import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
import { readPersistedQueue, writePersistedQueue, clearPersistedQueue } from './persisted';
import type { TrackRef } from '$lib/api/types';

const sampleTrack: TrackRef = {
  id: 't1',
  title: 'Foo',
  album_id: 'al1',
  album_title: 'Baz',
  artist_id: 'ar1',
  artist_name: 'Bar',
  duration_sec: 200,
  stream_url: '/stream/t1'
};

describe('persisted queue', () => {
  beforeEach(() => {
    localStorage.clear();
  });

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

  it('write-then-read round-trips queue / index / position', () => {
    writePersistedQueue('user-1', { queue: [sampleTrack], index: 0, position: 42.5 });
    const out = readPersistedQueue('user-1');
    expect(out).not.toBeNull();
    expect(out!.v).toBe(1);
    expect(out!.queue).toEqual([sampleTrack]);
    expect(out!.index).toBe(0);
    expect(out!.position).toBe(42.5);
    expect(typeof out!.savedAt).toBe('number');
  });

  it('read returns null when no entry is set', () => {
    expect(readPersistedQueue('user-1')).toBeNull();
  });

  it('read returns null on malformed JSON', () => {
    localStorage.setItem('minstrel.queue.user-1', '{not-json');
    expect(readPersistedQueue('user-1')).toBeNull();
  });

  it('read returns null when version is not 1', () => {
    localStorage.setItem(
      'minstrel.queue.user-1',
      JSON.stringify({ v: 2, queue: [], index: 0, position: 0, savedAt: 0 })
    );
    expect(readPersistedQueue('user-1')).toBeNull();
  });

  it('clearPersistedQueue removes only the named user key', () => {
    writePersistedQueue('user-a', { queue: [sampleTrack], index: 0, position: 0 });
    writePersistedQueue('user-b', { queue: [sampleTrack], index: 0, position: 0 });
    clearPersistedQueue('user-a');
    expect(readPersistedQueue('user-a')).toBeNull();
    expect(readPersistedQueue('user-b')).not.toBeNull();
  });

  it('write swallows QuotaExceededError without throwing', () => {
    const setItem = vi.spyOn(Storage.prototype, 'setItem').mockImplementation(() => {
      throw new Error('QuotaExceededError');
    });
    expect(() =>
      writePersistedQueue('user-1', { queue: [sampleTrack], index: 0, position: 0 })
    ).not.toThrow();
    setItem.mockRestore();
  });
});