// ============================================================================
// Viesta / Hantech / TCL Splitklima ESP32-S3 Gateway v2.0 FINAL
// Arduino-only Firmware, KEIN ESPHome
//
// Funktionen:
// - WLAN Auto-Reconnect + Fallback AP
// - Arduino OTA
// - Webserver mit Bedienung und Diagnose
// - MQTT + Home Assistant MQTT Climate Discovery
// - Lokale UART-Steuerung der Klima ueber TCL-Protokoll
// - Power / Mode / Temperatur / Luefter / Swing / Presets
// - Zyklischer State-Publish, damit Home Assistant die Steuerung nicht verliert
//
// Anschluss Klima -> ESP32-S3:
// Klima 5V  -> ESP 5V/VIN
// Klima GND -> ESP GND
// Klima TX  -> ESP GPIO16 RX
// Klima RX  -> ESP GPIO17 TX
// ============================================================================

#include <WiFi.h>
#include <HTTPClient.h>
#include <PubSubClient.h>
#include <WebServer.h>
#include <ArduinoOTA.h>
#include <Preferences.h>
#include "esp_system.h"

#define FW_VERSION "2.8.2-mobile-compact-buttons"

// ============================================================================
// WLAN / MQTT / OTA
// ============================================================================

const char* WIFI_SSID = "xxxxxxxxxx";
const char* WIFI_PASS = "xxxxxxxxxxx";

const char* MQTT_HOST = "192.168.178.xx";
const int   MQTT_PORT = 1883;
const char* MQTT_USER = "admin";
const char* MQTT_PASS = "admin";

const char* OTA_HOST = "viesta-klima";
const char* OTA_PASS = "viesta-ota";

const char* AP_SSID = "Viesta-Klima-Setup";
const char* AP_PASS = "viesta-setup-123";

const char* DEVICE_ID = "viesta_klima_gateway";
const char* DEVICE_NAME = "Viesta Klima Gateway";
const char* MQTT_BASE = "viesta/klima";
const char* HA_DISCOVERY_PREFIX = "homeassistant";

// ============================================================================
// Shelly Verbrauchsmessung
// ============================================================================
// IP frei konfigurierbar im Webinterface.
// Standard: Shelly an der Klima Wohnzimmer
String shellyHost = "192.168.178.79";
float shellyPowerW = NAN;
float shellyVoltageV = NAN;
float shellyCurrentA = NAN;
bool shellyOnline = false;
String shellyLastError = "-";
unsigned long shellyOkCount = 0;
unsigned long shellyErrCount = 0;
unsigned long lastShellyPollMs = 0;
const unsigned long SHELLY_POLL_MS = 5000;

// ============================================================================
// UART Klima
// ============================================================================

HardwareSerial klimaSerial(2);
static const int KLIMA_RX_PIN = 16;
static const int KLIMA_TX_PIN = 17;
static const uint32_t KLIMA_BAUD = 9600;
static const uint32_t KLIMA_CONFIG = SERIAL_8E1;

// TCL Poll: Status abfragen
uint8_t TCL_POLL[8] = {0xBB, 0x00, 0x01, 0x04, 0x02, 0x01, 0x00, 0xBD};

// RX Parser
uint8_t rxBuf[80];
uint8_t rxPos = 0;
uint8_t expectedLen = 0;
unsigned long lastRxMs = 0;

// ============================================================================
// Services
// ============================================================================

WiFiClient espClient;
PubSubClient mqtt(espClient);
WebServer server(80);
Preferences prefs;

// ============================================================================
// Klima State
// ============================================================================

String acMode = "off";       // off, auto, cool, heat, dry, fan_only
String fanMode = "auto";     // auto, low, medium, middle, high, quiet, focus, diffuse
String swingMode = "off";    // off, vertical, horizontal, both
String presetMode = "none";  // none, eco, sleep, comfort
float targetTemp = 24.0;
float currentTemp = NAN;
bool acOnline = false;
bool beepEnabled = true;
bool displayEnabled = true;

// Diagnose
unsigned long rxBytes = 0;
unsigned long txBytes = 0;
unsigned long rxFrames = 0;
unsigned long txFrames = 0;
unsigned long checksumErrors = 0;
unsigned long wrongBytes = 0;
unsigned long mqttReconnects = 0;
unsigned long wifiReconnects = 0;
String lastRxFrame = "-";
String lastTxFrame = "-";
String lastCommand = "-";
String lastError = "-";
String uartLog = "";
const size_t UART_LOG_MAX = 16000;

// Timings
unsigned long lastPollMs = 0;
unsigned long lastStatePublishMs = 0;
unsigned long lastWifiCheckMs = 0;
unsigned long lastMqttCheckMs = 0;
unsigned long lastDiscoveryMs = 0;
unsigned long bootMs = 0;

const unsigned long POLL_INTERVAL_MS = 5000;
const unsigned long STATE_PUBLISH_MS = 10000;
const unsigned long WIFI_RETRY_MS = 15000;
const unsigned long MQTT_RETRY_MS = 5000;
const unsigned long DISCOVERY_REFRESH_MS = 300000;

// ============================================================================
// Helpers
// ============================================================================

String htmlEscape(String s) {
  s.replace("&", "&amp;");
  s.replace("<", "&lt;");
  s.replace(">", "&gt;");
  s.replace("\"", "&quot;");
  return s;
}

String jsonEscape(String s) {
  s.replace("\\", "\\\\");
  s.replace("\"", "\\\"");
  s.replace("\r", "");
  s.replace("\n", "\\n");
  return s;
}

String twoDigits(unsigned long v) {
  return v < 10 ? "0" + String(v) : String(v);
}

String uptimeText() {
  unsigned long sec = millis() / 1000;
  unsigned long d = sec / 86400; sec %= 86400;
  unsigned long h = sec / 3600; sec %= 3600;
  unsigned long m = sec / 60; sec %= 60;
  return String(d) + "d " + twoDigits(h) + ":" + twoDigits(m) + ":" + twoDigits(sec);
}

String byteHex(uint8_t b) {
  char buf[4];
  snprintf(buf, sizeof(buf), "%02X", b);
  return String(buf);
}

String bytesToHex(const uint8_t* data, size_t len) {
  String out;
  out.reserve(len * 3);
  for (size_t i = 0; i < len; i++) {
    if (i) out += " ";
    out += byteHex(data[i]);
  }
  return out;
}

void appendLog(const String& line) {
  uartLog += line + "\n";
  if (uartLog.length() > UART_LOG_MAX) {
    uartLog = uartLog.substring(uartLog.length() - UART_LOG_MAX);
  }
}

uint8_t tclChecksum(const uint8_t* data, size_t len) {
  uint8_t crc = 0;
  for (size_t i = 0; i < len - 1; i++) crc ^= data[i];
  return crc;
}

String ipText() {
  if (WiFi.status() == WL_CONNECTED) return WiFi.localIP().toString();
  if (WiFi.getMode() & WIFI_AP) return WiFi.softAPIP().toString();
  return "-";
}

String rssiText() {
  if (WiFi.status() != WL_CONNECTED) return "-";
  return String(WiFi.RSSI()) + " dBm";
}

float chipTempC() {
#if defined(ARDUINO_ARCH_ESP32)
  return temperatureRead();
#else
  return NAN;
#endif
}

void saveState() {
  prefs.putString("mode", acMode);
  prefs.putString("fan", fanMode);
  prefs.putString("swing", swingMode);
  prefs.putString("preset", presetMode);
  prefs.putFloat("target", targetTemp);
  prefs.putString("shelly", shellyHost);
}

void loadState() {
  acMode = prefs.getString("mode", "off");
  fanMode = prefs.getString("fan", "auto");
  swingMode = prefs.getString("swing", "off");
  presetMode = prefs.getString("preset", "none");
  targetTemp = prefs.getFloat("target", 24.0);
  shellyHost = prefs.getString("shelly", "192.168.178.79");
  if (isnan(targetTemp) || targetTemp < 16 || targetTemp > 31) targetTemp = 24.0;
}

