px}
.card{background:#fff;border-radius:10px;padding:16px;margin-bottom:14px;box-shadow:0 2px 6px rgba(0,0,0,.08)}
.card h2{margin:0 0 10px;font-size:18px;color:#004280;border-left:5px solid #F39800;padding-left:10px}
.grid{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.v{background:#f4f7f6;border-radius:8px;padding:10px}.v b{display:block;font-size:26px;color:#004280}.v span{font-size:14px;color:#666}
.btn{display:block;width:100%;padding:16px;font-size:20px;font-weight:700;border:0;border-radius:8px;margin-top:8px;cursor:pointer;color:#fff;background:#004280;text-align:center;text-decoration:none}
.on{background:#2e7d32}.off{background:#c62828}.alt{background:#fff;color:#004280;border:2px solid #004280}
label{display:block;font-weight:600;margin-top:12px}input,select{width:100%;padding:12px;font-size:18px;border:1px solid #bbb;border-radius:6px;margin-top:4px}
.ok{color:#2e7d32;font-weight:700}.bad{color:#c62828;font-weight:700}.hint{font-size:14px;color:#666}
table{width:100%;border-collapse:collapse;font-size:16px}td{padding:6px;border-bottom:1px solid #eee}td:last-child{text-align:right;font-weight:600}
</style>)CSS";

String pageHead(const String& title) {
  String h = F("<!doctype html><html lang='id'><head><meta charset='utf-8'><meta name='viewport' content='width=device-width,initial-scale=1'><title>");
  h += title; h += F("</title>"); h += FPSTR(CSS);
  h += F("</head><body><header>"); h += title; h += F("<small>");
  h += htmlEscape(cfg.kitId + " @ " + cfg.inst); h += F(" &middot; firmware " FW_VERSION "</small></header><main>");
  return h;
}

void sendSetup() {
  int n = WiFi.scanNetworks();
  String h = pageHead("Pengaturan Kit");
  h += F("<form method='post' action='/save' class='card'><h2>1. WiFi Lab</h2><label>Nama WiFi</label><select name='ssid'>");
  for (int i = 0; i < n; i++) {
    String s = WiFi.SSID(i);
    h += "<option" + String(s == cfg.ssid ? " selected" : "") + ">" + htmlEscape(s) + "</option>";
  }
  h += F("</select><p class='hint'>Tidak muncul? Ketik manual di bawah.</p><input name='ssid2' placeholder='(opsional) nama WiFi manual'>");
  h += F("<label>Password WiFi</label><input name='pass' type='password' value='"); h += htmlEscape(cfg.pass); h += F("'>");
  h += F("<h2 style='margin-top:20px'>2. Lab Server</h2><label>Alamat IP Lab Server</label><input name='server' placeholder='contoh 192.168.1.10' value='");
  h += htmlEscape(cfg.server);
  h += F("'><label>Nama instance</label><input name='inst' placeholder='contoh peserta-03' value='"); h += htmlEscape(cfg.inst);
  h += F("'><label>Password instance</label><input name='ipass' type='password' value='"); h += htmlEscape(cfg.ipass);
  h += F("'><h2 style='margin-top:20px'>3. Identitas Kit</h2><label>ID Kit</label><input name='kit' value='"); h += htmlEscape(cfg.kitId);
  h += F("'><p class='hint'>Contoh kit-01. Huruf kecil, tanpa spasi. Protokol (MQTT/HTTP) diatur dari halaman instance di Lab Server.</p>");
  h += F("<button class='btn' type='submit'>Simpan &amp; Mulai Ulang</button></form>");
  if (!portalOnly) h += F("<a class='btn alt' href='/'>Kembali</a>");
  h += F("</main></body></html>");
  web.send(200, "text/html", h);
}

