package encoders

import (
	"github.com/pkg/errors"
	pb "go.unistack.org/unistack-org/pkgdash/proto/go_generate"
	"google.golang.org/protobuf/encoding/protojson"
	"google.golang.org/protobuf/proto"
	"io"
	"net/http"
)

var ErrWrongResponseType = errors.New("JSONProto: wrong response message type")

type JSONProto struct {
	m protojson.MarshalOptions
}

func NewJSONProto() *JSONProto {
	return &JSONProto{m: protojson.MarshalOptions{
		EmitUnpopulated: true,
		UseProtoNames:   false,
	}}
}

func (e *JSONProto) Success(rw http.ResponseWriter, response interface{}) error {
	rw.Header().Set("Content-Type", "application/json; charset=utf-8")
	rw.WriteHeader(http.StatusOK)

	if v, ok := response.(proto.Message); ok {
		return errors.WithStack(e.Fmarshal(rw, v))
	}

	return ErrWrongResponseType
}

func (e *JSONProto) Error(rw http.ResponseWriter, err *pb.Error, status int) error {
	rw.Header().Set("Content-Type", "application/problem+json; charset=utf-8")
	rw.WriteHeader(status)

	return errors.WithStack(e.Fmarshal(rw, &pb.ErrorRsp{Error: err}))
}

func (e *JSONProto) Fmarshal(w io.Writer, m proto.Message) error {
	b, err := e.m.Marshal(m)
	if len(b) > 0 {
		if _, err = w.Write(b); err != nil {
			return err
		}
	}
	return err
}