// @vitest-environment jsdom
//
// E28 review F7: while hidden the button only went transparent — a Tab still landed on the invisible
// control. And a keyboard press scrolled to the top and hid it with the focus still on it.
import { afterEach, describe, expect, it, vi } from "vitest";
import { act, cleanup, fireEvent, render, screen } from "@testing-library/react";

vi.mock("react-i18next", async (importOriginal) => ({
  ...(await importOriginal<typeof import("react-i18next")>()),
  useTranslation: () => ({ t: (k: string) => k }),
}));

import BackToTop from "./BackToTop";

afterEach(cleanup);

function scrolled(main: HTMLElement, top: number) {
  main.scrollTop = top;
  act(() => void main.dispatchEvent(new Event("scroll")));
}

describe("BackToTop", () => {
  it("is no Tab stop while hidden; a keyboard press leaves the focus on the page", () => {
    const main = document.createElement("main");
    main.tabIndex = -1;
    main.scrollTo = vi.fn();
    document.body.appendChild(main);
    render(<BackToTop />);
    const btn = screen.getByText("common.backToTop").closest("button")!;
    expect(btn.tabIndex).toBe(-1);
    scrolled(main, 900);
    expect(btn.tabIndex).toBe(0);
    btn.focus();
    fireEvent.click(btn, { detail: 0 });
    expect(main.scrollTo).toHaveBeenCalled();
    expect(document.activeElement).toBe(main);
    main.remove();
  });
});