String clean(String s) { s.trim(); s.toLowerCase(); s.replace(" ", "-"); return s; }

void handleSave() {
  String s = web.arg("ssid2"); s.trim();
  cfg.ssid = s.length() ? s : web.arg("ssid");
  cfg.pass = web.arg("pass");
  cfg.server = web.arg("server"); cfg.server.trim();
  cfg.inst = clean(web.arg("inst"));
  cfg.ipass = web.arg("ipass");
  String k = clean(web.arg("kit")); if (k.length()) cfg.kitId = k;
  saveConfig();
  String h = pageHead("Tersimpan");
  h += F("<div class='card'><h2>Pengaturan tersimpan</h2><p>Kit akan mulai ulang dan tersambung ke WiFi <b>");
  h += htmlEscape(cfg.ssid);
  h += F("</b>.</p><p>Sambungkan kembali HP ke WiFi lab, lalu lihat kit Anda di halaman instance (menu Perangkat).</p></div></main></body></html>");
  web.send(200, "text/html", h);
  delay(1500);
  ESP.restart();
}

const char HOME_JS[] PROGMEM = R"JS(
<script>
function g(id){return document.getElementById(id)}
async function upd(){try{const d=await (await fetch('/api/status')).json();
g('t').textContent=d.temp_c===null?'-':d.temp_c+' °C';g('h').textContent=d.hum_pct===null?'-':d.hum_pct+' %';
g('r').textContent=d.led?'MENYALA':'MATI';g('r').className=d.led?'ok':'bad';
g('pr').textContent=d.protokol.toUpperCase();g('rs').textContent=d.rssi+' dBm ('+d.rssi_ket+')';
g('mq').textContent=d.server?'Tersambung':'Terputus';g('mq').className=d.server?'ok':'bad';
g('up').textContent=Math.floor(d.uptime_s/60)+' menit';g('dr').textContent=d.dht_rate_pct+' %';g('av').textContent=d.avail_pct+' %';
g('hp').textContent=Math.round(d.heap/1024)+' KB';g('pf').textContent=d.pub_fail;g('wd').textContent=d.wifi_drop;}catch(e){}}
async function led(v){await fetch('/api/led?on='+v);upd()}
async function uji(){const b=g('bt');b.textContent='Sedang menguji... (±15 detik)';b.disabled=true;
try{const d=await (await fetch('/api/test')).json();
g('hasil').innerHTML='<table><tr><td>Kekuatan sinyal (rata-rata)</td><td>'+d.rssi_avg+' dBm</td></tr><tr><td>Kualitas sinyal</td><td>'+d.quality_pct+' %</td></tr><tr><td>Waktu tanggap (ping)</td><td>'+d.rtt_avg_ms+' ms</td></tr><tr><td>Variasi waktu (jitter)</td><td>'+d.jitter_ms+' ms</td></tr><tr><td>Paket hilang</td><td>'+d.loss_pct+' %</td></tr><tr><td>Kecepatan unduh</td><td>'+d.dl_kbps+' kbit/s</td></tr><tr><td>Kecepatan unggah</td><td>'+d.ul_kbps+' kbit/s</td></tr></table><p class=hint>Hasil juga terkirim ke halaman instance (menu Uji Koneksi).</p>';}
catch(e){g('hasil').textContent='Uji gagal. Pastikan Lab Server menyala.'}b.textContent='Uji Koneksi';b.disabled=false}
upd();setInterval(upd,2000);
</script>)JS";

