package pubsub

import (
	"context"
	"time"

	telemetrypb "git.wntrmute.dev/kyle/sensenet/proto"
	"github.com/go-zeromq/zmq4"
	"google.golang.org/protobuf/proto"
)

type Publisher struct {
	addr string
	sock zmq4.Socket
}

func NewPublisher(addr string) (*Publisher, error) {
	pub := &Publisher{
		addr: addr,
		sock: zmq4.NewPub(context.Background()),
	}

	pub.Conflate(1)
	err := pub.connect()
	if err != nil {
		return nil, err
	}

	return pub, nil
}

func (pub *Publisher) connect() error {
	return pub.sock.Listen(pub.addr)
}

func (pub *Publisher) Conflate(n int) {
	pub.sock.SetOption("CONFLATE", n)
}

func (pub *Publisher) Transmit(topic string, data []byte) error {
	packet, err := genPacket(topic, data)
	if err != nil {
		return err
	}

	msg := zmq4.Msg{
		Frames: [][]byte{packet},
	}

	return pub.sock.Send(msg)
}

func genPacket(topic string, payload []byte) ([]byte, error) {
	packet := &telemetrypb.Packet{
		Topic:     topic,
		Timestamp: uint64(time.Now().Unix()),
		Payload:   payload,
	}

	return proto.Marshal(packet)
}