package xugu

import (
	"bytes"
	"encoding/binary"
	"errors"
)

const RETURN_PREPARE_SELECT = 19665

func rhRecvStr(pConn *xugusqlConn, valp *[]byte) (int, error) {
	var len uint32
	if err := rhRecvInt32(pConn, &len); err != nil {
		return -4, err
	}
	pBuff := make([]byte, len+1)
	if err := rhRecv(pConn, pBuff, len); err != nil {
		return -4, err
	}
	pBuff[len] = 0x0
	*valp = pBuff
	return 0, nil
}

// 接收单个字符
func rhRecvChar(pConn *xugusqlConn, valp *byte) (bool, error) {

	var ch [1]byte
	err := rhRecv(pConn, ch[:], 1)
	if err != nil {
		return false, err
	}
	*valp = ch[0]
	return true, nil

}

// TODO : pConn.bkChar != 0x0  这一部分代码需要修改
func rhRecv(pConn *xugusqlConn, buff []byte, dLen uint32) error {
	//old_len := dLen
	if pConn.bkChar != 0x0 {
		buff[0] = pConn.bkChar
		pConn.bkChar = 0x0
		buff = buff[1:]
		dLen--
	}
	//接收加密登录信息
	if dLen != 0 {
		for dLen != 0 {
			if pConn.useSSL {
				buffer := make([]byte, 1024)
				n, err := pConn.conn.Read(buffer)
				if err != nil {
					return err
				} else {
					xgCacheRecv(pConn, buffer, int32(n))
				}
				if n <= 0 {
					return errors.New("read error")
				}

			}
		}
		//	DECRYPT(p_conn, buff, old_len); //解密缓冲
	}
	return nil
}

func rhRecvInt32(pconn *xugusqlConn, i *uint32) error {
	var buff [4]byte
	err := rhRecv(pconn, buff[:], 4)
	if err != nil {
		return err
	}

	// 将大端字节序转换为主机字节序
	*i = binary.BigEndian.Uint32(buff[:])

	return nil
}

func xgCacheRecv(pConn *xugusqlConn, buff []byte, dLen int32) (int, error) {
	return 0, nil
}

// 从连接中接收字段信息，并将其存储在 Result 结构体中。
func recvFiledsInfo(pConn *xugusqlConn, pRes *Result) (int, error) {
	var fieldNum uint32

	//var pRet *FieldInfo
	if err := rhRecvInt32(pConn, &fieldNum); err != nil {
		return XG_NET_ERROR, err
	}
	if fieldNum > 4000 {
		return XG_NET_ERROR, errors.New("fieldNum >4000")
	}

	pRes.FieldNum = fieldNum

	pRet := make([]FieldInfo, fieldNum)
	//接收字段详细信息
	for n := uint32(0); n < fieldNum; n++ {
		if ret, err := recvAttrDesItem(pConn, &pRet[n]); err != nil {
			return ret, err
		}
	}

	bytesN := (fieldNum*2 + 7) / 8
	for n := uint32(0); n < fieldNum; n++ {
		pRet[n].Offset = bytesN
		bytesN += uint32(getSQLCType(pRet[n].TypeID))
	}
	// TODO : 这里需要重新修改
	// 在c代码中这里还加上了 ROW_HEAD_SIZE
	pRes.RowSize = bytesN + 24
	pRes.ColInfos = pRet

	return 0, nil
}

// 接收字段属性描述
func recvAttrDesItem(pConn *xugusqlConn, pItem *FieldInfo) (int, error) {
	var nameLen uint32
	var tabName []byte
	var alias []byte

	if err := rhRecvInt32(pConn, &nameLen); err != nil {
		return XG_NET_ERROR, err
	}
	if nameLen > 1024 {
		return XG_NET_ERROR, errors.New("nameLen >1024")
	}
	var name []byte
	if err := rhRecv(pConn, name, nameLen); err != nil {
		return XG_NET_ERROR, err
	}

	if ret := bytes.IndexByte(name, '%'); ret != -1 {
		alias = name[ret+1:]
		name = name[:ret-1]
	}

	if ret := bytes.IndexByte(name, '.'); ret != -1 {
		//如果 return_schema_on 为真，那么这里将得到 schema_name.tab_name。
		tabName = name[:ret-1]
		name = name[ret+1:]
	}

	pItem.TabName = string(tabName)
	pItem.Name = string(name)
	pItem.Alias = string(alias)

	if err := rhRecvInt32(pConn, &pItem.TypeID); err != nil {
		return XG_NET_ERROR, err
	}
	if err := rhRecvInt32(pConn, &pItem.Modi); err != nil {
		return XG_NET_ERROR, err
	}
	if err := rhRecvInt32(pConn, &pItem.Flags); err != nil {
		return XG_NET_ERROR, err
	}

	pItem.CTypeID = uint32(getSQLCType(pItem.TypeID))

	return 0, nil
}

func recvParamsInfo2(pConn *xugusqlConn, params *XGCSParam) (int, error) {
	var paramNum uint32
	var i_ord []uint32
	var i_type []uint32
	var i_prescale []uint32
	pNames := make([][]byte, paramNum)
	rhRecvInt32(pConn, &paramNum)
	params.ParamNum = paramNum

	for n := uint32(0); n < paramNum; n++ {
		// 读取名称
		rhRecvStr(pConn, &pNames[n])
		// 读取序号
		rhRecvInt32(pConn, &i_ord[n])
		// 读取类型
		rhRecvInt32(pConn, &i_type[n])
		// 读取预缩放值
		rhRecvInt32(pConn, &i_prescale[n])
	}

	params.VParamName = pNames
	params.VParamNo = i_ord
	params.VType = i_type
	params.VParamSize = i_prescale

	return 0, nil
}