Obtaining the type under the cursor?

[digitaldias]

I am trying to write a command that mimics what Rider does in Navigate to consumed API, i.e. if I have a command named QueryPeople that I can invoke using Mediator.Send, then, when I'm looking at code like this:

var query = new QueryForPerson(name: "Gringo");
var result = await _mediator.Send(query, cancellationToken);

What I'd like my extension to do is when I have the cursor on the query on line two, I press my shortcut, and I can then somehow retrieve the type of query, and then look up any C# classes that have a Handle method for that type, in this case, a QueryForPersonHandler which then has the appropriate method: public async Task<something> Handle(QueryForPerson query, CancellationToken ct)

Thsi is my first time writing an extension for VS2022, I've watched @madskristensen s video introduction, and fell short immediately as the ActiveDocument does not appear to give me what I need. I'll do some google-fu meanwhile, but if you know how I can obtain this type, or even how I should approach this problem and can give me a few pseudo-code suggestions, I'd really appreciate it.

[reduckted]

First, you'll need to install the Microsoft.VisualStudio.LanguageServices NuGet package.

Then you can get the document in Roslyn like this:

// Get the workspace.
Workspace workspace = await VS.GetMefServiceAsync<VisualStudioWorkspace>();

// Get the active Visual Studio document.
DocumentView? documentView = await VS.Documents.GetActiveDocumentViewAsync();

if (document is not null) {
    // Get the Roslyn document for that file.
    DocumentId? id = workspace.CurrentSolution.GetDocumentIdsWithFilePath(documentView.FilePath).FirstOrDefault();

    if (id is not null) {
        Document roslynDocument = workspace.CurrentSolution.GetDocument(id);
    }
}

If you know your way around Roslyn, then it's probably not too difficult to get the type at the cursor. I haven't tried this, but it might point you in the right direction.

// Get the selection.
int position = documentView.TextView.Selection.ActivePoint.Position.Position;

// Get the syntax root.
SyntaxNode root = await roslynDocument.GetSyntaxRootAsync();

// Find the node at the selection.
SyntaxNode selectedNode = root.FindNode(new TextSpan(position, 1));

// Get the type information for that node.
SemanticModel model = await roslynDocument.GetSemanticModelAsync();
TypeInfo typeInfo = model.GetTypeInfo(node);

[digitaldias]

Thank you so much! It definetly got me closer, the typeInfo does not provide me with a type, but I see that the node is the correct one, so I can do some more research from there. Kudos for a very detailed reply!