/**
 * CYD ESP32-2432S028R — LVGL SGP30 空气质量仪表盘
 * SGP30 SDA -> GPIO22, SCL -> GPIO27
 */

#include <Arduino.h>
#include <Wire.h>
#include <lvgl.h>
#include <TFT_eSPI.h>
#include <XPT2046_Touchscreen.h>
#include <Adafruit_SGP30.h>
#include <math.h>

#define I2C_SDA 22
#define I2C_SCL 27
#if defined(CYD_BOARD_3248S035)
#define TFT_BL_PIN 27
#else
#define TFT_BL_PIN 21
#endif

#define XPT2046_IRQ 36
#define XPT2046_MOSI 32
#define XPT2046_MISO 39
#define XPT2046_CLK 25
#define XPT2046_CS 33

#if defined(CYD_BOARD_3248S035)
#define SCREEN_WIDTH 480
#define SCREEN_HEIGHT 320
#else
#define SCREEN_WIDTH 320
#define SCREEN_HEIGHT 240
#endif
#define SGP_READ_MS 1000
#define SGP_FAIL_TOLERANCE 3
#define EMA_ALPHA 0.35f
#define HISTORY_LEN 48
#define WARMUP_SEC 15
#define DRAW_BUF_SIZE (SCREEN_WIDTH * SCREEN_HEIGHT / 10 * (LV_COLOR_DEPTH / 8))

/* Gauge display clamps (arc range) */
#define ECO2_ARC_MAX 2000
#define TVOC_ARC_MAX 1000

/* Layout grid — every region has exclusive space, no overlaps */
#if defined(CYD_BOARD_3248S035)
#define UI_M 10
#define UI_G 10
#define UI_HDR_H 32
#define UI_GAUGE_H 168
#define UI_GAUGE_W 225
#define UI_ARC 120
#else
#define UI_M 6
#define UI_G 6
#define UI_HDR_H 22
#define UI_GAUGE_H 124
#define UI_GAUGE_W 151
#define UI_ARC 90
#endif
#define UI_BOT_Y (UI_HDR_H + UI_G + UI_GAUGE_H + UI_G) /* 158 */
#define UI_BOT_H (SCREEN_HEIGHT - UI_BOT_Y - UI_M)      /* 76 */
#define UI_BOT_W (SCREEN_WIDTH - 2 * UI_M)              /* 308 */
#if defined(CYD_BOARD_3248S035)
#define UI_INFO_W 180
#else
#define UI_INFO_W 124
#endif
#define UI_CHART_W (UI_BOT_W - 12 - UI_INFO_W - UI_G)   /* ~160 */

static const lv_color_t COL_BG = lv_color_hex(0x0A1018);
static const lv_color_t COL_PANEL = lv_color_hex(0x121C2A);
static const lv_color_t COL_EDGE = lv_color_hex(0x1E2C40);
static const lv_color_t COL_TEXT = lv_color_hex(0xF2F5FA);
static const lv_color_t COL_MUTED = lv_color_hex(0x7E90A8);
static const lv_color_t COL_ECO2 = lv_color_hex(0x4DA3FF);
static const lv_color_t COL_TVOC = lv_color_hex(0xB07CFF);
static const lv_color_t COL_OK = lv_color_hex(0x4CAF7A);
static const lv_color_t COL_WARN = lv_color_hex(0xE6B84D);
static const lv_color_t COL_BAD = lv_color_hex(0xE05A5A);
static const lv_color_t COL_ARC_BG = lv_color_hex(0x243247);
static const lv_color_t COL_CHART_BG = lv_color_hex(0x0E1622);

