package nsqd

import (

    "syscall"

    "unsafe"

)

var (

    modkernel32     = syscall.NewLazyDLL("kernel32.dll")

    procMoveFileExW = modkernel32.NewProc("MoveFileExW")

)

const (

    MOVEFILE_REPLACE_EXISTING = 1

)

func moveFileEx(sourceFile, targetFile *uint16, flags uint32) error {

    ret, _, err := procMoveFileExW.Call(uintptr(unsafe.Pointer(sourceFile)), uintptr(unsafe.Pointer(targetFile)), uintptr(flags))

    if ret == 0 {

        if err != nil {

            return err

        }

        return syscall.EINVAL

    }

    return nil

}

func atomicRename(sourceFile, targetFile string) error {

    lpReplacedFileName, err := syscall.UTF16PtrFromString(targetFile)

    if err != nil {

        return err

    }

    lpReplacementFileName, err := syscall.UTF16PtrFromString(sourceFile)

    if err != nil {

        return err

    }

    return moveFileEx(lpReplacementFileName, lpReplacedFileName, MOVEFILE_REPLACE_EXISTING)

}