package json

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

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

// clientMessage represents a JSON-RPC message sent to a client.
type clientMessage struct {
	Version     string               `json:"jsonrpc"`
	MessageType protocol.MessageType `json:"messageType"`
	Message     *json.RawMessage     `json:"message"`
}

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

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

// NewClientCodec returns a new JSON Codec.
func NewClientCodec() protocol.ClientCodec {
	return NewCustomClientCodec(codec.DefaultCodecSelector)
}

// ClientCodec creates a ClientCodecRequest to process each request.
type ClientCodec struct {
	codecSel codec.CodecSelector
}

func (cc *ClientCodec) WriteRequest(w io.Writer, method string, args interface{}, id interface{}) error {
	req := retainClientRequest(method, args, id)
	defer func() {
		releaseClientRequest(req)
	}()

	encoder := json.NewEncoder(cc.codecSel.SelectByWriter(w).Encode(w))
	if err := encoder.Encode(req); nil != err {
		return err
	}

	return nil
}

// NewMessage returns a ClientMessageCodec.
func (cc *ClientCodec) NewMessage(r io.Reader) (protocol.ClientMessageCodec, error) {
	return newClientMessageCodec(r, cc.codecSel.SelectByReader(r))
}

// newClientMessageCodec returns a new ClientMessageCodec.
func newClientMessageCodec(r io.Reader, codec codec.Codec) (protocol.ClientMessageCodec, error) {
	msg := retainClientMessage()
	err := json.NewDecoder(r).Decode(msg)
	if err != nil {
		if err == io.ErrUnexpectedEOF || err == io.EOF {
			return nil, err
		}
		err = &Error{
			Code:    E_PARSE,
			Message: err.Error(),
			Data:    msg,
		}
	}
	if msg.Version != Version {
		err = &Error{
			Code:    E_INVALID_REQ,
			Message: "jsonrpc must be " + Version,
			Data:    msg,
		}
	}

	return retainClientMessageCodec(msg, err, codec), nil
}

type ClientMessageCodec struct {
	msg   *clientMessage
	err   error
	codec codec.Codec
}

func (ccm *ClientMessageCodec) MessageType() protocol.MessageType {
	return ccm.msg.MessageType
}

func (ccm *ClientMessageCodec) MessageCodec() (interface{}, error) {
	switch ccm.msg.MessageType {
	case protocol.MessageTypeResponse:
		return newClientResponseCodec(ccm.msg.Message, ccm.codec)
	case protocol.MessageTypeNotification:
		return newClientNotificationCodec(ccm.msg.Message, ccm.codec)
	}
	return nil, fmt.Errorf("RPC: Not supported message type[%v]", ccm.msg.MessageType)
}

func (ccm *ClientMessageCodec) Close() {
	if nil != ccm.msg {
		releaseClientMessage(ccm.msg)
	}

	releaseClientMessageCodec(ccm)
}

var clientMessagePool sync.Pool

func retainClientMessage() *clientMessage {
	v := clientMessagePool.Get()
	if v == nil {
		return &clientMessage{}
	}
	return v.(*clientMessage)
}

func releaseClientMessage(cm *clientMessage) {
	clientMessagePool.Put(cm)
}

var clientMessageCodecPool sync.Pool

func retainClientMessageCodec(msg *clientMessage, err error, codec codec.Codec) *ClientMessageCodec {
	var ccm *ClientMessageCodec
	v := clientMessageCodecPool.Get()
	if v == nil {
		ccm = &ClientMessageCodec{}
	} else {
		ccm = v.(*ClientMessageCodec)
	}

	ccm.msg = msg
	ccm.err = err
	ccm.codec = codec

	return ccm
}

func releaseClientMessageCodec(cr *ClientMessageCodec) {

	clientMessageCodecPool.Put(cr)
}