SPIClass touchscreenSPI = SPIClass(VSPI);
XPT2046_Touchscreen touchscreen(XPT2046_CS, XPT2046_IRQ);
Adafruit_SGP30 sgp;

static uint32_t draw_buf[DRAW_BUF_SIZE / 4];

static lv_obj_t *arc_eco2;
static lv_obj_t *arc_tvoc;
static lv_obj_t *lbl_eco2_val;
static lv_obj_t *lbl_tvoc_val;
static lv_obj_t *lbl_eco2_range;
static lv_obj_t *lbl_tvoc_range;
static lv_obj_t *lbl_aqi;
static lv_obj_t *lbl_eco2_lvl;
static lv_obj_t *lbl_tvoc_lvl;
static lv_obj_t *lbl_status;
static lv_obj_t *lbl_uptime;
static lv_obj_t *lbl_hint;
static lv_obj_t *led_status;
static lv_obj_t *bar_aqi;
static lv_obj_t *chart;
static lv_chart_series_t *ser_eco2;
static lv_chart_series_t *ser_tvoc;

static float disp_eco2 = NAN;
static float disp_tvoc = NAN;
static float min_eco2 = NAN;
static float max_eco2 = NAN;
static float min_tvoc = NAN;
static float max_tvoc = NAN;
static uint32_t last_sgp_ms = 0;
static uint32_t last_ok_ms = 0;
static uint32_t boot_ms = 0;
static uint8_t fail_streak = 0;
static bool sensor_ok = false;
static bool iaq_ready = false;
static uint8_t bright_level = 2;
static const uint8_t BRIGHT_PWM[4] = {40, 90, 160, 255};
static uint32_t hint_until_ms = 0;

static void set_backlight(uint8_t level) {
  bright_level = level & 0x03;
  ledcWrite(0, BRIGHT_PWM[bright_level]);
}

static float ema(float prev, float sample) {
  if (isnan(prev)) return sample;
  return prev + EMA_ALPHA * (sample - prev);
}

/* eCO2 color bands (ppm) */
static lv_color_t eco2_color(float ppm) {
  if (isnan(ppm)) return COL_MUTED;
  if (ppm < 800.0f) return COL_OK;
  if (ppm < 1200.0f) return COL_WARN;
  return COL_BAD;
}

/* TVOC color bands (ppb) */
static lv_color_t tvoc_color(float ppb) {
  if (isnan(ppb)) return COL_MUTED;
  if (ppb < 220.0f) return COL_OK;
  if (ppb < 660.0f) return COL_WARN;
  return COL_BAD;
}

static const char *eco2_level_text(float ppm) {
  if (isnan(ppm)) return "eCO2 --";
  if (ppm < 800.0f) return "eCO2 Good";
  if (ppm < 1200.0f) return "eCO2 Fair";
  if (ppm < 2000.0f) return "eCO2 Poor";
  return "eCO2 Bad";
}

static const char *tvoc_level_text(float ppb) {
  if (isnan(ppb)) return "TVOC --";
  if (ppb < 220.0f) return "TVOC Good";
  if (ppb < 660.0f) return "TVOC Fair";
  if (ppb < 2200.0f) return "TVOC Poor";
  return "TVOC Bad";
}

static const char *aqi_text(float eco2, float tvoc) {
  if (isnan(eco2) || isnan(tvoc)) return "NO DATA";
  if (eco2 < 800.0f && tvoc < 220.0f) return "GOOD";
  if (eco2 < 1200.0f && tvoc < 660.0f) return "FAIR";
  if (eco2 < 2000.0f && tvoc < 2200.0f) return "POOR";
  return "BAD";
}

static lv_color_t aqi_color(float eco2, float tvoc) {
  if (isnan(eco2) || isnan(tvoc)) return COL_BAD;
  if (eco2 < 800.0f && tvoc < 220.0f) return COL_OK;
  if (eco2 < 1200.0f && tvoc < 660.0f) return COL_WARN;
  return COL_BAD;
}

/* 0..100 score: higher = better air */
static int aqi_score(float eco2, float tvoc) {
  if (isnan(eco2) || isnan(tvoc)) return 0;
  float e_score = 100.0f - (eco2 - 400.0f) * 0.06f; /* 400→100, ~2067→0 */
  float t_score = 100.0f - tvoc * 0.12f;             /* 0→100, ~833→0 */
  int score = (int)lroundf((constrain(e_score, 0.0f, 100.0f) +
                            constrain(t_score, 0.0f, 100.0f)) *
                           0.5f);
  return constrain(score, 0, 100);
}

