fix: resolve MediatR/Mediator request types from referenced assemblies

CHANGELOG.md

@@ -1,6 +1,13 @@
 # Changelog
 All notable changes to this project will be documented in this file.
 
+## 26.09.04XX
+- "Go to Handler" now also works with the caret anywhere inside a `mediator.Send(...)` /
+  `Publish(...)` call: the first argument's type is resolved, so there is no need to navigate to the
+  request declaration first.
+- Raise the inheritor search cap from 50 to 300 so solutions with many handlers no longer have the
+  matching handler truncated away before it can be selected.
+
 ## 26.08.20XX
 - Fix issue #117: updated SDK to 2026.2.
 

src/dotnet/MediatorPlugin/Actions/GoToHandlerAction.cs

@@ -9,6 +9,7 @@
 using JetBrains.TextControl;
 using JetBrains.Util;
 using ReSharper.MediatorPlugin.Diagnostics;
+using ReSharper.MediatorPlugin.ReSharper.Psi.Tree;
 using ReSharper.MediatorPlugin.Services.Find;
 using ReSharper.MediatorPlugin.Services.Navigation;
 
@@ -81,14 +82,12 @@ protected override Action<ITextControl> ExecutePsiTransaction(ISolution solution
     private static IIdentifier? GetSelectedMediatrRequest(LanguageIndependentContextActionDataProvider dataProvider)
     {
         var selectedTreeNode = dataProvider.GetSelectedTreeNode<ITreeNode>();
-
-        if (selectedTreeNode is IIdentifier identifier)
-        {
-            Logger.Instance.Log(LoggingLevel.VERBOSE, $"Selected tree node is an identifier: {identifier.Name}");
-            return identifier;
-        }
 
-        Logger.Instance.Log(LoggingLevel.VERBOSE, "Selected tree node is not an identifier");
-        return null;
+        IIdentifier? identifier = MediatorCallSite.ResolveRequestIdentifier(selectedTreeNode);
+
+        if (identifier is null)
+            Logger.Instance.Log(LoggingLevel.VERBOSE, "Selected tree node is not a Mediator request or dispatch call");
+
+        return identifier;
     }
 }

src/dotnet/MediatorPlugin/Actions/GoToHandlerNavigationAction.cs

@@ -7,6 +7,7 @@
 using JetBrains.ReSharper.Feature.Services.Navigation.ContextNavigation;
 using JetBrains.ReSharper.Psi.Tree;
 using ReSharper.MediatorPlugin.Diagnostics;
+using ReSharper.MediatorPlugin.ReSharper.Psi.Tree;
 using ReSharper.MediatorPlugin.Services.Find;
 using ReSharper.MediatorPlugin.Services.Navigation;
 
@@ -23,7 +24,9 @@ public bool Update(IDataContext context, ActionPresentation presentation, Delega
     {
         var selectedTreeNode = context.GetSelectedTreeNode<ITreeNode>();
 
-        if (selectedTreeNode is not IIdentifier identifier)
+        IIdentifier? identifier = MediatorCallSite.ResolveRequestIdentifier(selectedTreeNode);
+
+        if (identifier is null)
             return nextUpdate.Invoke();
 
         return _handlerSelector.IsMediatorRequestSupported(identifier);
@@ -36,12 +39,6 @@ public void Execute(IDataContext context, DelegateExecute nextExecute)
         var solution = context.GetComponent<ISolution>();
         var selectedTreeNode = context.GetSelectedTreeNode<ITreeNode>();
 
-        if (selectedTreeNode is not IIdentifier)
-        {
-            Logger.Instance.Log(LoggingLevel.VERBOSE, "Selected element is not an identifier");
-            return;
-        }
-
         _handlerSelector.NavigateToHandler
         (
             solution,

src/dotnet/MediatorPlugin/Navigations/Providers/MediatorRequestNavigateFromHereProvider.cs

@@ -33,18 +33,12 @@ IDataContext dataContext
                     var solution = dataContext.GetComponent<ISolution>();
                     var selectedTreeNode = dataContext.GetSelectedTreeNode<ITreeNode>();
 
-                    if (selectedTreeNode is not IIdentifier)
-                    {
-                        Logger.Instance.Log(LoggingLevel.VERBOSE, $"Selected element is not an instance {nameof(IIdentifier)}");
-                        return;
-                    }
-
                     _handlerSelector.NavigateToHandler
                     (
                         solution,
                         selectedTreeNode,
                         new DataContextNavigationOptionsFactory(dataContext)
-                    ); 
+                    );
                 }
             )
         };

src/dotnet/MediatorPlugin/ReSharper/Psi/Search/InheritorsConsumer.cs

@@ -6,7 +6,7 @@ namespace ReSharper.MediatorPlugin.ReSharper.Psi.Search;
 
 internal sealed class InheritorsConsumer : IFindResultConsumer<ITypeElement>
 {
-    private const int MaxInheritors = 50;
+    private const int MaxInheritors = 300;
 
