// @vitest-environment jsdom
//
// BootGate settles the tab's identity BEFORE the app tree mounts. The bug it replaced: a new tab (no
// pinned account in sessionStorage) built the app for "no account" first — so with Settings →
// Appearance → Startup turned off, NavigationProvider's initializer could not read the opt-out and
// landed on Home, mirrored ?page=home into the address bar, and then re-read its own mirror when the
// account was pinned, staying on Home. Only a same-tab reload (account already pinned) was right.
//
// Real NavigationProvider, real storage and i18n; only the two boot probes are stubbed. The probe
// records EVERY render, so "never showed the wrong page, not even for one render" is what is asserted.
import { describe, it, expect, vi, beforeEach, afterEach, type MockInstance } from "vitest";
import { render, screen, cleanup, act, fireEvent, waitFor } from "@testing-library/react";
import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
import { useEffect } from "react";
import { useTranslation } from "react-i18next";
import BootGate from "./BootGate";
import { NavigationProvider } from "./NavigationProvider";
import { useNavigation } from "./navigationContext";
import { api, type Me } from "../lib/api";
import { ACTIVE_ACCOUNT_KEY } from "../lib/activeAccount";
import { qk } from "../lib/queryKeys";
import i18n from "../i18n";

const renders: { page: string; lang: string }[] = [];
let mounts = 0;
const countMount = () => {
  mounts++; // outside the component: the compiler cannot lower `++` on a module variable in one
};
function Probe() {
  const { page } = useNavigation();
  const { i18n: inst } = useTranslation();
  renders.push({ page, lang: inst.language });
  useEffect(countMount, []);
  return <div data-testid="app">{page}</div>;
}

function mount() {
  const qc = new QueryClient({ defaultOptions: { queries: { retry: false } } });
  render(
    <QueryClientProvider client={qc}>
      <BootGate>
        <NavigationProvider>
          <Probe />
        </NavigationProvider>
      </BootGate>
    </QueryClientProvider>,
  );
  return qc;
}
const account = (over: Partial<Me> = {}) => ({ id: 5, preferences: {}, ...over }) as Me;
let savePrefs: MockInstance<typeof api.savePrefs>;
const retryButton = () => screen.findByRole("button", { name: i18n.t("common.retry") });

beforeEach(async () => {
  localStorage.clear();
  sessionStorage.clear(); // a NEW tab: nothing pinned yet
  window.history.replaceState(null, "", "/");
  renders.length = 0;
  mounts = 0;
  await i18n.changeLanguage("en");
  vi.spyOn(api, "setupStatus").mockResolvedValue({ configured: true });
  savePrefs = vi.spyOn(api, "savePrefs").mockResolvedValue({ ok: true } as never);
});
afterEach(() => {
  cleanup();
  vi.restoreAllMocks();
  vi.unstubAllGlobals();
});

describe("BootGate", () => {
  it("a new tab with Startup off opens on the page the account left — never on Home first", async () => {
    localStorage.setItem("siftlode.startOnHome.5", "0");
    localStorage.setItem("siftlode.page.5", "downloads");
    vi.spyOn(api, "me").mockResolvedValue(account());
    mount();

    expect((await screen.findByTestId("app")).textContent).toBe("downloads");
    expect(renders.map((r) => r.page)).toEqual(renders.map(() => "downloads"));
    expect(new URLSearchParams(window.location.search).get("page")).toBe("downloads");
    expect(sessionStorage.getItem(ACTIVE_ACCOUNT_KEY)).toBe("5"); // the tab is pinned
  });

  it("renders the app in the account's language from its first render", async () => {
    vi.spyOn(api, "me").mockResolvedValue(account({ preferences: { language: "hu" } }));
    mount();

    await screen.findByTestId("app");
    expect(renders.map((r) => r.lang)).toEqual(renders.map(() => "hu"));
  });

  it("an account with no language stored stores the one it is shown in, once", async () => {
    await i18n.changeLanguage("hu"); // the browser's language, never saved
    vi.spyOn(api, "me").mockResolvedValue(account());
    const qc = mount();

    await screen.findByTestId("app");
    await waitFor(() => expect(savePrefs).toHaveBeenCalledWith({ language: "hu" }));
    expect(savePrefs).toHaveBeenCalledTimes(1);
    // The server now sorts in Hungarian, and so does what reads the stored language.
    await waitFor(() => expect(qc.getQueryData<Me>(qk.me())?.preferences.language).toBe("hu"));
  });

  it("an account with its language stored stores nothing", async () => {
    vi.spyOn(api, "me").mockResolvedValue(account({ preferences: { language: "hu" } }));
    mount();

    await screen.findByTestId("app");
    expect(savePrefs).not.toHaveBeenCalled();
  });

  it("mounts nothing of the app while the identity is still unknown", async () => {
    vi.spyOn(api, "me").mockReturnValue(new Promise<Me | null>(() => {}));
    mount();
    await act(async () => {}); // the setup probe resolves; `me` never does

    expect(screen.queryByTestId("app")).toBeNull();
    expect(renders).toHaveLength(0);
  });

  it("signed out: mounts the app (App shows the landing) without pinning an account", async () => {
    vi.spyOn(api, "me").mockResolvedValue(null);
    mount();

    await screen.findByTestId("app");
    expect(sessionStorage.getItem(ACTIVE_ACCOUNT_KEY)).toBeNull();
  });

  it("setup mode: mounts the app (App shows the wizard) without asking for the account", async () => {
    vi.mocked(api.setupStatus).mockResolvedValue({ configured: false });
    const me = vi.spyOn(api, "me").mockResolvedValue(account());
    mount();

