package encoding

import (
	"encoding/json"
	"fmt"

	"google.golang.org/grpc/encoding"
	"google.golang.org/protobuf/encoding/protojson"
)

// JSONCodec is easyjson codec used for code generated by protogen.
// It is binary-level compatible with the standard protojson format, thus uses the same name.
type JSONCodec struct{}

var _ encoding.Codec = JSONCodec{}

func init() {
	encoding.RegisterCodec(JSONCodec{})
}

// Name implements the encoding.Codec interface.
func (JSONCodec) Name() string { return "json" }

// Marshal implements the encoding.Codec interface.
func (JSONCodec) Marshal(v any) ([]byte, error) {
	switch v := v.(type) {
	case json.Marshaler:
		return json.Marshal(v)
	default:
		if v := messageV2Of(v); v != nil {
			return protojson.Marshal(v)
		}
		return nil, fmt.Errorf("failed to marshal, message is %T, want proto.Message", v)
	}
}

// Unmarshal implements the encoding.Codec interface.
func (JSONCodec) Unmarshal(data []byte, v any) error {
	switch v := v.(type) {
	case json.Unmarshaler:
		return json.Unmarshal(data, v)
	default:
		if v := messageV2Of(v); v != nil {
			return protojson.Unmarshal(data, v)
		}
		return fmt.Errorf("failed to unmarshal, message is %T, want proto.Message", v)
	}
}