Shaker/Avalonia/ShakerApp/Tools/PluginsLoader.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Runtime.Loader;

namespace ShakerApp.Tools
{
    public class PluginsLoader
    {
        private string ext = "";
        private List<Assembly> LoadedAssemblies = new List<Assembly>();

        [AllowNull]
        private AssemblyDependencyResolver resolver;

        private List<string> AllDlls = new List<string>();

        private PluginsLoader()
        {
        }

        public List<T> Load<T>(string path)
        {
            try
            {
                resolver = new AssemblyDependencyResolver(path);
                AssemblyLoadContext.Default.Resolving += Default_Resolving;
                AssemblyLoadContext.Default.ResolvingUnmanagedDll += Default_ResolvingUnmanagedDll;
                AllDlls.Clear();
                AllDlls.AddRange(System.IO.Directory.GetFiles(path, "*.dll", System.IO.SearchOption.AllDirectories));
                var result = AllDlls
                    .SelectMany(x =>
                    {
                        try
                        {
                            var assembly = AssemblyLoadContext.Default.LoadFromAssemblyPath(x);
                            var types = assembly.GetTypes();
                            return types.Where(x => x.GetInterface(typeof(T).FullName!) != null && x.IsAnsiClass && !x.IsAbstract);
                        }
                        catch 
                        {
                        }
                        return new Type[0];
                    })
                    .Where(x => x != null)
                    .Select(x =>
                    {
                        return (T)Activator.CreateInstance(x!)!;
                    })
                    .Where(x => x != null)
                    .ToList();
                //AssemblyLoadContext.Default.Resolving -= Default_Resolving;
                return result;
            }
            catch
            {
                return new List<T>();
            }
        }

        [DllImport("kernel32.dll")]
        private static extern nint LoadLibrary(string path);

        private nint Default_ResolvingUnmanagedDll(Assembly arg1, string arg2)
        {
            var fileinfo = new FileInfo(arg1.Location);
            if (fileinfo?.Directory == null) return 0;
            string ext = "*.dll";
            var file = fileinfo.Directory.GetFiles(ext, SearchOption.AllDirectories).FirstOrDefault(x=>x.Name == arg2)?.FullName;
            
            if (System.IO.File.Exists(file))
            {
                return LoadLibrary(file);
            }
            throw new NotImplementedException();
        }

        private System.Reflection.Assembly? Default_Resolving(AssemblyLoadContext arg1, System.Reflection.AssemblyName arg2)
        {
            var assembly = AssemblyLoadContext.Default.Assemblies.FirstOrDefault(x => x.FullName == arg2.FullName);
            if (assembly != null) return assembly;
            assembly = LoadedAssemblies.FirstOrDefault(x => x.FullName == arg2.FullName);
            if (assembly != null) return assembly;
            string? path = resolver.ResolveAssemblyToPath(arg2);
            if (!string.IsNullOrEmpty(path))
            {
                assembly = arg1.LoadFromAssemblyPath(path);
                if (assembly != null)
                {
                    LoadedAssemblies.Add(assembly);
                    return assembly;
                }
            }
            else
            {
                var results = AllDlls.Where(x => x.IndexOf(arg2.Name!) >= 0).ToList();
                results.ForEach(x =>
                {
                    try
                    {
                        var tempassembly = arg1.LoadFromAssemblyPath(x);
                        if (tempassembly != null)
                        {
                            LoadedAssemblies.Add(tempassembly);
                        }
                    }
                    catch
                    {
                    }
                });
                assembly = LoadedAssemblies.FirstOrDefault(x => x.FullName == arg2.FullName);
                if (assembly != null) return assembly;
            }
            return null;
        }

        static PluginsLoader()
        {
        }

        public static PluginsLoader Defalut { get; } = new PluginsLoader();
    }
}