void sendHome() {
  String h = pageHead("Kit IoT");
  h += F("<div class='card'><h2>Data Sensor</h2><div class='grid'>"
         "<div class='v'><span>Suhu</span><b id='t'>-</b></div><div class='v'><span>Kelembapan</span><b id='h'>-</b></div>"
         "<div class='v' style='grid-column:1/3'><span>LED</span><b id='r'>-</b></div></div>"
         "<button class='btn on' onclick='led(1)'>NYALAKAN LED</button><button class='btn off' onclick='led(0)'>MATIKAN LED</button></div>");
  h += F("<div class='card'><h2>Kesehatan Perangkat</h2><table>"
         "<tr><td>Protokol aktif</td><td id='pr'>-</td></tr>"
         "<tr><td>Sinyal WiFi</td><td id='rs'>-</td></tr><tr><td>Koneksi ke Lab Server</td><td id='mq'>-</td></tr>"
         "<tr><td>Lama menyala</td><td id='up'>-</td></tr><tr><td>Keberhasilan baca sensor</td><td id='dr'>-</td></tr>"
         "<tr><td>Ketersediaan koneksi</td><td id='av'>-</td></tr><tr><td>Memori bebas</td><td id='hp'>-</td></tr>"
         "<tr><td>Kirim data gagal</td><td id='pf'>-</td></tr><tr><td>WiFi sempat putus</td><td id='wd'>-</td></tr></table>"
         "<a class='btn alt' href='/log.csv'>Unduh Catatan 30 Menit (CSV)</a></div>");
  h += F("<div class='card'><h2>Uji Koneksi</h2><button class='btn' id='bt' onclick='uji()'>Uji Koneksi</button><div id='hasil'></div></div>"
         "<a class='btn alt' href='/setup'>Pengaturan</a>");
  h += FPSTR(HOME_JS);
  h += F("</main></body></html>");
  web.send(200, "text/html", h);
}

const char* rssiKet(int r) {
  if (r == 0) return "terputus";
  if (r >= -50) return "sangat baik";
  if (r >= -60) return "baik";
  if (r >= -70) return "cukup";
  return "lemah";
}

String statusJson() {
  int r = WiFi.status() == WL_CONNECTED ? WiFi.RSSI() : 0;
  String j = "{\"kit\":\"" + cfg.kitId + "\",\"instance\":\"" + cfg.inst + "\",\"fw\":\"" FW_VERSION "\",\"ip\":\"" + WiFi.localIP().toString() + "\"";
  j += ",\"protokol\":\"" + proto + "\",\"uptime_s\":" + String(millis() / 1000UL);
  j += ",\"temp_c\":" + num(tempC) + ",\"hum_pct\":" + num(humid);
  j += ",\"led\":" + String(ledOn ? 1 : 0);
  j += ",\"rssi\":" + String(r) + ",\"rssi_ket\":\"" + rssiKet(r) + "\"";
  j += ",\"server\":" + String(serverOk() ? "true" : "false");
  j += ",\"heap\":" + String(ESP.getFreeHeap()) + ",\"min_heap\":" + String(ESP.getMinFreeHeap());
  j += ",\"dht_rate_pct\":" + String(dhtRate(), 1) + ",\"pub_ok\":" + String(pubOk) + ",\"pub_fail\":" + String(pubFail);
  j += ",\"mqtt_reconnect\":" + String(mqttReconnects) + ",\"wifi_drop\":" + String(wifiDrops);
  j += ",\"cmd_rx\":" + String(cmdRx) + ",\"loop_max_us\":" + String(loopMaxUs);
  j += ",\"avail_pct\":" + String(availPct(), 2) + ",\"mqtt_avail_pct\":" + String(availPct(), 2) + "}";
  return j;
}

void sendLogCsv() {
  String c = "uptime_s,protokol,rssi_dbm,heap,temp_c,hum_pct,led,dht_rate_pct,pub_fail,wifi_drop\n";
  int start = (logHead - logCount + LOG_N) % LOG_N;
  for (int i = 0; i < logCount; i++) {
    Sample& s = logBuf[(start + i) % LOG_N];
    c += String(s.up) + "," + String(s.p == 'h' ? "http" : "mqtt") + "," + String(s.rssi) + "," + String(s.heap) + "," +
         num(s.t) + "," + num(s.h) + "," + String(s.led) + "," + String(s.dhtRate, 1) + "," + String(s.pubFail) + "," + String(s.drops) + "\n";
  }
  web.sendHeader("Content-Disposition", "attachment; filename=\"" + cfg.kitId + "_catatan.csv\"");
  web.send(200, "text/csv", c);
}

