...

compiler/NubLang.LSP/HoverHandler.cs

@@ -1,28 +1,195 @@
+using System.Globalization;
+using NubLang.Ast;
 using OmniSharp.Extensions.LanguageServer.Protocol.Client.Capabilities;
 using OmniSharp.Extensions.LanguageServer.Protocol.Document;
 using OmniSharp.Extensions.LanguageServer.Protocol.Models;
 
 namespace NubLang.LSP;
 
-internal class HoverHandler : HoverHandlerBase
+internal class HoverHandler(WorkspaceManager workspaceManager) : HoverHandlerBase
 {
     protected override HoverRegistrationOptions CreateRegistrationOptions(HoverCapability capability, ClientCapabilities clientCapabilities)
     {
         return new HoverRegistrationOptions
         {
-            DocumentSelector = TextDocumentSelector.ForLanguage("nublang")
+            DocumentSelector = TextDocumentSelector.ForLanguage("nub")
         };
     }
 
-    public override async Task<Hover?> Handle(HoverParams request, CancellationToken cancellationToken)
+    public override Task<Hover?> Handle(HoverParams request, CancellationToken cancellationToken)
     {
+        return Task.FromResult(HandleSync(request));
+    }
+
+    private Hover? HandleSync(HoverParams request)
+    {
+        var compilationUnit = workspaceManager.GetCompilationUnit(request.TextDocument.Uri);
+        if (compilationUnit == null)
+        {
+            return null;
+        }
+
+        var line = request.Position.Line;
+        var character = request.Position.Character;
+
+        var hoveredNode = compilationUnit.Functions
+            .SelectMany(x => x.EnumerateDescendantsAndSelf())
+            .Where(n => IsHoveringOverNode(n, line, character))
+            .OrderBy(n => n.Tokens.First().Span.Start.Line)
+            .ThenBy(n => n.Tokens.First().Span.Start.Column)
+            .LastOrDefault();
+
+        if (hoveredNode == null)
+        {
+            return null;
+        }
+
+        var message = CreateMessage(hoveredNode, compilationUnit);
+        if (message == null)
+        {
+            return null;
+        }
+
         return new Hover
         {
             Contents = new MarkedStringsOrMarkupContent(new MarkupContent
             {
-                Value = "# uwu",
+                Value = message,
                 Kind = MarkupKind.Markdown,
             })
         };
     }
+
+    private static string? CreateMessage(Node hoveredNode, CompilationUnit compilationUnit)
+    {
+        return hoveredNode switch
+        {
+            FuncNode funcNode => CreateFuncPrototypeNodeMessage(funcNode.Prototype),
+            FuncPrototypeNode funcPrototypeNode => CreateFuncPrototypeNodeMessage(funcPrototypeNode),
+            FuncIdentifierNode funcIdentifierNode => CreateFuncIdentifierNodeMessage(funcIdentifierNode, compilationUnit),
+            FuncParameterNode funcParameterNode => CreateVariableIdentifierNodeMessage(funcParameterNode.Name, funcParameterNode.Type),
+            VariableIdentifierNode variableIdentifierNode => CreateVariableIdentifierNodeMessage(variableIdentifierNode.Name, variableIdentifierNode.Type),
+            VariableDeclarationNode variableDeclarationNode => CreateVariableIdentifierNodeMessage(variableDeclarationNode.Name, variableDeclarationNode.Type),
+            CStringLiteralNode cStringLiteralNode => CreateLiteralNodeMessage(cStringLiteralNode.Type, '"' + cStringLiteralNode.Value + '"'),
+            StringLiteralNode stringLiteralNode => CreateLiteralNodeMessage(stringLiteralNode.Type, '"' + stringLiteralNode.Value + '"'),
+            BoolLiteralNode boolLiteralNode => CreateLiteralNodeMessage(boolLiteralNode.Type, boolLiteralNode.Value.ToString()),
+            Float32LiteralNode float32LiteralNode => CreateLiteralNodeMessage(float32LiteralNode.Type, float32LiteralNode.Value.ToString(CultureInfo.InvariantCulture)),
+            Float64LiteralNode float64LiteralNode => CreateLiteralNodeMessage(float64LiteralNode.Type, float64LiteralNode.Value.ToString(CultureInfo.InvariantCulture)),
+            I8LiteralNode i8LiteralNode => CreateLiteralNodeMessage(i8LiteralNode.Type, i8LiteralNode.Value.ToString()),
+            I16LiteralNode i16LiteralNode => CreateLiteralNodeMessage(i16LiteralNode.Type, i16LiteralNode.Value.ToString()),
+            I32LiteralNode i32LiteralNode => CreateLiteralNodeMessage(i32LiteralNode.Type, i32LiteralNode.Value.ToString()),
