/** @babel */

import temp from 'temp'
import fs from 'fs-plus'
import path from 'path'
import { promisify } from 'util'

import { CompositeDisposable } from 'event-kit'
import { watchPath, stopAllWatchers } from '../src/path-watcher'

temp.track()

const writeFile = promisify(fs.writeFile)
const mkdir = promisify(fs.mkdir)
const appendFile = promisify(fs.appendFile)
const realpath = promisify(fs.realpath)

const tempMkdir = promisify(temp.mkdir)

describe('watchPath', function () {
  let subs

  beforeEach(function () {
    subs = new CompositeDisposable()
  })

  afterEach(async function () {
    subs.dispose()
    await stopAllWatchers()
  })

  function waitForChanges (watcher, ...fileNames) {
    const waiting = new Set(fileNames)
    let fired = false
    const relevantEvents = []

    return new Promise(resolve => {
      const sub = watcher.onDidChange(events => {
        for (const event of events) {
          if (waiting.delete(event.path)) {
            relevantEvents.push(event)
          }
        }

        if (!fired && waiting.size === 0) {
          fired = true
          resolve(relevantEvents)
          sub.dispose()
        }
      })
    })
  }

  describe('watchPath()', function () {
    it('resolves the returned promise when the watcher begins listening', async function () {
      const rootDir = await tempMkdir('atom-fsmanager-test-')

      const watcher = await watchPath(rootDir, {}, () => {})
      expect(watcher.constructor.name).toBe('PathWatcher')
    })

    it('reuses an existing native watcher and resolves getStartPromise immediately if attached to a running watcher', async function () {
      const rootDir = await tempMkdir('atom-fsmanager-test-')

      const watcher0 = await watchPath(rootDir, {}, () => {})
      const watcher1 = await watchPath(rootDir, {}, () => {})

      expect(watcher0.native).toBe(watcher1.native)
    })

    it("reuses existing native watchers even while they're still starting", async function () {
      const rootDir = await tempMkdir('atom-fsmanager-test-')

      const [watcher0, watcher1] = await Promise.all([
        watchPath(rootDir, {}, () => {}),
        watchPath(rootDir, {}, () => {})
      ])
      expect(watcher0.native).toBe(watcher1.native)
    })

    it("doesn't attach new watchers to a native watcher that's stopping", async function () {
      const rootDir = await tempMkdir('atom-fsmanager-test-')

      const watcher0 = await watchPath(rootDir, {}, () => {})
      const native0 = watcher0.native

      watcher0.dispose()
      const watcher1 = await watchPath(rootDir, {}, () => {})

      expect(watcher1.native).not.toBe(native0)
    })

    it('reuses an existing native watcher on a parent directory and filters events', async function () {
      const rootDir = await tempMkdir('atom-fsmanager-test-').then(realpath)
      const rootFile = path.join(rootDir, 'rootfile.txt')
      const subDir = path.join(rootDir, 'subdir')
      const subFile = path.join(subDir, 'subfile.txt')

      await mkdir(subDir)

      // Keep the watchers alive with an undisposed subscription
      const rootWatcher = await watchPath(rootDir, {}, () => {})
      const childWatcher = await watchPath(subDir, {}, () => {})

      expect(rootWatcher.native).toBe(childWatcher.native)
      expect(rootWatcher.native.isRunning()).toBe(true)

      const firstChanges = Promise.all([
        waitForChanges(rootWatcher, subFile),
        waitForChanges(childWatcher, subFile)
      ])
      await writeFile(subFile, 'subfile\n', { encoding: 'utf8' })
      await firstChanges

      const nextRootEvent = waitForChanges(rootWatcher, rootFile)
      await writeFile(rootFile, 'rootfile\n', { encoding: 'utf8' })
      await nextRootEvent
    })

    it('adopts existing child watchers and filters events appropriately to them', async function () {
      const parentDir = await tempMkdir('atom-fsmanager-test-')
        .then(realpath)

      // Create the directory tree
      const rootFile = path.join(parentDir, 'rootfile.txt')
      const subDir0 = path.join(parentDir, 'subdir0')
      const subFile0 = path.join(subDir0, 'subfile0.txt')
      const subDir1 = path.join(parentDir, 'subdir1')
      const subFile1 = path.join(subDir1, 'subfile1.txt')

      await mkdir(subDir0)
      await mkdir(subDir1)
      await Promise.all([
        writeFile(rootFile, 'rootfile\n', { encoding: 'utf8' }),
        writeFile(subFile0, 'subfile 0\n', { encoding: 'utf8' }),
        writeFile(subFile1, 'subfile 1\n', { encoding: 'utf8' })
      ])

      // Begin the child watchers and keep them alive
      const subWatcher0 = await watchPath(subDir0, {}, () => {})
      const subWatcherChanges0 = waitForChanges(subWatcher0, subFile0)

      const subWatcher1 = await watchPath(subDir1, {}, () => {})
      const subWatcherChanges1 = waitForChanges(subWatcher1, subFile1)

      expect(subWatcher0.native).not.toBe(subWatcher1.native)

      // Create the parent watcher
      const parentWatcher = await watchPath(parentDir, {}, () => {})
      const parentWatcherChanges = waitForChanges(
        parentWatcher,
        rootFile,
        subFile0,
        subFile1
      )

      expect(subWatcher0.native).toBe(parentWatcher.native)
      expect(subWatcher1.native).toBe(parentWatcher.native)

      // Ensure events are filtered correctly
      await Promise.all([
        appendFile(rootFile, 'change\n', { encoding: 'utf8' }),
        appendFile(subFile0, 'change\n', { encoding: 'utf8' }),
        appendFile(subFile1, 'change\n', { encoding: 'utf8' })
      ])

      await Promise.all([
        subWatcherChanges0,
        subWatcherChanges1,
        parentWatcherChanges
      ])
    })
  })
})