using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace LawFirmContracts.DI
{
	public static partial class ServiceProviderLoader
	{
		/// <summary>
		/// Загрузка всех классов-реализаций IImplementationExtension
		/// </summary>
		/// <returns></returns>
		public static IImplementationExtension? GetImplementationExtensions()
		{
			IImplementationExtension? source = null;
			var files =
			Directory.GetFiles(TryGetImplementationExtensionsFolder(), "*.dll",
			SearchOption.AllDirectories);
			foreach (var file in files.Distinct())
			{
				Assembly asm = Assembly.LoadFrom(file);
				foreach (var t in asm.GetExportedTypes())
				{
					if (t.IsClass &&
					typeof(IImplementationExtension).IsAssignableFrom(t))
					{
						if (source == null)
						{
							source =
							(IImplementationExtension)Activator.CreateInstance(t)!;
						}
						else
						{
							var newSource =
							(IImplementationExtension)Activator.CreateInstance(t)!;
							if (newSource.Priority >
							source.Priority)
							{
								source = newSource;
							}
						}
					}
				}
			}
			return source;
		}
		private static string TryGetImplementationExtensionsFolder()
		{
			var localAppDataFolder = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
			var implementationExtensionsFolder = Path.Combine(localAppDataFolder, "ImplementationExtensions");

			if (!Directory.Exists(implementationExtensionsFolder))
			{
				Directory.CreateDirectory(implementationExtensionsFolder);
			}

			return implementationExtensionsFolder;
		}
}