Added plugin architecture (#322)

app/MindWork AI Studio/Tools/PluginSystem/PluginLoader.cs

@@ -0,0 +1,48 @@
+using System.Text;
+
+using AIStudio.Settings;
+
+using Lua;
+
+namespace AIStudio.Tools.PluginSystem;
+
+/// <summary>
+/// Loads Lua modules from a plugin directory.
+/// </summary>
+/// <remarks>
+/// Any plugin can load Lua modules from its own directory. This class is used to load these modules.
+/// Loading other modules outside the plugin directory is not allowed.
+/// </remarks>
+/// <param name="pluginDirectory">The directory where the plugin is located.</param>
+public sealed class PluginLoader(string pluginDirectory) : ILuaModuleLoader
+{
+    private static readonly string PLUGIN_BASE_PATH = Path.Join(SettingsManager.DataDirectory, "plugins");
+
+    #region Implementation of ILuaModuleLoader
+
+    /// <inheritdoc />
+    public bool Exists(string moduleName)
+    {
+        // Ensure that the user doesn't try to escape the plugin directory:
+        if (moduleName.Contains("..") || pluginDirectory.Contains(".."))
+            return false;
+        
+        // Ensure that the plugin directory is nested in the plugin base path:
+        if (!pluginDirectory.StartsWith(PLUGIN_BASE_PATH, StringComparison.OrdinalIgnoreCase))
+            return false;
+        
+        var path = Path.Join(pluginDirectory, $"{moduleName}.lua");
+        return File.Exists(path);
+    }
+
+    /// <inheritdoc />
+    public async ValueTask<LuaModule> LoadAsync(string moduleName, CancellationToken cancellationToken = default)
+    {
+        var path = Path.Join(pluginDirectory, $"{moduleName}.lua");
+        var code = await File.ReadAllTextAsync(path, Encoding.UTF8, cancellationToken);
+		
+        return new(moduleName, code);
+    }
+
+    #endregion
+}