+            I64LiteralNode i64LiteralNode => CreateLiteralNodeMessage(i64LiteralNode.Type, i64LiteralNode.Value.ToString()),
+            U8LiteralNode u8LiteralNode => CreateLiteralNodeMessage(u8LiteralNode.Type, u8LiteralNode.Value.ToString()),
+            U16LiteralNode u16LiteralNode => CreateLiteralNodeMessage(u16LiteralNode.Type, u16LiteralNode.Value.ToString()),
+            U32LiteralNode u32LiteralNode => CreateLiteralNodeMessage(u32LiteralNode.Type, u32LiteralNode.Value.ToString()),
+            U64LiteralNode u64LiteralNode => CreateLiteralNodeMessage(u64LiteralNode.Type, u64LiteralNode.Value.ToString()),
+            // Expressions can have a generic fallback showing the resulting type
+            ExpressionNode expressionNode => CreateGenericExpressionNodeMessage(expressionNode),
+            // Explicit null returns, can be removed when the default is null instead of the debug type
+            BlockNode => null,
+            StatementNode statementNode => CreateGenericStatementNodeMessage(statementNode),
+            _ => hoveredNode.GetType().Name
+        };
+    }
+
+    private static string CreateLiteralNodeMessage(NubType type, string value)
+    {
+        return $"""
+                **Literal** `{type}`
+                ```nub
+                {value}: {type}
+                ```
+                """;
+    }
+
+    private static string CreateVariableIdentifierNodeMessage(string name, NubType type)
+    {
+        return $"""
+                **Variable** `{name}`
+                ```nub
+                {name}: {type}
+                ```
+                """;
+    }
+
+    private static string CreateFuncIdentifierNodeMessage(FuncIdentifierNode funcIdentifierNode, CompilationUnit compilationUnit)
+    {
+        var func = compilationUnit.ImportedFunctions.FirstOrDefault(x => x.Module == funcIdentifierNode.Module && x.Name == funcIdentifierNode.Name);
+        if (func == null)
+        {
+            return $"""
+                    **Function** `{funcIdentifierNode.Module}::{funcIdentifierNode.Name}`
+                    ```nub
+                    // Declaration not found
+                    ```
+                    """;
+        }
+
+        return CreateFuncPrototypeNodeMessage(func);
+    }
+
+    private static string CreateFuncPrototypeNodeMessage(FuncPrototypeNode funcPrototypeNode)
+    {
+        var parameterText = string.Join(", ", funcPrototypeNode.Parameters.Select(x => $"{x.Name}: {x.Type}"));
+        var externText = funcPrototypeNode.ExternSymbol != null ? $"extern \"{funcPrototypeNode.ExternSymbol}\" " : "";
+
+        return $"""
+                **Function** `{funcPrototypeNode.Name}`
+                ```nub
+                {externText}func {funcPrototypeNode.Name}({parameterText}): {funcPrototypeNode.ReturnType}
+                ```
+                """;
+    }
+
+    private static string CreateGenericStatementNodeMessage(StatementNode statementNode)
+    {
+        return $"**Statement** `{statementNode.GetType().Name}`";
+    }
+
+    private static string CreateGenericExpressionNodeMessage(ExpressionNode expressionNode)
+    {
+        return $"""
+                **Expression** `{expressionNode.GetType().Name}`
+                ```nub
+                {expressionNode.Type}
+                ```
+                """;
+    }
+
+    private static bool IsHoveringOverNode(Node node, int line, int character)
+    {
+        if (node.Tokens.Count == 0)
+        {
+            return false;
+        }
+
+        var start = node.Tokens.First().Span.Start;
+        var end = node.Tokens.Last().Span.End;
+
+        var startLine = start.Line - 1;
+        var startChar = start.Column - 1;
+        var endLine = end.Line - 1;
+        var endChar = end.Column - 1;
+
+        if (line < startLine || line > endLine) return false;
+
+        if (line > startLine && line < endLine) return true;
+
+        if (startLine == endLine)
+        {
+            return character >= startChar && character <= endChar;
+        }
+
+        if (line == startLine)
+        {
+            return character >= startChar;
+        }
+
+        if (line == endLine)
+        {
+            return character <= endChar;
+        }
+
+        return false;
+    }
 }