tokensave 6.4.3

/// Tree-sitter based Rust source code extractor.
///
/// Parses Rust source files and emits nodes and edges for the code graph.
use std::time::{Instant, SystemTime, UNIX_EPOCH};

use tree_sitter::{Node as TsNode, Parser, Tree};

use crate::extraction::complexity::{count_complexity, RUST_COMPLEXITY};
use crate::types::{
    generate_node_id, Edge, EdgeKind, ExtractionResult, Node, NodeKind, UnresolvedRef, Visibility,
};

/// Extracts code graph nodes and edges from Rust source files using tree-sitter.
pub struct RustExtractor;

/// Internal state used during AST traversal.
struct ExtractionState {
    nodes: Vec<Node>,
    edges: Vec<Edge>,
    unresolved_refs: Vec<UnresolvedRef>,
    errors: Vec<String>,
    /// Stack of (name, `node_id`) for building qualified names and parent edges.
    node_stack: Vec<(String, String)>,
    file_path: String,
    source: Vec<u8>,
    timestamp: u64,
}

impl ExtractionState {
    fn new(file_path: &str, source: &str) -> Self {
        let timestamp = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap_or_default()
            .as_secs();
        Self {
            nodes: Vec::new(),
            edges: Vec::new(),
            unresolved_refs: Vec::new(),
            errors: Vec::new(),
            node_stack: Vec::new(),
            file_path: file_path.to_string(),
            source: source.as_bytes().to_vec(),
            timestamp,
        }
    }

    /// Returns the current qualified name prefix from the node stack.
    ///
    /// The file root is pushed onto `node_stack` as the first frame when
    /// extraction begins, so iterating the stack already yields the file
    /// path as the leading segment — prepending `self.file_path` here was
    /// a leftover that duplicated the prefix (`<file>::<file>::Type::method`).
    fn qualified_prefix(&self) -> String {
        self.node_stack
            .iter()
            .map(|(name, _)| name.as_str())
            .collect::<Vec<_>>()
            .join("::")
    }

    /// Returns the current parent node ID, or None if at file root level.
    fn parent_node_id(&self) -> Option<&str> {
        self.node_stack.last().map(|(_, id)| id.as_str())
    }

    /// Gets the text of a tree-sitter node from the source.
    fn node_text(&self, node: TsNode<'_>) -> String {
        node.utf8_text(&self.source)
            .unwrap_or("<invalid utf8>")
            .to_string()
    }
}

impl RustExtractor {
    /// Extract code graph nodes and edges from a Rust source file.
    ///
    /// `file_path` is used for qualified names and node IDs (not for I/O).
    /// `source` is the Rust source code to parse.
    pub fn extract(file_path: &str, source: &str) -> ExtractionResult {
        let start = Instant::now();
        let mut state = ExtractionState::new(file_path, source);

        let tree = match Self::parse_source(source) {
            Ok(tree) => tree,
            Err(msg) => {
                state.errors.push(msg);
                return Self::build_result(state, start);
            }
        };

        // Create the File root node.
        let file_node = Node {
            id: generate_node_id(file_path, &NodeKind::File, file_path, 0),
            kind: NodeKind::File,
            name: file_path.to_string(),
            qualified_name: file_path.to_string(),
            file_path: file_path.to_string(),
            start_line: 0,
            attrs_start_line: 0,
            end_line: source.lines().count().saturating_sub(1) as u32,
            start_column: 0,
            end_column: 0,
            signature: None,
            docstring: None,
            visibility: Visibility::Pub,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        let file_node_id = file_node.id.clone();
        state.nodes.push(file_node);
        state.node_stack.push((file_path.to_string(), file_node_id));

        // Walk the AST.
        let root = tree.root_node();
        Self::visit_children(&mut state, root);

        state.node_stack.pop();

        Self::build_result(state, start)
    }

    /// Parse source code into a tree-sitter AST.
    fn parse_source(source: &str) -> Result<Tree, String> {
        let mut parser = Parser::new();
        let language = crate::extraction::ts_provider::language("rust");
        parser
            .set_language(&language)
            .map_err(|e| format!("failed to load Rust grammar: {e}"))?;
        parser
            .parse(source, None)
            .ok_or_else(|| "tree-sitter parse returned None".to_string())
    }

    /// Visit all named children of a node.
    fn visit_children(state: &mut ExtractionState, node: TsNode<'_>) {
        let mut cursor = node.walk();
        if cursor.goto_first_child() {
            loop {
                let child = cursor.node();
                Self::visit_node(state, child);
                if !cursor.goto_next_sibling() {
                    break;
                }
            }
        }
    }

    /// Visit a single AST node, dispatching on its type.
    fn visit_node(state: &mut ExtractionState, node: TsNode<'_>) {
        match node.kind() {
            "function_item" | "function_signature_item" => Self::visit_function(state, node),
            "struct_item" => Self::visit_struct(state, node),
            "enum_item" => Self::visit_enum(state, node),
            "trait_item" => Self::visit_trait(state, node),
            "impl_item" => Self::visit_impl(state, node),
            "use_declaration" => Self::visit_use(state, node),
            "const_item" => Self::visit_const(state, node),
            "static_item" => Self::visit_static(state, node),
            "type_item" => Self::visit_type_alias(state, node),
            "mod_item" => Self::visit_module(state, node),
            "macro_invocation" => Self::visit_macro_invocation(state, node),
            _ => {
                // For other node types, recurse into children to find nested items.
                Self::visit_children(state, node);
            }
        }
    }

