// Phase B verification of transparent-region flattening (finding #4): a scene
// with backgroundVideo set makes render.html skip the background fill, leaving
// transparent areas. With the opaque-white render window those areas must
// capture as white (~255), matching the server's omitBackground:false, not
// black. Builds the window exactly like renderWorker.createRenderWindow.
//
// Run: node_modules/.bin/electron scripts/verify-bg.cjs

const { app, BrowserWindow } = require('electron')
const path = require('node:path')
const { pathToFileURL } = require('node:url')

const RENDER_PARTITION = 'ruwio-render'

// backgroundVideo present -> render.html does NOT fill canvas.background.
const scene = {
  canvas: { width: 160, height: 120, background: '#202030' },
  backgroundVideo: { src: 'data:video/mp4,', duration: 1 },
  duration: 1,
  assets: [{ id: 'a1', kind: 'rect', width: 20, height: 20, fill: '#ff0000' }],
  layers: [
    {
      id: 'l1',
      assetId: 'a1',
      visible: true,
      base: { x: 30, y: 30, scaleX: 1, scaleY: 1, rotation: 0, opacity: 1 },
      keyframes: [],
    },
  ],
}

function createRenderWindow() {
  const win = new BrowserWindow({
    width: scene.canvas.width,
    height: scene.canvas.height,
    show: false,
    frame: false,
    transparent: false,
    backgroundColor: '#ffffff',
    webPreferences: {
      contextIsolation: true,
      nodeIntegration: false,
      sandbox: true,
      partition: RENDER_PARTITION,
    },
  })
  win.webContents.session.webRequest.onBeforeRequest({ urls: ['*://*/*'] }, (_d, cb) =>
    cb({ cancel: true }),
  )
  return win
}

app.on('window-all-closed', () => {})

app.whenReady().then(async () => {
  const win = createRenderWindow()
  const renderHtml = path.join(process.cwd(), 'server', 'render.html')
  await win.loadURL(pathToFileURL(renderHtml).toString())
  await win.webContents.executeJavaScript(`window.__animatrInit(${JSON.stringify(scene)})`, true)
  await win.webContents.executeJavaScript('window.__animatrSeek(0)', true)
  const img = await win.webContents.capturePage({ x: 0, y: 0, width: 160, height: 120 })
  const bmp = img.getBitmap() // BGRA

  // Sample a corner pixel (far from the red rect at 30,30): index 0 == (0,0).
  const corner = { b: bmp[0], g: bmp[1], r: bmp[2], a: bmp[3] }
  let white = 0
  let black = 0
  for (let i = 0; i < bmp.length; i += 4) {
    if (bmp[i] > 240 && bmp[i + 1] > 240 && bmp[i + 2] > 240) white++
    if (bmp[i] < 15 && bmp[i + 1] < 15 && bmp[i + 2] < 15) black++
  }

  const notes = []
  let pass = true
  if (!(corner.r > 240 && corner.g > 240 && corner.b > 240)) {
    pass = false
    notes.push(`corner is not white: rgb(${corner.r},${corner.g},${corner.b})`)
  }
  if (black > 100) {
    pass = false
    notes.push(`${black} near-black px present (transparent flattened to black?)`)
  }

  console.log(`corner=rgb(${corner.r},${corner.g},${corner.b}) whitePx=${white} blackPx=${black}`)
  console.log(notes.length ? 'NOTES:\n  ' + notes.join('\n  ') : 'NOTES: none')
  console.log(pass ? 'RESULT: PASS' : 'RESULT: FAIL')
  if (!win.isDestroyed()) win.close()
  app.exit(pass ? 0 : 1)
})