LineCounter/Program.cs

using System;
using System.IO;
using System.Text;

namespace LineCounter
{
    class Program
    {
        static int SearchDirectoryAndCountLines(string path, string searchQuery)
        {
            string[] folders = Directory.GetDirectories(path);
            string[] files = Directory.GetFiles(path, searchQuery);

            int count = 0;

            foreach (string folder in folders)
                count += SearchDirectoryAndCountLines(folder, searchQuery);

            foreach (string file in files)
                count += File.ReadAllLines(file).Length;
            
            return count;
        }

        static void Main(string[] args)
        {
            string SearchQuery = GetSearchQuery();

            if (args.Length == 0)
            {
                Console.WriteLine("No Arguments found, drop a folder to the executable");
                Console.ReadLine();
                return;
            }

            Console.WriteLine("Started counting...");

            string path = args[0];
            int lineCounts = SearchDirectoryAndCountLines(path, SearchQuery);
            
            Console.WriteLine($"{ path } has { lineCounts } lines with the search query of \"{ SearchQuery }\"");
            Console.ReadLine();
        }

        private static string GetSearchQuery()
        {
            const string defaultFileType = "*.cs";

            string searchQueryPath = Path.Combine(System.AppContext.BaseDirectory, "SearchQuery.txt");

            if (File.Exists(searchQueryPath))
                return File.ReadAllText(searchQueryPath);

            Console.WriteLine($"The search query file { searchQueryPath } was not found. The file is created at the executable folder with current query of \"{ defaultFileType }\"");
            FileStream fileStream = File.Create(searchQueryPath);
            fileStream.Write(Encoding.UTF8.GetBytes(defaultFileType));
            fileStream.Close();

            return defaultFileType;
        }
    }
}