const assert = require('node:assert/strict');
const fs = require('node:fs');
const path = require('node:path');
const vm = require('node:vm');

const html = fs.readFileSync(path.join(__dirname, '../src/renderer/public/slam-viewer/index.html'), 'utf8');
const source = html.slice(html.indexOf('function hasLiveCameraState()'), html.indexOf("cameraPreview?.addEventListener('load'"));
let now = 10000;
let requests = 0;
let ok = true;
let visible = false;
let afterBlob = () => {};
const context = vm.createContext({
  ENABLE_CAMERA_PREVIEW: true,
  cameraFrameRequestInFlight: false,
  cameraFrameRetryAt: 0,
  cameraFrameObjectUrl: null,
  cameraPreview: {},
  latestSlamState: null,
  latestSlamStateReceivedAt: now,
  document: { hidden: false },
  Date: { now: () => now },
  BACKEND_URL: 'http://localhost:8765',
  AbortSignal,
  URL: { createObjectURL: () => 'blob:frame', revokeObjectURL() {} },
  setCameraPreviewAvailable(value) { visible = value; },
  async fetch() {
    requests++;
    return { ok, async blob() { afterBlob(); return {}; } };
  },
});
vm.runInContext(source, context);
const refresh = () => context.refreshCameraFrame();
const available = (value) => {
  context.latestSlamState = { topic_status: { camera_image: { available: value } } };
  context.latestSlamStateReceivedAt = now;
};

(async () => {
  await refresh();
  available(false);
  await refresh();
  assert.equal(requests, 0, 'Absent camera must not fetch frames');
  available(true);
  await refresh();
  assert.equal(requests, 1);
  assert.equal(context.cameraPreview.src, 'blob:frame');
  now += 3001;
  await refresh();
  assert.equal(requests, 1, 'Stale websocket state must stop polling');
  assert.equal(visible, false);
  available(true);
  ok = false;
  await refresh();
  await refresh();
  assert.equal(requests, 2, 'HTTP errors must back off');
  now += 5000;
  available(true);
  ok = true;
  afterBlob = () => available(false);
  context.cameraPreview.src = '';
  await refresh();
  assert.equal(context.cameraPreview.src, '', 'Late responses must not revive a disconnected camera');
  assert.equal(context.cameraFrameRequestInFlight, false);
  afterBlob = () => {};
  available(true);
  await refresh();
  assert.equal(context.cameraPreview.src, 'blob:frame', 'Camera reconnect must resume frames');
  console.log('camera preview polling tests passed');
})().catch((error) => { console.error(error); process.exitCode = 1; });