/// <summary>
/// Return the first unconsumed resource found, or throw exception if no unconsumed resources exist.
/// </summary>
/// <param name="world"></param>
/// <returns></returns>
private Point LocateResource(World world)
{
if (!nextResourcePosition.IsEmpty)
{
return nextResourcePosition;
}
foreach (IResource res in world.Resources())
{
if (!res.IsConsumed())
return res.Position();
}
throw new NoValidResourcesException();
}