import { describe, expect, it } from 'vitest'
import { useAsync } from './useAsync'

/** 手动控制解析时机的 fetcher,复现请求乱序返回 */
function deferredFetcher<T>() {
  const pending: Array<{ resolve: (v: T) => void; reject: (e: unknown) => void }> = []
  const fetcher = () =>
    new Promise<T>((resolve, reject) => {
      pending.push({ resolve, reject })
    })
  return { fetcher, pending }
}

describe('useAsync 并发与乱序', () => {
  it('后发请求先返回时,先发请求的迟到结果被丢弃', async () => {
    const { fetcher, pending } = deferredFetcher<string>()
    const st = useAsync(fetcher, false)
    const p1 = st.run()
    const p2 = st.run()
    pending[1].resolve('新')
    await p2
    pending[0].resolve('旧')
    await p1
    expect(st.data.value).toBe('新')
    expect(st.loading.value).toBe(false)
  })

  it('迟到的失败不覆盖最新成功结果', async () => {
    const { fetcher, pending } = deferredFetcher<string>()
    const st = useAsync(fetcher, false)
    const p1 = st.run()
    const p2 = st.run()
    pending[1].resolve('新')
    await p2
    pending[0].reject(new Error('旧请求失败'))
    await p1
    expect(st.data.value).toBe('新')
    expect(st.error.value).toBe('')
  })

  it('silent 刷新不置 loading,普通刷新置 loading', async () => {
    const { fetcher, pending } = deferredFetcher<number>()
    const st = useAsync(fetcher, false)
    const p1 = st.run({ silent: true })
    expect(st.loading.value).toBe(false)
    pending[0].resolve(1)
    await p1
    const p2 = st.run()
    expect(st.loading.value).toBe(true)
    pending[1].resolve(2)
    await p2
    expect(st.loading.value).toBe(false)
    expect(st.data.value).toBe(2)
  })

  it('失败时记录 error 并清 loading', async () => {
    const { fetcher, pending } = deferredFetcher<string>()
    const st = useAsync(fetcher, false)
    const p1 = st.run()
    pending[0].reject(new Error('boom'))
    await p1
    expect(st.error.value).toBe('boom')
    expect(st.loading.value).toBe(false)
    expect(st.data.value).toBeNull()
  })
})