Localization/Localization/LocalizationMod.cs

using System;
using System.Collections.Generic;
using System.IO;
using GamecraftModdingAPI;
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"));
        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-us"));
                    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 =>
                {
                    settings["lang"] = lang;
                    using (var stream = new JsonTextWriter(new StreamWriter(File.OpenWrite(settingsPath))))
                        settings.WriteTo(stream);
                    LoadTranslation(lang);
                    
                }).Build();
        }

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

        private void LoadTranslation(string lang)
        {
            Logging.CommandLog("Loading translation for " + lang + "...");
            string langPath = Path.Combine(_pluginFolder.FullName, lang + ".json");
            if (!File.Exists(langPath))
            {
                Logging.CommandLogError("Could not find json file!");
                return;
            }

            var strings = JsonConvert.DeserializeObject<Dictionary<string, string>>(File.ReadAllText(langPath));
            var origStrings =
                (Dictionary<string, string>) AccessTools.Field(typeof(LocalizationService), "LocalizedStrings")
                    .GetValue(null);
            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)");
        }

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