fun readLine(): String {
    val line = source.readUtf8LineStrict(headerLimit)
    headerLimit -= line.length.toLong()
    return line
  }

  /** Reads headers or trailers. */
  fun readHeaders(): Headers {
    val result = Headers.Builder()
    while (true) {
      val line = readLine()
      if (line.isEmpty()) break
      result.addLenient(line)
    }
    return result.build()
  }

      throw IOException("Expected a SETTINGS frame but was ${formattedType(type)}")
    }

    when (type) {
      TYPE_DATA -> readData(handler, length, flags, streamId)
      TYPE_HEADERS -> readHeaders(handler, length, flags, streamId)
      TYPE_PRIORITY -> readPriority(handler, length, flags, streamId)
      TYPE_RST_STREAM -> readRstStream(handler, length, flags, streamId)

            throw ProtocolException("unexpected characters after boundary")
          }
        }
      }

      // There's another part. Parse its headers and return it.
      val headers = HeadersReader(source).readHeaders()
      val partSource = PartSource()
      currentPart = partSource
      return Part(headers, partSource.buffer())
    }

      /**
       * Read `byteCount` bytes of headers from the source stream. This implementation does not
       * propagate the never indexed flag of a header.
       */
      @Throws(IOException::class)
      fun readHeaders() {
        while (!source.exhausted()) {
          val b = source.readByte() and 0xff
          when {
            b == 0x80 -> {
              // 10000000
              throw IOException("index == 0")

      val responseBuilder =
        Response
          .Builder()
          .protocol(statusLine.protocol)
          .code(statusLine.code)
          .message(statusLine.message)
          .headers(headersReader.readHeaders())

      return when {
        expectContinue && statusLine.code == HTTP_CONTINUE -> {
          null
        }

        statusLine.code == HTTP_CONTINUE -> {

   */
  @Throws(IOException::class)
  fun processNextFrame() {
    check(!closed) { "closed" }

    readHeader()
    if (isControlFrame) {
      readControlFrame()
    } else {
      readMessageFrame()
    }
  }

  @Throws(IOException::class, ProtocolException::class)
  private fun readHeader() {
    if (receivedCloseFrame) throw IOException("closed")

    if (result == null) {
      result = readHeader()
      peekedHeader = result
    }

    if (result.isEndOfData) return null

    return result
  }

  /**
   * Consume the next header in the stream and return it. If there is no header to read because we
   * have reached a limit, this returns [END_OF_DATA].
   */
  internal fun readHeader(): DerHeader {
    require(peekedHeader == null)