package xlog

import (
	"bytes"
	"encoding/binary"
	"errors"
	"fmt"
	"fwh-toolbox-server/logger"
	"strings"
)

const (
	// Magic word
	_MAGIC_XLOG_SYSTEM_ uint32 = 0x99A3B417 // ARM的日志发送给PC

	// CmdType 命令类型 mainCmd(8bit) + subCmd(8bit)
	// mainCmd
	_XLOG_CMD_LOG_TO_PC_        uint8 = 0  // 心跳内容, 内容为"[x]\n"
	_XLOG_CMD_REPORT_BASICINFO_ uint8 = 1  // 上报sn + mac, 结构为 XlogSiteBaseInfo
	_XLOG_CMD_REPLY_BASICINFO_  uint8 = 2  // 回复sn + mac，暂不回复
	_XLOG_P2P_EXEC_BASH_CMD_    uint8 = 64 // pc    -> SERNAME_UB_SERVER -> xlogv3, 执行远程命令
	_XLOG_P2P_BASH_CMD_RESULT_  uint8 = 65 // xlogv3-> SERNAME_UB_SERVER -> pc      返回远程命令执行结果
)

func NewXlogPackageParser(ctx *ConnectContext) *XlogPackageParser {
	return &XlogPackageParser{
		crypt:        NewXlogEncrypt(),
		ctx:          ctx,
		cmdResultStr: "",
		Handshake:    false,
		Buffer:       make([]byte, 0),
	}
}

// 解析设备握手包
func (parser *XlogPackageParser) ParseXlogHandshakePackage(raw []byte) (*XlogHandshakePackageData, error) {
	reader := bytes.NewReader(raw)

	// 数据长度校验
	if len(raw) != 72 {
		return nil, fmt.Errorf("invalid handshake packet: data length error, expected 72, got %d", len(raw))
	}

	// 解析数据结构
	var p XlogHandshakePackage
	if err := binary.Read(reader, binary.LittleEndian, &p); err != nil {
		return nil, err
	}

	// 校验数据头
	if p.MagicWord != _MAGIC_XLOG_SYSTEM_ {
		return nil, errors.New("invalid magic")
	}
	if p.CmdLen != uint32(len(raw)-8) {
		return nil, fmt.Errorf("invalid handshake packet: data length error, CmdLen: %d", p.CmdLen)
	}

	// 解密数据
	handshakeData, err := parser.crypt.DecryptData(p.EncryptData[:])
	if err != nil {
		return nil, err
	}

	// 数据长度校验
	if len(handshakeData) != (16 + 36) {
		return nil, fmt.Errorf("invalid handshake packet: data length error, expected 52, got %d", len(handshakeData))
	}

	// 解析握手数据结构
	var h XlogHandshakePackageData
	reader = bytes.NewReader(handshakeData)
	if err := binary.Read(reader, binary.LittleEndian, &h); err != nil {
		return nil, err
	}

	// 更新IV
	if err := parser.crypt.SetNewIv(h.NewIv[:]); err != nil {
		return nil, err
	}

	return &h, nil
}

// 预解析数据包，数据提取，提取一个完整数据包
func (parser *XlogPackageParser) PreparserXlogPackage(raw []byte) {
	// 累积数据
	parser.Buffer = append(parser.Buffer, raw...)
	buffer := parser.Buffer

	for {
		// 不够一个包头和长度字段，继续收
		if len(buffer) < 8 {
			return
		}

		// 查找合法包头
		header := binary.LittleEndian.Uint32(buffer[:4])
		if header != _MAGIC_XLOG_SYSTEM_ {
			// 丢掉 1 字节，继续找包头
			buffer = buffer[1:]
			continue
		}

		// 读取长度
		length := binary.LittleEndian.Uint32(buffer[4:8])
		totalLen := 8 + int(length)

		// 数据是否完整
		if len(buffer) < totalLen {
			break
		}

		// 提取完整包
		packet := buffer[:totalLen]

		// 异步处理
		go parser.ParseXlogPackage(packet)

		// 移除已处理的数据
		parser.Buffer = buffer[totalLen:]
		buffer = parser.Buffer
	}
}

// 处理设备心跳信息
func (parser XlogPackageParser) handleHeartbeat(raw []byte) {
	logger.Std.Printf("%s - 接收到心跳：%s", parser.ctx.UUID, string(raw))
}

// 处理设备基本信息
func (parser XlogPackageParser) handleSiteBaseInfo(raw []byte) {
	// 解析基本信息
	infoReader := bytes.NewReader(raw)
	var info XlogSiteBaseInfo
	if err := binary.Read(infoReader, binary.LittleEndian, &info); err != nil {
		logger.Std.Printf("handleSiteBaseInfo failed: %s\n", err)
		return
	}

	// 更新SN
	parser.ctx.SN = string(bytes.TrimRight(info.SN[:], "\x00"))
	logger.Std.Printf("update SN: %s\n", parser.ctx.SN)
	logger.Std.Println("握手成功")
}

