using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
 
 
 
namespace FullDirectoryTraverse
{
 
    class FullDirTraverse
    {
        const string directory = @"../../";
        static string outputdir = System.Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
 
        static void WriteFiles(string dir) // write all files in a given directory
        {
            List<FileInfo> allFiles = new DirectoryInfo(dir).GetFiles().ToList();
            var sortedFiles = allFiles.OrderBy(file => file.Length).GroupBy(file => file.Extension).OrderByDescending(group => group.Count()).OrderBy(group => group.Key);
            using (var resultWriter = new StreamWriter(outputdir + @"/log.txt", true))
            {
                foreach(var group in sortedFiles)
                {
                    resultWriter.WriteLine(group.Key);
                    foreach (var pair in group)
                    {
                        resultWriter.WriteLine("name: {0} -- size: {1} bytes ", pair.Name, pair.Length);
                    }
                }
            }
        }
        static void DirectorySearch(string dirPath) // recursion
        {
            WriteFiles(dirPath); // first write all file in a given Directory
            try
            {
               
                foreach(string dir in Directory.GetDirectories(dirPath)) // get all directories from the folder
                {
                    WriteFiles(dir);
                    DirectorySearch(dir); // try the recursion for each of them.
                }              
 
            }
            catch(SystemException exception)
            {
                Console.WriteLine(exception.Message);
            }
        }
 
        static void Main()
        {
            DirectorySearch(directory);
        }
    }
}