package json

import (
	"encoding/json"
	"io"

	"git.loafle.net/commons_go/rpc/codec"
	"git.loafle.net/commons_go/rpc/protocol"
)

var null = json.RawMessage([]byte("null"))

// ----------------------------------------------------------------------------
// Codec
// ----------------------------------------------------------------------------

// NewCustomServerCodec returns a new JSON Codec based on passed encoder selector.
func NewCustomServerCodec(codecSel codec.CodecSelector) protocol.ServerCodec {
	return &ServerCodec{codecSel: codecSel}
}

// NewServerCodec returns a new JSON Codec.
func NewServerCodec() protocol.ServerCodec {
	return NewCustomServerCodec(codec.DefaultCodecSelector)
}

// ServerCodec creates a ServerRequestCodec to process each request.
type ServerCodec struct {
	codecSel codec.CodecSelector
}

// NewRequest returns a ServerRequestCodec.
func (sc *ServerCodec) NewRequest(r io.Reader) (protocol.ServerRequestCodec, error) {
	return newServerRequestCodec(r, sc.codecSel.SelectByReader(r))
}

// WriteNotification send a notification from server to client.
func (sc *ServerCodec) WriteNotification(w io.Writer, method string, args []interface{}) error {
	params, err := convertParamsToStringArray(args)
	if nil != err {
		return err
	}

	noti := &serverNotification{Method: method, Params: params}
	res := &serverResponse{Version: Version, Result: noti}

	encoder := json.NewEncoder(sc.codecSel.SelectByWriter(w).Encode(w))
	// Not sure in which case will this happen. But seems harmless.
	if err := encoder.Encode(res); nil != err {
		return err
	}
	return nil
}