async _processSingleAssetRequest()

in packages/metro/src/Server.js [374:425]
46 lines of code
12 McCabe index (conditional complexity)

  async _processSingleAssetRequest(req: IncomingMessage, res: ServerResponse) {
    const urlObj = url.parse(decodeURI(req.url), true);
    let [, assetPath] =
      (urlObj &&
        urlObj.pathname &&
        urlObj.pathname.match(/^\/assets\/(.+)$/)) ||
      [];

    if (!assetPath && urlObj && urlObj.query && urlObj.query.unstable_path) {
      const [, actualPath, secondaryQuery] = nullthrows(
        urlObj.query.unstable_path.match(/^([^?]*)\??(.*)$/),
      );
      if (secondaryQuery) {
        Object.assign(urlObj.query, querystring.parse(secondaryQuery));
      }
      assetPath = actualPath;
    }

    if (!assetPath) {
      throw new Error('Could not extract asset path from URL');
    }

    const processingAssetRequestLogEntry = log(
      createActionStartEntry({
        action_name: 'Processing asset request',
        asset: assetPath[1],
      }),
    );

    try {
      const data = await getAsset(
        assetPath,
        this._config.projectRoot,
        this._config.watchFolders,
        urlObj.query.platform,
        this._config.resolver.assetExts,
      );
      // Tell clients to cache this for 1 year.
      // This is safe as the asset url contains a hash of the asset.
      if (process.env.REACT_NATIVE_ENABLE_ASSET_CACHING === true) {
        res.setHeader('Cache-Control', 'max-age=31536000');
      }
      res.end(this._rangeRequestMiddleware(req, res, data, assetPath));
      process.nextTick(() => {
        log(createActionEndEntry(processingAssetRequestLogEntry));
      });
    } catch (error) {
      console.error(error.stack);
      res.writeHead(404);
      res.end('Asset not found');
    }
  }