Update to Simple Data Extender to take into account Group membership

SmartTargetSecurityExtender.cs

public override XmlTextReader ProcessResponse(XmlTextReader reader, PipelineContext context)
{
    var command = context.Parameters["command"] as String;
    command = command.ToLower();
    if (command == "getpromotions" || command == "getregions")
    {
        UserData currentUser = new CoreServiceHelper(System.Web.HttpContext.Current.User.Identity.Name).GetCurrentUser();
        if (currentUser.Privileges != 1) //Skip for Admins
        {
            List<String> data = GetRegionPrefixesForUser(currentUser);
            switch (command)
            {
                case "getregions":
                    return FilterRegions(reader, context, data);
                case "getpromotions" :
                    return FilterPromotions(reader, context, data);
            }
            
        }
    }
    return reader;//default is to return unaltered XML
}

//Cache the region prefixes in a static variable to make processing a bit more efficient
public static ConcurrentDictionary<String, List<String>> UserRegionPrefixes = new ConcurrentDictionary<string, List<string>>();

private List<String> GetRegionPrefixesForUser(UserData currentUser)
{
    if (!UserRegionPrefixes.ContainsKey(currentUser.Id))
    {
        List<String> regionPrefixes = new List<string>();
        foreach (var groupTitle in currentUser.GroupMemberships.Select(m => m.Group.Title))
        {
            var match = Regex.Match(groupTitle, @".*\[Region Prefix (.*?)\]");
            if (match.Success)
            {
                regionPrefixes.Add(match.Groups[1].Value);
            }
        }
        UserRegionPrefixes.AddOrUpdate(currentUser.Id, regionPrefixes, (key, oldvalue) => regionPrefixes);
    }
    return UserRegionPrefixes[currentUser.Id];
}