// ============================================================================
// TCL Klima Protokoll
// Abgeleitet aus tclac: Header BB 00 01 03 20..., XOR Checksumme.
// ============================================================================

void sendPoll() {
  klimaSerial.write(TCL_POLL, sizeof(TCL_POLL));
  txBytes += sizeof(TCL_POLL);
  txFrames++;
  lastTxFrame = bytesToHex(TCL_POLL, sizeof(TCL_POLL));
}

uint8_t modeCode(const String& m) {
  if (m == "heat") return 0x01;
  if (m == "dry") return 0x02;
  if (m == "cool") return 0x03;
  if (m == "fan_only") return 0x07;
  if (m == "auto") return 0x08;
  return 0x08;
}

void sendControl() {
  if (targetTemp < 16) targetTemp = 16;
  if (targetTemp > 31) targetTemp = 31;

  uint8_t data[38];
  memset(data, 0, sizeof(data));

  data[0] = 0xBB;
  data[1] = 0x00;
  data[2] = 0x01;
  data[3] = 0x03;  // control
  data[4] = 0x20;  // length
  data[5] = 0x03;
  data[6] = 0x01;

  // Byte 7: eco/display/beep/power
  data[7] = 0x00;
  if (beepEnabled) data[7] |= 0x20;
  if (displayEnabled && acMode != "off") data[7] |= 0x40;
  if (presetMode == "eco") data[7] |= 0x80;

  // Power + mode
  if (acMode == "off") {
    data[8] = 0x00;
  } else {
    data[7] |= 0x04;              // power on
    data[8] |= modeCode(acMode);  // heat/dry/cool/fan/auto
  }

  // Fan special bits
  if (fanMode == "quiet") {
    data[8] |= 0x80;
  } else if (fanMode == "diffuse") {
    data[8] |= 0x40;
  }

  if (presetMode == "comfort") data[8] |= 0x10;

  // Temperatur: TCL = 31 - Solltemperatur
  data[9] = (uint8_t)(31 - (int)round(targetTemp));

  // Fan + vertical swing
  data[10] = 0x00;
  if (fanMode == "low") data[10] |= 0x01;
  else if (fanMode == "medium") data[10] |= 0x03;
  else if (fanMode == "middle") data[10] |= 0x06;
  else if (fanMode == "high") data[10] |= 0x07;
  else if (fanMode == "focus") data[10] |= 0x05;
  // auto/quiet/diffuse bleiben 0 im unteren Fan-Nibble

  if (swingMode == "vertical" || swingMode == "both") data[10] |= 0x38;

  // Horizontal swing
  data[11] = 0x00;
  if (swingMode == "horizontal" || swingMode == "both") data[11] |= 0x08;

  data[12] = 0x00;
  data[13] = 0x01;
  data[14] = 0x00;
  data[15] = 0x00;
  data[16] = 0x00;
  data[17] = 0x00;
  data[18] = 0x00;
  data[19] = (presetMode == "sleep") ? 0x01 : 0x00;

  // 20-31 bleiben 0

  // Vertikale Lamellenposition/Swing-Richtung Standard: up/down
  // Wenn Swing aus, bleibt letzte Position.
  data[32] = 0x00;
  if (swingMode == "vertical" || swingMode == "both") data[32] |= 0x08;

  // Horizontale Lamellenposition/Swing-Richtung Standard: left/right
  data[33] = 0x00;
  if (swingMode == "horizontal" || swingMode == "both") data[33] |= 0x08;

  data[34] = 0x00;
  data[35] = 0x00;
  data[36] = 0x00;
  data[37] = tclChecksum(data, sizeof(data));

  klimaSerial.write(data, sizeof(data));
  txBytes += sizeof(data);
  txFrames++;
  lastTxFrame = bytesToHex(data, sizeof(data));
  appendLog("TX " + lastTxFrame);

  saveState();
}

void parseTclFrame(const uint8_t* d, size_t len) {
  if (len < 61) return;

  // Current temp nach tclac: (((raw / 374) - 32) / 1.8)
  uint16_t rawTemp = ((uint16_t)d[17] << 8) | d[18];
  float ct = (((float)rawTemp / 374.0f) - 32.0f) / 1.8f;
  if (ct > -20 && ct < 80) currentTemp = ct;

  float tt = (float)((d[8] & 0x0F) + 16);
  if (tt >= 16 && tt <= 31) targetTemp = tt;

  bool powerOn = d[7] & 0x10;
  if (!powerOn) {
    acMode = "off";
    presetMode = "none";
  } else {
    uint8_t m = d[7] & 0x3F;
    if (m == 0x35) acMode = "auto";
    else if (m == 0x31) acMode = "cool";
    else if (m == 0x33) acMode = "dry";
    else if (m == 0x32) acMode = "fan_only";
    else if (m == 0x34) acMode = "heat";

    uint8_t f = d[8] & 0xF0;
    if (d[33] & 0x80) fanMode = "quiet";
    else if (d[7] & 0x80) fanMode = "diffuse";
    else if (f == 0x80) fanMode = "auto";
    else if (f == 0x90) fanMode = "low";
    else if (f == 0xA0) fanMode = "medium";
    else if (f == 0xC0) fanMode = "middle";
    else if (f == 0xD0) fanMode = "high";
    else if (f == 0xB0) fanMode = "focus";

    uint8_t sw = d[10] & 0x60;
    if (sw == 0x00) swingMode = "off";
    else if (sw == 0x20) swingMode = "horizontal";
    else if (sw == 0x40) swingMode = "vertical";
    else if (sw == 0x60) swingMode = "both";

    presetMode = "none";
    if (d[7] & 0x40) presetMode = "eco";
    else if (d[9] & 0x04) presetMode = "comfort";
    else if (d[19] & 0x01) presetMode = "sleep";
  }

  acOnline = true;
  publishState();
}

void processUart() {
  while (klimaSerial.available()) {
    uint8_t b = klimaSerial.read();
    rxBytes++;
    lastRxMs = millis();

    if (rxPos == 0) {
      if (b != 0xBB) {
        wrongBytes++;
        continue;
      }
      rxBuf[rxPos++] = b;
      expectedLen = 0;
      continue;
    }

    rxBuf[rxPos++] = b;

    if (rxPos == 5) {
      expectedLen = rxBuf[4] + 6; // Header 5 + payload length + checksum
      if (expectedLen > sizeof(rxBuf) || expectedLen < 8) {
        rxPos = 0;
        expectedLen = 0;
        checksumErrors++;
      }
    }

    if (expectedLen > 0 && rxPos >= expectedLen) {
      uint8_t crc = tclChecksum(rxBuf, expectedLen);
      lastRxFrame = bytesToHex(rxBuf, expectedLen);
      appendLog("RX " + lastRxFrame);
      rxFrames++;

      if (crc == rxBuf[expectedLen - 1]) {
        parseTclFrame(rxBuf, expectedLen);
      } else {
        checksumErrors++;
        lastError = "Checksum Fehler: erwartet " + byteHex(crc) + " bekommen " + byteHex(rxBuf[expectedLen - 1]);
      }

      rxPos = 0;
      expectedLen = 0;
    }

    if (rxPos >= sizeof(rxBuf)) {
      rxPos = 0;
      expectedLen = 0;
    }
  }

  // Timeout fuer halbe Frames
  if (rxPos > 0 && millis() - lastRxMs > 200) {
    rxPos = 0;
    expectedLen = 0;
  }
}


