peanats/msg.go at main · mikluko/peanats · GitHub

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package peanats

import (
	"context"
	"net/textproto"
	"time"

	"github.com/nats-io/nats.go"
	"github.com/nats-io/nats.go/jetstream"

	"github.com/mikluko/peanats/codec"
)

type Header = textproto.MIMEHeader

type Msg interface {
	Subject() string
	Header() Header
	Data() []byte
}

type Metadatable interface {
	Metadata() (*jetstream.MsgMetadata, error)
}

type Respondable interface {
	Respond(context.Context, any) error
	RespondHeader(context.Context, any, Header) error
	RespondMsg(context.Context, Msg) error
}

type Ackable interface {
	Ack(context.Context) error
	Nak(context.Context) error
	NackWithDelay(context.Context, time.Duration) error
	Term(context.Context) error
	TermWithReason(context.Context, string) error
	InProgress(context.Context) error
}

type MsgJetstream interface {
	Msg
	Metadatable
	Ackable
}

type MsgHandler interface {
	HandleMsg(context.Context, Msg) error
}

type MsgHandlerFunc func(context.Context, Msg) error

func (f MsgHandlerFunc) HandleMsg(ctx context.Context, m Msg) error {
	return f(ctx, m)
}

type MsgMiddleware func(MsgHandler) MsgHandler

func ChainMsgMiddleware(h MsgHandler, mw ...MsgMiddleware) MsgHandler {
	for i := range mw {
		h = mw[i](h)
	}
	return h
}

func NewMsg(m *nats.Msg) Msg {
	return &msgImpl{m, nil}
}

type msgImpl struct {
	*nats.Msg
	header Header
}

func (m *msgImpl) Subject() string {
	return m.Msg.Subject
}

func (m *msgImpl) Header() Header {
	if m.header == nil {
		m.header = canonicalizeHeader(m.Msg.Header)
	}
	return m.header
}

func (m *msgImpl) Data() []byte {
	return m.Msg.Data
}

func (m *msgImpl) Respond(ctx context.Context, x any) error {
	return m.RespondHeader(ctx, x, nil)
}

func (m *msgImpl) RespondHeader(_ context.Context, x any, header Header) error {
	if header == nil {
		header = make(Header)
	}
	data, err := codec.MarshalHeader(x, header)
	if err != nil {
		return err
	}
	return m.Msg.RespondMsg(&nats.Msg{
		Data:   data,
		Header: nats.Header(header),
	})
}

func (m *msgImpl) RespondMsg(_ context.Context, msg Msg) error {
	return m.Msg.RespondMsg(&nats.Msg{
		Data:   msg.Data(),
		Header: nats.Header(msg.Header()),
	})
}

func NewJetstream(m jetstream.Msg) MsgJetstream {
	return &msgJetstreamImpl{m, nil}
}

type msgJetstreamImpl struct {
	jetstream.Msg
	header Header
}

func (m *msgJetstreamImpl) Ack(_ context.Context) error {
	return m.Msg.Ack()
}

func (m *msgJetstreamImpl) Nak(_ context.Context) error {
	return m.Msg.Nak()
}

func (m *msgJetstreamImpl) NackWithDelay(_ context.Context, d time.Duration) error {
	return m.Msg.NakWithDelay(d)
}

func (m *msgJetstreamImpl) Term(_ context.Context) error {
	return m.Msg.Term()
}

func (m *msgJetstreamImpl) TermWithReason(_ context.Context, s string) error {
	return m.Msg.TermWithReason(s)
}

func (m *msgJetstreamImpl) InProgress(_ context.Context) error {
	return m.Msg.InProgress()
}

func (m *msgJetstreamImpl) Header() Header {
	if m.header == nil {
		m.header = canonicalizeHeader(m.Msg.Headers())
	}
	return m.header
}

// canonicalizeHeader converts a nats.Header to a Header with keys canonicalization.
func canonicalizeHeader(h nats.Header) Header {
	if h == nil {
		return make(Header)
	}
	canonical := make(Header, len(h))
	for k, v := range h {
		canonical[textproto.CanonicalMIMEHeaderKey(k)] = v
	}
	return canonical
}