package utils

import (
	"bytes"
	"io"

	"github.com/lucas-clemente/quic-go/protocol"
)

// A ByteOrder specifies how to convert byte sequences into 16-, 32-, or 64-bit unsigned integers.
type ByteOrder interface {
	ReadUintN(b io.ByteReader, length uint8) (uint64, error)
	ReadUint64(io.ByteReader) (uint64, error)
	ReadUint32(io.ByteReader) (uint32, error)
	ReadUint16(io.ByteReader) (uint16, error)

	WriteUint64(*bytes.Buffer, uint64)
	WriteUint56(*bytes.Buffer, uint64)
	WriteUint48(*bytes.Buffer, uint64)
	WriteUint40(*bytes.Buffer, uint64)
	WriteUint32(*bytes.Buffer, uint32)
	WriteUint24(*bytes.Buffer, uint32)
	WriteUint16(*bytes.Buffer, uint16)

	ReadUfloat16(io.ByteReader) (uint64, error)
	WriteUfloat16(*bytes.Buffer, uint64)
}

// GetByteOrder gets the ByteOrder (little endian or big endian) used to represent values on the wire
// from QUIC 39, values are encoded in big endian, before that in little endian
func GetByteOrder(v protocol.VersionNumber) ByteOrder {
	if v < protocol.Version39 {
		return LittleEndian
	}
	return BigEndian
}