public IActionResult CheckUserValidity(string username)
        {
            if (_bUser.IsValidUser(username))
            {
                return(Ok());
            }

            return(NotFound());
        }
        public bool IsUserGroupMember(string groupName, string username)
        {
            if (!IsValidGroup(groupName))
            {
                return(false);
            }
            if (!_bUser.IsValidUser(username))
            {
                return(false);
            }

            var groupList = new HashSet <string>
            {
                groupName
            };

            while (groupList.Count > 0)
            {
                var currentGroup = groupList.First();
                using (var ctx = new PrincipalContext(ContextType.Domain))
                {
                    var group = GroupPrincipal.FindByIdentity(ctx, currentGroup);
                    if (group == null)
                    {
                        groupList.Remove(currentGroup);
                        continue;
                    }

                    foreach (var principal in group.GetMembers())
                    {
                        if (principal is UserPrincipal)
                        {
                            if (principal.SamAccountName == username)
                            {
                                return(true);
                            }
                        }
                        else
                        {
                            groupList.Add(principal.SamAccountName);
                        }
                    }
                }
                groupList.Remove(currentGroup);
            }
            return(false);
        }