// ============================================================================
// Shelly HTTP Direktabfrage
// ============================================================================

String normalizeShellyHost(String v) {
  v.trim();
  v.replace("http://", "");
  v.replace("https://", "");
  int slash = v.indexOf('/');
  if (slash >= 0) v = v.substring(0, slash);
  return v;
}

float jsonFloatValue(const String& body, const String& key, float fallback = NAN) {
  String needle = "\"" + key + "\":";
  int p = body.indexOf(needle);
  if (p < 0) return fallback;
  p += needle.length();
  while (p < (int)body.length() && body[p] == ' ') p++;

  int e = p;
  while (e < (int)body.length()) {
    char c = body[e];
    if ((c >= '0' && c <= '9') || c == '-' || c == '+' || c == '.' || c == 'e' || c == 'E') {
      e++;
    } else {
      break;
    }
  }

  if (e <= p) return fallback;
  return body.substring(p, e).toFloat();
}

void pollShelly() {
  if (WiFi.status() != WL_CONNECTED) return;

  String host = normalizeShellyHost(shellyHost);
  if (host.length() < 7) {
    shellyOnline = false;
    shellyLastError = "Shelly IP fehlt";
    return;
  }

  HTTPClient http;
  String url = "http://" + host + "/rpc/Switch.GetStatus?id=0";
  http.setConnectTimeout(1200);
  http.setTimeout(1800);

  if (!http.begin(url)) {
    shellyOnline = false;
    shellyErrCount++;
    shellyLastError = "HTTP begin fehlgeschlagen";
    return;
  }

  int code = http.GET();
  if (code == 200) {
    String body = http.getString();
    float p = jsonFloatValue(body, "apower");
    float v = jsonFloatValue(body, "voltage");
    float c = jsonFloatValue(body, "current");

    if (!isnan(p)) shellyPowerW = p;
    if (!isnan(v)) shellyVoltageV = v;
    if (!isnan(c)) shellyCurrentA = c;

    shellyOnline = true;
    shellyOkCount++;
    shellyLastError = "-";
  } else {
    shellyOnline = false;
    shellyErrCount++;
    shellyLastError = "HTTP " + String(code);
  }

  http.end();
}

// ============================================================================
// MQTT / Home Assistant Discovery
// ============================================================================

String topic(const String& sub) {
  return String(MQTT_BASE) + "/" + sub;
}

void mqttPublish(const String& t, const String& payload, bool retained = true) {
  if (mqtt.connected()) mqtt.publish(t.c_str(), payload.c_str(), retained);
}

void publishState() {
  if (!mqtt.connected()) return;

  mqttPublish(topic("state/mode"), acMode);
  mqttPublish(topic("state/target_temperature"), String(targetTemp, 0));
  mqttPublish(topic("state/current_temperature"), isnan(currentTemp) ? String("") : String(currentTemp, 1));
  mqttPublish(topic("state/fan_mode"), fanMode);
  mqttPublish(topic("state/swing_mode"), swingMode);
  mqttPublish(topic("state/preset_mode"), presetMode);
  mqttPublish(topic("state/online"), acOnline ? "online" : "offline");

  mqttPublish(topic("diag/ip"), ipText());
  mqttPublish(topic("diag/rssi"), String(WiFi.RSSI()));
  mqttPublish(topic("diag/uptime"), String(millis() / 1000));
  mqttPublish(topic("diag/free_heap"), String(ESP.getFreeHeap()));
  mqttPublish(topic("diag/chip_temp"), String(chipTempC(), 1));
  mqttPublish(topic("diag/rx_bytes"), String(rxBytes));
  mqttPublish(topic("diag/tx_bytes"), String(txBytes));
  mqttPublish(topic("diag/rx_frames"), String(rxFrames));
  mqttPublish(topic("diag/tx_frames"), String(txFrames));
  mqttPublish(topic("diag/checksum_errors"), String(checksumErrors));
  mqttPublish(topic("diag/wrong_bytes"), String(wrongBytes));
  mqttPublish(topic("diag/last_error"), lastError);
  mqttPublish(topic("diag/firmware"), FW_VERSION);
  mqttPublish(topic("diag/last_command"), lastCommand);
  mqttPublish(topic("diag/wifi_reconnects"), String(wifiReconnects));
  mqttPublish(topic("diag/mqtt_reconnects"), String(mqttReconnects));

  mqttPublish(topic("shelly/power"), isnan(shellyPowerW) ? String("") : String(shellyPowerW, 1));
  mqttPublish(topic("shelly/voltage"), isnan(shellyVoltageV) ? String("") : String(shellyVoltageV, 1));
  mqttPublish(topic("shelly/current"), isnan(shellyCurrentA) ? String("") : String(shellyCurrentA, 3));
  mqttPublish(topic("shelly/online"), shellyOnline ? "online" : "offline");
  mqttPublish(topic("shelly/host"), shellyHost);
  mqttPublish(topic("shelly/last_error"), shellyLastError);
}

String deviceJson() {
  return String("{\"identifiers\":[\"") + DEVICE_ID + "\"],\"name\":\"" + DEVICE_NAME + "\",\"manufacturer\":\"Viesta/Hantech/TCL OEM\",\"model\":\"ESP32-S3 UART Gateway\",\"sw_version\":\"" + FW_VERSION + "\"}";
}

void publishDiscovery() {
  if (!mqtt.connected()) return;

  String dev = deviceJson();
  String base = MQTT_BASE;

  String climateConfig = "{";
  climateConfig += "\"name\":\"Viesta Klima\",";
  climateConfig += "\"unique_id\":\"viesta_klima_climate\",";
  climateConfig += "\"object_id\":\"viesta_klima\",";
  climateConfig += "\"modes\":[\"off\",\"auto\",\"cool\",\"heat\",\"dry\",\"fan_only\"],";
  climateConfig += "\"fan_modes\":[\"auto\",\"quiet\",\"low\",\"medium\",\"middle\",\"high\",\"focus\",\"diffuse\"],";
  climateConfig += "\"swing_modes\":[\"off\",\"vertical\",\"horizontal\",\"both\"],";
  climateConfig += "\"preset_modes\":[\"none\",\"eco\",\"sleep\",\"comfort\"],";
  climateConfig += "\"mode_state_topic\":\"" + base + "/state/mode\",";
  climateConfig += "\"mode_command_topic\":\"" + base + "/cmd/mode\",";
  climateConfig += "\"temperature_state_topic\":\"" + base + "/state/target_temperature\",";
  climateConfig += "\"temperature_command_topic\":\"" + base + "/cmd/target_temperature\",";
  climateConfig += "\"current_temperature_topic\":\"" + base + "/state/current_temperature\",";
  climateConfig += "\"fan_mode_state_topic\":\"" + base + "/state/fan_mode\",";
  climateConfig += "\"fan_mode_command_topic\":\"" + base + "/cmd/fan_mode\",";
  climateConfig += "\"swing_mode_state_topic\":\"" + base + "/state/swing_mode\",";
  climateConfig += "\"swing_mode_command_topic\":\"" + base + "/cmd/swing_mode\",";
  climateConfig += "\"preset_mode_state_topic\":\"" + base + "/state/preset_mode\",";
  climateConfig += "\"preset_mode_command_topic\":\"" + base + "/cmd/preset_mode\",";
  climateConfig += "\"min_temp\":16,\"max_temp\":31,\"temp_step\":1,\"precision\":1,";
  climateConfig += "\"availability_topic\":\"" + base + "/availability\",";
  climateConfig += "\"payload_available\":\"online\",\"payload_not_available\":\"offline\",";
  climateConfig += "\"device\":" + dev;
  climateConfig += "}";

