class DirUseInfo
{
    public string Path { get; private set; }
    public int Percent { get; private set; }
    public int FileCount { get; set; }
    public long Size { get; set; }
            
    Lazy<DirUseInfo[]> subDirs;
    public DirUseInfo[] SubDirs { get { return subDirs.Value; } }

    private DirUseInfo(string path, long size, int fileCount,int percent)
    {
        this.Path = path;
        this.Size = size;
        this.FileCount = fileCount;
        this.Percent = percent;
        this.subDirs = fileCount == 0 ? new Lazy<DirUseInfo[]>() : new Lazy<DirUseInfo[]>(() => GetDirUseInfo(path));
    }

    public override string ToString()
    {
        return string.Format("[{0}% {1} {2}]", Percent, Size, Path);
    }

    public static DirUseInfo[] GetDirUseInfo(string dir)
    {
        var subDirs = Directory.GetDirectories(dir);
        var p = Process.Start(new ProcessStartInfo(@"D:\Tools\Du\diruse.exe", @"/* " + dir)
        {
            UseShellExecute = false,
            RedirectStandardOutput = true,
        });    
        p.WaitForExit();

        var output = p.StandardOutput.ReadToEnd();
        var matches = Regex.Matches(output, @"(\d+|Access Denied)\s+(\d+).+");

        if(subDirs.Length!=matches.Count-1)    //match最后一項是匯總
            throw new InvalidOperationException();

        var totalSize = long.Parse(matches[matches.Count - 1].Groups[1].Value);

        var dirsUseInfo = new DirUseInfo[subDirs.Length];
        for (int i = 0; i < dirsUseInfo.Length; i++)
        {
            var groups = matches[i].Groups;
            var path = subDirs[i];
            var fileCount = int.Parse(groups[2].Value);
            var size = matches[i].Value.StartsWith("Access Denied") ? 0 : long.Parse(groups[1].Value);
            var percent = (int)(size * 100 / totalSize);

            dirsUseInfo[i] = new DirUseInfo(path, size, fileCount, percent);
        }

        return dirsUseInfo;
    }
}