class QuicPacketBuilder:
    """
    Helper for building QUIC packets.
    """

    def __init__(
        self,
        *,
        host_cid: bytes,
        peer_cid: bytes,
        version: int,
        is_client: bool,
        max_datagram_size: int,
        packet_number: int = 0,
        peer_token: bytes = b"",
        quic_logger: Optional[QuicLoggerTrace] = None,
        spin_bit: bool = False,
    ):
        self.max_flight_bytes: Optional[int] = None
        self.max_total_bytes: Optional[int] = None
        self.quic_logger_frames: Optional[List[Dict]] = None

        self._host_cid = host_cid
        self._is_client = is_client
        self._peer_cid = peer_cid
        self._peer_token = peer_token
        self._quic_logger = quic_logger
        self._spin_bit = spin_bit
        self._version = version

        # assembled datagrams and packets
        self._datagrams: List[bytes] = []
        self._datagram_flight_bytes = 0
        self._datagram_init = True
        self._datagram_needs_padding = False
        self._packets: List[QuicSentPacket] = []
        self._flight_bytes = 0
        self._total_bytes = 0

        # current packet
        self._header_size = 0
        self._packet: Optional[QuicSentPacket] = None
        self._packet_crypto: Optional[CryptoPair] = None
        self._packet_number = packet_number
        self._packet_start = 0
        self._packet_type: Optional[QuicPacketType] = None

        self._buffer = Buffer(max_datagram_size)
        self._buffer_capacity = max_datagram_size
        self._flight_capacity = max_datagram_size