borealis.go/message.go

package borealis

import (
	"fmt"

	"github.com/fxamacker/cbor/v2"
)

const (
	V1MessageVersion = 1
	V1MessageMinLen  = 23
)

type V1MessageEncoder struct{}

func (encoder *V1MessageEncoder) Encode(stream string, message interface{}) ([]byte, error) {
	output, err := cbor.Marshal(message)
	if err != nil {
		return nil, err
	}
	return append([]byte{V1MessageVersion}, output...), nil
}

func (encoder *V1MessageEncoder) Decode(stream string, input []byte, messagePtr interface{}) error {
	if len(input) < V1MessageMinLen {
		return fmt.Errorf("expected message length %d+, but got %d", V1MessageMinLen, len(input))
	}
	if input[0] != V1MessageVersion {
		return fmt.Errorf("expected message version %d, but got %d", V1MessageVersion, input[0])
	}
	switch message := messagePtr.(type) {
	case *[]byte:
		*message = input[1:]
		return nil
	default:
		return cbor.Unmarshal(input[1:], message)
	}
}