using ModelTools.Extensions;
using ModelTools.Interfaces;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Xml.XPath;

namespace ModelTools.BusinessLogics
{
	/// <summary>
	/// Загрузчик данных
	/// </summary>
	public static class ServiceProviderLoader
	{
		private static readonly string _configFileName = "DepartmentPortal.config";

		private static readonly string _pathToLoaderExt = "..\\..\\..\\..\\Extensions\\";

		/// <summary>
		/// Получение данных с файла настроек
		/// </summary>
		/// <param name="key"></param>
		/// <returns></returns>
		public static string GetConfigData(string key)
		{
			var fileName = GetFile(_configFileName);
			if (!File.Exists(fileName))
			{
				return string.Empty;
			}

			var doc = new XPathDocument(fileName);
			var nav = doc.CreateNavigator();
			var data = nav.SelectDescendants(key, "", false);
			data.MoveNext();
			return data.Current.Value;
		}

		/// <summary>
		/// Загрузка всех классов-реализаций ILoaderExtensions
		/// </summary>
		/// <returns></returns>
		public static List<ILoaderExtensions> GetLoaderExtensions()
		{
			var list = new List<ILoaderExtensions>();
			if(Directory.Exists(_pathToLoaderExt))
			{
				var files = Directory.GetFiles(_pathToLoaderExt, "*.dll", SearchOption.AllDirectories);
				var loadedFiles = new List<string>();
				foreach(var file in files.Distinct())
				{
					if(loadedFiles.Contains(file.GetFileName()))
					{
						continue;
					}
					Assembly asm = Assembly.LoadFrom(file);
					foreach (var t in asm.GetExportedTypes())
					{
						if (t.IsClass && typeof(ILoaderExtensions).IsAssignableFrom(t))
						{
							list.Add((ILoaderExtensions)Activator.CreateInstance(t));
						}
					}
					loadedFiles.Add(file.GetFileName());
				}
			}
			return list;
		}

		/// <summary>
		/// Получение имени файла
		/// </summary>
		/// <param name="fileName"></param>
		/// <returns></returns>
		private static string GetFile(string fileName) => Path.Combine(Path.GetDirectoryName(Assembly.GetEntryAssembly().Location), fileName);
	}
}