// ================================================================
//  UJI KONEKSI (measurement test) ke Lab Server
// ================================================================
void keepAlive() { if (proto == "mqtt" && mqtt.connected()) mqtt.loop(); }   // jangan panggil web.handleClient di sini

String runTest() {
  long rs = 0; int rmin = 0, rmax = -200;
  for (int i = 0; i < 20; i++) {
    int r = WiFi.RSSI(); rs += r;
    if (i == 0 || r < rmin) rmin = r;
    if (r > rmax) rmax = r;
    delay(100);
  }
  float ravg = rs / 20.0f;
  int q = (int)(2 * (ravg + 100)); q = q < 0 ? 0 : (q > 100 ? 100 : q);

  WiFiUDP udp; udp.begin(4210);
  const int N = 50; int got = 0; float sum = 0, prev = -1, jsum = 0, mn = 1e9, mx = 0; int jn = 0;
  uint8_t tx[32], rx[64];
  for (uint32_t s = 1; s <= (uint32_t)N; s++) {
    memset(tx, 0, sizeof(tx)); memcpy(tx, &s, 4);
    uint32_t t0 = micros();
    udp.beginPacket(cfg.server.c_str(), ECHO_PORT); udp.write(tx, sizeof(tx)); udp.endPacket();
    bool ok = false;
    while (micros() - t0 < 500000UL) {
      int n = udp.parsePacket();
      if (n >= 4) { udp.read(rx, sizeof(rx)); uint32_t rsq; memcpy(&rsq, rx, 4); if (rsq == s) { ok = true; break; } }
      delay(0);
    }
    if (ok) {
      float rtt = (micros() - t0) / 1000.0f; got++; sum += rtt;
      if (rtt < mn) mn = rtt;
      if (rtt > mx) mx = rtt;
      if (prev >= 0) { jsum += fabsf(rtt - prev); jn++; }
      prev = rtt;
    }
    keepAlive(); delay(40);
  }
  udp.stop();
  float loss = 100.0f * (N - got) / N, ravgRtt = got ? sum / got : 0, jit = jn ? jsum / jn : 0;

  const uint32_t BYTES = 131072;
  float dl = 0, ul = 0;
  WiFiClient c;
  if (c.connect(cfg.server.c_str(), TP_PORT)) {
    c.printf("DL %lu\n", (unsigned long)BYTES);
    uint8_t buf[1024]; uint32_t n = 0, t0 = millis();
    while (n < BYTES && millis() - t0 < 15000) {
      int a = c.available();
      if (a > 0) { int r = c.read(buf, a > (int)sizeof(buf) ? sizeof(buf) : a); if (r > 0) n += r; }
      else if (!c.connected()) break; else delay(1);
    }
    uint32_t ms = millis() - t0; c.stop();
    dl = ms ? n * 8.0f / ms : 0;
  }
  keepAlive();
  if (c.connect(cfg.server.c_str(), TP_PORT)) {
    c.printf("UL %lu\n", (unsigned long)BYTES);
    static uint8_t buf[1024]; memset(buf, 0xA5, sizeof(buf));
    uint32_t sent = 0, t0 = millis();
    while (sent < BYTES && millis() - t0 < 15000) {
      size_t w = c.write(buf, BYTES - sent > sizeof(buf) ? sizeof(buf) : BYTES - sent);
      if (w == 0) { if (!c.connected()) break; delay(1); }
      sent += w;
    }
    uint32_t tw = millis();
    while (millis() - tw < 8000) {
      if (c.available()) { if (c.read() == '\n') break; }
      else if (!c.connected()) break; else delay(1);
    }
    uint32_t ms = millis() - t0; c.stop();
    ul = ms ? sent * 8.0f / ms : 0;
  }

