#define CONFIG_TFT_HEIGHT 240 // usally defind in kconfig or whatever
#define CONFIG_TFT_WIDTH 240 // usally defind in kconfig or whatever

#define DRAW_BUF_SIZE (CONFIG_TFT_WIDTH * CONFIG_TFT_HEIGHT / 10 * (LV_COLOR_DEPTH / 8)) // 1/10th buffer size is min required

static uint32_t my_tick_get_cb(void) { // Tells LVGL how long the program has been running
    return millis(); // for esp-idf use `esp_timer_get_time() / 1000;` instead
}

void my_disp_flush(lv_display_t * disp, const lv_area_t *area, void * px_map) { // Lets LVGL draw onto an area of the display
    uint32_t w = (area->x2 - area->x1 + 1);
    uint32_t h = (area->y2 - area->y1 + 1);

    // Draw buffer into "area->x1, area->y1, w, h"

    lv_disp_flush_ready(disp);
}

void init_lvgl() {
    lv_init();
    lv_tick_set_cb(my_tick_get_cb);

    uint8_t* draw_buf = (uint8_t*)malloc(DRAW_BUF_SIZE);
    lv_display_t * disp;
    disp = lv_display_create(CONFIG_TFT_HEIGHT, CONFIG_TFT_WIDTH);
    lv_display_set_flush_cb(disp, (lv_display_flush_cb_t)my_disp_flush);
    lv_display_set_buffers(disp, draw_buf, NULL, DRAW_BUF_SIZE, LV_DISPLAY_RENDER_MODE_PARTIAL);

    lv_indev_t * indev = lv_indev_create();
    lv_indev_set_type(indev, LV_INDEV_TYPE_POINTER); /*Touchpad should have POINTER type*/
}

void app_main() {
    init_lvgl();

    lv_obj_t * spinner_screen = lv_obj_create(NULL); // Create an emtpy screen (like a div in HTML)
    lv_obj_set_size(spinner_screen, CONFIG_TFT_HEIGHT, CONFIG_TFT_WIDTH); // set size so it take up whole display
    lv_obj_set_pos(spinner_screen, 0, 0); // Set the top-left of the screen to the top-left of the display

    lv_obj_t * spinner = lv_spinner_create(spinner_screen); // Create a spinner widget with the `spinner_screen` as a parent
    lv_obj_set_size(spinner, 100, 100);
    lv_obj_center(spinner); // Center the spinner inside the parent
    lv_spinner_set_anim_params(spinner, 5000, 200); // Check docs for more info (https://docs.lvgl.io/9.2/API/widgets/spinner/lv_spinner.html#_CPPv426lv_spinner_set_anim_paramsP8lv_obj_t8uint32_t8uint32_t)

    lv_obj_t * label_screen = lv_obj_create(NULL);
    lv_obj_set_size(label_screen, CONFIG_TFT_HEIGHT, CONFIG_TFT_WIDTH);
    lv_obj_set_pos(label_screen, 0, 0);

    lv_obj_t * label = lv_label_create(label_screen);
    lv_label_set_text(label, "HELLO WORLD!");
    lv_obj_set_width(label, 150);
    lv_obj_set_style_text_align(label, LV_TEXT_ALIGN_CENTER, 0);
    lv_obj_align(label, LV_ALIGN_CENTER, 0, -40);

    lv_screen_load(spinner_screen);

    bool switch_screen_flag = true;
    while (true) {
        lv_timer_handler(); /* let the UI do its work */
        vTaskDelay( 10 ); // `delay` for arduino

        if (switch_screen_flag && millis() > 5000) {
            switch_screen_flag = false;

            // Load the label screen after 5s of run time, by fading it in for 1s.
            lv_screen_load_anim(label_screen, LV_SCR_LOAD_ANIM_FADE_IN, 1000, 0, false); // Check docs for more info (https://docs.lvgl.io/9.2/API/display/lv_display.html#_CPPv419lv_screen_load_animP8lv_obj_t21lv_screen_load_anim_t8uint32_t8uint32_tb)
        }
    }

}