package wire

import (
	
	
	

	
	
	
)

var errUnknownFrameType = errors.New("unknown frame type")

// The FrameParser parses QUIC frames, one by one.
type FrameParser struct {
	ackDelayExponent         uint8
	supportsDatagrams        bool
	supportsResetStreamAt    bool
	supportsAckFrequency     bool
	supportsMultipath        bool
	supportsAddressDiscovery bool
	supportsNATTraversal     bool

	// To avoid allocating when parsing, keep a single ACK frame struct.
	// It is used over and over again.
	ackFrame *AckFrame
}

// NewFrameParser creates a new frame parser. supportsMultipath admits the QUIC
// multipath frame types (draft-ietf-quic-multipath); it is false unless the
// connection has negotiated multipath, so single-path parsing is unchanged.
func (, , ,  bool) *FrameParser {
	return &FrameParser{
		supportsDatagrams:     ,
		supportsResetStreamAt: ,
		supportsAckFrequency:  ,
		supportsMultipath:     ,
		ackFrame:              &AckFrame{},
	}
}

// ParseType parses the frame type of the next frame.
// It skips over PADDING frames.
func ( *FrameParser) ( []byte,  protocol.EncryptionLevel) (FrameType, int, error) {
	var  int
	for len() != 0 {
		, ,  := quicvarint.Parse()
		 += 
		if  != nil {
			return 0, , &qerr.TransportError{
				ErrorCode:    qerr.FrameEncodingError,
				ErrorMessage: .Error(),
			}
		}
		 = [:]
		if  == 0x0 { // skip PADDING frames
			continue
		}
		 := FrameType()
		 := .isValidRFC9000() ||
			(.supportsDatagrams && .IsDatagramFrameType()) ||
			(.supportsResetStreamAt &&  == FrameTypeResetStreamAt) ||
			(.supportsAckFrequency && ( == FrameTypeAckFrequency ||  == FrameTypeImmediateAck)) ||
			(.supportsMultipath && .isMultipathFrameType()) ||
			(.supportsAddressDiscovery && .isAddressDiscoveryFrameType()) ||
			(.supportsNATTraversal && .isNATTraversalFrameType())
		if ! {
			return 0, , &qerr.TransportError{
				ErrorCode:    qerr.FrameEncodingError,
				FrameType:    ,
				ErrorMessage: errUnknownFrameType.Error(),
			}
		}
		if !.isAllowedAtEncLevel() {
			return 0, , &qerr.TransportError{
				ErrorCode:    qerr.FrameEncodingError,
				FrameType:    ,
				ErrorMessage: fmt.Sprintf("%d not allowed at encryption level %s", , ),
			}
		}
		return , , nil
	}
	return 0, , io.EOF
}

func ( *FrameParser) ( FrameType,  []byte,  protocol.Version) (*StreamFrame, int, error) {
	, ,  := ParseStreamFrame(, , )
	if  != nil {
		return nil, , &qerr.TransportError{
			ErrorCode:    qerr.FrameEncodingError,
			FrameType:    uint64(),
			ErrorMessage: .Error(),
		}
	}
	return , , nil
}

func ( *FrameParser) ( FrameType,  []byte,  protocol.EncryptionLevel,  protocol.Version) (*AckFrame, int, error) {
	 := .ackDelayExponent
	if  != protocol.Encryption1RTT {
		 = protocol.DefaultAckDelayExponent
	}
	.ackFrame.Reset()
	,  := parseAckFrame(.ackFrame, , , , )
	if  != nil {
		return nil, , &qerr.TransportError{
			ErrorCode:    qerr.FrameEncodingError,
			FrameType:    uint64(),
			ErrorMessage: .Error(),
		}
	}

	return .ackFrame, , nil
}

func ( *FrameParser) ( FrameType,  []byte,  protocol.Version) (*DatagramFrame, int, error) {
	, ,  := parseDatagramFrame(, , )
	if  != nil {
		return nil, 0, &qerr.TransportError{
			ErrorCode:    qerr.FrameEncodingError,
			FrameType:    uint64(),
			ErrorMessage: .Error(),
		}
	}
	return , , nil
}

