import { expect } from 'chai'
import * as ChildProcess from 'child_process'
import * as path from 'path'
import { emittedOnce } from './events-helpers'
import { closeWindow } from './window-helpers'

import { webContents, TopLevelWindow, WebContentsView } from 'electron'

describe('WebContentsView', () => {
  let w: TopLevelWindow
  afterEach(() => closeWindow(w as any).then(() => { w = null as unknown as TopLevelWindow }))

  it('can be used as content view', () => {
    const web = (webContents as any).create({})
    w = new TopLevelWindow({ show: false })
    w.setContentView(new WebContentsView(web))
  })

  it('prevents adding same WebContents', () => {
    const web = (webContents as any).create({})
    w = new TopLevelWindow({ show: false })
    w.setContentView(new WebContentsView(web))
    expect(() => {
      w.setContentView(new WebContentsView(web))
    }).to.throw('The WebContents has already been added to a View')
  })

  describe('new WebContentsView()', () => {
    it('does not crash on exit', async () => {
      const appPath = path.join(__dirname, 'fixtures', 'api', 'leak-exit-webcontentsview.js')
      const electronPath = process.execPath
      const appProcess = ChildProcess.spawn(electronPath, ['--enable-logging', appPath])
      let output = ''
      appProcess.stdout.on('data', data => { output += data })
      appProcess.stderr.on('data', data => { output += data })
      const [code] = await emittedOnce(appProcess, 'exit')
      if (code !== 0) {
        console.log(code, output)
      }
      expect(code).to.equal(0)
    })
  })

  function triggerGCByAllocation () {
    const arr = []
    for (let i = 0; i < 1000000; i++) {
      arr.push([])
    }
    return arr
  }

  it(`doesn't crash when GCed during allocation`, (done) => {
    const web = (webContents as any).create({})
    // eslint-disable-next-line no-new
    new WebContentsView(web)
    setTimeout(() => {
      // NB. the crash we're testing for is the lack of a current `v8::Context`
      // when emitting an event in WebContents's destructor. V8 is inconsistent
      // about whether or not there's a current context during garbage
      // collection, and it seems that `v8Util.requestGarbageCollectionForTesting`
      // causes a GC in which there _is_ a current context, so the crash isn't
      // triggered. Thus, we force a GC by other means: namely, by allocating a
      // bunch of stuff.
      triggerGCByAllocation()
      done()
    })
  })
})