video-workflow/server/routes/video-download.js

function registerVideoDownloadRoutes(app, deps) {
  const {
    path,
    fs,
    crypto,
    Readable,
    Transform,
    pipeline,
    dataVideoDir,
    downloadTasks,
    normalizeRemoteUrls,
    ensureVideoFilename,
    ensureUniqueVideoFilename,
    fetchRemoteVideoResponse,
    createManagedVideoEntry,
    readManifest,
    writeManifest,
    removeFileIfExists,
  } = deps;

  app.post('/api/download/video', (req, res) => {
    const {
      url,
      urls,
      filename,
      title,
      description,
      tags,
      thumbnail,
      duration,
      resolution,
      awemeId,
      authorName,
    } = req.body || {};

    if (!url || typeof url !== 'string') {
      return res.status(400).json({ error: '缺少 url 参数' });
    }

    const candidateUrls = normalizeRemoteUrls(url, urls);
    if (candidateUrls.length === 0) {
      return res.status(400).json({ error: '无效的视频地址' });
    }

    const safeFilename = ensureUniqueVideoFilename(ensureVideoFilename(filename || title || awemeId || 'douyin-video.mp4', url));
    const filePath = path.join(dataVideoDir, safeFilename);
    const taskId = `DL-${Date.now()}-${crypto.randomBytes(4).toString('hex')}`;
    const task = {
      id: taskId,
      status: 'pending',
      progress: 0,
      downloadedBytes: 0,
      totalBytes: 0,
      filename: safeFilename,
      created_at: new Date().toISOString(),
    };

    downloadTasks.set(taskId, task);
    res.json({ success: true, taskId, filename: safeFilename });

    (async () => {
      try {
        task.status = 'downloading';
        console.log(`📥 开始下载远程视频: ${safeFilename} ← ${candidateUrls[0]}`);

        const { url: resolvedUrl, response } = await fetchRemoteVideoResponse(candidateUrls, {
          Accept: '*/*',
          'User-Agent': 'Mozilla/5.0',
          Referer: 'https://www.douyin.com/',
          Origin: 'https://www.douyin.com',
        });
        task.sourceUrl = resolvedUrl;

        const totalBytes = Number.parseInt(response.headers.get('content-length') || '0', 10) || 0;
        task.totalBytes = totalBytes;

        let downloadedBytes = 0;
        let chunkCount = 0;

        const progressStream = new Transform({
          transform(chunk, encoding, callback) {
            downloadedBytes += chunk.length;
            chunkCount += 1;
            task.downloadedBytes = downloadedBytes;
            task.progress = totalBytes > 0
              ? Math.min(99, Math.round((downloadedBytes / totalBytes) * 100))
              : Math.min(95, Math.max(task.progress || 0, Math.min(95, chunkCount)));
            callback(null, chunk);
          },
        });

        await pipeline(
          Readable.fromWeb(response.body),
          progressStream,
          fs.createWriteStream(filePath),
        );

        const stat = fs.statSync(filePath);
        const manifest = readManifest();
        const videoEntry = createManagedVideoEntry({
          filename: safeFilename,
          title,
          description,
          tags,
          thumbnail,
          duration,
          resolution,
          awemeId,
          authorName,
          size: stat.size,
        });

        manifest.push(videoEntry);
        writeManifest(manifest);

        task.status = 'completed';
        task.progress = 100;
        task.completed_at = new Date().toISOString();
        task.video = videoEntry;

        console.log(`✅ 远程视频下载完成: ${safeFilename} (${(stat.size / 1024 / 1024).toFixed(1)}MB)`);
      } catch (error) {
        removeFileIfExists(filePath);
        task.status = 'failed';
        task.error = error.message;
        task.failed_at = new Date().toISOString();
        console.error('❌ 远程视频下载失败:', error);
      }
    })();
  });

  app.get('/api/download/video/:taskId', (req, res) => {
    const task = downloadTasks.get(req.params.taskId);
    if (!task) {
      return res.status(404).json({ error: '未找到下载任务' });
    }

    res.json(task);
  });
}

module.exports = { registerVideoDownloadRoutes };