import { act, fireEvent, render, screen } from "@testing-library/react";
import {
  resetHomeArrivalState,
  useHomeFragmentNavigation,
} from "./useHomeFragmentNavigation";

function HomeNavigation() {
  const onLayoutReady = useHomeFragmentNavigation();
  return (
    <>
      <button type="button" onClick={onLayoutReady}>
        Establish layout
      </button>
      <a href="/#about">Sobre</a>
      <a href="/#contact">Contato</a>
      <section id="about" aria-label="Sobre">
        <button type="button">Read biography</button>
      </section>
      <section id="contact" aria-label="Contato">
        <button type="button">Send message</button>
      </section>
    </>
  );
}

const originalScrollIntoView = HTMLElement.prototype.scrollIntoView;

beforeEach(() => {
  resetHomeArrivalState();
  window.history.replaceState(null, "", "/");
  HTMLElement.prototype.scrollIntoView = jest.fn();
});

afterEach(() => {
  jest.restoreAllMocks();
  window.history.replaceState(null, "", "/");
  if (originalScrollIntoView) {
    HTMLElement.prototype.scrollIntoView = originalScrollIntoView;
  } else {
    Reflect.deleteProperty(HTMLElement.prototype, "scrollIntoView");
  }
});

describe("home fragment navigation", () => {
  it("starts an unfragmented visit at the top after the home establishes layout", () => {
    let restoredPosition = 3200;
    jest
      .spyOn(window, "scrollTo")
      .mockImplementation((options: ScrollToOptions | number) => {
        if (typeof options === "object")
          restoredPosition = options.top ?? restoredPosition;
      });
    render(<HomeNavigation />);
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    expect(restoredPosition).toBe(0);
  });

  it("leaves a same-document return to the position the browser restores", () => {
    const scrollTo = jest
      .spyOn(window, "scrollTo")
      .mockImplementation(() => {});
    const firstVisit = render(<HomeNavigation />);
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    firstVisit.unmount();
    expect(window.history.scrollRestoration).not.toBe("manual");

    scrollTo.mockClear();
    render(<HomeNavigation />);
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    expect(scrollTo).not.toHaveBeenCalled();
    expect(window.history.scrollRestoration).not.toBe("manual");
  });

  it("does not reset the visitor's position after intentional scrolling during startup", () => {
    let position = 0;
    jest
      .spyOn(window, "scrollTo")
      .mockImplementation((options: ScrollToOptions | number) => {
        if (typeof options === "object") position = options.top ?? position;
      });
    render(<HomeNavigation />);
    position = 600;
    fireEvent.wheel(window, { deltaY: 600 });
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    expect(position).toBe(600);
  });

  it("waits for the home layout on fragment arrival, then never steals focus on refresh", () => {
    window.history.replaceState(null, "", "/#contact");
    render(<HomeNavigation />);
    const contact = screen.getByRole("region", { name: "Contato" });
    expect(contact).not.toHaveFocus();

    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    expect(contact).toHaveFocus();
    screen.getByRole("button", { name: "Read biography" }).focus();
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    expect(
      screen.getByRole("button", { name: "Read biography" }),
    ).toHaveFocus();
  });

  it("abandons a pending arrival when the visitor intentionally scrolls", () => {
    window.history.replaceState(null, "", "/#about");
    render(<HomeNavigation />);
    const message = screen.getByRole("button", { name: "Send message" });
    message.focus();
    fireEvent.wheel(window, { deltaY: 200 });
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    expect(message).toHaveFocus();
  });

  it("keeps repeated same-fragment links native while moving focus to the destination", () => {
    window.history.replaceState(null, "", "/#about");
    render(<HomeNavigation />);
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    const link = screen.getByRole("link", { name: "Sobre" });
    link.focus();
    expect(fireEvent.click(link)).toBe(true);
    expect(screen.getByRole("region", { name: "Sobre" })).toHaveFocus();
    link.focus();
    expect(fireEvent.click(link)).toBe(true);
    expect(screen.getByRole("region", { name: "Sobre" })).toHaveFocus();
    link.focus();
    fireEvent.click(link, { ctrlKey: true });
    expect(link).toHaveFocus();
  });

  it("does not resurrect a stale fragment when the URL changes before readiness", () => {
    window.history.replaceState(null, "", "/#about");
    render(<HomeNavigation />);
    const message = screen.getByRole("button", { name: "Send message" });
    message.focus();
    act(() => {
      window.history.replaceState(null, "", "/#contact");
      window.dispatchEvent(new HashChangeEvent("hashchange"));
    });
    fireEvent.click(
      screen.getByRole("button", { name: "Establish layout" }),
    );
    expect(message).toHaveFocus();
  });
});