    await screen.findByTestId("app");
    expect(me).not.toHaveBeenCalled();
    expect(sessionStorage.getItem(ACTIVE_ACCOUNT_KEY)).toBeNull();
  });

  it("an unanswered setup probe is an error with a retry — never the signed-out landing", async () => {
    vi.mocked(api.setupStatus)
      .mockRejectedValueOnce(new Error("502"))
      .mockResolvedValue({ configured: true });
    vi.spyOn(api, "me").mockResolvedValue(account());
    mount();

    fireEvent.click(await retryButton());
    await screen.findByTestId("app");
    expect(renders.length).toBeGreaterThan(0);
    expect(sessionStorage.getItem(ACTIVE_ACCOUNT_KEY)).toBe("5"); // it mounted for the account
  });

  it("an unanswered first account probe is an error with a retry", async () => {
    vi.spyOn(api, "me").mockRejectedValueOnce(new Error("502")).mockResolvedValue(account());
    mount();

    fireEvent.click(await retryButton());
    await screen.findByTestId("app");
    expect(sessionStorage.getItem(ACTIVE_ACCOUNT_KEY)).toBe("5");
  });

  it("a background refetch that fails keeps the app mounted, as it was", async () => {
    const me = vi.spyOn(api, "me").mockResolvedValue(account());
    const qc = mount();
    await screen.findByTestId("app");

    me.mockRejectedValue(new Error("502"));
    await act(() => qc.refetchQueries({ queryKey: qk.me() }));
    // react-query hands the error to its observers on a timer: let that render land before asserting.
    await act(() => new Promise((r) => setTimeout(r, 20)));

    expect(qc.getQueryState(qk.me())?.status).toBe("error");
    expect(screen.getByTestId("app")).toBeTruthy();
    expect(mounts).toBe(1);
  });

  it("a pin naming another account than the server answered as is corrected before the app reads it", async () => {
    // Pinned to 9, but 9 was signed out in another tab: the server answers as the browser's default, 5.
    sessionStorage.setItem(ACTIVE_ACCOUNT_KEY, "9");
    localStorage.setItem("siftlode.startOnHome.5", "0");
    localStorage.setItem("siftlode.page.5", "downloads");
    vi.spyOn(api, "me").mockResolvedValue(account());
    mount();

    expect((await screen.findByTestId("app")).textContent).toBe("downloads");
    expect(renders.map((r) => r.page)).toEqual(renders.map(() => "downloads"));
    expect(sessionStorage.getItem(ACTIVE_ACCOUNT_KEY)).toBe("5");
  });

  it("a mounted tab whose identity changes reloads rather than keep the previous account's tree", async () => {
    const me = vi.spyOn(api, "me").mockResolvedValue(account());
    const qc = mount();
    await screen.findByTestId("app");
    const reload = vi.fn();
    vi.stubGlobal("location", { ...window.location, reload });

    me.mockResolvedValue(null); // the session ended
    await act(() => qc.refetchQueries({ queryKey: qk.me() }));

    await waitFor(() => expect(reload).toHaveBeenCalled());
  });

  it("an identity change reloads without moving the pin first", async () => {
    // The tree being torn down still runs its unmount saves before the page goes; with the pin already
    // moved they would land under the NEW account's local keys (a player volume still pending, say).
    const me = vi.spyOn(api, "me").mockResolvedValue(account());
    const qc = mount();
    await screen.findByTestId("app");
    const reload = vi.fn();
    vi.stubGlobal("location", { ...window.location, reload });

    me.mockResolvedValue(account({ id: 6 })); // 5 was signed out elsewhere: the server answers as 6
    await act(() => qc.refetchQueries({ queryKey: qk.me() }));

    await waitFor(() => expect(reload).toHaveBeenCalled());
    expect(sessionStorage.getItem(ACTIVE_ACCOUNT_KEY)).toBe("5");
  });

  // The adoption effect is idempotent for the identity it already adopted, and that is load-bearing
  // rather than tidy: a re-run reloads the page, so an effect that cannot tell "already adopted this
  // account" from "adopted a different one" turns an ordinary boot into a reload loop. The spy is
  // installed BEFORE mounting on purpose — the other reload tests stub it after the app is up, which
  // is exactly late enough to miss the re-run that setting `readyFor` triggers.
  it("a plain boot never reloads, however many times the adoption effect re-runs", async () => {
    const reload = vi.fn();
    vi.stubGlobal("location", { ...window.location, reload });
    vi.spyOn(api, "me").mockResolvedValue(account());

    const qc = mount();
    await screen.findByTestId("app");
    // Anything that re-renders the gate must leave it alone: a pref save, a background refetch.
    act(() => {
      qc.setQueryData(qk.me(), account({ preferences: { startup: "last" } }));
    });
    await act(() => new Promise((r) => setTimeout(r, 20)));

    expect(reload).not.toHaveBeenCalled();
    expect(mounts).toBe(1);
  });

  it("a change to the account's data, not its identity, leaves the app as it is", async () => {
    vi.spyOn(api, "me").mockResolvedValue(account());
    const qc = mount();
    await screen.findByTestId("app");
    const reload = vi.fn();
    vi.stubGlobal("location", { ...window.location, reload });

    // What every pref save does to the cache (usePref's mergePrefsCache): a new `me` for the same account.
    act(() => {
      qc.setQueryData(qk.me(), account({ preferences: { language: "hu" } }));
    });
    await act(() => new Promise((r) => setTimeout(r, 20)));

    expect(reload).not.toHaveBeenCalled();
    expect(mounts).toBe(1);
    expect(i18n.language).toBe("en"); // the language is adopted once, never over the user's own choice
  });
});