package json

import (
	"encoding/json"
	"fmt"
	"io"

	"git.loafle.net/commons_go/rpc/codec"
	"git.loafle.net/commons_go/rpc/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   error            `json:"error,omitempty"`
	ID      interface{}      `json:"id,omitempty"`
}

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

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

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

	return crc.err
}

func (crc *ClientResponseCodec) Error() 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("RPC[JSON]: This is not notification")
	}

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

	return &ClientNotificationCodec{noti: noti, err: err, codec: crc.codec}, nil
}

// newClientMessageCodec returns a new ClientMessageCodec.
func newClientResponseCodec(r io.Reader, codec codec.Codec) (protocol.ClientResponseCodec, error) {
	decoder := json.NewDecoder(r)
	if nil == r {
		return nil, io.EOF
	}

	res := &clientResponse{}
	err := decoder.Decode(res)
	if err != nil {
		if err == io.ErrUnexpectedEOF || err == io.EOF {
			return nil, err
		}
		err = &Error{
			Code:    E_PARSE,
			Message: err.Error(),
			Data:    res,
		}
	}
	if res.Version != Version {
		err = &Error{
			Code:    E_INVALID_REQ,
			Message: "jsonrpc must be " + Version,
			Data:    res,
		}
	}

	return &ClientResponseCodec{res: res, err: err, codec: codec}, nil
}