    /// Extract a function or free function node.
    fn visit_function(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let is_inside_impl = state
            .node_stack
            .iter()
            .any(|(_, id)| id.starts_with("impl:"));
        let is_inside_trait = state
            .node_stack
            .iter()
            .any(|(_, id)| id.starts_with("trait:"));
        let kind = if is_inside_impl || is_inside_trait {
            NodeKind::Method
        } else {
            NodeKind::Function
        };
        let visibility = Self::extract_visibility(node, state);
        let signature = Some(Self::extract_function_signature(state, node));
        let docstring = Self::extract_docstring(state, node);
        let is_async = Self::detect_async(state, node);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &kind, &name, start_line);
        let metrics = count_complexity(node, &RUST_COMPLEXITY, &state.source);

        let graph_node = Node {
            id: id.clone(),
            kind,
            name,
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring,
            visibility,
            is_async,
            branches: metrics.branches,
            loops: metrics.loops,
            returns: metrics.returns,
            max_nesting: metrics.max_nesting,
            unsafe_blocks: metrics.unsafe_blocks,
            unchecked_calls: metrics.unchecked_calls,
            assertions: metrics.assertions,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // Extract call sites from the function body.
        Self::extract_call_sites(state, node, &id);

        // Receiver-type-aware method calls (#141): `recv.method()` is otherwise
        // emitted only as the bare `method`, which mis-resolves when several
        // types define a method of that name. Build a local var->type table and
        // emit a precise `Type::method` ref so the resolver's qualified/suffix
        // match binds to the right impl.
        let self_type = Self::enclosing_impl_type(state);
        let var_types = Self::collect_var_types(state, node, self_type.as_deref());
        Self::extract_typed_method_calls(state, node, &id, &var_types);

        // Extract attribute annotations (e.g. #[test], #[inline]).
        Self::extract_annotations_from_modifiers(state, node, &id);

        // Emit TypeOf refs for parameter types and Returns refs for the return
        // type. Lets refactoring tools cluster items "anchored on T" without
        // walking source again.
        if let Some(params) = node.child_by_field_name("parameters") {
            let mut cursor = params.walk();
            if cursor.goto_first_child() {
                loop {
                    let child = cursor.node();
                    if let Some(ty) = child.child_by_field_name("type") {
                        Self::emit_type_refs(state, ty, &id, EdgeKind::TypeOf);
                    }
                    if !cursor.goto_next_sibling() {
                        break;
                    }
                }
            }
        }
        if let Some(ret) = node.child_by_field_name("return_type") {
            Self::emit_type_refs(state, ret, &id, EdgeKind::Returns);
        }
    }

    /// Extract a struct node and its fields.
    fn visit_struct(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let signature = Some(Self::extract_struct_signature(state, node));
        let docstring = Self::extract_docstring(state, node);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::Struct, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Struct,
            name: name.clone(),
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // Check for derive macros on preceding attribute items.
        Self::extract_derive_macros(state, node, &id);

        // Extract attribute annotations (e.g. #[cfg(...), #[allow(...)]).
        Self::extract_annotations_from_modifiers(state, node, &id);

        // Extract fields.
        state.node_stack.push((name, id.clone()));
        Self::extract_fields(state, node);
        state.node_stack.pop();
    }

    /// Extract an enum node and its variants.
    fn visit_enum(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let docstring = Self::extract_docstring(state, node);
        let text = state.node_text(node);
        let signature = Some(text.lines().next().unwrap_or("").to_string());
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::Enum, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Enum,
            name: name.clone(),
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // Check for derive macros on preceding attribute items.
        Self::extract_derive_macros(state, node, &id);

        // Extract attribute annotations (e.g. #[repr(C)]).
        Self::extract_annotations_from_modifiers(state, node, &id);

        // Extract enum variants.
        state.node_stack.push((name, id.clone()));
        Self::extract_enum_variants(state, node);
        state.node_stack.pop();
    }

    /// Extract a trait node and its methods.
    fn visit_trait(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let docstring = Self::extract_docstring(state, node);
        let signature = Some(format!("trait {name}"));
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::Trait, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Trait,
            name: name.clone(),
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // Extract attribute annotations.
        Self::extract_annotations_from_modifiers(state, node, &id);

        // Supertrait bounds (`trait Leaf: Middle + Base`) — emit one
        // unresolved `Extends` ref per bound so the resolver can hook them
        // up to the corresponding trait nodes. Each bound is a
        // `type_identifier` reachable through the `bounds: trait_bounds`
        // field, possibly wrapped in `higher_ranked_trait_bound`. We pull
        // the right-most identifier from each bound to ignore lifetime
        // params (`'a`) and generic args.
        if let Some(bounds) = node.child_by_field_name("bounds") {
            let mut cursor = bounds.walk();
            for child in bounds.children(&mut cursor) {
                let kind = child.kind();
                if kind == "," || kind == ":" || kind == "+" {
                    continue;
                }
                if let Some(bound_name) = Self::extract_trait_bound_name(state, child) {
                    state.unresolved_refs.push(UnresolvedRef {
                        from_node_id: id.clone(),
                        reference_name: bound_name,
                        reference_kind: EdgeKind::Extends,
                        line: child.start_position().row as u32,
                        column: child.start_position().column as u32,
                        file_path: state.file_path.clone(),
                    });
                }
            }
        }

