add a simple plugin system

Pilz.Plugins/IPlugin.cs

@@ -0,0 +1,7 @@
+namespace Pilz.Plugins
+{
+    public interface IPlugin
+    {
+        public string Name { get; }
+    }
+}

Pilz.Plugins/Pilz.Plugins.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

Pilz.Plugins/PluginLoadContext.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Loader;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pilz.Plugins
+{
+    internal class PluginLoadContext : AssemblyLoadContext
+    {
+        private readonly AssemblyDependencyResolver _resolver;
+
+        public PluginLoadContext(string pluginPath)
+        {
+            _resolver = new AssemblyDependencyResolver(pluginPath);
+        }
+
+        protected override Assembly? Load(AssemblyName assemblyName)
+        {
+            var assemblyPath = _resolver.ResolveAssemblyToPath(assemblyName);
+
+            if (assemblyPath != null)
+                return LoadFromAssemblyPath(assemblyPath);
+
+            return null;
+        }
+
+        protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
+        {
+            var libraryPath = _resolver.ResolveUnmanagedDllToPath(unmanagedDllName);
+
+            if (libraryPath != null)
+                return LoadUnmanagedDllFromPath(libraryPath);
+
+            return IntPtr.Zero;
+        }
+    }
+}

Pilz.Plugins/PluginManager.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pilz.Plugins
+{
+    public class PluginManager : PluginManager<IPlugin, PluginRuntimeInfo>
+    {
+        public static PluginManager Instance { get; private set; } = new();
+    }
+}

Pilz.Plugins/PluginManagerT.cs

@@ -0,0 +1,71 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pilz.Plugins
+{
+    public class PluginManager<TPluginInterface, TPluginRuntimeInfo> where TPluginInterface : class where TPluginRuntimeInfo : PluginRuntimeInfo<TPluginInterface>
+    {
+        public static IEnumerable<TPluginRuntimeInfo> LoadPlugins(string[] paths)
+        {
+            var states = new List<TPluginRuntimeInfo>();
+
+            foreach (string path in paths)
+                states.Add(LoadPlugin(path));
+
+            return states;
+        }
+
+        public static TPluginRuntimeInfo LoadPlugin(string path)
+        {
+            var info = Activator.CreateInstance<TPluginRuntimeInfo>();
+            var irmplugin = typeof(TPluginInterface);
+            var loadContext = new PluginLoadContext(path);
+            Assembly? assembly = null;
+
+            if (File.Exists(path))
+            {
+                try
+                {
+                    assembly = loadContext.LoadFromAssemblyName(new AssemblyName(Path.GetFileNameWithoutExtension(path)));
+                }
+                catch
+                {
+                    info.Status = PluginStatus.ErrorAtLoading;
+                }
+            }
+            else
+                info.Status = PluginStatus.FileNotFound;
+
+            if (assembly != null)
+            {
+                foreach (var type in assembly.GetTypes())
+                {
+                    if (info.Plugin == null && irmplugin.IsAssignableFrom(type))
+                    {
+                        try
+                        {
+                            if (Activator.CreateInstance(type) is TPluginInterface plugin)
+                            {
+                                info.Plugin = plugin;
+                                info.Status = PluginStatus.Success;
+                            }
+                        }
+                        catch
+                        {
+                            info.Status = PluginStatus.ErrorAtInitializing;
+                        }
+                    }
+                }
+
+                if (info.Plugin == null)
+                    info.Status = PluginStatus.NoValidPlugin;
+            }
+
+            return info;
+        }
+    }
+}

Pilz.Plugins/PluginRuntimeInfo.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pilz.Plugins
+{
+    public class PluginRuntimeInfo : PluginRuntimeInfo<IPlugin>
+    {
+    }
+}

Pilz.Plugins/PluginRuntimeInfoT.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pilz.Plugins
+{
+    public class PluginRuntimeInfo<T> where T : class
+    {
+        public T? Plugin { get; internal set; }
+        public PluginStatus Status { get; internal set; }
+    }
+}

Pilz.Plugins/PluginStatus.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pilz.Plugins
+{
+    public enum PluginStatus
+    {
+        None,
+        Success,
+        FileNotFound,
+        ErrorAtLoading,
+        ErrorAtInitializing,
+        NoValidPlugin
+    }
+}