  mqtt.publish((String(HA_DISCOVERY_PREFIX) + "/climate/viesta_klima/config").c_str(), climateConfig.c_str(), true);

  auto sensorConfig = [&](const String& id, const String& name, const String& st, const String& unit, const String& devClass, const String& stateClass) {
    String cfg = "{";
    cfg += "\"name\":\"" + name + "\",";
    cfg += "\"unique_id\":\"viesta_klima_" + id + "\",";
    cfg += "\"object_id\":\"viesta_klima_" + id + "\",";
    cfg += "\"state_topic\":\"" + base + "/" + st + "\",";
    if (unit.length()) cfg += "\"unit_of_measurement\":\"" + unit + "\",";
    if (devClass.length()) cfg += "\"device_class\":\"" + devClass + "\",";
    if (stateClass.length()) cfg += "\"state_class\":\"" + stateClass + "\",";
    cfg += "\"availability_topic\":\"" + base + "/availability\",";
    cfg += "\"device\":" + dev;
    cfg += "}";
    mqtt.publish((String(HA_DISCOVERY_PREFIX) + "/sensor/viesta_klima_" + id + "/config").c_str(), cfg.c_str(), true);
  };

  sensorConfig("esp_temperatur", "Viesta Klima ESP Temperatur", "diag/chip_temp", "°C", "temperature", "measurement");
  sensorConfig("wlan_signal", "Viesta Klima WLAN Signal", "diag/rssi", "dBm", "signal_strength", "measurement");
  sensorConfig("uptime", "Viesta Klima Uptime Sekunden", "diag/uptime", "s", "duration", "total_increasing");
  sensorConfig("free_heap", "Viesta Klima Freier Heap", "diag/free_heap", "B", "", "measurement");
  sensorConfig("rx_bytes", "Viesta Klima UART RX Bytes", "diag/rx_bytes", "B", "", "total_increasing");
  sensorConfig("tx_bytes", "Viesta Klima UART TX Bytes", "diag/tx_bytes", "B", "", "total_increasing");
  sensorConfig("rx_frames", "Viesta Klima UART RX Frames", "diag/rx_frames", "", "", "total_increasing");
  sensorConfig("tx_frames", "Viesta Klima UART TX Frames", "diag/tx_frames", "", "", "total_increasing");
  sensorConfig("checksum_errors", "Viesta Klima Checksum Fehler", "diag/checksum_errors", "", "", "total_increasing");
  sensorConfig("wrong_bytes", "Viesta Klima Wrong Bytes", "diag/wrong_bytes", "", "", "total_increasing");
  sensorConfig("wifi_reconnects", "Viesta Klima WLAN Reconnects", "diag/wifi_reconnects", "", "", "total_increasing");
  sensorConfig("mqtt_reconnects", "Viesta Klima MQTT Reconnects", "diag/mqtt_reconnects", "", "", "total_increasing");
  sensorConfig("shelly_power", "Viesta Klima Shelly Leistung", "shelly/power", "W", "power", "measurement");
  sensorConfig("shelly_voltage", "Viesta Klima Shelly Spannung", "shelly/voltage", "V", "voltage", "measurement");
  sensorConfig("shelly_current", "Viesta Klima Shelly Strom", "shelly/current", "A", "current", "measurement");

  auto textSensorConfig = [&](const String& id, const String& name, const String& st) {
    String cfg = "{";
    cfg += "\"name\":\"" + name + "\",";
    cfg += "\"unique_id\":\"viesta_klima_" + id + "\",";
    cfg += "\"object_id\":\"viesta_klima_" + id + "\",";
    cfg += "\"state_topic\":\"" + base + "/" + st + "\",";
    cfg += "\"availability_topic\":\"" + base + "/availability\",";
    cfg += "\"device\":" + dev;
    cfg += "}";
    mqtt.publish((String(HA_DISCOVERY_PREFIX) + "/sensor/viesta_klima_" + id + "/config").c_str(), cfg.c_str(), true);
  };
  textSensorConfig("ip", "Viesta Klima IP", "diag/ip");
  textSensorConfig("firmware", "Viesta Klima Firmware", "diag/firmware");
  textSensorConfig("last_command", "Viesta Klima Letzter Befehl", "diag/last_command");
  textSensorConfig("last_error", "Viesta Klima Letzter Fehler", "diag/last_error");
  textSensorConfig("shelly_host", "Viesta Klima Shelly IP", "shelly/host");
  textSensorConfig("shelly_online", "Viesta Klima Shelly Status", "shelly/online");
  textSensorConfig("shelly_error", "Viesta Klima Shelly Fehler", "shelly/last_error");

  String btn = "{\"name\":\"Viesta Klima Neustart\",\"unique_id\":\"viesta_klima_restart\",\"command_topic\":\"" + base + "/cmd/restart\",\"payload_press\":\"restart\",\"device\":" + dev + "}";
  mqtt.publish((String(HA_DISCOVERY_PREFIX) + "/button/viesta_klima_restart/config").c_str(), btn.c_str(), true);

  mqttPublish(topic("availability"), "online", true);
  publishState();
}

void mqttCallback(char* topicC, byte* payload, unsigned int length) {
  String t = String(topicC);
  String msg;
  for (unsigned int i = 0; i < length; i++) msg += (char)payload[i];
  msg.trim();
  msg.toLowerCase();

  bool changed = false;

  if (t.endsWith("/cmd/mode")) {
    if (msg == "off" || msg == "auto" || msg == "cool" || msg == "heat" || msg == "dry" || msg == "fan_only") {
      acMode = msg; changed = true; lastCommand = "MQTT mode=" + msg;
    }
  } else if (t.endsWith("/cmd/target_temperature")) {
    float v = msg.toFloat();
    if (v >= 16 && v <= 31) { targetTemp = round(v); changed = true; lastCommand = "MQTT temp=" + String(targetTemp,0); }
  } else if (t.endsWith("/cmd/fan_mode")) {
    if (msg == "auto" || msg == "quiet" || msg == "low" || msg == "medium" || msg == "middle" || msg == "high" || msg == "focus" || msg == "diffuse") {
      fanMode = msg; changed = true; lastCommand = "MQTT fan=" + msg;
    }
  } else if (t.endsWith("/cmd/swing_mode")) {
    if (msg == "off" || msg == "vertical" || msg == "horizontal" || msg == "both") {
      swingMode = msg; changed = true; lastCommand = "MQTT swing=" + msg;
    }
  } else if (t.endsWith("/cmd/preset_mode")) {
    if (msg == "none" || msg == "eco" || msg == "sleep" || msg == "comfort") {
      presetMode = msg; changed = true; lastCommand = "MQTT preset=" + msg;
    }
  } else if (t.endsWith("/cmd/restart")) {
    ESP.restart();
  } else if (t.endsWith("/cmd/raw")) {
    // Optional: Raw Hex direkt senden, z.B. BB 00 ...
    // bewusst minimal gehalten; Web UI ist dafuer komfortabler
  }

  if (changed) {
    sendControl();
    publishState();
  }
}

bool connectMqtt() {
  if (WiFi.status() != WL_CONNECTED) return false;
  if (mqtt.connected()) return true;

  mqtt.setServer(MQTT_HOST, MQTT_PORT);
  mqtt.setCallback(mqttCallback);
  mqtt.setBufferSize(4096);