        // Visit trait body: methods inside become Method nodes.
        state.node_stack.push((name, id));
        if let Some(body) = node.child_by_field_name("body") {
            Self::visit_children(state, body);
        }
        state.node_stack.pop();
    }

    /// Extract the trait identifier from a single bound node. Returns
    /// `None` for lifetime params or anything that isn't a named trait.
    fn extract_trait_bound_name(state: &ExtractionState, bound: TsNode<'_>) -> Option<String> {
        match bound.kind() {
            "type_identifier" => Some(state.node_text(bound)),
            // `Module::Trait` or `Trait<Generics>` — take the right-most
            // identifier so we ignore module paths and generic args.
            "scoped_type_identifier" | "generic_type" => {
                let mut cursor = bound.walk();
                let mut name = None;
                for c in bound.children(&mut cursor) {
                    if c.kind() == "type_identifier" {
                        name = Some(state.node_text(c));
                    }
                }
                name
            }
            // `for<'a> Trait` shape.
            "higher_ranked_trait_bound" => bound
                .child_by_field_name("type")
                .and_then(|inner| Self::extract_trait_bound_name(state, inner)),
            _ => None,
        }
    }

    /// Extract an impl block node and its methods.
    fn visit_impl(state: &mut ExtractionState, node: TsNode<'_>) {
        let type_name =
            Self::extract_impl_type_name(state, node).unwrap_or_else(|| "<unknown>".to_string());
        let trait_name = Self::extract_impl_trait_name(state, node);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), type_name);
        let id = generate_node_id(&state.file_path, &NodeKind::Impl, &type_name, start_line);

        let signature = if let Some(ref trait_n) = trait_name {
            Some(format!("impl {trait_n} for {type_name}"))
        } else {
            Some(format!("impl {type_name}"))
        };

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Impl,
            name: type_name.clone(),
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring: None,
            visibility: Visibility::Private,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // If this is a trait impl, create an Implements edge/ref.
        if let Some(ref trait_n) = trait_name {
            state.unresolved_refs.push(UnresolvedRef {
                from_node_id: id.clone(),
                reference_name: trait_n.clone(),
                reference_kind: EdgeKind::Implements,
                line: start_line,
                column: start_column,
                file_path: state.file_path.clone(),
            });
        }

        // Extract attribute annotations.
        Self::extract_annotations_from_modifiers(state, node, &id);

        // Visit impl body: functions become Method nodes.
        state.node_stack.push((type_name, id));
        if let Some(body) = node.child_by_field_name("body") {
            Self::visit_children(state, body);
        }
        state.node_stack.pop();
    }

    /// Extract a use declaration node.
    fn visit_use(state: &mut ExtractionState, node: TsNode<'_>) {
        let text = state.node_text(node);
        // Strip the `use ` prefix and trailing `;`.
        let path = text
            .trim()
            .strip_prefix("use ")
            .unwrap_or(&text)
            .trim_end_matches(';')
            .trim()
            .to_string();
        let visibility = Self::extract_visibility(node, state);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), path);
        let id = generate_node_id(&state.file_path, &NodeKind::Use, &path, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Use,
            name: path.clone(),
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature: Some(text.trim().to_string()),
            docstring: None,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // Unresolved Uses reference.
        state.unresolved_refs.push(UnresolvedRef {
            from_node_id: id,
            reference_name: path,
            reference_kind: EdgeKind::Uses,
            line: start_line,
            column: start_column,
            file_path: state.file_path.clone(),
        });
    }

    /// Extract a const item node.
    fn visit_const(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let docstring = Self::extract_docstring(state, node);
        let text = state.node_text(node);
        let signature = Some(text.lines().next().unwrap_or("").to_string());
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::Const, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Const,
            name,
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id,
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }
    }

    /// Extract a static item node.
    fn visit_static(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let docstring = Self::extract_docstring(state, node);
        let text = state.node_text(node);
        let signature = Some(text.lines().next().unwrap_or("").to_string());
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::Static, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Static,
            name,
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id,
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }
    }

    /// Extract a type alias node.
    fn visit_type_alias(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let docstring = Self::extract_docstring(state, node);
        let text = state.node_text(node);
        let signature = Some(text.trim().to_string());
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::TypeAlias, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::TypeAlias,
            name,
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature,
            docstring,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id,
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }
    }

    /// Extract a module item node.
    fn visit_module(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let docstring = Self::extract_docstring(state, node);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::Module, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Module,
            name: name.clone(),
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature: Some(format!("mod {name}")),
            docstring,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent.
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // Extract attribute annotations (e.g. #[cfg(test)]).
        Self::extract_annotations_from_modifiers(state, node, &id);

        // Visit the module body.
        state.node_stack.push((name, id));
        if let Some(body) = node.child_by_field_name("body") {
            Self::visit_children(state, body);
        }
        state.node_stack.pop();
    }

