import { describe, expect, it, vi } from 'vitest'
import { EventEmitter } from '../../src/utils/event-emitter.js'

type Events = { tick: number; done: void }

describe('EventEmitter', () => {
  it('delivers payloads as-is (no cloning or freezing) and supports off', () => {
    const emitter = new EventEmitter<Events & { obj: { n: number } }>()
    const seen: unknown[] = []
    const payload = { n: 1 }
    const off = emitter.on('obj', (p) => seen.push(p))
    expect(emitter.emit('obj', payload)).toBe(true)
    off()
    expect(emitter.emit('obj', payload)).toBe(false)
    expect(seen[0]).toBe(payload)
    expect(Object.isFrozen(payload)).toBe(false)
  })

  it('once fires a single time; listener errors are logged, not thrown', () => {
    const error = vi.spyOn(console, 'error').mockImplementation(() => {})
    const emitter = new EventEmitter<Events>()
    const once = vi.fn()
    emitter.once('tick', once)
    emitter.on('tick', () => {
      throw new Error('boom')
    })
    emitter.emit('tick', 1)
    emitter.emit('tick', 2)
    expect(once).toHaveBeenCalledTimes(1)
    expect(error).toHaveBeenCalledTimes(2)
    error.mockRestore()
  })

  it('debounces and cancels pending debounced calls on off', async () => {
    vi.useFakeTimers()
    const emitter = new EventEmitter<Events>()
    const listener = vi.fn()
    const off = emitter.on('tick', listener, 50)
    emitter.emit('tick', 1)
    emitter.emit('tick', 2)
    vi.advanceTimersByTime(60)
    expect(listener).toHaveBeenCalledExactlyOnceWith(2)
    emitter.emit('tick', 3)
    off()
    vi.advanceTimersByTime(60)
    expect(listener).toHaveBeenCalledTimes(1)
    vi.useRealTimers()
  })

  it('waitFor resolves on a matching payload and rejects on timeout', async () => {
    const emitter = new EventEmitter<Events>()
    const waiting = emitter.waitFor('tick', (n) => n > 1)
    emitter.emit('tick', 1)
    emitter.emit('tick', 2)
    expect(await waiting).toBe(2)
    await expect(emitter.waitFor('done', () => true, 5)).rejects.toThrow(/Timed out waiting for "done"/)
  })
})