Future _handle()

in build_runner/lib/src/server/server.dart [318:375]
50 lines of code
12 McCabe index (conditional complexity)

  Future<shelf.Response> _handle(shelf.Request request, AssetId assetId,
      {bool fallbackToDirectoryList = false}) async {
    try {
      try {
        if (!await _reader.canRead(assetId)) {
          var reason = await _reader.unreadableReason(assetId);
          switch (reason) {
            case UnreadableReason.failed:
              return shelf.Response.internalServerError(
                  body: 'Build failed for $assetId');
            case UnreadableReason.notOutput:
              return shelf.Response.notFound('$assetId was not output');
            case UnreadableReason.notFound:
              if (fallbackToDirectoryList) {
                return shelf.Response.notFound(
                    await _findDirectoryList(assetId));
              }
              return shelf.Response.notFound('Not Found');
            default:
              return shelf.Response.notFound('Not Found');
          }
        }
      } on ArgumentError catch (_) {
        return shelf.Response.notFound('Not Found');
      }

      var etag = base64.encode((await _reader.digest(assetId)).bytes);
      var contentType = _typeResolver.lookup(assetId.path);
      if (contentType == 'text/x-dart') {
        contentType = '$contentType; charset=utf-8';
      }
      var headers = <String, Object>{
        if (contentType != null) HttpHeaders.contentTypeHeader: contentType,
        HttpHeaders.etagHeader: etag,
        // We always want this revalidated, which requires specifying both
        // max-age=0 and must-revalidate.
        //
        // See spec https://goo.gl/Lhvttg for more info about this header.
        HttpHeaders.cacheControlHeader: 'max-age=0, must-revalidate',
      };

      if (request.headers[HttpHeaders.ifNoneMatchHeader] == etag) {
        // This behavior is still useful for cases where a file is hit
        // without a cache-busting query string.
        return shelf.Response.notModified(headers: headers);
      }
      List<int>? body;
      if (request.method != 'HEAD') {
        body = await _reader.readAsBytes(assetId);
        headers[HttpHeaders.contentLengthHeader] = '${body.length}';
      }
      return shelf.Response.ok(body, headers: headers);
    } catch (e, s) {
      _logger.finest(
          'Error on request ${request.method} ${request.requestedUri}', e, s);
      rethrow;
    }
  }