static void show_hint(const char *text, uint32_t ms) {
  lv_label_set_text(lbl_hint, text);
  lv_obj_remove_flag(lbl_hint, LV_OBJ_FLAG_HIDDEN);
  lv_obj_move_foreground(lbl_hint);
  hint_until_ms = millis() + ms;
}

static void reset_minmax(void) {
  if (!isnan(disp_eco2)) {
    min_eco2 = max_eco2 = disp_eco2;
  } else {
    min_eco2 = max_eco2 = NAN;
  }
  if (!isnan(disp_tvoc)) {
    min_tvoc = max_tvoc = disp_tvoc;
  } else {
    min_tvoc = max_tvoc = NAN;
  }
  show_hint("min/max reset", 1200);
}

static void touchscreen_read(lv_indev_t *indev, lv_indev_data_t *data) {
  LV_UNUSED(indev);
  static bool was_pressed = false;
  static uint32_t press_ms = 0;

  if (touchscreen.tirqTouched() && touchscreen.touched()) {
    TS_Point p = touchscreen.getPoint();
    data->point.x = map(p.y, 240, 3800, 1, SCREEN_WIDTH);
    data->point.y = map(p.x, 200, 3700, SCREEN_HEIGHT, 1);
    data->state = LV_INDEV_STATE_PRESSED;
    if (!was_pressed) {
      was_pressed = true;
      press_ms = millis();
    }
  } else {
    data->state = LV_INDEV_STATE_RELEASED;
    if (was_pressed) {
      was_pressed = false;
      uint32_t held = millis() - press_ms;
      if (held >= 700) {
        reset_minmax();
      } else if (held < 400) {
        set_backlight((bright_level + 1) & 0x03);
        char buf[20];
        lv_snprintf(buf, sizeof(buf), "brightness %u/3", (unsigned)bright_level);
        show_hint(buf, 900);
      }
    }
  }
}

static void arc_anim_exec(void *obj, int32_t v) {
  lv_arc_set_value((lv_obj_t *)obj, v);
}

static void anim_arc(lv_obj_t *arc, int32_t value) {
  int32_t cur = lv_arc_get_value(arc);
  if (cur == value) return;
  lv_anim_t a;
  lv_anim_init(&a);
  lv_anim_set_var(&a, arc);
  lv_anim_set_values(&a, cur, value);
  lv_anim_set_duration(&a, 520);
  lv_anim_set_exec_cb(&a, arc_anim_exec);
  lv_anim_set_path_cb(&a, lv_anim_path_ease_out);
  lv_anim_start(&a);
}

static void bar_anim_exec(void *obj, int32_t v) {
  lv_bar_set_value((lv_obj_t *)obj, v, LV_ANIM_OFF);
}

static void anim_bar(lv_obj_t *bar, int32_t value) {
  int32_t cur = lv_bar_get_value(bar);
  if (cur == value) return;
  lv_anim_t a;
  lv_anim_init(&a);
  lv_anim_set_var(&a, bar);
  lv_anim_set_values(&a, cur, value);
  lv_anim_set_duration(&a, 400);
  lv_anim_set_exec_cb(&a, bar_anim_exec);
  lv_anim_set_path_cb(&a, lv_anim_path_ease_out);
  lv_anim_start(&a);
}

static lv_obj_t *make_panel(lv_obj_t *parent, int x, int y, int w, int h) {
  lv_obj_t *p = lv_obj_create(parent);
  lv_obj_set_pos(p, x, y);
  lv_obj_set_size(p, w, h);
  lv_obj_set_style_bg_color(p, COL_PANEL, 0);
  lv_obj_set_style_bg_opa(p, LV_OPA_COVER, 0);
  lv_obj_set_style_border_color(p, COL_EDGE, 0);
  lv_obj_set_style_border_width(p, 1, 0);
  lv_obj_set_style_radius(p, 12, 0);
  lv_obj_set_style_pad_all(p, 6, 0);
  lv_obj_set_style_pad_row(p, 0, 0);
  lv_obj_set_style_pad_column(p, 0, 0);
  lv_obj_clear_flag(p, LV_OBJ_FLAG_SCROLLABLE);
  lv_obj_remove_flag(p, LV_OBJ_FLAG_SCROLLABLE);
  return p;
}