  String j = "{\"kit\":\"" + cfg.kitId + "\",\"rssi_avg\":" + String(ravg, 1) + ",\"rssi_min\":" + String(rmin) +
             ",\"rssi_max\":" + String(rmax) + ",\"quality_pct\":" + String(q) +
             ",\"rtt_avg_ms\":" + String(ravgRtt, 1) + ",\"rtt_min_ms\":" + String(got ? mn : 0, 1) +
             ",\"rtt_max_ms\":" + String(mx, 1) + ",\"jitter_ms\":" + String(jit, 2) + ",\"loss_pct\":" + String(loss, 1) +
             ",\"dl_kbps\":" + String(dl, 0) + ",\"ul_kbps\":" + String(ul, 0) + "}";
  sendKind("test", j);
  return j;
}

// ================================================================
//  MODE HOTSPOT (portal pengaturan)
// ================================================================
void startAP() {
  if (apActive) return;
  WiFi.mode(portalOnly ? WIFI_AP : WIFI_AP_STA);
  WiFi.softAP(apName.c_str(), AP_PASS);
  dns.start(53, "*", WiFi.softAPIP());
  apActive = true;
}

void stopAP() {
  if (!apActive || portalOnly) return;
  dns.stop();
  WiFi.softAPdisconnect(true);
  WiFi.mode(WIFI_STA);
  apActive = false;
}

void setupRoutes() {
  web.on("/", []() { if (portalOnly) sendSetup(); else sendHome(); });
  web.on("/setup", sendSetup);
  web.on("/save", HTTP_POST, handleSave);
  web.on("/api/status", []() { web.send(200, "application/json", statusJson()); });
  web.on("/api/led", []() {
    if (web.hasArg("on")) { setLed(web.arg("on") == "1"); publishState(0, "web"); }
    web.send(200, "application/json", statusJson());
  });
  web.on("/api/test", []() {
    if (WiFi.status() != WL_CONNECTED || cfg.server == "") { web.send(503, "application/json", "{\"error\":\"belum tersambung\"}"); return; }
    web.send(200, "application/json", runTest());
  });
  web.on("/log.csv", sendLogCsv);
  web.onNotFound([]() {
    if (apActive) {
      web.sendHeader("Location", String("http://") + WiFi.softAPIP().toString() + "/");
      web.send(302, "text/plain", "");
    } else {
      web.send(404, "text/plain", "Halaman tidak ada");
    }
  });
}

void setup() {
  Serial.begin(115200);
  pinMode(PIN_LED, OUTPUT); pinMode(PIN_ONBOARD, OUTPUT); pinMode(PIN_BTN, INPUT_PULLUP);
  setLed(false);
  dht.begin();
  loadConfig();

  uint64_t mac = ESP.getEfuseMac();
  char ap[24]; snprintf(ap, sizeof(ap), "KIT-IOT-%04X", (unsigned)(mac >> 32) & 0xFFFF);
  apName = ap;

  const char* i = cfg.inst.c_str(); const char* k = cfg.kitId.c_str();
  snprintf(clientId, sizeof(clientId), "%s@%s", k, i);     // unik antar instance
  snprintf(tStatus, sizeof(tStatus), "lab/%s/%s/status", i, k);
  snprintf(tTele,   sizeof(tTele),   "lab/%s/%s/telemetry", i, k);
  snprintf(tHealth, sizeof(tHealth), "lab/%s/%s/health", i, k);
  snprintf(tSet,    sizeof(tSet),    "lab/%s/%s/led/set", i, k);
  snprintf(tState,  sizeof(tState),  "lab/%s/%s/led/state", i, k);
  snprintf(tTest,   sizeof(tTest),   "lab/%s/%s/test", i, k);

  portalOnly = (cfg.ssid == "");
  if (portalOnly) {
    startAP();
    Serial.printf("Mode pengaturan: sambungkan ke WiFi %s (password %s), buka http://192.168.4.1\n", ap, AP_PASS);
  } else {
    WiFi.mode(WIFI_STA);
    WiFi.setAutoReconnect(true);
    WiFi.begin(cfg.ssid.c_str(), cfg.pass.c_str());
    mqtt.setServer(cfg.server.c_str(), MQTT_PORT);
    mqtt.setCallback(onMessage);
    mqtt.setBufferSize(768);
    mqtt.setKeepAlive(15);
  }
  setupRoutes();
  web.begin();
  lastAcc = millis();
}

void loop() {
  uint32_t t0 = micros();
  unsigned long now = millis();

  if (apActive) dns.processNextRequest();
  web.handleClient();