    /// Record a macro invocation as an unresolved call reference.
    fn visit_macro_invocation(state: &mut ExtractionState, node: TsNode<'_>) {
        let macro_name = node.child_by_field_name("macro").map_or_else(
            || {
                // Fallback: first named child is typically the macro name.
                let text = state.node_text(node);
                text.split('!').next().unwrap_or("").trim().to_string()
            },
            |n| state.node_text(n),
        );
        let start_line = node.start_position().row as u32;
        let start_column = node.start_position().column as u32;

        if let Some(parent_id) = state.parent_node_id() {
            state.unresolved_refs.push(UnresolvedRef {
                from_node_id: parent_id.to_string(),
                reference_name: macro_name,
                reference_kind: EdgeKind::Calls,
                line: start_line,
                column: start_column,
                file_path: state.file_path.clone(),
            });
        }
    }

    // ----------------------------
    // Helper extraction methods
    // ----------------------------

    /// Extract the name of a node by looking for a "name" field child.
    fn extract_name(state: &ExtractionState, node: TsNode<'_>) -> Option<String> {
        node.child_by_field_name("name").map(|n| state.node_text(n))
    }

    /// Extract the type name from an `impl_item` (the "type" field).
    fn extract_impl_type_name(state: &ExtractionState, node: TsNode<'_>) -> Option<String> {
        node.child_by_field_name("type").map(|n| state.node_text(n))
    }

    /// Extract the trait name from an `impl_item`, if it is a trait impl.
    ///
    /// For `impl Trait for Type`, tree-sitter gives us a "trait" field.
    fn extract_impl_trait_name(state: &ExtractionState, node: TsNode<'_>) -> Option<String> {
        node.child_by_field_name("trait")
            .map(|n| state.node_text(n))
    }

    /// Extract visibility from a node.
    fn extract_visibility(node: TsNode<'_>, state: &ExtractionState) -> Visibility {
        let mut cursor = node.walk();
        if cursor.goto_first_child() {
            loop {
                let child = cursor.node();
                if child.kind() == "visibility_modifier" {
                    let text = state.node_text(child);
                    return match text.as_str() {
                        "pub" => Visibility::Pub,
                        s if s.contains("crate") => Visibility::PubCrate,
                        s if s.contains("super") => Visibility::PubSuper,
                        _ => Visibility::Pub,
                    };
                }
                if !cursor.goto_next_sibling() {
                    break;
                }
            }
        }
        Visibility::Private
    }

    /// Extract the function signature (everything from `fn` up to the body `{`).
    fn extract_function_signature(state: &ExtractionState, node: TsNode<'_>) -> String {
        let text = state.node_text(node);
        // Find the opening brace and take everything before it.
        if let Some(brace_pos) = text.find('{') {
            text[..brace_pos].trim().to_string()
        } else {
            // For trait method declarations without a body (ending with `;`).
            text.trim_end_matches(';').trim().to_string()
        }
    }

    /// Extract the struct signature (the header line).
    fn extract_struct_signature(state: &ExtractionState, node: TsNode<'_>) -> String {
        let text = state.node_text(node);
        // Take the first line, or up to the opening brace.
        if let Some(brace_pos) = text.find('{') {
            text[..brace_pos].trim().to_string()
        } else {
            text.lines().next().unwrap_or("").trim().to_string()
        }
    }

    /// Extract docstrings from preceding comment nodes.
    fn extract_docstring(state: &ExtractionState, node: TsNode<'_>) -> Option<String> {
        let mut comments = Vec::new();
        let mut current = node.prev_named_sibling();
        while let Some(sibling) = current {
            match sibling.kind() {
                "line_comment" | "block_comment" => {
                    let text = state.node_text(sibling);
                    comments.push(text);
                    current = sibling.prev_named_sibling();
                }
                "attribute_item" => {
                    // Skip attributes (like #[derive(...)]) that sit between doc
                    // comments and the item.
                    current = sibling.prev_named_sibling();
                }
                _ => break,
            }
        }
        if comments.is_empty() {
            return None;
        }
        // Comments are collected in reverse order (closest first).
        comments.reverse();
        let cleaned: Vec<String> = comments.iter().map(|c| Self::clean_comment(c)).collect();
        let result = cleaned.join("\n").trim().to_string();
        if result.is_empty() {
            None
        } else {
            Some(result)
        }
    }

    /// Strip comment markers from a single comment text.
    fn clean_comment(comment: &str) -> String {
        let trimmed = comment.trim();
        if let Some(stripped) = trimmed.strip_prefix("///") {
            stripped.strip_prefix(' ').unwrap_or(stripped).to_string()
        } else if let Some(stripped) = trimmed.strip_prefix("//!") {
            stripped.strip_prefix(' ').unwrap_or(stripped).to_string()
        } else if let Some(stripped) = trimmed.strip_prefix("//") {
            stripped.strip_prefix(' ').unwrap_or(stripped).to_string()
        } else if trimmed.starts_with("/*") && trimmed.ends_with("*/") {
            // Block comment: strip /* and */ and clean each line.
            let inner = &trimmed[2..trimmed.len() - 2];
            inner
                .lines()
                .map(|line| {
                    let l = line.trim();
                    l.strip_prefix("* ")
                        .or_else(|| l.strip_prefix('*'))
                        .unwrap_or(l)
                })
                .collect::<Vec<_>>()
                .join("\n")
                .trim()
                .to_string()
        } else {
            trimmed.to_string()
        }
    }

    /// Detect if a function is async.
    fn detect_async(state: &ExtractionState, node: TsNode<'_>) -> bool {
        let text = state.node_text(node);
        let trimmed = text.trim_start();
        trimmed.starts_with("async ")
            || trimmed.starts_with("pub async ")
            || trimmed.starts_with("pub(crate) async ")
            || trimmed.starts_with("pub(super) async ")
    }

