import { afterEach, describe, expect, it, vi } from "vitest";
import {
  createPreferencesStore,
  DEFAULT_PREFERENCES,
  PREFERENCES_KEY,
  reducedMotionOn,
  type PreferenceStorage,
} from "../src/state/preferences";

/** An in-memory storage, like localStorage. */
function memoryStorage(): PreferenceStorage & { data: Map<string, string> } {
  const data = new Map<string, string>();
  return {
    data,
    getItem: (key) => data.get(key) ?? null,
    setItem: (key, value) => void data.set(key, value),
  };
}

/** jsdom has no matchMedia: stand one in that answers the reduced-motion query. */
const mockOsReducedMotion = (reduce: boolean) =>
  vi.stubGlobal("matchMedia", (query: string) => ({ matches: reduce, media: query }));

describe("device preferences (Step 10K.1)", () => {
  afterEach(() => vi.unstubAllGlobals());

  it("starts with the defaults: locale clock, real-time countdowns, the device's reduced motion", () => {
    const store = createPreferencesStore(memoryStorage());
    expect(store.getState()).toMatchObject(DEFAULT_PREFERENCES);

    mockOsReducedMotion(true);
    expect(reducedMotionOn(store.getState())).toBe(true);
    mockOsReducedMotion(false);
    expect(reducedMotionOn(store.getState())).toBe(false);
    // An override wins over the device.
    store.getState().set({ reducedMotion: true });
    expect(reducedMotionOn(store.getState())).toBe(true);
  });

  it("keeps saved values across a reload", () => {
    const storage = memoryStorage();
    const first = createPreferencesStore(storage);
    first.getState().set({ clock: "24h", countdown: "both" });
    first.getState().dismissTip("tutorial-intro");
    first.getState().set({ mapCamera: { zoom: 3, panX: 10, panY: -4 } });

    const reloaded = createPreferencesStore(storage);
    expect(reloaded.getState()).toMatchObject({
      clock: "24h",
      countdown: "both",
      dismissedTips: ["tutorial-intro"],
      mapCamera: { zoom: 3, panX: 10, panY: -4 },
    });
  });

  it("ignores broken saved data", () => {
    const storage = memoryStorage();
    storage.setItem(PREFERENCES_KEY, "{not json");
    expect(createPreferencesStore(storage).getState()).toMatchObject(DEFAULT_PREFERENCES);
    storage.setItem(
      PREFERENCES_KEY,
      JSON.stringify({ clock: "sundial", mapCamera: { zoom: "x" } }),
    );
    expect(createPreferencesStore(storage).getState()).toMatchObject(DEFAULT_PREFERENCES);
  });

  it("works in memory when storage throws, without errors", () => {
    const broken: PreferenceStorage = {
      getItem: () => {
        throw new Error("SecurityError");
      },
      setItem: () => {
        throw new Error("QuotaExceededError");
      },
    };
    const store = createPreferencesStore(broken);
    expect(store.getState()).toMatchObject(DEFAULT_PREFERENCES);
    expect(() => store.getState().set({ clock: "12h" })).not.toThrow();
    expect(store.getState().clock).toBe("12h");
    expect(() => createPreferencesStore(null).getState().dismissTip("x")).not.toThrow();
  });
});