Localization/Localization/LocalizationMod.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using GamecraftModdingAPI;
using GamecraftModdingAPI.App;
using GamecraftModdingAPI.Commands;
using GamecraftModdingAPI.Utility;
using HarmonyLib;
using IllusionPlugin;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using ServiceLayer;

namespace Localization
{
    public class LocalizationMod : IEnhancedPlugin
    {
        private readonly DirectoryInfo _pluginFolder = new DirectoryInfo(Path.Combine("Plugins", "Localization"));
        private Dictionary<string, string> _origStrings;
        private readonly string[] _embeddedLanguages = Assembly.GetExecutingAssembly().GetManifestResourceNames();

        public override void OnApplicationStart()
        {
            Main.Init();
            if (!_pluginFolder.Exists)
                _pluginFolder.Create();
            string settingsPath = Path.Combine(_pluginFolder.FullName, "settings.json");
            JObject settings;
            if (File.Exists(settingsPath))
            {
                try
                {
                    using (var stream = new JsonTextReader(File.OpenText(settingsPath)))
                        settings = JObject.Load(stream);
                    string lang = (string) (settings["lang"] ?? (settings["lang"] = "en"));
                    lang = lang.ToLower();
                    if (lang != "en")
                        LoadTranslation(lang);
                }
                catch (Exception e)
                {
                    Logging.LogError(e);
                    settings = new JObject();
                }
            }
            else
                settings = new JObject();

            CommandBuilder.Builder("SetLanguage", "Sets the game's language")
                .Action<string>(lang =>
                {
                    lang = lang.ToLower();
                    settings["lang"] = lang;
                    using (var stream = new JsonTextWriter(new StreamWriter(File.OpenWrite(settingsPath))))
                        settings.WriteTo(stream);
                    LoadTranslation(lang);

                }).Build();
            CommandBuilder.Builder("ListLanguages", "Lists available languages")
                .Action(() =>
                {
                    Logging.CommandLog(new[] {"en"}.Concat(_pluginFolder.EnumerateFiles()
                            .Where(file => file.Extension == ".json"
                                           && (file.Name.Length < 8 || file.Name.Contains("-")))
                            .Select(file => file.Name.Replace(file.Extension, "")))
                        .Concat(_embeddedLanguages)
                        .Select(lang => lang.Replace("Localization.", "").Replace(".json", ""))
                        .Distinct().Aggregate((a, b) => a + ", " + b));
                }).Build();
            CommandBuilder.Builder("DumpLangStrings", "Dumps the current strings. Set language to en first.")
                .Action(() =>
                {
                    File.WriteAllText(Path.Combine(_pluginFolder.FullName, "dumped.json"),
                        JsonConvert.SerializeObject(_origStrings, Formatting.Indented));
                }).Build();

            if (!settings.ContainsKey("autoload"))
            {
                settings["autoload"] = true;
                using (var stream = new JsonTextWriter(new StreamWriter(File.OpenWrite(settingsPath))))
                    settings.WriteTo(stream);
            }
            
            if ((bool) settings["autoload"])
                Client.EnterMenu += TryLoadSteamLanguageMenuEnterEvent;
        }

        public override void OnApplicationQuit()
        {
            Main.Shutdown();
        }

        private void LoadTranslation(string lang)
        {
            Logging.CommandLog("Loading translation for " + lang + "...");
            LoadOriginalStrings();
            string langPath = Path.Combine(_pluginFolder.FullName, lang + ".json");
            if (!File.Exists(langPath))
            {
                if (_embeddedLanguages.Contains("Localization." + lang + ".json"))
                    langPath = null;
                else
                {
                    if (lang == "en")
                    {
                        AccessTools.Method(typeof(LocalizationService), "Init").Invoke(null, new object[0]);
                        _origStrings = null; //Reset as the object changed
                        LoadOriginalStrings();
                        Logging.CommandLog("Strings reset to default. (" + _origStrings.Count + " strings in total)");
                        return;
                    }

                    Logging.CommandLogError("Could not find json file!");
                    return;
                }
            }

            string jsonText = langPath != null ? File.ReadAllText(langPath) : null;
            if (jsonText == null)
            {
                var stream = Assembly.GetExecutingAssembly()
                    .GetManifestResourceStream("Localization." + lang + ".json");
                if (stream != null)
                    using (var st = new StreamReader(stream))
                        jsonText = st.ReadToEnd();
                else
                {
                    Logging.CommandLogError("Failed to load embedded translation for " + lang);
                    return;
                }
            }

            var strings = JsonConvert.DeserializeObject<Dictionary<string, string>>(jsonText);
            foreach (var kv in strings)
            { 
                if (!_origStrings.Remove(kv.Key))
                    Logging.CommandLogWarning(kv.Key + " wasn't in the original file.");
                _origStrings.Add(kv.Key, kv.Value);
            }

            Logging.CommandLog("Updated " + strings.Count + " strings (" + _origStrings.Count + " strings in total)");
        }

        private void LoadOriginalStrings()
        {
            if (_origStrings != null) return;
            _origStrings =
                (Dictionary<string, string>) AccessTools.Field(typeof(LocalizationService), "LocalizedStrings")
                    .GetValue(null);
        }

        private void TryLoadSteamLanguageMenuEnterEvent(object sender, MenuEventArgs args)
        {
            TryLoadSteamLanguage();
            Client.EnterMenu -= TryLoadSteamLanguageMenuEnterEvent;
        }

        private void TryLoadSteamLanguage()
        {
            string lang = Steamworks.SteamUtils.SteamUILanguage;
            string first2 = lang.Substring(0, 2);
            // try some possibly valid language codes
            if (File.Exists(Path.Combine(_pluginFolder.FullName, lang + ".json")))
            {
                Logging.MetaLog($"Automatically detected Steam UI language {lang}, loading translations...");
                LoadTranslation(lang);
            }
            else if (File.Exists(Path.Combine(_pluginFolder.FullName, first2 + ".json")))
            {
                lang = first2;
                Logging.MetaLog($"Automatically detected Steam UI language {lang}, loading translations...");
                LoadTranslation(lang);
            }
            else if (File.Exists(Path.Combine(_pluginFolder.FullName, first2 + "-" + first2 + ".json")))
            {
                // a lot of standard languages codes are like fr-fr (French from France), but this won't work for English (nor fr-CA French from Canada)
                lang = first2 + "-" + first2;
                Logging.MetaLog($"Automatically detected Steam UI language {lang}, loading translations...");
                LoadTranslation(lang);
            }
            else
            {
                Logging.MetaLog($"Translations for Steam UI language {lang} are not available, skipping...");
            }
                
        }

        public override string Name { get; } = "LocalizationMod";
        public override string Version { get; } = "1.0.0";
    }
}