/// <summary>
/// Gets the deepest wildcard Domain, if any, from a group of Domains, in a node path.
/// </summary>
/// <param name="domains">The domains.</param>
/// <param name="path">The node path eg '-1,1234,5678'.</param>
/// <param name="rootNodeId">The current domain root node identifier, or null.</param>
/// <returns>The deepest wildcard Domain in the path, or null.</returns>
/// <remarks>Looks _under_ rootNodeId but not _at_ rootNodeId.</remarks>
internal static Domain FindWildcardDomainInPath(Domain[] domains, string path, int? rootNodeId)
{
var stopNodeId = rootNodeId ?? -1;
return path.Split(',')
.Reverse()
.Select(int.Parse)
.TakeWhile(id => id != stopNodeId)
.Select(id => domains.FirstOrDefault(d => d.RootNodeId == id && d.IsWildcard))
.FirstOrDefault(domain => domain != null);
}