  String clientId = String("viesta-klima-") + String((uint32_t)ESP.getEfuseMac(), HEX);
  bool ok;
  if (strlen(MQTT_USER) > 0) {
    ok = mqtt.connect(clientId.c_str(), MQTT_USER, MQTT_PASS, topic("availability").c_str(), 0, true, "offline");
  } else {
    ok = mqtt.connect(clientId.c_str(), topic("availability").c_str(), 0, true, "offline");
  }

  if (ok) {
    mqttReconnects++;
    mqtt.subscribe(topic("cmd/#").c_str());
    publishDiscovery();
    mqttPublish(topic("availability"), "online", true);
    appendLog("MQTT verbunden");
  } else {
    lastError = "MQTT connect failed rc=" + String(mqtt.state());
  }
  return ok;
}

// ============================================================================
// WLAN / OTA
// ============================================================================

void startWiFi() {
  WiFi.mode(WIFI_STA);
  WiFi.setHostname("viesta-klima");
  WiFi.begin(WIFI_SSID, WIFI_PASS);

  unsigned long start = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - start < 15000) {
    delay(250);
  }

  if (WiFi.status() != WL_CONNECTED) {
    WiFi.mode(WIFI_AP_STA);
    WiFi.softAP(AP_SSID, AP_PASS);
    lastError = "WLAN nicht verbunden, Fallback AP aktiv";
  }
}

void setupOTA() {
  ArduinoOTA.setHostname(OTA_HOST);
  ArduinoOTA.setPassword(OTA_PASS);
  ArduinoOTA.onStart([]() { appendLog("OTA Start"); });
  ArduinoOTA.onEnd([]() { appendLog("OTA Ende"); });
  ArduinoOTA.onError([](ota_error_t error) { lastError = "OTA Fehler " + String((int)error); });
  ArduinoOTA.begin();
}

// ============================================================================
// Webserver
// ============================================================================

String option(const String& value, const String& current, const String& label) {
  return "<option value='" + value + "'" + (value == current ? " selected" : "") + ">" + label + "</option>";
}

void handleRoot() {
  String html = "<!doctype html><html><head><meta charset='utf-8'><meta name='viewport' content='width=device-width,initial-scale=1'>";
  html += "<title>Viesta Klima Gateway</title><style>";
  html += ":root{--bg:#080b0f;--card:#151b23;--card2:#10161d;--line:#29313d;--txt:#edf6ff;--muted:#93a4b7;--cyan:#4ddcff;--green:#62ff9b;--yellow:#ffe66d;--red:#ff6b6b;--blue:#4da3ff}";
  html += "*{box-sizing:border-box}body{background:radial-gradient(circle at 25% 0%,#162331 0,#080b0f 44%,#05070a 100%);color:var(--txt);font-family:Arial,Helvetica,sans-serif;margin:0;padding:14px}h1{margin:0 0 10px;font-size:clamp(21px,5vw,28px);color:var(--cyan)}h2{margin:0 0 12px;font-size:18px;color:#dff8ff}.sub{color:var(--muted);font-size:12px}.shell{display:grid;grid-template-columns:minmax(0,1fr) 330px;gap:14px;align-items:start}.mainGrid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.side{display:flex;flex-direction:column;gap:10px;position:sticky;top:10px}.card,details{background:linear-gradient(180deg,var(--card),var(--card2));border:1px solid var(--line);border-radius:18px;padding:15px;box-shadow:0 8px 28px #0009}.wide{grid-column:1/-1}.ok{color:var(--green)}.bad{color:var(--red)}label{display:block;margin-top:9px;color:var(--muted);font-size:13px}input,select,button{width:100%;box-sizing:border-box;padding:10px;margin-top:5px;border-radius:12px;border:1px solid #3a4655;background:#202832;color:#fff;font-size:15px}button{cursor:pointer;background:linear-gradient(180deg,#087ea1,#055d78);border:0;font-weight:bold}.row{display:grid;grid-template-columns:1fr 1fr;gap:8px}.pill{display:inline-block;padding:5px 9px;border-radius:999px;background:#223040;border:1px solid #35465a;margin:3px;color:#d7ecff;font-size:12px}.gaugeWrap{display:flex;justify-content:center;align-items:center;padding:4px 0}.gauge{width:min(210px,70vw);height:min(210px,70vw);border-radius:50%;background:conic-gradient(var(--cyan) 0deg, var(--cyan) calc((var(--temp) - 16) * 24deg), #27313d 0deg);display:flex;align-items:center;justify-content:center;box-shadow:inset 0 0 24px #000b,0 0 28px #00d9ff22}.gaugeInner{width:75%;height:75%;border-radius:50%;background:#10161d;display:flex;flex-direction:column;align-items:center;justify-content:center;border:1px solid #2b3a49}.tempBig{font-size:42px;font-weight:800;color:#fff}.tempUnit{color:var(--muted);font-size:13px}.quick button{min-height:42px}.log{font-family:Consolas,monospace;white-space:pre-wrap;word-break:break-word;background:#050708;padding:10px;border-radius:10px;max-height:300px;overflow:auto;color:#00e6ff;font-size:12px}table{width:100%;border-collapse:collapse}td{border-bottom:1px solid #28313d;padding:6px 4px;vertical-align:top}td:first-child{color:var(--muted)}.small{font-size:12px;color:var(--muted)}input[type=range]{accent-color:var(--cyan);padding:0;border:0;background:transparent}summary{cursor:pointer;color:#dff8ff;font-weight:700;font-size:16px;list-style:none}summary::-webkit-details-marker{display:none}summary:after{content:'+';float:right;color:var(--cyan);font-size:20px;line-height:16px}details[open] summary:after{content:'–'}.mini{font-size:12px;color:var(--muted);margin-top:4px}.compact table td{font-size:13px;padding:5px 3px}.topbar{display:flex;justify-content:space-between;align-items:flex-start;gap:10px;flex-wrap:wrap}.badge{border:1px solid #35465a;background:#172231;border-radius:999px;padding:6px 10px;color:#d7ecff;font-size:12px}";
  html += "@media(max-width:900px){.shell{grid-template-columns:1fr}.side{position:static;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.mainGrid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:560px){body{padding:10px}.mainGrid,.side{grid-template-columns:repeat(2,minmax(0,1fr));gap:9px}.card,details{border-radius:14px;padding:11px}h2{font-size:15px}.tempBig{font-size:34px}input,select,button{font-size:14px;padding:9px}.row{grid-template-columns:1fr}.wide{grid-column:1/-1}.log{max-height:220px;font-size:11px}}";
  html += R"rawliteral(
/* ---- v2.6 Mobile UI Optimierung ---- */
.action-grid,.mode-grid,.fan-grid,.swing-grid,.preset-grid,.button-grid{
  display:grid !important;
  grid-template-columns:repeat(2,minmax(0,1fr)) !important;
  gap:12px !important;
}
.action-grid .btn,.mode-grid .btn,.fan-grid .btn,.swing-grid .btn,
.preset-grid .btn,.button-grid .btn,button.btn,a.btn{
  width:auto !important;
  min-width:0 !important;
  padding:14px 12px !important;
  min-height:54px !important;
  font-size:1.02rem !important;
  border-radius:18px !important;
}
.temp-card,.temperature-card,.controls-card,.klima-card{
  width:100% !important;
  max-width:430px !important;
}
.temp-actions{
  display:grid !important;
  grid-template-columns:repeat(2,minmax(0,1fr)) !important;
  gap:12px !important;
}
details:not([open]) > *:not(summary){
  display:none !important;
}
@media (max-width:760px){
  body{
    padding-left:10px !important;
    padding-right:10px !important;
  }
  .card,
  .temp-card,
  .temperature-card,
  .controls-card,
  .klima-card{
    width:calc(100vw - 28px) !important;
    max-width:430px !important;
    margin-left:auto !important;
    margin-right:auto !important;
    padding:18px !important;
  }
  .action-grid,
  .mode-grid,
  .fan-grid,
  .swing-grid,
  .preset-grid,
  .button-grid{
    grid-template-columns:repeat(2,minmax(0,1fr)) !important;
    gap:10px !important;
  }
  button.btn,
  a.btn{
    padding:13px 8px !important;
    min-height:52px !important;
    font-size:0.98rem !important;
  }
}

