AppHarbor.CompressionExtensions.GetFiles C# (CSharp) Method

        private static IEnumerable<FileInfo> GetFiles(DirectoryInfo directory, string[] excludedDirectories)
        {
            return directory.GetFiles("*", SearchOption.TopDirectoryOnly)
                .Concat(directory.GetDirectories()
                .Where(x => !excludedDirectories.Select(y => y.ToLower()).Contains(x.Name.ToLower()))
                .SelectMany(x => GetFiles(x, excludedDirectories)));
        }