import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
import { loadPanelLayout, savePanelLayout } from './ux-prefs';

const KEY = 'astrolabe:ux-prefs';

/** In-memory localStorage stub (Node's global one is non-functional). */
function makeStorageStub() {
  const map = new Map<string, string>();
  return {
    getItem: (k: string) => (map.has(k) ? map.get(k)! : null),
    setItem: (k: string, v: string) => void map.set(k, String(v)),
    removeItem: (k: string) => void map.delete(k),
    clear: () => map.clear(),
    key: (i: number) => [...map.keys()][i] ?? null,
    get length() {
      return map.size;
    },
  };
}

describe('ux-prefs · panelLayout', () => {
  beforeEach(() => vi.stubGlobal('localStorage', makeStorageStub()));
  afterEach(() => vi.unstubAllGlobals());

  it('returns empty widths when nothing is stored', () => {
    expect(loadPanelLayout()).toEqual({ libraryWidth: undefined, previewWidth: undefined });
  });

  it('round-trips stored widths', () => {
    savePanelLayout({ libraryWidth: 300, previewWidth: 420 });
    expect(loadPanelLayout()).toEqual({ libraryWidth: 300, previewWidth: 420 });
  });

  it('merges partial writes without dropping the other width', () => {
    savePanelLayout({ libraryWidth: 300, previewWidth: 420 });
    savePanelLayout({ libraryWidth: 250 });
    expect(loadPanelLayout()).toEqual({ libraryWidth: 250, previewWidth: 420 });
  });

  it('rejects non-positive / non-finite junk', () => {
    localStorage.setItem(
      KEY,
      JSON.stringify({ panelLayout: { libraryWidth: -5, previewWidth: 'wide' } }),
    );
    expect(loadPanelLayout()).toEqual({ libraryWidth: undefined, previewWidth: undefined });
  });

  it('tolerates malformed JSON', () => {
    localStorage.setItem(KEY, '{ not json');
    expect(loadPanelLayout()).toEqual({ libraryWidth: undefined, previewWidth: undefined });
  });

  it('preserves unrelated keys in the record (forward-compatible merge)', () => {
    localStorage.setItem(KEY, JSON.stringify({ sort: { sortBy: 'name', sortOrder: 'asc' } }));
    savePanelLayout({ libraryWidth: 260 });
    const stored = JSON.parse(localStorage.getItem(KEY)!) as {
      sort: { sortBy: string };
      panelLayout: { libraryWidth: number };
    };
    expect(stored.sort.sortBy).toBe('name');
    expect(stored.panelLayout.libraryWidth).toBe(260);
  });
});