feature: first

CringePlugins/Loader/PluginInstance.cs

@@ -0,0 +1,55 @@
+using System.Runtime.Loader;
+using CringeBootstrap.Abstractions;
+using CringePlugins.Utils;
+using VRage.Plugins;
+
+namespace CringePlugins.Loader;
+
+internal sealed class PluginInstance
+{
+    private readonly string _entrypointPath;
+    private PluginAssemblyLoadContext? _context;
+    private IPlugin? _instance;
+    private IHandleInputPlugin? _handleInputInstance;
+    public PluginMetadata Metadata { get; }
+
+    public PluginInstance(PluginMetadata metadata, string entrypointPath)
+    {
+        _entrypointPath = entrypointPath;
+        Metadata = metadata;
+    }
+    
+    public PluginInstance(string entrypointPath) : this(PluginMetadata.ReadFromEntrypoint(entrypointPath), entrypointPath)
+    {
+    }
+
+    public void Instantiate()
+    {
+        if (AssemblyLoadContext.GetLoadContext(typeof(PluginInstance).Assembly) is not ICoreLoadContext parentContext)
+            throw new NotSupportedException("Plugin instantiation is not supported in this context");
+        
+        _context = new PluginAssemblyLoadContext(parentContext, _entrypointPath);
+        
+        var entrypoint = _context.LoadEntrypoint();
+
+        var plugins = IntrospectionContext.Global.CollectDerivedTypes<IPlugin>(entrypoint.GetMainModule()).ToArray();
+        
+        if (plugins.Length == 0)
+            throw new InvalidOperationException("Entrypoint does not contain any plugins");
+        if (plugins.Length > 1)
+            throw new InvalidOperationException("Entrypoint contains multiple plugins");
+
+        _instance = (IPlugin) Activator.CreateInstance(plugins[0])!;
+        _handleInputInstance = _instance as IHandleInputPlugin;
+    }
+
+    public void RegisterLifetime()
+    {
+        if (_instance is null)
+            throw new InvalidOperationException("Must call Instantiate first");
+        
+        MyPlugins.m_plugins.Add(_instance);
+        if (_handleInputInstance is not null)
+            MyPlugins.m_handleInputPlugins.Add(_handleInputInstance);
+    }
+}