File Hash Generator

using System;
using System.IO;
using System.Security.Cryptography;

namespace FileHashGenerator {
    class Program {
        static void Main( string[] args ) {
            if( args.Length==0 ) {
                PrintHelp();
            }
            else {
                FileHashGeneratorInput programInput = new FileHashGeneratorInput(args);
                SearchOption option = programInput.IsWithSubFolders ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;
                string[] files = programInput.Sourcetype==FileHashGeneratorInput.SourceType.File ? new[] {programInput.Source} : Directory.GetFiles(programInput.Source, "*.*", option);
                using( TextWriter tw = programInput.Target=="" ? Console.Out : new StreamWriter(programInput.Target) ) {
                    foreach( string file in files ) {
                        tw.WriteLine(file+" : "+GenerateHash(file));
                    }
                    tw.Flush();
                }
            }
        }
        private static string GenerateHash(string fileName) {
            try {
                using( FileStream file = new FileStream(fileName, FileMode.Open) ) {
                    return Convert.ToBase64String(new MD5CryptoServiceProvider().ComputeHash(file));
                }
            }
            catch( Exception e) {
                return "Cannot generate hash for file ("+e.Message+")";
            }
        }
        private static void PrintHelp() {
            Console.WriteLine("\tGenerate MD5 hash string for a file.");
            Console.WriteLine("FileHashGenerator.exe -source <filePath\\dirPath> [-target <outputFilePath>] [-withSubs]");
            Console.WriteLine("-source     : file or directory path");
            Console.WriteLine("[-target]  : file path to output data (by default Console.Out)");
            Console.WriteLine("[-withSubs] : determines whether get hash from sub folders (works only if -source is folder)");
            Console.WriteLine("Examples:");
            Console.WriteLine(@"FileHashGenerator.exe -source c:\temp");
            Console.WriteLine(@"FileHashGenerator.exe -source c:\temp\text.txt");
            Console.WriteLine(@"FileHashGenerator.exe -source c:\temp -target c:\tempDirHash.txt -withSubs");
        }
    }
    public class FileHashGeneratorInput {
        public string Source { get; set; }
        public string Target { get; set; }
        public bool IsWithSubFolders { get; set; }
        public SourceType Sourcetype { get; set; }
        public FileHashGeneratorInput( string[] args ) {
            try {
                //TODO: refactor to CaseInsensetive
                this.Source = args[Array.IndexOf(args, "-source")+1];
                this.Target = Array.Find(args, s => s.ToLower()=="-target")!=null ? args[Array.IndexOf(args, "-target")+1] : "";
                this.IsWithSubFolders = Array.Find(args, s => s.ToLower()=="-withsubs")!=null;
            }
            catch {
                Console.WriteLine("Incorrect arguments");
            }
            this.Sourcetype = Directory.Exists(this.Source) ? SourceType.Folder : SourceType.File;
        }
        public enum SourceType {
            File,
            Folder
        }
    }
}

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