/* ---- v2.8.2-mobile-compact-buttons Desktop/Mobil Layout: Shelly-Gauge oben neben Temperatur ---- */
.mainGrid{display:grid !important;grid-template-columns:minmax(330px,430px) minmax(330px,430px) !important;gap:14px !important;align-items:start !important}
.wide{grid-column:1/-1 !important}
.mainGrid>.card{max-width:430px !important;width:100% !important}
.mainGrid>.card.wide{max-width:874px !important;width:100% !important}
.shellyStats{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;margin-top:10px}
.shellyStats .pill{display:block;text-align:center;margin:0;padding:7px 8px}
@media(max-width:900px){.mainGrid{grid-template-columns:1fr !important}.mainGrid>.card,.mainGrid>.card.wide{max-width:430px !important;width:calc(100vw - 28px) !important;margin-left:auto !important;margin-right:auto !important}.wide{grid-column:auto !important}}
@media(max-width:560px){.shellyStats{grid-template-columns:repeat(2,minmax(0,1fr))}.quick button{min-height:46px}}


.mode-grid .btn,
.fan-grid .btn,
.swing-grid .btn,
.button-grid .btn{
width:auto !important;
min-height:48px !important;
padding:10px 8px !important;
font-size:.95rem !important;
border-radius:16px !important;
display:flex !important;
align-items:center !important;
justify-content:center !important;
text-align:center !important;
}

@media (max-width:760px){
.mode-grid,
.fan-grid,
.swing-grid,
.button-grid{
display:grid !important;
grid-template-columns:repeat(2,minmax(0,1fr)) !important;
gap:10px !important;
}

.mode-grid .btn,
.fan-grid .btn,
.swing-grid .btn,
.button-grid .btn{
min-height:50px !important;
padding:10px 6px !important;
font-size:.92rem !important;
}
}

</style></head><body>
)rawliteral";
  html += "<div class='topbar'><h1>Viesta Klima Gateway <span class='sub'>" + String(FW_VERSION) + "</span></h1><div class='badge' id='topBadge'>IP " + ipText() + " · " + rssiText() + "</div></div>";
  html += "<div class='shell'><main class='mainGrid'>";

  int tempInt = (int)round(targetTemp);
  html += "<div class='card'><h2>Temperatur</h2><div class='gaugeWrap'><div class='gauge' id='gauge' style='--temp:" + String(tempInt) + "'><div class='gaugeInner'><div class='tempBig' id='tempBig'>" + String(tempInt) + "°</div><div class='tempUnit'>Solltemperatur</div></div></div></div>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='temp_delta' value='-1'><button type='submit'>− 1 °C</button></form><form action='/quick'><input type='hidden' name='temp_delta' value='1'><button type='submit'>+ 1 °C</button></form></div>";
  html += "<div class='small'>Schieberegler entfernt. Temperatur wird jetzt nur noch über Plus/Minus geändert.</div></div>";

  html += "<div class='card'><h2>Leistung Shelly</h2><div class='gaugeWrap'><div class='gauge' id='shellyGauge' style='--temp:24'><div class='gaugeInner'><div class='tempBig'><span id='shellyPower'>" + (isnan(shellyPowerW) ? String("-") : String(shellyPowerW,0)) + "</span></div><div class='tempUnit'>Watt aktuell</div></div></div></div>";
  html += "<div class='shellyStats'><span class='pill'>Status: <span id='shellyOnline' class='" + String(shellyOnline ? "ok" : "bad") + "'>" + String(shellyOnline ? "online" : "offline") + "</span></span><span class='pill'>IP: <span id='shellyHost'>" + htmlEscape(shellyHost) + "</span></span><span class='pill'>Spannung: <span id='shellyVoltage'>" + (isnan(shellyVoltageV) ? String("-") : String(shellyVoltageV,1)) + "</span> V</span><span class='pill'>Strom: <span id='shellyCurrent'>" + (isnan(shellyCurrentA) ? String("-") : String(shellyCurrentA,3)) + "</span> A</span></div>";
  html += "<form method='get' action='/shelly'><label>Shelly IP frei konfigurieren</label><input name='host' value='" + htmlEscape(shellyHost) + "' placeholder='192.168.178.79'><button type='submit'>Shelly IP speichern</button></form></div>";

  html += "<div class='card wide'><h2>Klima Bedienung</h2>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='mode' value='off'><button>Aus</button></form><form action='/quick'><input type='hidden' name='mode' value='cool'><button>Kühlen</button></form></div>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='mode' value='heat'><button>Heizen</button></form><form action='/quick'><input type='hidden' name='mode' value='dry'><button>Dry</button></form></div>";
  html += "<h2 style='margin-top:14px'>Lüfter direkt</h2>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='fan' value='quiet'><button>Leise</button></form><form action='/quick'><input type='hidden' name='fan' value='low'><button>Niedrig</button></form></div>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='fan' value='medium'><button>Mittel</button></form><form action='/quick'><input type='hidden' name='fan' value='high'><button>Hoch</button></form></div>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='fan' value='auto'><button>Lüfter Auto</button></form><form action='/quick'><input type='hidden' name='fan' value='diffuse'><button>Diffuse</button></form></div>";
  html += "<h2 style='margin-top:14px'>Lamellen direkt</h2>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='swing' value='vertical'><button>Vertikal AN</button></form><form action='/quick'><input type='hidden' name='swing' value='off'><button>Vertikal AUS</button></form></div>";
  html += "<div class='row quick'><form action='/quick'><input type='hidden' name='swing' value='horizontal'><button>Horizontal AN</button></form><form action='/quick'><input type='hidden' name='swing' value='off'><button>Horizontal AUS</button></form></div>";
  html += "<details class='compact'><summary>Erweiterte Einstellungen</summary>";
  html += "<form method='get' action='/set'>";
  html += "<label>Modus</label><select name='mode'>";
  html += option("off", acMode, "Aus") + option("auto", acMode, "Auto") + option("cool", acMode, "Kühlen") + option("heat", acMode, "Heizen") + option("dry", acMode, "Entfeuchten / Dry") + option("fan_only", acMode, "Nur Lüfter") + "</select>";
  html += "<label>Temperatur</label><input type='number' min='16' max='31' step='1' name='temp' value='" + String(targetTemp,0) + "'>";
  html += "<label>Lüfter</label><select name='fan'>";
  html += option("auto", fanMode, "Auto") + option("quiet", fanMode, "Leise") + option("low", fanMode, "Niedrig") + option("medium", fanMode, "Mittel") + option("middle", fanMode, "Mittel 2") + option("high", fanMode, "Hoch") + option("focus", fanMode, "Focus") + option("diffuse", fanMode, "Diffuse") + "</select>";
  html += "<label>Lamellen / Swing</label><select name='swing'>";
  html += option("off", swingMode, "Aus") + option("vertical", swingMode, "Vertikal") + option("horizontal", swingMode, "Horizontal") + option("both", swingMode, "Beide") + "</select>";
  html += "<label>Preset</label><select name='preset'>";
  html += option("none", presetMode, "Kein") + option("eco", presetMode, "Eco") + option("sleep", presetMode, "Sleep") + option("comfort", presetMode, "Comfort") + "</select>";
  html += "<button type='submit'>Alle Werte senden</button></form></details></div>";