    /// Extract fields from a struct's `field_declaration_list`.
    fn extract_fields(state: &mut ExtractionState, struct_node: TsNode<'_>) {
        if let Some(body) = struct_node.child_by_field_name("body") {
            let mut cursor = body.walk();
            if cursor.goto_first_child() {
                loop {
                    let child = cursor.node();
                    if child.kind() == "field_declaration" {
                        Self::extract_single_field(state, child);
                    }
                    if !cursor.goto_next_sibling() {
                        break;
                    }
                }
            }
        }
    }

    /// Extract a single `field_declaration` node.
    fn extract_single_field(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let visibility = Self::extract_visibility(node, state);
        let text = state.node_text(node);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::Field, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::Field,
            name,
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature: Some(text.trim().trim_end_matches(',').trim().to_string()),
            docstring: None,
            visibility,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent (the struct).
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id.clone(),
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }

        // Emit TypeOf refs for the field's declared type.
        if let Some(type_node) = node.child_by_field_name("type") {
            Self::emit_type_refs(state, type_node, &id, EdgeKind::TypeOf);
        }
    }

    /// Extract enum variants from the enum body.
    fn extract_enum_variants(state: &mut ExtractionState, enum_node: TsNode<'_>) {
        if let Some(body) = enum_node.child_by_field_name("body") {
            let mut cursor = body.walk();
            if cursor.goto_first_child() {
                loop {
                    let child = cursor.node();
                    if child.kind() == "enum_variant" {
                        Self::extract_single_variant(state, child);
                    }
                    if !cursor.goto_next_sibling() {
                        break;
                    }
                }
            }
        }
    }

    /// Extract a single enum variant.
    fn extract_single_variant(state: &mut ExtractionState, node: TsNode<'_>) {
        let name = Self::extract_name(state, node).unwrap_or_else(|| "<anonymous>".to_string());
        let text = state.node_text(node);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::{}", state.qualified_prefix(), name);
        let id = generate_node_id(&state.file_path, &NodeKind::EnumVariant, &name, start_line);

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::EnumVariant,
            name,
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature: Some(text.trim().trim_end_matches(',').to_string()),
            docstring: None,
            visibility: Visibility::Pub,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Contains edge from parent (the enum).
        if let Some(parent_id) = state.parent_node_id() {
            state.edges.push(Edge {
                source: parent_id.to_string(),
                target: id,
                kind: EdgeKind::Contains,
                line: Some(start_line),
            });
        }
    }

    /// Recursively find `call_expression` nodes inside a given node and create
    /// unresolved Calls references.
    /// Type-method names that, in `let x = Type::ctor(...)`, let us infer the
    /// binding's type as `Type` (`new`/`from`/… return `Self`/the named type).
    const CONSTRUCTOR_NAMES: &'static [&'static str] = &[
        "new",
        "default",
        "with_capacity",
        "from",
        "try_from",
        "build",
        "create",
        "open",
        "init",
        "builder",
        "from_str",
    ];

    /// Returns the type name of the nearest enclosing `impl` block, used to
    /// resolve `self`/`Self` receivers to a concrete type.
    fn enclosing_impl_type(state: &ExtractionState) -> Option<String> {
        state
            .node_stack
            .iter()
            .rev()
            .find(|(_, id)| id.starts_with("impl:"))
            .map(|(name, _)| name.clone())
    }

    /// Normalizes a Rust type-expression text to a bare type name for
    /// `Type::method` matching: strips leading `&`/`&mut`/`mut`/lifetimes,
    /// generic arguments, and any path prefix. `&mut MermaidRenderer` ->
    /// `MermaidRenderer`, `std::vec::Vec<u8>` -> `Vec`. Returns `None` for
    /// shapes that aren't a plain named type (tuples, slices, `dyn`, etc.).
    fn normalize_type_name(raw: &str) -> Option<String> {
        let mut s = raw.trim();
        loop {
            if let Some(r) = s.strip_prefix('&') {
                s = r.trim_start();
            } else if let Some(r) = s.strip_prefix("mut ") {
                s = r.trim_start();
            } else if s.starts_with('\'') {
                // lifetime token like `'a` — drop up to the next whitespace.
                match s.find(char::is_whitespace) {
                    Some(pos) => s = s[pos..].trim_start(),
                    None => return None,
                }
            } else {
                break;
            }
        }
        // `dyn Trait` / `impl Trait` aren't concrete named types we can match.
        if let Some(r) = s.strip_prefix("dyn ") {
            s = r.trim_start();
        }
        if s.starts_with("impl ") {
            return None;
        }
        if let Some(pos) = s.find('<') {
            s = s[..pos].trim_end();
        }
        let seg = s.rsplit("::").next().unwrap_or(s).trim();
        let first = seg.chars().next()?;
        if !first.is_alphabetic() && first != '_' {
            return None;
        }
        Some(seg.to_string())
    }

    /// Extracts the bound identifier from a `let` pattern (`x` or `mut x`).
    fn binding_ident(state: &ExtractionState, pat: TsNode<'_>) -> Option<String> {
        match pat.kind() {
            "identifier" => Some(state.node_text(pat)),
            "mut_pattern" => pat
                .named_child(0)
                .filter(|c| c.kind() == "identifier")
                .map(|c| state.node_text(c)),
            _ => None,
        }
    }

