"fmt"
	"os"
	"syscall"
	"unsafe"

	"golang.org/x/sys/windows"
)

var (
	kernel32 = windows.NewLazySystemDLL("kernel32.dll")

	// GetDiskFreeSpaceEx - https://msdn.microsoft.com/en-us/library/windows/desktop/aa364937(v=vs.85).aspx
	// Retrieves information about the amount of space that is available on a disk volume,
	// which is the total amount of space, the total amount of free space, and the total

	procLockFileEx = modkernel32.NewProc("LockFileEx")
)

const (
	// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
	lockFileExclusiveLock   = 2
	lockFileFailImmediately = 1

	// see https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
	errLockViolation syscall.Errno = 0x21
)

// lockedOpenFile is an internal function.

		// Recognize "fixed", "removable", "remote" and "ramdisk" drives as proper drives
		// which can be treated as an actual mount-point, rest can be ignored.
		// https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-getdrivetypew
		mountPointCache.Store(path, true)
		return true
	}
	mountPointCache.Store(path, false)
	return false