import { describe, it, expect, vi } from 'vitest'
import { SerialQueue } from '../src/queue.js'

describe('SerialQueue', () => {
  it('runs tasks strictly in order even when they resolve out of order', async () => {
    const q = new SerialQueue()
    const order: number[] = []
    const slow = () => new Promise((r) => setTimeout(r, 20)).then(() => order.push(1))
    const fast = () => Promise.resolve().then(() => order.push(2))
    await Promise.all([q.run(slow), q.run(fast)])
    expect(order).toEqual([1, 2])
  })

  it('continues after a failing task', async () => {
    const q = new SerialQueue()
    await expect(
      q.run(async () => {
        throw new Error('boom')
      })
    ).rejects.toThrow('boom')
    const result = await q.run(async () => 'ok')
    expect(result).toBe('ok')
  })

  it('paces call starts at least minIntervalMs apart', async () => {
    vi.useFakeTimers()
    const q = new SerialQueue({ minIntervalMs: 1000 })
    let t1 = 0
    let t2 = 0
    const p1 = q.run(async () => {
      t1 = Date.now()
    })
    const p2 = q.run(async () => {
      t2 = Date.now()
    })
    await vi.advanceTimersByTimeAsync(1000)
    await vi.advanceTimersByTimeAsync(1000)
    await Promise.all([p1, p2])
    expect(t2 - t1).toBeGreaterThanOrEqual(1000)
    vi.useRealTimers()
  })
})