package wire

import (
	

	
	
)

// MaxDatagramSize is the maximum size of a DATAGRAM frame (RFC 9221).
// By setting it to a large value, we allow all datagrams that fit into a QUIC packet.
// The value is chosen such that it can still be encoded as a 2 byte varint.
// This is a var and not a const so it can be set in tests.
var MaxDatagramSize protocol.ByteCount = 16383

// A DatagramFrame is a DATAGRAM frame
type DatagramFrame struct {
	DataLenPresent bool
	Data           []byte
}

func parseDatagramFrame( []byte,  FrameType,  protocol.Version) (*DatagramFrame, int, error) {
	 := len()
	 := &DatagramFrame{}
	.DataLenPresent = uint64()&0x1 > 0

	var  uint64
	if .DataLenPresent {
		var  error
		var  int
		, ,  = quicvarint.Parse()
		if  != nil {
			return nil, 0, replaceUnexpectedEOF()
		}
		 = [:]
		if  > uint64(len()) {
			return nil, 0, io.EOF
		}
	} else {
		 = uint64(len())
	}
	.Data = make([]byte, )
	copy(.Data, )
	return ,  - len() + int(), nil
}

func ( *DatagramFrame) ( []byte,  protocol.Version) ([]byte, error) {
	 := uint8(0x30)
	if .DataLenPresent {
		 ^= 0b1
	}
	 = append(, )
	if .DataLenPresent {
		 = quicvarint.Append(, uint64(len(.Data)))
	}
	 = append(, .Data...)
	return , nil
}

// MaxDataLen returns the maximum data length
func ( *DatagramFrame) ( protocol.ByteCount,  protocol.Version) protocol.ByteCount {
	 := protocol.ByteCount(1)
	if .DataLenPresent {
		// pretend that the data size will be 1 bytes
		// if it turns out that varint encoding the length will consume 2 bytes, we need to adjust the data length afterwards
		++
	}
	if  >  {
		return 0
	}
	 :=  - 
	if .DataLenPresent && quicvarint.Len(uint64()) != 1 {
		--
	}
	return 
}

// Length of a written frame
func ( *DatagramFrame) ( protocol.Version) protocol.ByteCount {
	 := 1 + protocol.ByteCount(len(.Data))
	if .DataLenPresent {
		 += protocol.ByteCount(quicvarint.Len(uint64(len(.Data))))
	}
	return 
}