import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
import { useRef } from "react";
import { act, render, screen, waitFor, within } from "@testing-library/react";
import userEvent from "@testing-library/user-event";
import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
import { discardQueueItem, listQueue, summarizeQueue, type QueueItem } from "@/lib/offline/db";
import { resumeSync, syncPendingEntries } from "@/lib/offline/sync";
import { OfflineBand } from "./offline-band";

vi.mock("@/lib/offline/db", () => ({
  summarizeQueue: vi.fn(),
  listQueue: vi.fn(),
  discardQueueItem: vi.fn(),
}));
vi.mock("@/lib/offline/sync", () => ({ syncPendingEntries: vi.fn(), resumeSync: vi.fn() }));

const NOTHING_SENT = { synced: 0, failed: 0, skippedForeign: 0 };
const REJECTED: QueueItem = {
  store: "pending-inspections",
  id: 7,
  label: "Durchsicht",
  queuedAt: "2026-10-13T08:15:00.000Z",
  lastError: { status: 400, message: "Volk V-03 ist beendet.", at: "2026-10-13T09:00:00.000Z" },
};
const WAITING: QueueItem = {
  store: "pending-feedings",
  id: 3,
  label: "Fütterung",
  queuedAt: "2026-10-13T08:20:00.000Z",
};

function setOnLine(value: boolean) {
  vi.spyOn(window.navigator, "onLine", "get").mockReturnValue(value);
}

/** The band as the layout places it: above the page content wrapper. */
function BandOnPage({ syncEnabled }: { syncEnabled?: boolean }) {
  const pageContentRef = useRef<HTMLDivElement>(null);
  return (
    <>
      <OfflineBand userId="user-1" pageContentRef={pageContentRef} syncEnabled={syncEnabled} />
      <div ref={pageContentRef} tabIndex={-1} data-testid="page-content">
        Seiteninhalt
      </div>
    </>
  );
}

function renderBand(props: { syncEnabled?: boolean } = {}) {
  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
  return render(
    <QueryClientProvider client={client}>
      <BandOnPage {...props} />
    </QueryClientProvider>,
  );
}

/** Opens the sheet from the rejected entries and discards the rejected one. */
async function discardRejectedEntry(nextSummary: { own: number; failed: number; foreign: number }) {
  await userEvent.click(
    await screen.findByRole("button", { name: "1 Eintrag abgelehnt – ansehen" }),
  );
  const sheet = await screen.findByRole("dialog", { name: "Wartende Einträge" });
  vi.mocked(summarizeQueue).mockResolvedValue(nextSummary);
  vi.mocked(listQueue).mockResolvedValue(nextSummary.own > 0 ? [WAITING] : []);
  await userEvent.click(
    await within(sheet).findByRole("button", { name: /^Verwerfen: Durchsicht vom / }),
  );
  const confirm = await screen.findByRole("dialog", { name: /^Durchsicht vom .+ verwerfen\?$/ });
  await userEvent.click(within(confirm).getByRole("button", { name: "Verwerfen" }));
  await waitFor(() => expect(discardQueueItem).toHaveBeenCalledWith(REJECTED));
  return sheet;
}

describe("OfflineBand", () => {
  beforeEach(() => {
    vi.mocked(summarizeQueue).mockReset();
    vi.mocked(listQueue).mockReset().mockResolvedValue([]);
    vi.mocked(discardQueueItem).mockReset().mockResolvedValue(undefined);
    vi.mocked(syncPendingEntries).mockReset().mockResolvedValue(NOTHING_SENT);
    vi.mocked(resumeSync).mockReset();
  });

  afterEach(() => {
    vi.restoreAllMocks();
  });

  it("announces „Offline – 2 Einträge warten\" in a status region", async () => {
    setOnLine(false);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 2, failed: 0, foreign: 0 });

    renderBand();