static lv_obj_t *make_gauge(lv_obj_t *parent, lv_color_t accent, int max_val) {
  lv_obj_t *arc = lv_arc_create(parent);
  lv_obj_set_size(arc, UI_ARC, UI_ARC);
  lv_obj_align(arc, LV_ALIGN_TOP_MID, 0, 2);
  lv_arc_set_rotation(arc, 135);
  lv_arc_set_bg_angles(arc, 0, 270);
  lv_arc_set_range(arc, 0, max_val);
  lv_arc_set_value(arc, 0);
  lv_obj_remove_style(arc, NULL, LV_PART_KNOB);
  lv_obj_clear_flag(arc, LV_OBJ_FLAG_CLICKABLE);
  lv_obj_set_style_arc_color(arc, COL_ARC_BG, LV_PART_MAIN);
  lv_obj_set_style_arc_width(arc, 10, LV_PART_MAIN);
  lv_obj_set_style_arc_color(arc, accent, LV_PART_INDICATOR);
  lv_obj_set_style_arc_width(arc, 10, LV_PART_INDICATOR);
  lv_obj_set_style_arc_rounded(arc, true, LV_PART_MAIN);
  lv_obj_set_style_arc_rounded(arc, true, LV_PART_INDICATOR);
  return arc;
}

static void create_ui(void) {
  lv_obj_t *scr = lv_screen_active();
  lv_obj_set_style_bg_color(scr, COL_BG, 0);
  lv_obj_set_style_bg_opa(scr, LV_OPA_COVER, 0);
  lv_obj_clear_flag(scr, LV_OBJ_FLAG_SCROLLABLE);

  lv_obj_t *title = lv_label_create(scr);
  lv_label_set_text(title, "AIR");
  lv_obj_set_style_text_font(title, &lv_font_montserrat_14, 0);
  lv_obj_set_style_text_color(title, COL_TEXT, 0);
  lv_obj_set_pos(title, UI_M, 4);

  lbl_uptime = lv_label_create(scr);
  lv_label_set_text(lbl_uptime, "up 00:00");
  lv_obj_set_style_text_font(lbl_uptime, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(lbl_uptime, COL_MUTED, 0);
  lv_obj_align_to(lbl_uptime, title, LV_ALIGN_OUT_RIGHT_MID, 8, 1);

  led_status = lv_led_create(scr);
  lv_obj_set_size(led_status, 9, 9);
  lv_obj_align(led_status, LV_ALIGN_TOP_RIGHT, -UI_M, 6);
  lv_led_set_color(led_status, COL_WARN);
  lv_led_on(led_status);

  lbl_status = lv_label_create(scr);
  lv_label_set_text(lbl_status, "INIT");
  lv_obj_set_style_text_font(lbl_status, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(lbl_status, COL_MUTED, 0);
  lv_obj_align(lbl_status, LV_ALIGN_TOP_RIGHT, -(UI_M + 16), 4);

  lbl_hint = lv_label_create(scr);
  lv_label_set_text(lbl_hint, "");
  lv_obj_set_style_text_font(lbl_hint, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(lbl_hint, COL_WARN, 0);
  lv_obj_set_style_bg_color(lbl_hint, COL_BG, 0);
  lv_obj_set_style_bg_opa(lbl_hint, LV_OPA_COVER, 0);
  lv_obj_set_style_pad_hor(lbl_hint, 6, 0);
  lv_obj_align(lbl_hint, LV_ALIGN_TOP_MID, 0, 4);
  lv_obj_add_flag(lbl_hint, LV_OBJ_FLAG_HIDDEN);

  const int gy = UI_HDR_H + UI_G;

  lv_obj_t *p_eco2 = make_panel(scr, UI_M, gy, UI_GAUGE_W, UI_GAUGE_H);
  lv_obj_t *e_cap = lv_label_create(p_eco2);
  lv_label_set_text(e_cap, "eCO2");
  lv_obj_set_style_text_font(e_cap, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(e_cap, COL_MUTED, 0);
  lv_obj_align(e_cap, LV_ALIGN_TOP_LEFT, 0, -2);