// ParseLessCommonFrame parses everything except STREAM, ACK or DATAGRAM.
// These cases should be handled separately for performance reasons.
func ( *FrameParser) ( FrameType,  []byte,  protocol.Version) (Frame, int, error) {
	var  Frame
	var  int
	var  error
	//nolint:exhaustive // Common frames should already be handled.
	switch  {
	case FrameTypePing:
		 = &PingFrame{}
	case FrameTypeResetStream:
		, ,  = parseResetStreamFrame(, false, )
	case FrameTypeStopSending:
		, ,  = parseStopSendingFrame(, )
	case FrameTypeCrypto:
		, ,  = parseCryptoFrame(, )
	case FrameTypeNewToken:
		, ,  = parseNewTokenFrame(, )
	case FrameTypeMaxData:
		, ,  = parseMaxDataFrame(, )
	case FrameTypeMaxStreamData:
		, ,  = parseMaxStreamDataFrame(, )
	case FrameTypeBidiMaxStreams, FrameTypeUniMaxStreams:
		, ,  = parseMaxStreamsFrame(, , )
	case FrameTypeDataBlocked:
		, ,  = parseDataBlockedFrame(, )
	case FrameTypeStreamDataBlocked:
		, ,  = parseStreamDataBlockedFrame(, )
	case FrameTypeBidiStreamBlocked, FrameTypeUniStreamBlocked:
		, ,  = parseStreamsBlockedFrame(, , )
	case FrameTypeNewConnectionID:
		, ,  = parseNewConnectionIDFrame(, false, )
	case FrameTypeRetireConnectionID:
		, ,  = parseRetireConnectionIDFrame(, false, )
	case FrameTypePathChallenge:
		, ,  = parsePathChallengeFrame(, )
	case FrameTypePathResponse:
		, ,  = parsePathResponseFrame(, )
	case FrameTypeConnectionClose, FrameTypeApplicationClose:
		, ,  = parseConnectionCloseFrame(, , )
	case FrameTypeHandshakeDone:
		 = &HandshakeDoneFrame{}
	case FrameTypeResetStreamAt:
		, ,  = parseResetStreamFrame(, true, )
	case FrameTypeAckFrequency:
		, ,  = parseAckFrequencyFrame(, )
	case FrameTypeImmediateAck:
		 = &ImmediateAckFrame{}
	// QUIC Address Discovery OBSERVED_ADDRESS frames
	// (draft-seemann-quic-address-discovery). ParseType only routes here when
	// supportsAddressDiscovery is set, so these cases are inert until QAD is
	// negotiated. The frame type selects the address family (frame.rs:1665-1668).
	case FrameTypeObservedIPv4Addr:
		, ,  = parseObservedAddrFrame(, false, )
	case FrameTypeObservedIPv6Addr:
		, ,  = parseObservedAddrFrame(, true, )
	// QUIC multipath frames (draft-ietf-quic-multipath). ParseType only routes
	// here when supportsMultipath is set, so these cases are inert single-path.
	// PATH_ACK/PATH_ACK_ECN are not base ACK types (IsAckFrameType is false for
	// 0x3e/0x3f), so they arrive here rather than in ParseAckFrame; multipath is
	// 1-RTT only, so the negotiated ack delay exponent always applies.
	case FrameTypePathAck:
		, ,  = parsePathAckFrame(, false, .ackDelayExponent, )
	case FrameTypePathAckECN:
		, ,  = parsePathAckFrame(, true, .ackDelayExponent, )
	case FrameTypePathAbandon:
		, ,  = parsePathAbandonFrame(, )
	case FrameTypePathStatusBackup:
		, ,  = parsePathStatusBackupFrame(, )
	case FrameTypePathStatusAvailable:
		, ,  = parsePathStatusAvailableFrame(, )
	case FrameTypePathNewConnectionID:
		, ,  = parseNewConnectionIDFrame(, true, )
	case FrameTypePathRetireConnectionID:
		, ,  = parseRetireConnectionIDFrame(, true, )
	case FrameTypeMaxPathID:
		, ,  = parseMaxPathIDFrame(, )
	case FrameTypePathsBlocked:
		, ,  = parsePathsBlockedFrame(, )
	case FrameTypePathCIDsBlocked:
		, ,  = parsePathCIDsBlockedFrame(, )
	// n0 NAT traversal frames. ParseType only routes here when
	// supportsNATTraversal is set, so these cases are inert until QNT is
	// negotiated. The frame type selects the address family.
	case FrameTypeAddIPv4Address:
		, ,  = parseAddAddressFrame(, false, )
	case FrameTypeAddIPv6Address:
		, ,  = parseAddAddressFrame(, true, )
	case FrameTypeReachOutAtIPv4:
		, ,  = parseReachOutFrame(, false, )
	case FrameTypeReachOutAtIPv6:
		, ,  = parseReachOutFrame(, true, )
	case FrameTypeRemoveAddress:
		, ,  = parseRemoveAddressFrame(, )
	default:
		 = errUnknownFrameType
	}
	if  != nil {
		return , , &qerr.TransportError{
			ErrorCode:    qerr.FrameEncodingError,
			FrameType:    uint64(),
			ErrorMessage: .Error(),
		}
	}
	return , , 
}

// SetAckDelayExponent sets the acknowledgment delay exponent (sent in the transport parameters).
// This value is used to scale the ACK Delay field in the ACK frame.
func ( *FrameParser) ( uint8) {
	.ackDelayExponent = 
}

// SetSupportsMultipath admits the QUIC multipath frame types
// (draft-ietf-quic-multipath). It is set after the handshake, once both peers
// have advertised the initial_max_path_id transport parameter. Before that the
// parser stays in single-path mode and rejects multipath frames as unknown.
func ( *FrameParser) ( bool) {
	.supportsMultipath = 
}

// SetSupportsAddressDiscovery admits the QUIC Address Discovery
// OBSERVED_ADDRESS frame types (draft-seemann-quic-address-discovery). It is set
// after the handshake, once the peer's address-discovery role permits it to
// report observed addresses to us (i.e. peer.should_report(local) is true).
// Before that the parser rejects OBSERVED_ADDRESS frames as unknown, keeping
// un-negotiated connections byte-identical.
func ( *FrameParser) ( bool) {
	.supportsAddressDiscovery = 
}

// SetSupportsNATTraversal admits the n0 NAT traversal frame types. It is set
// after the handshake once both peers negotiated the n0_nat_traversal transport
// parameter. Before that the parser rejects QNT frames as unknown.
func ( *FrameParser) ( bool) {
	.supportsNATTraversal = 
}

func replaceUnexpectedEOF( error) error {
	if  == io.ErrUnexpectedEOF {
		return io.EOF
	}
	return 
}