     private readonly HashSet<ITypeElement> _elements = new();
 

src/dotnet/MediatorPlugin/ReSharper/Psi/Tree/MediatorCallSite.cs

@@ -0,0 +1,81 @@
+using System.Linq;
+using JetBrains.Diagnostics;
+using JetBrains.ReSharper.Psi;
+using JetBrains.ReSharper.Psi.CSharp;
+using JetBrains.ReSharper.Psi.CSharp.Tree;
+using JetBrains.ReSharper.Psi.Tree;
+using JetBrains.ReSharper.Psi.Util;
+using ReSharper.MediatorPlugin.Diagnostics;
+
+namespace ReSharper.MediatorPlugin.ReSharper.Psi.Tree;
+
+internal static class MediatorCallSite
+{
+    public static IIdentifier? ResolveRequestIdentifier(ITreeNode? node)
+    {
+        if (node is null)
+            return null;
+
+        return ResolveFromEnclosingCall(node) ?? node as IIdentifier;
+    }
+
+    private static IIdentifier? ResolveFromEnclosingCall(ITreeNode node)
+    {
+        IInvocationExpression? invocation = node.GetContainingNode<IInvocationExpression>(returnThis: true);
+
+        if (invocation is null)
+        {
+            Logger.Instance.Log(LoggingLevel.VERBOSE, "> Caret is not inside an invocation expression");
+            return null;
+        }
+
+        foreach (ICSharpArgument argument in invocation.Arguments)
+        {
+            IIdentifier? identifier = ArgumentTypeDeclarationIdentifier(argument.Value);
+
+            if (identifier is not null)
+                return identifier;
+        }
+
+        Logger.Instance.Log(LoggingLevel.VERBOSE, $"> No invocation argument resolved to a navigable type declaration (method '{InvokedMethodName(invocation)}')");
+        return null;
+    }
+
+    private static IIdentifier? ArgumentTypeDeclarationIdentifier(ICSharpExpression? argumentValue)
+    {
+        ITypeElement? typeElement = ResolveTypeElement(argumentValue);
+
+        if (typeElement is null)
+            return null;
+
+        if (typeElement.GetDeclarations().FirstOrDefault() is not IClassLikeDeclaration declaration)
+        {
+            Logger.Instance.Log(LoggingLevel.VERBOSE, $"> Argument type '{typeElement.GetClrName().FullName}' has no source declaration to navigate from");
+            return null;
+        }
+
+        Logger.Instance.Log(LoggingLevel.VERBOSE, $"> Resolved invocation argument to type '{declaration.DeclaredName}'");
+        return declaration.NameIdentifier;
+    }
+
+    private static ITypeElement? ResolveTypeElement(ICSharpExpression? expression)
+    {
+        switch (expression)
+        {
+            case null:
+                return null;
+
+            case IObjectCreationExpression objectCreation
+                when objectCreation.TypeReference?.Resolve().DeclaredElement is ITypeElement created:
+                return created;
+
+            default:
+                return (expression.GetExpressionType().ToIType() as IDeclaredType)?.GetTypeElement();
+        }
+    }
+
+    private static string InvokedMethodName(IInvocationExpression invocation)
+    {
+        return (invocation.InvokedExpression as IReferenceExpression)?.Reference.GetName() ?? "<unknown>";
+    }
+}

src/dotnet/MediatorPlugin/Services/Find/HandlerSelector.cs

@@ -7,6 +7,7 @@
 using JetBrains.ReSharper.Psi.Tree;
 using JetBrains.TextControl;
 using ReSharper.MediatorPlugin.Diagnostics;
+using ReSharper.MediatorPlugin.ReSharper.Psi.Tree;
 using ReSharper.MediatorPlugin.Services.Libraries;
 using ReSharper.MediatorPlugin.Services.Navigation;
 using System.Collections.Generic;
@@ -34,13 +35,15 @@ IIdentifier identifier
     public void NavigateToHandler
     (
         ISolution solution,
-        ITreeNode selectedTreeNode,
+        ITreeNode? selectedTreeNode,
         INavigationOptionsFactory navigationOptionsFactory
     )
     {
-        if (selectedTreeNode is not IIdentifier selectedIdentifier)
+        IIdentifier? selectedIdentifier = MediatorCallSite.ResolveRequestIdentifier(selectedTreeNode);
+
+        if (selectedIdentifier is null)
         {
-            Logger.Instance.Log(LoggingLevel.VERBOSE, $"Selected element is not an instance {nameof(IIdentifier)}");
+            Logger.Instance.Log(LoggingLevel.VERBOSE, "Selected element is not a Mediator request or dispatch call");
             return;
         }
 

src/dotnet/MediatorPlugin/Services/Find/IHandlerSelector.cs

@@ -14,7 +14,7 @@ IIdentifier identifier
     void NavigateToHandler
     (
         ISolution solution,
-        ITreeNode selectedTreeNode,
+        ITreeNode? selectedTreeNode,
         INavigationOptionsFactory navigationOptionsFactory
     );
 }