    await waitFor(() =>
      expect(screen.getByRole("status")).toHaveTextContent("Offline – 2 Einträge warten"),
    );
    expect(screen.getByRole("status")).toHaveAttribute("aria-live", "polite");
    expect(summarizeQueue).toHaveBeenCalledWith("user-1");
    expect(syncPendingEntries).not.toHaveBeenCalled();
  });

  it("says „1 Eintrag wartet\" for a single entry", async () => {
    setOnLine(false);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 1, failed: 0, foreign: 0 });

    renderBand();

    await waitFor(() =>
      expect(screen.getByRole("status")).toHaveTextContent("Offline – 1 Eintrag wartet"),
    );
  });

  it("tells that input is kept while offline with an empty queue", async () => {
    setOnLine(false);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 0, failed: 0, foreign: 0 });

    renderBand();

    expect(await screen.findByRole("status")).toHaveTextContent(
      "Offline – Eingaben werden gespeichert und später gesendet",
    );
  });

  it("keeps an empty status region online with an empty queue", async () => {
    setOnLine(true);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 0, failed: 0, foreign: 3 });

    renderBand();

    await waitFor(() => expect(summarizeQueue).toHaveBeenCalled());
    await act(async () => {});
    // The live region must exist before its first message, or that message is not announced.
    const status = screen.getByRole("status");
    expect(status).toHaveAttribute("aria-live", "polite");
    expect(status).toBeEmptyDOMElement();
  });

  it("„Jetzt senden\" starts syncPendingEntries", async () => {
    setOnLine(true);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 2, failed: 0, foreign: 0 });
    renderBand();
    const button = await screen.findByRole("button", { name: "2 Einträge warten – Jetzt senden" });
    // Online on mount the band already tries once by itself.
    await waitFor(() => expect(syncPendingEntries).toHaveBeenCalledTimes(1));

    await userEvent.click(button);

    await waitFor(() => expect(syncPendingEntries).toHaveBeenCalledTimes(2));
    expect(syncPendingEntries).toHaveBeenLastCalledWith("user-1");
  });

  it("its button is at least 44 px", async () => {
    setOnLine(true);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 1, failed: 1, foreign: 0 });

    renderBand();

    expect(
      await screen.findByRole("button", { name: "1 Eintrag wartet – Jetzt senden" }),
    ).toHaveClass("min-h-11");
    expect(screen.getByRole("button", { name: "1 Eintrag abgelehnt – ansehen" })).toHaveClass(
      "min-h-11",
    );
  });

  it("opens the queue sheet from the rejected entries", async () => {
    setOnLine(true);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 0, failed: 2, foreign: 0 });
    renderBand();

    await userEvent.click(
      await screen.findByRole("button", { name: "2 Einträge abgelehnt – ansehen" }),
    );

    expect(await screen.findByRole("dialog", { name: "Wartende Einträge" })).toBeInTheDocument();
    expect(listQueue).toHaveBeenCalledWith("user-1");
  });

  it("closes the sheet once nothing is left and keeps focus in the band while it has content", async () => {
    setOnLine(false);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 0, failed: 1, foreign: 0 });
    vi.mocked(listQueue).mockResolvedValue([REJECTED]);
    renderBand();

    await discardRejectedEntry({ own: 0, failed: 0, foreign: 0 });

    await waitFor(() =>
      expect(screen.queryByRole("dialog", { name: "Wartende Einträge" })).not.toBeInTheDocument(),
    );
    // Offline, the band still says so - focus lands on that message.
    await waitFor(() => expect(screen.getByRole("status")).toHaveFocus());
  });

  it("moves focus to the page content when the band has nothing left to show", async () => {
    setOnLine(true);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 0, failed: 1, foreign: 0 });
    vi.mocked(listQueue).mockResolvedValue([REJECTED]);
    renderBand();

    await discardRejectedEntry({ own: 0, failed: 0, foreign: 0 });

    await waitFor(() =>
      expect(screen.queryByRole("dialog", { name: "Wartende Einträge" })).not.toBeInTheDocument(),
    );
    await waitFor(() => expect(screen.getByTestId("page-content")).toHaveFocus());
    expect(screen.getByRole("status")).toBeEmptyDOMElement();
  });