// 处理命令执行结果
func (parser *XlogPackageParser) handleCmdResult(raw []byte) {
	resStr := string(raw[:])
	if strings.HasPrefix(resStr, "\n***above is result of:") {
		parser.cmdResultStr = parser.cmdResultStr + resStr
		select {
		case parser.ctx.DoneChan <- parser.cmdResultStr:
			// 成功写入结果
			logger.Std.Printf("%s - 回传结果：%s\n", parser.ctx.UUID, parser.cmdResultStr)
		default:
			// channel 已经满（说明调用方可能已经超时退出了）
			logger.Std.Printf("%s - DoneChan已满或超时。\n", parser.ctx.UUID)
		}
	} else {
		parser.cmdResultStr = resStr
	}
}

// 解析设备数据包
func (parser *XlogPackageParser) ParseXlogPackage(raw []byte) {
	// 数据长度校验
	headerPackageSize := binary.Size(XlogPackageHeader{})
	if len(raw) < headerPackageSize {
		logger.Std.Printf("invalid packet: data length error, expected >= %d, got %d\n", headerPackageSize, len(raw))
		return
	}

	headerRaw := raw[:headerPackageSize] // 非加密头部
	headerReader := bytes.NewReader(headerRaw)

	// 解析头部
	var h XlogPackageHeader
	if err := binary.Read(headerReader, binary.LittleEndian, &h); err != nil {
		logger.Std.Printf("XlogPackage header parsing error: %s\n", err.Error())
		return
	}

	if len(raw) > headerPackageSize {
		encryptRaw := raw[headerPackageSize:] // 加密数据

		// 解密Payload
		bodyRaw, err := parser.crypt.DecryptData(encryptRaw)
		if err != nil {
			logger.Std.Println("DecryptData error: " + err.Error())
			return
		}

		// 判断包类型
		switch h.MainCmd {
		case _XLOG_CMD_LOG_TO_PC_:
			parser.handleHeartbeat(bodyRaw)
		case _XLOG_CMD_REPORT_BASICINFO_:
			parser.handleSiteBaseInfo(bodyRaw)
		case _XLOG_P2P_BASH_CMD_RESULT_:
			parser.handleCmdResult(bodyRaw)
		}

	}
}

// 创建握手响应包
func (parser XlogPackageParser) CreateXlogHandshakePackage() ([]byte, error) {
	encryptData, err := parser.crypt.EncryptData([]byte("0123456789abcdef"))
	if err != nil {
		return nil, err
	}

	buf := new(bytes.Buffer)
	// 按小端序写入，先写头部
	if err := binary.Write(buf, binary.LittleEndian, _MAGIC_XLOG_SYSTEM_); err != nil {
		return nil, fmt.Errorf("failed to write XlogHandshakeResponsePackage magic word: %w", err)
	}
	if err := binary.Write(buf, binary.LittleEndian, uint32(32)); err != nil {
		return nil, fmt.Errorf("failed to write XlogHandshakeResponsePackage magic word: %w", err)
	}
	// 再写 EncryptData
	if _, err := buf.Write(encryptData); err != nil {
		return nil, fmt.Errorf("failed to write XlogHandshakeResponsePackage EncryptData: %w", err)
	}

	return buf.Bytes(), nil
}

// 创建发送命令数据包
func (parser XlogPackageParser) CreateXlogCmdPackage(payload []byte) ([]byte, error) {
	var dstServiceName [12]byte
	copy(dstServiceName[:], "Xlog")
	h := XlogPackageHeader{
		MagicWord:      _MAGIC_XLOG_SYSTEM_,
		CmdLen:         0,
		MainCmd:        _XLOG_P2P_EXEC_BASH_CMD_,
		SubCmd:         0,
		ControlBitData: 0,
		DstServiceName: dstServiceName,
		ToBeSendLen:    0,
		IgnoredLen:     0,
		UpTime:         0,
	}

	encryptData := []byte{}
	if len(payload) > 0 {
		encrypted, err := parser.crypt.EncryptData(payload)
		if err != nil {
			return nil, err
		}
		encryptData = encrypted
	}

	// 36是XlogPackageHeader字节数，8是MagicWord + CmdLen字节数
	h.CmdLen = uint32(36 + len(encryptData) - 8)

	p := XlogPackage{
		Header:         h,
		EncryptPayload: encryptData,
	}

	buf := new(bytes.Buffer)
	// 按小端序写入，先写头部
	if err := binary.Write(buf, binary.LittleEndian, p.Header); err != nil {
		return nil, fmt.Errorf("failed to write XlogPackage header: %w", err)
	}
	// 再写 payload
	if _, err := buf.Write(p.EncryptPayload); err != nil {
		return nil, fmt.Errorf("failed to write XlogPackage payload: %w", err)
	}

	return buf.Bytes(), nil
}