import assert from 'node:assert/strict'
import { test } from 'node:test'
import { createRegenerationQueue } from '../dev-reload.js'

const waitFor = async (predicate) => {
  for (let attempt = 0; attempt < 100; attempt += 1) {
    if (predicate()) return
    await new Promise((resolve) => setTimeout(resolve, 5))
  }
  assert.fail('timed out waiting for generation')
}

test('rapid edits coalesce and only the latest generation reloads', async () => {
  const pending = []
  const events = []
  const queue = createRegenerationQueue({
    generate: () => new Promise((resolve) => pending.push(resolve)),
    onSuccess: () => events.push('reload'),
    onError: () => events.push('error'),
    delay: 1,
  })
  try {
    queue.request()
    queue.request()
    await waitFor(() => pending.length === 1)
    queue.request()
    pending[0]()
    await waitFor(() => pending.length === 2)
    assert.deepEqual(events, [])
    pending[1]()
    await waitFor(() => events.length === 1)
    assert.deepEqual(events, ['reload'])
  } finally {
    queue.close()
  }
})

test('failed latest generation reports an error without reloading', async () => {
  const events = []
  const queue = createRegenerationQueue({
    generate: () => Promise.reject(new Error('broken content')),
    onSuccess: () => events.push('reload'),
    onError: (error) => events.push(error.message),
    delay: 1,
  })
  try {
    queue.request()
    await waitFor(() => events.length === 1)
    assert.deepEqual(events, ['broken content'])
  } finally {
    queue.close()
  }
})