  arc_eco2 = make_gauge(p_eco2, COL_ECO2, ECO2_ARC_MAX);
  lbl_eco2_val = lv_label_create(p_eco2);
  lv_label_set_text(lbl_eco2_val, "----");
  lv_obj_set_style_text_font(lbl_eco2_val, &lv_font_montserrat_24, 0);
  lv_obj_set_style_text_color(lbl_eco2_val, COL_ECO2, 0);
  lv_obj_align(lbl_eco2_val, LV_ALIGN_TOP_MID, 0, 32);

  lv_obj_t *e_unit = lv_label_create(p_eco2);
  lv_label_set_text(e_unit, "ppm");
  lv_obj_set_style_text_font(e_unit, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(e_unit, COL_MUTED, 0);
  lv_obj_align(e_unit, LV_ALIGN_TOP_MID, 0, 58);

  lbl_eco2_range = lv_label_create(p_eco2);
  lv_label_set_text(lbl_eco2_range, "-- / --");
  lv_obj_set_style_text_font(lbl_eco2_range, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(lbl_eco2_range, COL_MUTED, 0);
  lv_obj_align(lbl_eco2_range, LV_ALIGN_BOTTOM_MID, 0, 2);

  lv_obj_t *p_tvoc = make_panel(scr, UI_M + UI_GAUGE_W + UI_G, gy, UI_GAUGE_W, UI_GAUGE_H);
  lv_obj_t *t_cap = lv_label_create(p_tvoc);
  lv_label_set_text(t_cap, "TVOC");
  lv_obj_set_style_text_font(t_cap, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(t_cap, COL_MUTED, 0);
  lv_obj_align(t_cap, LV_ALIGN_TOP_LEFT, 0, -2);

  arc_tvoc = make_gauge(p_tvoc, COL_TVOC, TVOC_ARC_MAX);
  lbl_tvoc_val = lv_label_create(p_tvoc);
  lv_label_set_text(lbl_tvoc_val, "----");
  lv_obj_set_style_text_font(lbl_tvoc_val, &lv_font_montserrat_24, 0);
  lv_obj_set_style_text_color(lbl_tvoc_val, COL_TVOC, 0);
  lv_obj_align(lbl_tvoc_val, LV_ALIGN_TOP_MID, 0, 32);

  lv_obj_t *t_unit = lv_label_create(p_tvoc);
  lv_label_set_text(t_unit, "ppb");
  lv_obj_set_style_text_font(t_unit, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(t_unit, COL_MUTED, 0);
  lv_obj_align(t_unit, LV_ALIGN_TOP_MID, 0, 58);

  lbl_tvoc_range = lv_label_create(p_tvoc);
  lv_label_set_text(lbl_tvoc_range, "-- / --");
  lv_obj_set_style_text_font(lbl_tvoc_range, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(lbl_tvoc_range, COL_MUTED, 0);
  lv_obj_align(lbl_tvoc_range, LV_ALIGN_BOTTOM_MID, 0, 2);

  lv_obj_t *p_bot = make_panel(scr, UI_M, UI_BOT_Y, UI_BOT_W, UI_BOT_H);

  lv_obj_t *info = lv_obj_create(p_bot);
  lv_obj_set_size(info, UI_INFO_W, UI_BOT_H - 12);
  lv_obj_align(info, LV_ALIGN_LEFT_MID, 0, 0);
  lv_obj_set_style_bg_opa(info, LV_OPA_TRANSP, 0);
  lv_obj_set_style_border_width(info, 0, 0);
  lv_obj_set_style_pad_all(info, 0, 0);
  lv_obj_clear_flag(info, LV_OBJ_FLAG_SCROLLABLE);

  lbl_aqi = lv_label_create(info);
  lv_label_set_text(lbl_aqi, "WARMUP");
  lv_obj_set_style_text_font(lbl_aqi, &lv_font_montserrat_14, 0);
  lv_obj_set_style_text_color(lbl_aqi, COL_WARN, 0);
  lv_obj_set_width(lbl_aqi, UI_INFO_W);
  lv_label_set_long_mode(lbl_aqi, LV_LABEL_LONG_CLIP);
  lv_obj_align(lbl_aqi, LV_ALIGN_TOP_LEFT, 0, 0);

