// Package logtransport provides a transport that logs all of its messages.
package tunnelrpc

import (
	"bytes"
	"context"

	"github.com/rs/zerolog"
	"zombiezen.com/go/capnproto2/encoding/text"
	"zombiezen.com/go/capnproto2/rpc"
	rpccapnp "zombiezen.com/go/capnproto2/std/capnp/rpc"
)

type transport struct {
	rpc.Transport
	log *zerolog.Logger
}

// NewTransportLogger creates a new logger that proxies messages to and from t and
// logs them to log.  If log is nil, then the log package's default
// logger is used.
func NewTransportLogger(log *zerolog.Logger, t rpc.Transport) rpc.Transport {
	return &transport{Transport: t, log: log}
}

func (t *transport) SendMessage(ctx context.Context, msg rpccapnp.Message) error {
	t.log.Trace().Msgf("rpc tx: %s", formatMsg(msg))
	return t.Transport.SendMessage(ctx, msg)
}

func (t *transport) RecvMessage(ctx context.Context) (rpccapnp.Message, error) {
	msg, err := t.Transport.RecvMessage(ctx)
	if err != nil {
		t.log.Debug().Msgf("rpc rx error: %s", err)
		return msg, err
	}
	t.log.Trace().Msgf("rpc rx: %s", formatMsg(msg))
	return msg, nil
}

func formatMsg(m rpccapnp.Message) string {
	var buf bytes.Buffer
	_ = text.NewEncoder(&buf).Encode(0x91b79f1f808db032, m.Struct)
	return buf.String()
}