    /// Best-effort type inference for a `let` RHS expression: a constructor
    /// call `Type::new(...)` or a struct literal `Type { .. }`. `Self::new(...)`
    /// resolves to `self_type`.
    fn infer_expr_type(
        state: &ExtractionState,
        value: TsNode<'_>,
        self_type: Option<&str>,
    ) -> Option<String> {
        match value.kind() {
            "call_expression" => {
                let func = value.child_by_field_name("function")?;
                if func.kind() != "scoped_identifier" {
                    return None;
                }
                let name = func
                    .child_by_field_name("name")
                    .map(|n| state.node_text(n))?;
                if !Self::CONSTRUCTOR_NAMES.contains(&name.as_str()) {
                    return None;
                }
                let path = func.child_by_field_name("path")?;
                let ty = Self::normalize_type_name(&state.node_text(path))?;
                if ty == "Self" {
                    self_type.map(str::to_string)
                } else {
                    Some(ty)
                }
            }
            "struct_expression" => {
                let name = value.child_by_field_name("name")?;
                Self::normalize_type_name(&state.node_text(name))
            }
            // `let x = &expr` / `let x = expr?` — peel one layer and retry.
            "reference_expression" | "try_expression" => value
                .named_child(0)
                .and_then(|inner| Self::infer_expr_type(state, inner, self_type)),
            _ => None,
        }
    }

    /// Builds a `var-name -> type-name` table for a function body from typed
    /// parameters and `let` bindings (annotation or constructor RHS). `self`
    /// maps to the enclosing impl type.
    fn collect_var_types(
        state: &ExtractionState,
        fn_node: TsNode<'_>,
        self_type: Option<&str>,
    ) -> std::collections::HashMap<String, String> {
        let mut map = std::collections::HashMap::new();
        if let Some(t) = self_type {
            map.insert("self".to_string(), t.to_string());
        }
        if let Some(params) = fn_node.child_by_field_name("parameters") {
            let mut cursor = params.walk();
            if cursor.goto_first_child() {
                loop {
                    let p = cursor.node();
                    if p.kind() == "parameter" {
                        if let (Some(pat), Some(ty)) = (
                            p.child_by_field_name("pattern"),
                            p.child_by_field_name("type"),
                        ) {
                            if pat.kind() == "identifier" {
                                if let Some(tn) = Self::normalize_type_name(&state.node_text(ty)) {
                                    map.insert(state.node_text(pat), tn);
                                }
                            }
                        }
                    }
                    if !cursor.goto_next_sibling() {
                        break;
                    }
                }
            }
        }
        if let Some(body) = fn_node.child_by_field_name("body") {
            Self::collect_let_types(state, body, self_type, &mut map);
        }
        map
    }

    /// Recursively records `let`-binding types into `map`, skipping nested
    /// function items (they have their own scope).
    fn collect_let_types(
        state: &ExtractionState,
        node: TsNode<'_>,
        self_type: Option<&str>,
        map: &mut std::collections::HashMap<String, String>,
    ) {
        let mut cursor = node.walk();
        if cursor.goto_first_child() {
            loop {
                let c = cursor.node();
                if c.kind() == "let_declaration" {
                    if let Some(var) = c
                        .child_by_field_name("pattern")
                        .and_then(|pat| Self::binding_ident(state, pat))
                    {
                        let ty = c
                            .child_by_field_name("type")
                            .and_then(|t| Self::normalize_type_name(&state.node_text(t)))
                            .or_else(|| {
                                c.child_by_field_name("value")
                                    .and_then(|v| Self::infer_expr_type(state, v, self_type))
                            });
                        if let Some(t) = ty {
                            map.insert(var, t);
                        }
                    }
                }
                if c.kind() != "function_item" {
                    Self::collect_let_types(state, c, self_type, map);
                }
                if !cursor.goto_next_sibling() {
                    break;
                }
            }
        }
    }

    /// Emits a precise `Type::method` Calls ref for every `recv.method(...)`
    /// whose receiver type is known from `var_types` (or `self`).
    fn extract_typed_method_calls(
        state: &mut ExtractionState,
        node: TsNode<'_>,
        fn_node_id: &str,
        var_types: &std::collections::HashMap<String, String>,
    ) {
        let mut cursor = node.walk();
        if cursor.goto_first_child() {
            loop {
                let child = cursor.node();
                if child.kind() == "call_expression" {
                    if let Some(func) = child.child_by_field_name("function") {
                        if func.kind() == "field_expression" {
                            if let (Some(recv), Some(field)) = (
                                func.child_by_field_name("value"),
                                func.child_by_field_name("field"),
                            ) {
                                if field.kind() == "field_identifier" {
                                    let ty = match recv.kind() {
                                        "self" => var_types.get("self").cloned(),
                                        "identifier" => {
                                            var_types.get(&state.node_text(recv)).cloned()
                                        }
                                        _ => None,
                                    };
                                    if let Some(ty) = ty {
                                        let method = state.node_text(field);
                                        state.unresolved_refs.push(UnresolvedRef {
                                            from_node_id: fn_node_id.to_string(),
                                            reference_name: format!("{ty}::{method}"),
                                            reference_kind: EdgeKind::Calls,
                                            line: child.start_position().row as u32,
                                            column: child.start_position().column as u32,
                                            file_path: state.file_path.clone(),
                                        });
                                    }
                                }
                            }
                        }
                    }
                }
                if child.kind() != "function_item" {
                    Self::extract_typed_method_calls(state, child, fn_node_id, var_types);
                }
                if !cursor.goto_next_sibling() {
                    break;
                }
            }
        }
    }

