package socket

import (
	"bytes"
	"errors"
	"io"
	"sync"

	"github.com/gobwas/ws"
	"github.com/gobwas/ws/wsutil"
	"github.com/panjf2000/gnet/v2"
	"github.com/panjf2000/gnet/v2/pkg/logging"
)

type Conn struct {
	MainConn gnet.Conn `struc:"[0]pad"` //TODO 不序列化,,序列化下面的作为blob存数据库
	Mu       sync.Mutex
}

func NewConn(c gnet.Conn) *Conn {
	return &Conn{MainConn: c}
}

type WsCodec struct {
	Upgraded bool         // 链接是否升级
	Buf      bytes.Buffer // 从实际socket中读取到的数据缓存
	wsMsgBuf wsMessageBuf // ws 消息缓存
	//Isinitws bool
}

type wsMessageBuf struct {
	curHeader *ws.Header
	cachedBuf bytes.Buffer
}

type readWrite struct {
	io.Reader
	io.Writer
}

func (w *WsCodec) Upgrade(c gnet.Conn) (ok bool, action gnet.Action) {
	if w.Upgraded {
		ok = true
		return
	}
	buf := &w.Buf
	tmpReader := bytes.NewReader(buf.Bytes())
	oldLen := tmpReader.Len()
	logging.Infof("do Upgrade")

	hs, err := ws.Upgrade(readWrite{tmpReader, c})
	skipN := oldLen - tmpReader.Len()
	if err != nil {
		if err == io.EOF || errors.Is(err, io.ErrUnexpectedEOF) { //数据不完整，不跳过 buf 中的 skipN 字节（此时 buf 中存放的仅是部分 "handshake data" bytes），下次再尝试读取
			return
		}
		buf.Next(skipN)
		logging.Errorf("conn[%v] [err=%v]", c.RemoteAddr().String(), err.Error())
		action = gnet.Close
		return
	}
	buf.Next(skipN)
	logging.Infof("conn[%v] upgrade websocket protocol! Handshake: %v", c.RemoteAddr().String(), hs)

	ok = true
	w.Upgraded = true
	return
}
func (w *WsCodec) ReadBufferBytes(c gnet.Conn) (gnet.Action, int) {
	size := c.InboundBuffered()
	//buf := make([]byte, size)
	read, err := c.Peek(size)
	if err != nil {
		logging.Errorf("read err! %v", err)
		return gnet.Close, 0
	}
	// if read < size {
	// 	logging.Errorf("read bytes len err! size: %d read: %d", size, read)
	// 	return gnet.Close
	// }
	w.Buf.Write(read)
	return gnet.None, size
}
func (w *WsCodec) Decode(c gnet.Conn) (outs []wsutil.Message, err error) {
	//	fmt.Println("do Decode")
	messages, err := w.readWsMessages()
	if err != nil {
		logging.Errorf("Error reading message! %v", err)
		return nil, err
	}
	if messages == nil || len(messages) <= 0 { //没有读到完整数据 不处理
		return
	}
	for _, message := range messages {
		if message.OpCode.IsControl() {
			err = wsutil.HandleClientControlMessage(c, message)
			if err != nil {
				return
			}
			continue
		}
		if message.OpCode == ws.OpText || message.OpCode == ws.OpBinary {
			outs = append(outs, message)
		}
	}
	return
}

func (w *WsCodec) readWsMessages() (messages []wsutil.Message, err error) {
	msgBuf := &w.wsMsgBuf
	in := &w.Buf
	for {
		// 从 in 中读出 header，并将 header bytes 写入 msgBuf.cachedBuf
		if msgBuf.curHeader == nil {
			if in.Len() < ws.MinHeaderSize { //头长度至少是2
				return
			}
			var head ws.Header
			if in.Len() >= ws.MaxHeaderSize {
				head, err = ws.ReadHeader(in)
				if err != nil {
					return messages, err
				}
			} else { //有可能不完整，构建新的 reader 读取 head，读取成功才实际对 in 进行读操作
				tmpReader := bytes.NewReader(in.Bytes())
				oldLen := tmpReader.Len()
				head, err = ws.ReadHeader(tmpReader)
				skipN := oldLen - tmpReader.Len()
				if err != nil {
					if err == io.EOF || errors.Is(err, io.ErrUnexpectedEOF) { //数据不完整
						return messages, nil
					}
					in.Next(skipN)
					return nil, err
				}
				in.Next(skipN)
			}

			msgBuf.curHeader = &head
			err = ws.WriteHeader(&msgBuf.cachedBuf, head)
			if err != nil {
				return nil, err
			}
		}
		dataLen := (int)(msgBuf.curHeader.Length)
		// 从 in 中读出 data，并将 data bytes 写入 msgBuf.cachedBuf
		if dataLen > 0 {
			if in.Len() < dataLen { //数据不完整

				logging.Infof("incomplete data")
				return
			}

			_, err = io.CopyN(&msgBuf.cachedBuf, in, int64(dataLen))
			if err != nil {
				return
			}
		}
		if msgBuf.curHeader.Fin { //当前 header 已经是一个完整消息
			messages, err = wsutil.ReadClientMessage(&msgBuf.cachedBuf, messages)
			if err != nil {
				return nil, err
			}
			msgBuf.cachedBuf.Reset()
		} else {
			logging.Infof("The data is split into multiple frames")
		}
		msgBuf.curHeader = nil
	}
}