add a uniquie event for plugin function execution

Pilz.Plugins.Advanced.UI/PluginModule{T}.cs

@@ -1,16 +1,7 @@
-using System.Reflection.Metadata;
-
-namespace Pilz.Plugins.Advanced.UI;
+namespace Pilz.Plugins.Advanced.UI;
 
 public abstract class PluginModule<TPluginModuleUI> : PluginModuleBase where TPluginModuleUI : Control
 {
-    public delegate void PluginModuleUIEventHandler(PluginModuleBase module, TPluginModuleUI ui);
-
-    /// <summary>
-    /// Fires when a <see cref="PluginModuleUI"/> instance has been created.
-    /// </summary>
-    public static event PluginModuleUIEventHandler? OnUICreated;
-
     public bool Visible { get; set; } = true;
     public bool AllowEmbedding { get; set; } = true;
 
@@ -40,17 +31,22 @@ public abstract class PluginModule<TPluginModuleUI> : PluginModuleBase where TPl
     {
     }
 
-    public virtual TPluginModuleUI CreateUI()
+    public virtual TPluginModuleUI? CreateUI()
     {
         return CreateUI(null);
     }
 
-    public virtual TPluginModuleUI CreateUI(PluginFunctionParameter? @params)
+    public virtual TPluginModuleUI? CreateUI(PluginFunctionParameter? @params)
     {
-        var ui = CreateNewUI(@params);
-        OnUICreated?.Invoke(this, ui);
-        return ui;
+        object? ui = default;
+
+        if (!OnPreExecute(@params, ref ui))
+            ui = CreateNewUI(@params);
+
+        OnPostExecute(@params, ref ui);
+
+        return ui as TPluginModuleUI;
     }
 
-    protected abstract TPluginModuleUI CreateNewUI(PluginFunctionParameter? @params);
+    protected abstract TPluginModuleUI? CreateNewUI(PluginFunctionParameter? @params);
 }

Pilz.Plugins.Advanced/Delegates.cs

@@ -0,0 +1,3 @@
+namespace Pilz.Plugins.Advanced;
+
+public delegate void PluginFeatureExecuteEventHandler(object sender, PluginFeatureExecuteEventArgs e);

Pilz.Plugins.Advanced/PluginFeature.cs

@@ -1,7 +1,17 @@
-namespace Pilz.Plugins.Advanced;
+using System.Reflection.Metadata;
+
+namespace Pilz.Plugins.Advanced;
 
 public abstract class PluginFeature
 {
+    /// <summary>
+    /// Fires when the plugin feature gets used.
+    /// <br/>- For <see cref="PluginFunction"/> this fires on <see cref="PluginFunction.ExecuteFunction(PluginFunctionParameter?)"/>.
+    /// <br/>- For <see cref="T:PluginModule"/> this fires on <see cref="T:PluginModule.CreateNewUI(PluginFunctionParameter?)"/>.
+    /// <br/>- For any other custom feature implementation this may variate.
+    /// </summary>
+    public static event PluginFeatureExecuteEventHandler? OnExecute;
+
     /// <summary>
     /// The type of the feature defines where the feature get integrated.
     /// </summary>
@@ -50,4 +60,49 @@ public abstract class PluginFeature
     {
         return $"{featureType}:{identifier}";
     }
+
+    /// <summary>
+    /// Fires the <see cref="OnExecute"/> event with the status <see cref="PluginFeatureExecuteEventType.PostEvent"/>.
+    /// </summary>
+    /// <param name="params">The present <see cref="PluginFunctionParameter"/>.</param>
+    /// <param name="result">The resulting object that will be returned.</param>
+    /// <returns>Returns true if the original function should be executed.</returns>
+    protected bool OnPreExecute(PluginFunctionParameter? @params, ref object? result)
+    {
+        if (OnExecute != null)
+        {
+            var args = new PluginFeatureExecuteEventArgs(PluginFeatureExecuteEventType.PreEvent, @params);
+
+            OnExecute.Invoke(this, args);
+
+            if (args.Handled)
+            {
+                result = args.Result;
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /// <summary>
+    /// Fires the <see cref="OnExecute"/> event with the status <see cref="PluginFeatureExecuteEventType.PostEvent"/>.
+    /// </summary>
+    /// <param name="params">The present <see cref="PluginFunctionParameter"/>.</param>
+    /// <param name="result">The resulting object that will be returned.</param>
+    protected void OnPostExecute(PluginFunctionParameter? @params, ref object? result)
+    {
+        if (OnExecute != null)
+        {
+            var args = new PluginFeatureExecuteEventArgs(PluginFeatureExecuteEventType.PostEvent, @params)
+            {
+                Result = result
+            };
+
+            OnExecute.Invoke(this, args);
+
+            if (args.Handled)
+                result = args.Result;
+        }
+    }
 }

Pilz.Plugins.Advanced/PluginFeatureExecuteEventArgs.cs

@@ -0,0 +1,9 @@
+namespace Pilz.Plugins.Advanced;
+
+public class PluginFeatureExecuteEventArgs(PluginFeatureExecuteEventType eventType, PluginFunctionParameter? parameters) : EventArgs
+{
+    public PluginFeatureExecuteEventType EventType { get; } = eventType;
+    public PluginFunctionParameter? Parameters { get; } = parameters;
+    public bool Handled { get; set; }
+    public object? Result { get; set; }
+}

Pilz.Plugins.Advanced/PluginFeatureExecuteEventType.cs

@@ -0,0 +1,7 @@
+namespace Pilz.Plugins.Advanced;
+
+public enum PluginFeatureExecuteEventType
+{
+    PreEvent,
+    PostEvent,
+}

Pilz.Plugins.Advanced/PluginFunction.cs

@@ -34,7 +34,14 @@ public abstract class PluginFunction : PluginFeature
 
     public virtual object? Execute(PluginFunctionParameter? @params)
     {
-        return ExecuteFunction(@params);
+        object? result = default;
+
+        if (!OnPreExecute(@params, ref result))
+            result = ExecuteFunction(@params);
+
+        OnPostExecute(@params, ref result);
+
+        return result;
     }
 
     protected abstract object? ExecuteFunction(PluginFunctionParameter? @params);