Converts Teach2000 files to CSV and Anki's APKG format.

TeachConvert.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Text;
using System.Xml;
using AnkiSharp;    // Import form NuGet package

namespace TeachConvert
{
    [SuppressMessage("ReSharper", "PossibleNullReferenceException")]
    internal static class Program
    {
        public static void Main(string[] args)
        {
            if (args.Length != 1) {
                Console.WriteLine("Pass me a folder containing .t2k files.");
                Console.WriteLine("If you don't know how, just drag the folder on this exe.");
                Console.ReadLine();
                return;
            }

            string path = args[0];
            if (!Directory.Exists(path)) {
                Console.WriteLine("Passed argument is not a directory.");
                Console.ReadLine();
                return;
            }

            foreach (string filePath in Directory.EnumerateFiles(path, "*.t2k", SearchOption.AllDirectories)) {
                try {
                    string folder = Path.GetDirectoryName(filePath);
                    string file = Path.GetFileName(filePath);
                    string fileClean = Path.GetFileNameWithoutExtension(filePath);

                    var dic = LoadFile(filePath);
                    Console.WriteLine($"Loaded {dic.Count} lines from {file}.");
                    WriteCsv(Path.Combine(folder, fileClean + ".csv"), dic);
                    WriteAnki(Path.Combine(folder, fileClean + ".apkg"), dic, fileClean);
                } catch (Exception e) {
                    Console.WriteLine($"! Failed to process {filePath}, {e.Message}");
                }
            }
        }

        private static void WriteAnki(string outFile, Dictionary<string, string> dic, string packageName)
        {
            var anki = new Anki(packageName);
            foreach (var pair in dic)
                anki.AddItem(pair.Key, pair.Value);
            anki.CreateApkgFile(Path.GetDirectoryName(outFile));    // quality API design, AnkiSharp :(
        }

        private static void WriteCsv(string outFile, Dictionary<string, string> dic)
        {
            const char separator = ',';
            string Escaped(string s) => $"\"{s}\"";    // csv is weird, man

            using (var sw = new StreamWriter(outFile, false, Encoding.Unicode)) {    // using UTF16 is the only way to make Excel happy :(
                sw.WriteLine($"Question{separator}Answer");

                foreach (var pair in dic) {
                    sw.WriteLine(Escaped(pair.Key) + separator + Escaped(pair.Value));
                }
            }
        }

        private static Dictionary<string, string> LoadFile(string path)
        {
            var dic = new Dictionary<string, string>();

            var doc = new XmlDocument();
            doc.Load(path);
            var items = doc.DocumentElement.SelectNodes("/teach2000/message_data/items/item");

            foreach (XmlElement elem in items) {
                var ql = elem.SelectNodes("questions/question");
                var al = elem.SelectNodes("answers/answer");
                var q = string.Join("/", ql.OfType<XmlElement>().Select(x => x.InnerText));
                var a = string.Join("/", al.OfType<XmlElement>().Select(x => x.InnerText));
                // Console.WriteLine($"{q};{a}");
                dic[q] = a;
            }

            return dic;
        }
    }
}