#include <lvgl.h>
#include <TFT_eSPI.h>
#include <Arduino.h>

/* Physical screen (ILI9341) */
#define TFT_HOR_RES 320
#define TFT_VER_RES 240

/* Logical UI size (Waveshare 1.47") */
#define UI_HOR_RES 172
#define UI_VER_RES 320

static lv_disp_draw_buf_t draw_buf;
static lv_color_t buf1[TFT_HOR_RES * 20];

TFT_eSPI tft = TFT_eSPI();

/* Flush callback */
void my_disp_flush(lv_disp_drv_t *disp,
                   const lv_area_t *area,
                   lv_color_t *color_p) {

  uint32_t w = area->x2 - area->x1 + 1;
  uint32_t h = area->y2 - area->y1 + 1;

  tft.startWrite();
  tft.setAddrWindow(area->x1, area->y1, w, h);
  tft.pushColors((uint16_t *)&color_p->full, w * h, true);
  tft.endWrite();

  lv_disp_flush_ready(disp);
}

/* Button callback */
static void btn_event_cb(lv_event_t *e) {
  lv_event_code_t code = lv_event_get_code(e);

  if (code == LV_EVENT_CLICKED) {
    Serial.println("Button clicked!");

    lv_obj_t *label = lv_event_get_user_data(e);
    lv_label_set_text(label, "Clicked!");
  }
}

void setup() {
  Serial.begin(115200);

  lv_init();

  tft.begin();
  tft.setRotation(1);

  lv_disp_draw_buf_init(&draw_buf, buf1, NULL, TFT_HOR_RES * 20);

  static lv_disp_drv_t disp_drv;
  lv_disp_drv_init(&disp_drv);
  disp_drv.hor_res = TFT_HOR_RES;
  disp_drv.ver_res = TFT_VER_RES;
  disp_drv.flush_cb = my_disp_flush;
  disp_drv.draw_buf = &draw_buf;
  lv_disp_drv_register(&disp_drv);

  /* ===== UI ROOT (letterbox) ===== */
  lv_obj_t *root = lv_obj_create(lv_scr_act());
  lv_obj_set_size(root, UI_HOR_RES, UI_VER_RES);
  lv_obj_center(root);
  lv_obj_set_style_bg_color(root, lv_color_black(), 0);
  lv_obj_set_style_pad_all(root, 0, 0);

  /* Button */
  lv_obj_t *btn = lv_btn_create(root);
  lv_obj_set_size(btn, 120, 50);
  lv_obj_align(btn, LV_ALIGN_CENTER, 0, 0);

  lv_obj_t *label = lv_label_create(btn);
  lv_label_set_text(label, "Press me");
  lv_obj_center(label);

  lv_obj_add_event_cb(btn, btn_event_cb, LV_EVENT_CLICKED, label);
}

void loop() {
  lv_timer_handler();
  delay(5);
}