    fn extract_call_sites(state: &mut ExtractionState, node: TsNode<'_>, fn_node_id: &str) {
        let mut cursor = node.walk();
        if cursor.goto_first_child() {
            loop {
                let child = cursor.node();
                match child.kind() {
                    "call_expression" => {
                        if let Some(callee) = child.child_by_field_name("function") {
                            let callee_name = state.node_text(callee);
                            state.unresolved_refs.push(UnresolvedRef {
                                from_node_id: fn_node_id.to_string(),
                                reference_name: callee_name.clone(),
                                reference_kind: EdgeKind::Calls,
                                line: child.start_position().row as u32,
                                column: child.start_position().column as u32,
                                file_path: state.file_path.clone(),
                            });
                            // For dot-calls (e.g. `instance.method()`), also emit
                            // a ref with just the method name so the resolver can
                            // match it against impl method definitions.
                            if let Some(method_name) = callee_name.rsplit('.').next() {
                                if method_name != callee_name {
                                    state.unresolved_refs.push(UnresolvedRef {
                                        from_node_id: fn_node_id.to_string(),
                                        reference_name: method_name.to_string(),
                                        reference_kind: EdgeKind::Calls,
                                        line: child.start_position().row as u32,
                                        column: child.start_position().column as u32,
                                        file_path: state.file_path.clone(),
                                    });
                                }
                            }
                        }
                        // Also recurse into the call expression for nested calls.
                        Self::extract_call_sites(state, child, fn_node_id);
                    }
                    "macro_invocation" => {
                        let macro_name = child.child_by_field_name("macro").map_or_else(
                            || {
                                let text = state.node_text(child);
                                text.split('!').next().unwrap_or("").trim().to_string()
                            },
                            |n| state.node_text(n),
                        );
                        state.unresolved_refs.push(UnresolvedRef {
                            from_node_id: fn_node_id.to_string(),
                            reference_name: macro_name,
                            reference_kind: EdgeKind::Calls,
                            line: child.start_position().row as u32,
                            column: child.start_position().column as u32,
                            file_path: state.file_path.clone(),
                        });
                        // Recurse into macro arguments to find nested calls.
                        Self::extract_call_sites(state, child, fn_node_id);
                    }
                    // Inside a macro's token_tree, the grammar does not produce
                    // call_expression nodes. Instead, a function call appears as
                    // an identifier immediately followed by a token_tree sibling
                    // (e.g. `check_count(5)` → identifier "check_count" + token_tree
                    // "(5)"). Detect that pattern and emit Calls edges, then recurse
                    // into the token_tree to handle further nesting.
                    "token_tree" => {
                        Self::extract_calls_in_token_tree(state, child, fn_node_id);
                    }
                    // Skip nested function definitions — they are handled separately.
                    "function_item" => {}
                    _ => {
                        Self::extract_call_sites(state, child, fn_node_id);
                    }
                }
                if !cursor.goto_next_sibling() {
                    break;
                }
            }
        }
    }

    /// Scan the children of a `token_tree` node (macro argument list) for
    /// function-call patterns: an `identifier` immediately followed by a
    /// `token_tree` sibling is treated as a call.  We also recurse into nested
    /// `token_tree` nodes so that deeply-nested calls are found too.
    fn extract_calls_in_token_tree(
        state: &mut ExtractionState,
        node: TsNode<'_>,
        fn_node_id: &str,
    ) {
        // Collect the named children so we can look ahead by one position.
        let mut children = Vec::new();
        let mut cursor = node.walk();
        if cursor.goto_first_child() {
            loop {
                children.push(cursor.node());
                if !cursor.goto_next_sibling() {
                    break;
                }
            }
        }

        let mut i = 0;
        while i < children.len() {
            let cur = children[i];
            if cur.kind() == "identifier" {
                // Check whether the next sibling is a token_tree (call arguments).
                if i + 1 < children.len() && children[i + 1].kind() == "token_tree" {
                    let callee_name = state.node_text(cur);
                    state.unresolved_refs.push(UnresolvedRef {
                        from_node_id: fn_node_id.to_string(),
                        reference_name: callee_name,
                        reference_kind: EdgeKind::Calls,
                        line: cur.start_position().row as u32,
                        column: cur.start_position().column as u32,
                        file_path: state.file_path.clone(),
                    });
                    // Recurse into the argument token_tree for further nested calls.
                    Self::extract_calls_in_token_tree(state, children[i + 1], fn_node_id);
                    i += 2; // skip the token_tree we just handled
                    continue;
                }
            } else if cur.kind() == "token_tree" {
                // Standalone token_tree (e.g. `{…}` or `(…)` block) — recurse.
                Self::extract_calls_in_token_tree(state, cur, fn_node_id);
            } else if cur.kind() == "macro_invocation" {
                // Nested macro inside a macro — handled via extract_call_sites.
                Self::extract_call_sites(state, cur, fn_node_id);
            }
            i += 1;
        }
    }

