import { describe, it, expect, vi, beforeEach } from 'vitest';
import { getEventBus, _resetEventBus } from './event-bus.js';

describe('DomainEventBus', () => {
  beforeEach(() => { _resetEventBus(); });

  it('delivers event to subscriber', async () => {
    const bus = getEventBus();
    const handler = vi.fn();
    bus.on('timer.created', handler);
    await bus.emit('timer.created', { timerId: 't1', userId: 'u1', label: 'Test' });
    expect(handler).toHaveBeenCalledOnce();
  });

  it('unsubscribe stops delivery', async () => {
    const bus = getEventBus();
    const handler = vi.fn();
    const unsub = bus.on('timer.created', handler);
    unsub();
    await bus.emit('timer.created', { timerId: 't1', userId: 'u1', label: 'Test' });
    expect(handler).not.toHaveBeenCalled();
  });

  it('failing handler does not block others', async () => {
    const bus = getEventBus();
    const good = vi.fn();
    bus.on('timer.created', () => { throw new Error('boom'); });
    bus.on('timer.created', good);
    await bus.emit('timer.created', { timerId: 't1', userId: 'u1', label: 'Test' });
    expect(good).toHaveBeenCalledOnce();
  });

  it('singleton returns same instance', () => {
    expect(getEventBus()).toBe(getEventBus());
  });

  it('_resetEventBus creates fresh instance', () => {
    const a = getEventBus();
    _resetEventBus();
    expect(getEventBus()).not.toBe(a);
  });

  it('removeAll clears handlers', async () => {
    const bus = getEventBus();
    const handler = vi.fn();
    bus.on('timer.created', handler);
    bus.removeAll();
    await bus.emit('timer.created', { timerId: 't1', userId: 'u1', label: 'Test' });
    expect(handler).not.toHaveBeenCalled();
  });
});