  bar_aqi = lv_bar_create(info);
  lv_obj_set_size(bar_aqi, UI_INFO_W - 4, 8);
  lv_obj_align(bar_aqi, LV_ALIGN_TOP_LEFT, 0, 20);
  lv_bar_set_range(bar_aqi, 0, 100);
  lv_bar_set_value(bar_aqi, 0, LV_ANIM_OFF);
  lv_obj_set_style_bg_color(bar_aqi, COL_ARC_BG, LV_PART_MAIN);
  lv_obj_set_style_bg_opa(bar_aqi, LV_OPA_COVER, LV_PART_MAIN);
  lv_obj_set_style_radius(bar_aqi, 4, LV_PART_MAIN);
  lv_obj_set_style_bg_color(bar_aqi, COL_WARN, LV_PART_INDICATOR);
  lv_obj_set_style_radius(bar_aqi, 4, LV_PART_INDICATOR);

  lbl_eco2_lvl = lv_label_create(info);
  lv_label_set_text(lbl_eco2_lvl, "eCO2 --");
  lv_obj_set_style_text_font(lbl_eco2_lvl, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(lbl_eco2_lvl, COL_MUTED, 0);
  lv_obj_set_width(lbl_eco2_lvl, UI_INFO_W);
  lv_label_set_long_mode(lbl_eco2_lvl, LV_LABEL_LONG_CLIP);
  lv_obj_align(lbl_eco2_lvl, LV_ALIGN_TOP_LEFT, 0, 34);

  lbl_tvoc_lvl = lv_label_create(info);
  lv_label_set_text(lbl_tvoc_lvl, "TVOC --");
  lv_obj_set_style_text_font(lbl_tvoc_lvl, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(lbl_tvoc_lvl, COL_MUTED, 0);
  lv_obj_set_width(lbl_tvoc_lvl, UI_INFO_W);
  lv_label_set_long_mode(lbl_tvoc_lvl, LV_LABEL_LONG_CLIP);
  lv_obj_align(lbl_tvoc_lvl, LV_ALIGN_TOP_LEFT, 0, 48);

  chart = lv_chart_create(p_bot);
  lv_obj_set_size(chart, UI_CHART_W, UI_BOT_H - 16);
  lv_obj_align(chart, LV_ALIGN_RIGHT_MID, 0, 0);
  lv_chart_set_type(chart, LV_CHART_TYPE_LINE);
  lv_chart_set_point_count(chart, HISTORY_LEN);
  lv_chart_set_range(chart, LV_CHART_AXIS_PRIMARY_Y, 400, ECO2_ARC_MAX);
  lv_chart_set_range(chart, LV_CHART_AXIS_SECONDARY_Y, 0, TVOC_ARC_MAX);
  lv_chart_set_update_mode(chart, LV_CHART_UPDATE_MODE_SHIFT);
  lv_obj_set_style_bg_color(chart, COL_CHART_BG, 0);
  lv_obj_set_style_bg_opa(chart, LV_OPA_COVER, 0);
  lv_obj_set_style_border_color(chart, COL_EDGE, 0);
  lv_obj_set_style_border_width(chart, 1, 0);
  lv_obj_set_style_radius(chart, 8, 0);
  lv_obj_set_style_pad_all(chart, 4, 0);
  lv_obj_set_style_line_width(chart, 2, LV_PART_ITEMS);
  lv_chart_set_div_line_count(chart, 2, 4);
  lv_obj_set_style_line_color(chart, COL_EDGE, LV_PART_MAIN);
  lv_obj_set_style_line_opa(chart, LV_OPA_40, LV_PART_MAIN);
  ser_eco2 = lv_chart_add_series(chart, COL_ECO2, LV_CHART_AXIS_PRIMARY_Y);
  ser_tvoc = lv_chart_add_series(chart, COL_TVOC, LV_CHART_AXIS_SECONDARY_Y);