  

  html += "<details class='wide'><summary>UART Log</summary><div class='mini'>Live-Auszug der seriellen Kommunikation. Live-Aktualisierung ohne Seitenreload alle 3 s.</div><div class='log' id='uartLog'>" + htmlEscape(uartLog) + "</div></details>";
  html += "</main><aside class='side'>";

  html += "<details class='compact'><summary>Status</summary><p>";
  html += "<span class='pill'>Mode: <span id='stMode'>" + acMode + "</span></span><span class='pill'>Fan: <span id='stFan'>" + fanMode + "</span></span><span class='pill'>Swing: <span id='stSwing'>" + swingMode + "</span></span><span class='pill'>Preset: <span id='stPreset'>" + presetMode + "</span></span></p><table>";
  html += "<tr><td>Soll</td><td><span id='stTarget'>" + String(targetTemp,0) + "</span> °C</td></tr>";
  html += "<tr><td>Ist</td><td><span id='stCurrent'>" + (isnan(currentTemp) ? String("-") : String(currentTemp,1)) + "</span> °C</td></tr>";
  html += "<tr><td>AC Online</td><td><span id='stOnline' class='" + String(acOnline ? "ok" : "bad") + "'>" + String(acOnline ? "ja" : "nein") + "</span></td></tr>";
  html += "<tr><td>Letzter Befehl</td><td><span id='stCommand'>" + htmlEscape(lastCommand) + "</span></td></tr>";
  html += "</table></details>";

  html += "<details class='compact'><summary>ESP Diagnose</summary><table>";
  html += "<tr><td>Firmware</td><td>" + String(FW_VERSION) + "</td></tr>";
  html += "<tr><td>IP</td><td><span id='diagIp'>" + ipText() + "</span></td></tr>";
  html += "<tr><td>MAC</td><td>" + WiFi.macAddress() + "</td></tr>";
  html += "<tr><td>WLAN</td><td>" + String(WiFi.status() == WL_CONNECTED ? "<span class='ok'>verbunden</span>" : "<span class='bad'>nicht verbunden</span>") + "</td></tr>";
  html += "<tr><td>RSSI</td><td><span id='diagRssi'>" + rssiText() + "</span></td></tr>";
  html += "<tr><td>Uptime</td><td><span id='diagUptime'>" + uptimeText() + "</span></td></tr>";
  html += "<tr><td>Heap frei</td><td><span id='diagHeap'>" + String(ESP.getFreeHeap()) + "</span> B</td></tr>";
  html += "<tr><td>ESP Temp</td><td><span id='diagTemp'>" + String(chipTempC(),1) + "</span> °C</td></tr>";
  html += "<tr><td>MQTT</td><td><span id='diagMqtt' class='" + String(mqtt.connected() ? "ok" : "bad") + "'>" + String(mqtt.connected() ? "verbunden" : "getrennt") + "</span></td></tr>";
  html += "<tr><td>Shelly Leistung</td><td><span id='diagShellyPower'>" + (isnan(shellyPowerW) ? String("-") : String(shellyPowerW,1)) + "</span> W</td></tr>";
  html += "<tr><td>Shelly Spannung</td><td><span id='diagShellyVoltage'>" + (isnan(shellyVoltageV) ? String("-") : String(shellyVoltageV,1)) + "</span> V</td></tr>";
  html += "<tr><td>Shelly Strom</td><td><span id='diagShellyCurrent'>" + (isnan(shellyCurrentA) ? String("-") : String(shellyCurrentA,3)) + "</span> A</td></tr>";
  html += "</table><div class='row'><form action='/restart'><button>Neustart</button></form><form action='/clearlog'><button>Log löschen</button></form></div></details>";

  html += "<details class='compact'><summary>UART</summary><table>";
  html += "<tr><td>RX Bytes</td><td><span id='uartrxBytes'>" + String(rxBytes) + "</span></td></tr>";
  html += "<tr><td>TX Bytes</td><td><span id='uarttxBytes'>" + String(txBytes) + "</span></td></tr>";
  html += "<tr><td>RX Frames</td><td><span id='uartrxFrames'>" + String(rxFrames) + "</span></td></tr>";
  html += "<tr><td>TX Frames</td><td><span id='uarttxFrames'>" + String(txFrames) + "</span></td></tr>";
  html += "<tr><td>Checksum</td><td><span id='uartchecksumErrors'>" + String(checksumErrors) + "</span></td></tr>";
  html += "<tr><td>Wrong Bytes</td><td><span id='uartwrongBytes'>" + String(wrongBytes) + "</span></td></tr>";
  html += "<tr><td>Letzter Fehler</td><td><span id='uartLastError'>" + htmlEscape(lastError) + "</span></td></tr>";
  html += "</table></details>";

  html += "</aside></div><p class='small'>MQTT Climate: Modi off/auto/cool/heat/dry/fan_only · Fan auto/quiet/low/medium/middle/high/focus/diffuse · Swing off/vertical/horizontal/both · Preset none/eco/sleep/comfort</p>";
  html += R"rawliteral(<script>
function setText(id,val){const e=document.getElementById(id);if(e&&val!==undefined&&val!==null)e.textContent=val;}
function setClass(id,ok){const e=document.getElementById(id);if(e){e.className=ok?'ok':'bad';}}
async function refreshState(){try{const r=await fetch('/state.json?ts='+Date.now(),{cache:'no-store'});const s=await r.json();
setText('topBadge','IP '+s.ip+' · '+s.rssi);
setText('tempBig',s.target+'°');const g=document.getElementById('gauge');if(g)g.style.setProperty('--temp',s.target);
setText('stTarget',s.target);setText('stCurrent',s.current===null?'-':s.current);
setText('stMode',s.mode);setText('stFan',s.fan);setText('stSwing',s.swing);setText('stPreset',s.preset);
setText('stOnline',s.online?'ja':'nein');setClass('stOnline',s.online);setText('stCommand',s.command);
setText('diagIp',s.ip);setText('diagRssi',s.rssi);setText('diagUptime',s.uptime);setText('diagHeap',s.heap);setText('diagTemp',s.chip_temp);
setText('diagMqtt',s.mqtt?'verbunden':'getrennt');setClass('diagMqtt',s.mqtt);
setText('shellyPower',s.shelly_power===null?'-':Math.round(s.shelly_power));const sg=document.getElementById('shellyGauge');if(sg&&s.shelly_power!==null){sg.style.setProperty('--temp',Math.max(16,Math.min(31,16+(s.shelly_power/2000*15))));}setText('shellyVoltage',s.shelly_voltage===null?'-':s.shelly_voltage);setText('shellyCurrent',s.shelly_current===null?'-':s.shelly_current);setText('shellyOnline',s.shelly_online?'online':'offline');setClass('shellyOnline',s.shelly_online);setText('shellyHost',s.shelly_host);setText('diagShellyPower',s.shelly_power===null?'-':s.shelly_power);setText('diagShellyVoltage',s.shelly_voltage===null?'-':s.shelly_voltage);setText('diagShellyCurrent',s.shelly_current===null?'-':s.shelly_current);
setText('uartrxBytes',s.rx_bytes);setText('uarttxBytes',s.tx_bytes);setText('uartrxFrames',s.rx_frames);setText('uarttxFrames',s.tx_frames);setText('uartchecksumErrors',s.checksum_errors);setText('uartwrongBytes',s.wrong_bytes);setText('uartLastError',s.last_error);
const log=document.getElementById('uartLog');if(log){const nearBottom=(log.scrollTop+log.clientHeight+20)>=log.scrollHeight;log.textContent=s.log;if(nearBottom)log.scrollTop=log.scrollHeight;}
}catch(e){console.log(e);}}
setInterval(refreshState,3000);setTimeout(refreshState,700);
</script>)rawliteral";
  html += "</body></html>";
  server.send(200, "text/html", html);
}

