package rasrush

import (
	"bytes"

	"github.com/nsqio/go-nsq"
	"github.com/pkg/errors"
	"github.com/vmihailenco/msgpack/v5"
)

type Marshaler interface {
	Marshal(topic string, msg *Event) ([]byte, error)
}

type Unmarshaler interface {
	Unmarshal(*nsq.Message) (*Event, error)
}

type MsgPackMarshaler struct{}

func (MsgPackMarshaler) Marshal(topic string, msg *Event) ([]byte, error) {
	// buffer holder
	buf := bytes.Buffer{}
	// create encoder
	encoder := msgpack.NewEncoder(&buf)
	// encode message
	if err := encoder.Encode(msg); err != nil {
		return nil, errors.Wrap(err, "cannot encode message")
	}
	// return encoded message
	return buf.Bytes(), nil
}

func (MsgPackMarshaler) Unmarshal(data []byte) (*Event, error) {
	// buffer holder
	buf := new(bytes.Buffer)
	// write message data to buffer
	_, err := buf.Write(data)
	if err != nil {
		return nil, errors.Wrap(err, "cannot write data buffer")
	}
	// create decoder
	decoder := msgpack.NewDecoder(buf)
	// decode event from buffer message
	var decodedEvent Event
	// decode message
	if err := decoder.Decode(&decodedEvent); err != nil {
		return nil, errors.Wrap(err, "cannot decode message")
	}
	// return decoded message
	return &decodedEvent, nil
}