package codec

import (
	"blazing/common/data/entity"
	"encoding/binary"
	"errors"
	"io"
	"log"

	"github.com/panjf2000/gnet/v2"
)

// CROSS_DOMAIN 定义跨域策略文件内容
const CROSS_DOMAIN = "<?xml version=\"1.0\"?><!DOCTYPE cross-domain-policy><cross-domain-policy><allow-access-from domain=\"*\" to-ports=\"*\" /></cross-domain-policy>\x00"

// TEXT 定义跨域请求的文本格式
const TEXT = "<policy-file-request/>\x00"

var ErrIncompletePacket = errors.New("incomplete packet")

// TomeeSocketCodec 协议格式:
//
// * 0           4
// * +-----------+
// * |  body len  |
// * +-----------+
// * |           |
// * +           +
// * | body bytes|
// * +           +
// * |  ... ...  |
// * +-----------+
type TomeeSocketCodec struct{}

var _ SocketCodec = (*TomeeSocketCodec)(nil)

func NewTomeeSocketCodec() *TomeeSocketCodec {
	return &TomeeSocketCodec{}

}

func handle(c gnet.Conn) {
	clientdata := c.Context().(*entity.ClientData)
	if clientdata.IsCrossDomain {
		return

	}
	// 读取数据并检查是否为跨域请求
	data, err := c.Peek(len(TEXT))
	if err != nil {
		log.Printf("Error reading cross-domain request: %v", err)
		return
	}

	if string(data) == TEXT { //判断是否是跨域请求
		log.Printf("Received cross-domain request from %s", c.RemoteAddr())
		// 处理跨域请求
		c.Write([]byte(CROSS_DOMAIN))
		c.Discard(len(TEXT))

		clientdata.IsCrossDomain = true
		return
	}

	//return
}
func (codec TomeeSocketCodec) Encode(buf []byte) ([]byte, error) {
	bodyLen := len(buf)
	data := make([]byte, 4+bodyLen)

	// 写入4字节的包长度
	binary.BigEndian.PutUint32(data[:4], uint32(bodyLen))
	// 写入包体
	copy(data[4:], buf)

	return data, nil
}

func (codec TomeeSocketCodec) Decode(c gnet.Conn) ([]byte, error) {

	handle(c)
	// 先读取4字节的包长度
	lenBuf, err := c.Peek(4)
	if err != nil {
		if errors.Is(err, io.ErrShortBuffer) {
			return nil, ErrIncompletePacket
		}
		return nil, err
	}

	bodyLen := binary.BigEndian.Uint32(lenBuf)
	totalLen := 4 + int(bodyLen)

	// 检查整个包是否完整
	buf, err := c.Peek(int(bodyLen))
	if err != nil {
		if errors.Is(err, io.ErrShortBuffer) {
			return nil, ErrIncompletePacket
		}
		return nil, err
	}

	// 提取包体
	body := make([]byte, bodyLen)
	copy(body, buf)

	// 从缓冲区中丢弃已读取的数据
	_, _ = c.Discard(totalLen)

	return body, nil
}