createReadStream: function createReadStream()

in lib/request.js [568:673]
87 lines of code
17 McCabe index (conditional complexity)

  createReadStream: function createReadStream() {
    var streams = AWS.util.stream;
    var req = this;
    var stream = null;

    if (AWS.HttpClient.streamsApiVersion === 2) {
      stream = new streams.PassThrough();
      process.nextTick(function() { req.send(); });
    } else {
      stream = new streams.Stream();
      stream.readable = true;

      stream.sent = false;
      stream.on('newListener', function(event) {
        if (!stream.sent && event === 'data') {
          stream.sent = true;
          process.nextTick(function() { req.send(); });
        }
      });
    }

    this.on('error', function(err) {
      stream.emit('error', err);
    });

    this.on('httpHeaders', function streamHeaders(statusCode, headers, resp) {
      if (statusCode < 300) {
        req.removeListener('httpData', AWS.EventListeners.Core.HTTP_DATA);
        req.removeListener('httpError', AWS.EventListeners.Core.HTTP_ERROR);
        req.on('httpError', function streamHttpError(error) {
          resp.error = error;
          resp.error.retryable = false;
        });

        var shouldCheckContentLength = false;
        var expectedLen;
        if (req.httpRequest.method !== 'HEAD') {
          expectedLen = parseInt(headers['content-length'], 10);
        }
        if (expectedLen !== undefined && !isNaN(expectedLen) && expectedLen >= 0) {
          shouldCheckContentLength = true;
          var receivedLen = 0;
        }

        var checkContentLengthAndEmit = function checkContentLengthAndEmit() {
          if (shouldCheckContentLength && receivedLen !== expectedLen) {
            stream.emit('error', AWS.util.error(
              new Error('Stream content length mismatch. Received ' +
                receivedLen + ' of ' + expectedLen + ' bytes.'),
              { code: 'StreamContentLengthMismatch' }
            ));
          } else if (AWS.HttpClient.streamsApiVersion === 2) {
            stream.end();
          } else {
            stream.emit('end');
          }
        };

        var httpStream = resp.httpResponse.createUnbufferedStream();

        if (AWS.HttpClient.streamsApiVersion === 2) {
          if (shouldCheckContentLength) {
            var lengthAccumulator = new streams.PassThrough();
            lengthAccumulator._write = function(chunk) {
              if (chunk && chunk.length) {
                receivedLen += chunk.length;
              }
              return streams.PassThrough.prototype._write.apply(this, arguments);
            };

            lengthAccumulator.on('end', checkContentLengthAndEmit);
            stream.on('error', function(err) {
              shouldCheckContentLength = false;
              httpStream.unpipe(lengthAccumulator);
              lengthAccumulator.emit('end');
              lengthAccumulator.end();
            });
            httpStream.pipe(lengthAccumulator).pipe(stream, { end: false });
          } else {
            httpStream.pipe(stream);
          }
        } else {

          if (shouldCheckContentLength) {
            httpStream.on('data', function(arg) {
              if (arg && arg.length) {
                receivedLen += arg.length;
              }
            });
          }

          httpStream.on('data', function(arg) {
            stream.emit('data', arg);
          });
          httpStream.on('end', checkContentLengthAndEmit);
        }

        httpStream.on('error', function(err) {
          shouldCheckContentLength = false;
          stream.emit('error', err);
        });
      }
    });

    return stream;
  },