  it("keeps the sheet open with the waiting entries after the last rejected one is discarded", async () => {
    setOnLine(true);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 1, failed: 1, foreign: 0 });
    vi.mocked(listQueue).mockResolvedValue([REJECTED, WAITING]);
    renderBand();

    const sheet = await discardRejectedEntry({ own: 1, failed: 0, foreign: 0 });

    await waitFor(() =>
      expect(screen.queryByRole("button", { name: /abgelehnt – ansehen/ })).not.toBeInTheDocument(),
    );
    expect(within(sheet).getByText("Fütterung")).toBeInTheDocument();
    expect(screen.getByRole("dialog", { name: "Wartende Einträge" })).toBeInTheDocument();

    await userEvent.click(within(sheet).getByRole("button", { name: "Schließen" }));

    await waitFor(() =>
      expect(screen.queryByRole("dialog", { name: "Wartende Einträge" })).not.toBeInTheDocument(),
    );
    // The trigger is gone; focus goes to the band, which still shows the
    // waiting entry (Base UI picks its first focusable element, the send button).
    await waitFor(() =>
      expect(screen.getByRole("status")).toContainElement(document.activeElement as HTMLElement),
    );
    expect(screen.getByRole("button", { name: "1 Eintrag wartet – Jetzt senden" })).toHaveFocus();
  });

  it("opens sync for the signed-in user before its first automatic sync", async () => {
    setOnLine(true);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 1, failed: 0, foreign: 0 });

    renderBand();

    await waitFor(() => expect(syncPendingEntries).toHaveBeenCalledWith("user-1"));
    expect(resumeSync).toHaveBeenCalledTimes(1);
    expect(vi.mocked(resumeSync).mock.invocationCallOrder[0]).toBeLessThan(
      vi.mocked(syncPendingEntries).mock.invocationCallOrder[0],
    );
  });

  it("sends by itself as soon as the connection is back", async () => {
    setOnLine(false);
    vi.mocked(summarizeQueue).mockResolvedValue({ own: 1, failed: 0, foreign: 0 });
    renderBand();
    await screen.findByText("Offline – 1 Eintrag wartet");
    expect(syncPendingEntries).not.toHaveBeenCalled();

    setOnLine(true);
    act(() => {
      window.dispatchEvent(new Event("online"));
    });

    await waitFor(() => expect(syncPendingEntries).toHaveBeenCalledWith("user-1"));
  });

  describe("in an offline session (no access token)", () => {
    it("neither opens the sync gate nor sends, even when the connection is back", async () => {
      setOnLine(true);
      vi.mocked(summarizeQueue).mockResolvedValue({ own: 2, failed: 0, foreign: 0 });

      renderBand({ syncEnabled: false });
      await screen.findByText("Offline – 2 Einträge warten");
      act(() => {
        window.dispatchEvent(new Event("online"));
      });

      expect(resumeSync).not.toHaveBeenCalled();
      expect(syncPendingEntries).not.toHaveBeenCalled();
      expect(screen.queryByRole("button", { name: /Jetzt senden/ })).not.toBeInTheDocument();
    });

    it("opens the gate and sends as soon as the session is online again", async () => {
      setOnLine(true);
      vi.mocked(summarizeQueue).mockResolvedValue({ own: 1, failed: 0, foreign: 0 });
      const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
      const view = (syncEnabled: boolean) => (
        <QueryClientProvider client={client}>
          <BandOnPage syncEnabled={syncEnabled} />
        </QueryClientProvider>
      );
      const { rerender } = render(view(false));
      await screen.findByText("Offline – 1 Eintrag wartet");

      rerender(view(true));

      await waitFor(() => expect(syncPendingEntries).toHaveBeenCalledWith("user-1"));
      expect(resumeSync).toHaveBeenCalled();
    });
  });
});