TranslatorBase.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace VPet.Plugin.AutoMTL
{
	public abstract class TranslatorBase
	{
		// Stuff that needs to be implemented in class that adds a translator
		// cf. TranslatorGoogle
		public static string providerName = "None";
		public static string providerId = "none";

		// Provider needs to implement this function, actually translates a string
		// This class takes care of all the caching and rate limiting
		public abstract string TranslateString(string input);
		// This is the getter that returns all the languages that can be used
		public static Dictionary<string, string> providedLanguages => null;

		// Other stuff

		// Can be changed on the fly
		public long msBetweenCalls;
		// Can't be changed on the fly, needs to clear cache and restart
		public bool titleCase;

		public readonly string srcLang;
		public readonly string dstLang;

		// Private stuff

		private readonly string cacheBase;
		private readonly string cacheFile;
		private TextInfo txtInfo;
		private Dictionary<string, string> cache;
		private long lastTime;

		public TranslatorBase(string srcLang, string dstLang, string cacheBase)
		{
			this.lastTime = 0;
			this.titleCase = true;
			this.msBetweenCalls = 20;
			this.srcLang = srcLang;
			this.dstLang = dstLang;
			this.cacheBase = cacheBase + @"\mtl";
			string providerId = TranslatorMananger.GetProviderId(this);
			this.cacheFile = this.cacheBase + String.Format(@"\{0}-{1}-{2}.json", providerId, srcLang, dstLang);
			this.txtInfo = new CultureInfo("en-US", false).TextInfo;
			InitCache();
		}

		void InitCache()
		{
			if (!Directory.Exists(cacheBase))
				Directory.CreateDirectory(cacheBase);

			if (File.Exists(cacheFile))
				cache = JsonConvert.DeserializeObject<Dictionary<string, string>>(File.ReadAllText(cacheFile));
			else
				cache = new Dictionary<string, string>();
		}

		void SaveCache()
		{
			File.WriteAllText(cacheFile, JsonConvert.SerializeObject(cache, Formatting.Indented));
		}

		public void ClearCache()
		{
			cache.Clear();
			if (File.Exists(cacheFile))
				File.Delete(cacheFile);
		}

		public string Translate(string input)
		{
			// Already in cache
			if (cache.ContainsKey(input))
				return cache[input];

			// Do rate limiting if needed
			long currentTime = DateTimeOffset.Now.ToUnixTimeMilliseconds();
			long timeDiff = currentTime - lastTime;
			if (timeDiff < msBetweenCalls)
				Thread.Sleep((int)timeDiff);
			lastTime = DateTimeOffset.Now.ToUnixTimeMilliseconds();

			// Run the translator
			string output = TranslateString(input);
			if (output == null)
				return null;

			// Check if it's the same as the input (could be same language)
			if (output.ToLower().Trim() == input.ToLower().Trim())
				return null;

			// Format if needed
			if (titleCase)
				output = txtInfo.ToTitleCase(output);

			// Cache the output and return
			cache[input] = output;
			// Saving at every change is not great...
			SaveCache();
			return output;
		}
	}
}