  lv_obj_move_foreground(title);
  lv_obj_move_foreground(lbl_uptime);
  lv_obj_move_foreground(lbl_status);
  lv_obj_move_foreground(led_status);
  lv_obj_move_foreground(lbl_hint);
}

static void refresh_meta(void) {
  char buf[40];
  uint32_t up = millis() / 1000;
  lv_snprintf(buf, sizeof(buf), "up %02lu:%02lu  bl%u",
              (unsigned long)(up / 60), (unsigned long)(up % 60), (unsigned)bright_level);
  lv_label_set_text(lbl_uptime, buf);

  if (hint_until_ms && (int32_t)(millis() - hint_until_ms) >= 0) {
    hint_until_ms = 0;
    lv_obj_add_flag(lbl_hint, LV_OBJ_FLAG_HIDDEN);
  }

  if (!iaq_ready) {
    uint32_t left = WARMUP_SEC - (millis() - boot_ms) / 1000;
    if ((int32_t)left < 0) left = 0;
    lv_snprintf(buf, sizeof(buf), "WARM %lus", (unsigned long)left);
    lv_label_set_text(lbl_status, buf);
    lv_led_set_color(led_status, COL_WARN);
  } else if (sensor_ok) {
    uint32_t age = (millis() - last_ok_ms) / 1000;
    lv_snprintf(buf, sizeof(buf), "LIVE %lus", (unsigned long)age);
    lv_label_set_text(lbl_status, buf);
    lv_led_set_color(led_status, COL_OK);
  }
}

static void update_ui(bool ok) {
  char buf[32];

  if (ok && !isnan(disp_eco2) && !isnan(disp_tvoc)) {
    lv_color_t ec = eco2_color(disp_eco2);
    lv_color_t tc = tvoc_color(disp_tvoc);

    lv_snprintf(buf, sizeof(buf), "%.0f", disp_eco2);
    lv_label_set_text(lbl_eco2_val, buf);
    lv_obj_set_style_text_color(lbl_eco2_val, ec, 0);
    lv_obj_set_style_arc_color(arc_eco2, ec, LV_PART_INDICATOR);
    anim_arc(arc_eco2, (int)lroundf(constrain(disp_eco2, 0.0f, (float)ECO2_ARC_MAX)));

    lv_snprintf(buf, sizeof(buf), "%.0f", disp_tvoc);
    lv_label_set_text(lbl_tvoc_val, buf);
    lv_obj_set_style_text_color(lbl_tvoc_val, tc, 0);
    lv_obj_set_style_arc_color(arc_tvoc, tc, LV_PART_INDICATOR);
    anim_arc(arc_tvoc, (int)lroundf(constrain(disp_tvoc, 0.0f, (float)TVOC_ARC_MAX)));

    lv_snprintf(buf, sizeof(buf), "%.0f / %.0f", min_eco2, max_eco2);
    lv_label_set_text(lbl_eco2_range, buf);
    lv_snprintf(buf, sizeof(buf), "%.0f / %.0f", min_tvoc, max_tvoc);
    lv_label_set_text(lbl_tvoc_range, buf);

    lv_label_set_text(lbl_eco2_lvl, eco2_level_text(disp_eco2));
    lv_obj_set_style_text_color(lbl_eco2_lvl, ec, 0);
    lv_label_set_text(lbl_tvoc_lvl, tvoc_level_text(disp_tvoc));
    lv_obj_set_style_text_color(lbl_tvoc_lvl, tc, 0);

    lv_color_t ac = aqi_color(disp_eco2, disp_tvoc);
    lv_label_set_text(lbl_aqi, aqi_text(disp_eco2, disp_tvoc));
    lv_obj_set_style_text_color(lbl_aqi, ac, 0);
    anim_bar(bar_aqi, aqi_score(disp_eco2, disp_tvoc));
    lv_obj_set_style_bg_color(bar_aqi, ac, LV_PART_INDICATOR);