void handleSet() {
  if (server.hasArg("mode")) acMode = server.arg("mode");
  if (server.hasArg("temp")) targetTemp = constrain(server.arg("temp").toFloat(), 16.0f, 31.0f);
  if (server.hasArg("fan")) fanMode = server.arg("fan");
  if (server.hasArg("swing")) swingMode = server.arg("swing");
  if (server.hasArg("preset")) presetMode = server.arg("preset");
  lastCommand = "WEB set";
  sendControl();
  publishState();
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleQuick() {
  if (server.hasArg("mode")) acMode = server.arg("mode");
  if (server.hasArg("fan")) fanMode = server.arg("fan");
  if (server.hasArg("swing")) swingMode = server.arg("swing");
  if (server.hasArg("preset")) presetMode = server.arg("preset");
  if (server.hasArg("temp")) targetTemp = constrain(server.arg("temp").toFloat(), 16.0f, 31.0f);
  if (server.hasArg("temp_delta")) targetTemp = constrain(targetTemp + server.arg("temp_delta").toFloat(), 16.0f, 31.0f);
  lastCommand = "WEB quick";
  sendControl();
  publishState();
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleShellyConfig() {
  if (server.hasArg("host")) {
    String h = normalizeShellyHost(server.arg("host"));
    if (h.length() >= 7) {
      shellyHost = h;
      prefs.putString("shelly", shellyHost);
      lastCommand = "WEB Shelly IP=" + shellyHost;
      pollShelly();
      publishState();
    }
  }
  server.sendHeader("Location", "/");
  server.send(303);
}

void setupWeb() {
  server.on("/", handleRoot);
  server.on("/set", handleSet);
  server.on("/quick", handleQuick);
  server.on("/shelly", handleShellyConfig);
  server.on("/restart", []() { server.send(200, "text/plain", "restart"); delay(300); ESP.restart(); });
  server.on("/clearlog", []() { uartLog = ""; server.sendHeader("Location", "/"); server.send(303); });
  server.on("/state.json", []() {
    String logTail = uartLog;
    if (logTail.length() > 6000) logTail = logTail.substring(logTail.length() - 6000);
    String js = "{";
    js += "\"mode\":\"" + jsonEscape(acMode) + "\",";
    js += "\"target\":" + String(targetTemp,0) + ",";
    js += "\"current\":" + (isnan(currentTemp) ? String("null") : String(currentTemp,1)) + ",";
    js += "\"fan\":\"" + jsonEscape(fanMode) + "\",";
    js += "\"swing\":\"" + jsonEscape(swingMode) + "\",";
    js += "\"preset\":\"" + jsonEscape(presetMode) + "\",";
    js += "\"online\":" + String(acOnline ? "true" : "false") + ",";
    js += "\"command\":\"" + jsonEscape(lastCommand) + "\",";
    js += "\"ip\":\"" + jsonEscape(ipText()) + "\",";
    js += "\"rssi\":\"" + jsonEscape(rssiText()) + "\",";
    js += "\"uptime\":\"" + jsonEscape(uptimeText()) + "\",";
    js += "\"heap\":" + String(ESP.getFreeHeap()) + ",";
    js += "\"chip_temp\":" + String(chipTempC(),1) + ",";
    js += "\"mqtt\":" + String(mqtt.connected() ? "true" : "false") + ",";
    js += "\"rx_bytes\":" + String(rxBytes) + ",";
    js += "\"tx_bytes\":" + String(txBytes) + ",";
    js += "\"rx_frames\":" + String(rxFrames) + ",";
    js += "\"tx_frames\":" + String(txFrames) + ",";
    js += "\"checksum_errors\":" + String(checksumErrors) + ",";
    js += "\"wrong_bytes\":" + String(wrongBytes) + ",";
    js += "\"last_error\":\"" + jsonEscape(lastError) + "\",";
    js += "\"fw\":\"" + String(FW_VERSION) + "\",";
    js += "\"shelly_power\":" + (isnan(shellyPowerW) ? String("null") : String(shellyPowerW,1)) + ",";
    js += "\"shelly_voltage\":" + (isnan(shellyVoltageV) ? String("null") : String(shellyVoltageV,1)) + ",";
    js += "\"shelly_current\":" + (isnan(shellyCurrentA) ? String("null") : String(shellyCurrentA,3)) + ",";
    js += "\"shelly_online\":" + String(shellyOnline ? "true" : "false") + ",";
    js += "\"shelly_host\":\"" + jsonEscape(shellyHost) + "\",";
    js += "\"shelly_error\":\"" + jsonEscape(shellyLastError) + "\",";
    js += "\"log\":\"" + jsonEscape(logTail) + "\"";
    js += "}";
    server.send(200, "application/json", js);
  });
  server.begin();
}

// ============================================================================
// Setup / Loop
// ============================================================================

void setup() {
  Serial.begin(115200);
  delay(300);
  bootMs = millis();

  prefs.begin("viesta-ac", false);
  loadState();

  klimaSerial.begin(KLIMA_BAUD, KLIMA_CONFIG, KLIMA_RX_PIN, KLIMA_TX_PIN);

  startWiFi();
  setupOTA();
  setupWeb();

  mqtt.setServer(MQTT_HOST, MQTT_PORT);
  mqtt.setCallback(mqttCallback);
  mqtt.setBufferSize(4096);

  appendLog(String("BOOT ") + FW_VERSION);
  appendLog("IP " + ipText());

  connectMqtt();
  pollShelly();
  publishState();
  sendPoll();
}

void loop() {
  ArduinoOTA.handle();
  server.handleClient();
  processUart();

  unsigned long now = millis();

  if (now - lastWifiCheckMs > WIFI_RETRY_MS) {
    lastWifiCheckMs = now;
    if (WiFi.status() != WL_CONNECTED) {
      wifiReconnects++;
      WiFi.disconnect(false);
      WiFi.begin(WIFI_SSID, WIFI_PASS);
    }
  }

  if (WiFi.status() == WL_CONNECTED) {
    if (!mqtt.connected() && now - lastMqttCheckMs > MQTT_RETRY_MS) {
      lastMqttCheckMs = now;
      connectMqtt();
    }
    if (mqtt.connected()) mqtt.loop();
  }

  if (now - lastPollMs > POLL_INTERVAL_MS) {
    lastPollMs = now;
    sendPoll();
  }

  if (now - lastShellyPollMs > SHELLY_POLL_MS) {
    lastShellyPollMs = now;
    pollShelly();
  }

  if (now - lastStatePublishMs > STATE_PUBLISH_MS) {
    lastStatePublishMs = now;
    // Wichtig: State zyklisch publishen, damit Home Assistant die Steuerung nicht verliert
    if (isnan(targetTemp) || targetTemp < 16 || targetTemp > 31) targetTemp = 24;
    publishState();
  }

  if (mqtt.connected() && now - lastDiscoveryMs > DISCOVERY_REFRESH_MS) {
    lastDiscoveryMs = now;
    publishDiscovery();
  }
}