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

	// 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.
func (, ,  bool) *FrameParser {
	return &FrameParser{
		supportsDatagrams:     ,
		supportsResetStreamAt: ,
		supportsAckFrequency:  ,
		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))
		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(, )
	case FrameTypeRetireConnectionID:
		, ,  = parseRetireConnectionIDFrame(, )
	case FrameTypePathChallenge:
		, ,  = parsePathChallengeFrame(, )
	case FrameTypePathResponse:
		, ,  = parsePathResponseFrame(, )
	case FrameTypeConnectionClose, FrameTypeApplicationClose:
		, ,  = parseConnectionCloseFrame(, , )
	case FrameTypeHandshakeDone:
		 = &HandshakeDoneFrame{}
	case FrameTypeResetStreamAt:
		, ,  = parseResetStreamFrame(, true, )
	case FrameTypeAckFrequency:
		, ,  = parseAckFrequencyFrame(, )
	case FrameTypeImmediateAck:
		 = &ImmediateAckFrame{}
	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 = 
}

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