    lv_chart_set_next_value(chart, ser_eco2, (int32_t)lroundf(disp_eco2));
    lv_chart_set_next_value(chart, ser_tvoc, (int32_t)lroundf(disp_tvoc));
    refresh_meta();
  } else {
    lv_label_set_text(lbl_aqi, "ERROR");
    lv_obj_set_style_text_color(lbl_aqi, COL_BAD, 0);
    lv_label_set_text(lbl_status, "ERR");
    lv_led_set_color(led_status, COL_BAD);
  }
}

static void read_sgp(void) {
  if (!sgp.IAQmeasure()) {
    fail_streak++;
    Serial.printf("SGP30 fail(%u)\n", fail_streak);
    if (fail_streak >= SGP_FAIL_TOLERANCE) {
      sensor_ok = false;
      update_ui(false);
    }
    return;
  }

  fail_streak = 0;
  sensor_ok = true;
  last_ok_ms = millis();

  float eco2 = (float)sgp.eCO2;
  float tvoc = (float)sgp.TVOC;

  if (!iaq_ready) {
    if ((millis() - boot_ms) / 1000 >= WARMUP_SEC) {
      iaq_ready = true;
      show_hint("IAQ ready", 1200);
    } else {
      /* Still show raw warmup readings */
    }
  }

  disp_eco2 = ema(disp_eco2, eco2);
  disp_tvoc = ema(disp_tvoc, tvoc);

  if (isnan(min_eco2) || disp_eco2 < min_eco2) min_eco2 = disp_eco2;
  if (isnan(max_eco2) || disp_eco2 > max_eco2) max_eco2 = disp_eco2;
  if (isnan(min_tvoc) || disp_tvoc < min_tvoc) min_tvoc = disp_tvoc;
  if (isnan(max_tvoc) || disp_tvoc > max_tvoc) max_tvoc = disp_tvoc;

  Serial.printf("eCO2=%.0f(%.0f) ppm  TVOC=%.0f(%.0f) ppb\n",
                disp_eco2, eco2, disp_tvoc, tvoc);
  update_ui(true);
}

void setup() {
  Serial.begin(115200);
  delay(200);
  boot_ms = millis();

  ledcSetup(0, 5000, 8);
  ledcAttachPin(TFT_BL_PIN, 0);
  set_backlight(2);

  Serial.println("CYD LVGL SGP30 Air Quality Dashboard");
  Serial.printf("LVGL %d.%d.%d  SDA=GPIO%d SCL=GPIO%d\n",
                lv_version_major(), lv_version_minor(), lv_version_patch(),
                I2C_SDA, I2C_SCL);

  Wire.begin(I2C_SDA, I2C_SCL);
  Wire.setClock(100000);

  if (!sgp.begin()) {
    Serial.println("SGP30 not found — check wiring (SDA22/SCL27)");
  } else {
    Serial.printf("SGP30 OK  serial 0x%04X%04X\n",
                  sgp.serialnumber[0], sgp.serialnumber[1]);
    /* Absolute humidity optional; skip until DHT available */
  }

  lv_init();

  touchscreenSPI.begin(XPT2046_CLK, XPT2046_MISO, XPT2046_MOSI, XPT2046_CS);
  touchscreen.begin(touchscreenSPI);
  touchscreen.setRotation(2);

  #if defined(CYD_BOARD_3248S035)
  lv_display_t *disp = lv_tft_espi_create(320, 480, draw_buf, sizeof(draw_buf));
#else
  lv_display_t *disp = lv_tft_espi_create(240, 320, draw_buf, sizeof(draw_buf));
#endif
  lv_display_set_rotation(disp, LV_DISPLAY_ROTATION_270);

  lv_indev_t *indev = lv_indev_create();
  lv_indev_set_type(indev, LV_INDEV_TYPE_POINTER);
  lv_indev_set_read_cb(indev, touchscreen_read);

  create_ui();
  delay(200);
  last_sgp_ms = 0;
}

void loop() {
  uint32_t now = millis();
  if (now - last_sgp_ms >= SGP_READ_MS) {
    last_sgp_ms = now;
    read_sgp();
  }

  static uint32_t last_meta_ms = 0;
  if (now - last_meta_ms >= 1000) {
    last_meta_ms = now;
    refresh_meta();
  }

  lv_timer_handler();
  lv_tick_inc(5);
  delay(5);
}