Find similar file names, group them, display size in descending order.

Program.cs

/**
 * Copyright (c) 2017 Yuki Ono
 * Licensed under the MIT License.
 */ 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.IO;
using Microsoft.VisualBasic.FileIO;

namespace GetFileSizeGroup {
    class Program {
        // https://discuss.leetcode.com/topic/17639/20ms-detailed-explained-c-solutions-o-n-space
        static int MinDistance(string w1, string w2) {
            var M = w1.Length; var N = w2.Length;
            var cur = Enumerable.Range(0, M + 1).ToArray();

            foreach (var j in Enumerable.Range(1, N)) {
                var pre = cur.First();
                cur[0] = j;

                foreach (var i in Enumerable.Range(1, M)) {
                    var temp = cur[i];
                    cur[i] = (w1[i - 1] == w2[j - 1]) ? pre
                        : Math.Min(pre + 1, Math.Min(cur[i] + 1, cur[i - 1] + 1));
                    pre = temp;
                }
            }
            return cur.Last();
        }

        static IEnumerable<string[]> ReadCSV(string csvPath) {
            using (var tfp = new TextFieldParser(csvPath)) {
                tfp.CommentTokens = new string[] { "#" };
                tfp.SetDelimiters(new string[] { "," });
                tfp.HasFieldsEnclosedInQuotes = true;

                tfp.ReadLine();
                tfp.ReadLine();

                while (!tfp.EndOfData)
                    yield return tfp.ReadFields();
            }
        }

        static string GetSizeMB(long size) =>
            (size / 1024 / 1024) + "MB";

        static long GetGroupSize(List<(string, long)> fileList) =>
            fileList.Select(f => f.Item2).Sum();

        static readonly Regex SPACE_REG = new Regex(@"[_-]", RegexOptions.Compiled);

        // without file extension
        static string GetCompName(string path) {
            var name = Path.GetFileNameWithoutExtension(path);
            return SPACE_REG.Replace(name.ToLower(), " ");
        }

        // https://stackoverflow.com/questions/381366/is-there-a-wildcard-expansion-option-for-net-apps
        static string[] ExpandPath(string path) {
            var dir = Path.GetDirectoryName(path);
            dir = String.IsNullOrEmpty(dir) ? "./" : dir;
            var file = Path.GetFileName(path);

            return Directory.GetFiles(dir, file);
        }

        static string[] GetCSVFiles(string[] args) {
            return args.SelectMany(ExpandPath)
                .Where(p => p.EndsWith(".csv")).ToArray();
        }

        static bool CompareName(string[] x, string[] y) {
            var w1 = GetCompName(x[0]);
            var w2 = GetCompName(y[0]);
            return (MinDistance(w1, w2) < 5);
        }

        static void Main(string[] args) {
            var csvFiles = GetCSVFiles(args);
            if (csvFiles.Length == 0) {
                Console.WriteLine("Usage:");
                Console.WriteLine(@"Get-ChildItem C:\ -rec | where {!$_.PSIsContainer} | select-object FullName, Length | export-csv -encoding utf8 -path C:\file-list.csv");
                Console.WriteLine("GetFileSizeGroup *.csv > fsg-list.txt");
                return;
            }

            LinkedList<string[]> fileList = new LinkedList<string[]>(csvFiles.SelectMany(fn => ReadCSV(fn)));

            var fileGroups = new List<(List<(string, long)>, long)>();
            while (fileList.Count != 0) {
                var x = fileList.First.Value;
                fileList.RemoveFirst();

                (string, long) makeTuple(string[] fields) =>
                    (fields[0], long.Parse(fields[1]));

                var group = new List<(string, long)> { makeTuple(x) };
                foreach (var f in fileList.AsParallel().Where(y => CompareName(x, y)).ToArray()) {
                    group.Add(makeTuple(f));
                    fileList.Remove(f);
                }

                fileGroups.Add((group, GetGroupSize(group)));
            }

            foreach (var (fileGroup, groupSize, index) in fileGroups.OrderByDescending(fg => fg.Item2).Select((f, i) => (f.Item1, f.Item2, i))) {
                Console.WriteLine((index + 1) + ": " + GetSizeMB(groupSize));

                foreach (var fg in fileGroup)
                    Console.WriteLine(fg.Item1 + ": " + fg.Item2);

                Console.WriteLine();
                Console.WriteLine();
            }

            //Console.ReadKey();
        }
    }
}