package json

import (
	"encoding/json"
	"fmt"

	"git.loafle.net/commons/rpc-go/protocol"
)

// ----------------------------------------------------------------------------
// ClientResponseCodec
// ----------------------------------------------------------------------------
// clientResponse represents a JSON-RPC response returned to a client.
type clientResponse struct {
	Version string           `json:"jsonrpc"`
	Result  *json.RawMessage `json:"result,omitempty"`
	Error   *protocol.Error  `json:"error,omitempty"`
	ID      interface{}      `json:"id,omitempty"`
}

// ClientResponseCodec decodes and encodes a single request.
type ClientResponseCodec struct {
	res *clientResponse
}

func (crc *ClientResponseCodec) ID() interface{} {
	return crc.res.ID
}

func (crc *ClientResponseCodec) Result(result interface{}) error {
	if nil == crc.res.Error && nil != crc.res.Result {
		if err := json.Unmarshal(*crc.res.Result, result); nil != err {
			return err
		}
		return nil
	}

	return fmt.Errorf("There is no result")
}

func (crc *ClientResponseCodec) Error() *protocol.Error {
	return crc.res.Error
}

func (crc *ClientResponseCodec) Notification() (protocol.ClientNotificationCodec, error) {
	if nil != crc.res.ID || nil == crc.res.Result {
		return nil, fmt.Errorf("This is not notification")
	}

	noti := &clientNotification{}
	err := json.Unmarshal(*crc.res.Result, noti)
	if nil != err {
		return nil, err
	}

	return &ClientNotificationCodec{noti: noti}, nil
}

// newClientMessageCodec returns a new ClientMessageCodec.
func newClientResponseCodec(buf []byte) (protocol.ClientResponseCodec, error) {

	res := &clientResponse{}
	err := json.Unmarshal(buf, res)

	if err != nil {
		return nil, fmt.Errorf("Cannot unmarshal response [%s] err: %v", string(buf), err)
	}
	if res.Version != Version {
		return nil, fmt.Errorf("The protocol version of response[%s] is not %s", string(buf), Version)
	}

	return &ClientResponseCodec{res: res}, nil
}