  // tombol BOOT: tekan singkat = nyala/matikan LED, tahan 5 s = reset pengaturan
  bool down = digitalRead(PIN_BTN) == LOW;
  if (down && btnDownAt == 0) btnDownAt = now;
  if (!down && btnDownAt) {
    unsigned long held = now - btnDownAt; btnDownAt = 0;
    if (held > 50 && held < 2000) { setLed(!ledOn); publishState(0, "button"); }
  }
  if (down && btnDownAt && now - btnDownAt > 5000) factoryReset();

  if (now - tSensor >= 2000) {
    tSensor = now;
    float t = dht.readTemperature(), h = dht.readHumidity();
    if (isnan(t) || isnan(h)) dhtFail++; else { tempC = t; humid = h; dhtOk++; }
  }

  if (!portalOnly) {
    bool wifiOk = WiFi.status() == WL_CONNECTED;
    if (wifiOk) {
      if (!wasConnected) {
        wasConnected = true; wifiLostAt = 0; stopAP();
        Serial.printf("WiFi OK, IP kit: %s\n", WiFi.localIP().toString().c_str());
        fetchConfig(); tCfg = now;
      }
      if (now - tCfg >= 30000) { tCfg = now; fetchConfig(); }      // ikuti pengaturan instance
      if (proto == "mqtt") {
        if (!mqtt.connected() && now - tMqttTry > 5000) { tMqttTry = now; mqttReconnects++; connectMqtt(); }
        if (mqtt.connected()) mqtt.loop();
      } else {
        if (mqtt.connected()) mqtt.disconnect();
        if (now - tPoll >= pollMs) { tPoll = now; pollCommand(); }   // HTTP: tanya perintah
      }
    } else {
      if (wasConnected) { wasConnected = false; wifiDrops++; }
      if (wifiLostAt == 0) wifiLostAt = now;
      if (now - wifiLostAt > 30000) startAP();
    }
    if (serverOk()) upMs += now - lastAcc;
    lastAcc = now;

    // seq tetap naik walau putus: platform dapat menghitung data hilang
    if (now - tTele0 >= intervalMs) {
      tTele0 = now; seq++;
      String j = "{\"seq\":" + String(seq) + ",\"temp_c\":" + num(tempC) + ",\"hum_pct\":" + num(humid) +
                 ",\"led\":" + String(ledOn ? 1 : 0) + ",\"rssi\":" + String(WiFi.RSSI()) + "}";
      if (wifiOk) sendKind("telemetry", j); else pubFail++;
    }
    if (wifiOk && now - tHealth0 >= 30000) { tHealth0 = now; sendKind("health", statusJson()); }
  }

  if (now - tLog >= 15000) {
    tLog = now;
    Sample& s = logBuf[logHead];
    s.up = now / 1000; s.rssi = WiFi.status() == WL_CONNECTED ? WiFi.RSSI() : 0; s.heap = ESP.getFreeHeap();
    s.t = tempC; s.h = humid; s.led = ledOn; s.dhtRate = dhtRate(); s.pubFail = pubFail; s.drops = wifiDrops;
    s.p = proto == "http" ? 'h' : 'm';
    logHead = (logHead + 1) % LOG_N; if (logCount < LOG_N) logCount++;
  }

  uint32_t dt = micros() - t0;
  if (dt > loopMaxUs && now > 10000) loopMaxUs = dt;
}