    /// Extract derive macros from attribute items preceding a struct/enum.
    fn extract_derive_macros(state: &mut ExtractionState, node: TsNode<'_>, item_id: &str) {
        let mut current = node.prev_named_sibling();
        while let Some(sibling) = current {
            if sibling.kind() == "attribute_item" {
                let text = state.node_text(sibling);
                if text.contains("derive") {
                    Self::parse_derive_list(state, &text, item_id, sibling);
                }
                current = sibling.prev_named_sibling();
            } else if sibling.kind() == "line_comment" || sibling.kind() == "block_comment" {
                // Skip comments between attributes and the item.
                current = sibling.prev_named_sibling();
            } else {
                break;
            }
        }
    }

    /// Parse a derive attribute list and emit `DerivesMacro` edges.
    fn parse_derive_list(
        state: &mut ExtractionState,
        attr_text: &str,
        item_id: &str,
        attr_node: TsNode<'_>,
    ) {
        // attr_text is like: `#[derive(Debug, Clone, Serialize)]`
        // Find the content inside derive(...).
        if let Some(start) = attr_text.find("derive(") {
            let after = &attr_text[start + 7..];
            if let Some(end) = after.find(')') {
                let inner = &after[..end];
                let line = attr_node.start_position().row as u32;
                for trait_name in inner.split(',') {
                    let trait_name = trait_name.trim();
                    if !trait_name.is_empty() {
                        state.unresolved_refs.push(UnresolvedRef {
                            from_node_id: item_id.to_string(),
                            reference_name: trait_name.to_string(),
                            reference_kind: EdgeKind::DerivesMacro,
                            line,
                            column: attr_node.start_position().column as u32,
                            file_path: state.file_path.clone(),
                        });
                    }
                }
            }
        }
    }

    /// Returns the line of the earliest preceding doc-comment / attribute
    /// sibling of `node`, or `node`'s own start line when there is no leading
    /// block. Walks back over `attribute_item`, `line_comment`, and
    /// `block_comment` siblings; stops at the first node of any other kind.
    ///
    /// Lets refactoring tools select the full span of an item (delete, move,
    /// rewrite) without losing its leading documentation or attributes.
    fn compute_attrs_start_line(node: TsNode<'_>) -> u32 {
        let mut earliest = node.start_position().row as u32;
        let mut current = node.prev_named_sibling();
        while let Some(sibling) = current {
            match sibling.kind() {
                "attribute_item" | "line_comment" | "block_comment" => {
                    earliest = sibling.start_position().row as u32;
                    current = sibling.prev_named_sibling();
                }
                _ => break,
            }
        }
        earliest
    }

    /// Walks a type expression and emits an `UnresolvedRef` of the given kind
    /// for every named type identifier it contains. For a type like
    /// `Result<Vec<T>, MyError>` this yields refs for `Result`, `Vec`, `T`,
    /// and `MyError` — letting the resolver wire them up to declared nodes.
    fn emit_type_refs(
        state: &mut ExtractionState,
        type_node: TsNode<'_>,
        from_id: &str,
        kind: EdgeKind,
    ) {
        let mut cursor = type_node.walk();
        Self::emit_type_refs_walk(state, &mut cursor, from_id, kind);
    }

    fn emit_type_refs_walk(
        state: &mut ExtractionState,
        cursor: &mut tree_sitter::TreeCursor<'_>,
        from_id: &str,
        kind: EdgeKind,
    ) {
        let n = cursor.node();
        if n.kind() == "type_identifier" || n.kind() == "primitive_type" {
            state.unresolved_refs.push(UnresolvedRef {
                from_node_id: from_id.to_string(),
                reference_name: state.node_text(n),
                reference_kind: kind,
                line: n.start_position().row as u32,
                column: n.start_position().column as u32,
                file_path: state.file_path.clone(),
            });
        }
        if cursor.goto_first_child() {
            loop {
                Self::emit_type_refs_walk(state, cursor, from_id, kind);
                if !cursor.goto_next_sibling() {
                    break;
                }
            }
            cursor.goto_parent();
        }
    }

    /// Walk previous siblings of a declaration looking for `attribute_item` nodes
    /// and extract annotation usages from each one (skipping `derive` attributes,
    /// which are already handled by `extract_derive_macros`).
    fn extract_annotations_from_modifiers(
        state: &mut ExtractionState,
        node: TsNode<'_>,
        target_id: &str,
    ) {
        let mut current = node.prev_named_sibling();
        while let Some(sibling) = current {
            if sibling.kind() == "attribute_item" {
                let text = state.node_text(sibling);
                // Skip derive attributes — they are handled by extract_derive_macros.
                if !text.contains("derive") {
                    Self::extract_annotations_from_node(state, sibling, target_id);
                }
                current = sibling.prev_named_sibling();
            } else if sibling.kind() == "line_comment" || sibling.kind() == "block_comment" {
                current = sibling.prev_named_sibling();
            } else {
                break;
            }
        }
    }

    /// Create an `AnnotationUsage` node and edges for a single `attribute_item` node.
    fn extract_annotations_from_node(
        state: &mut ExtractionState,
        node: TsNode<'_>,
        target_id: &str,
    ) {
        let annot_name = Self::extract_annotation_name(state, node);
        let start_line = node.start_position().row as u32;
        let end_line = node.end_position().row as u32;
        let start_column = node.start_position().column as u32;
        let end_column = node.end_position().column as u32;
        let qualified_name = format!("{}::@{}", state.qualified_prefix(), annot_name);
        let id = generate_node_id(
            &state.file_path,
            &NodeKind::AnnotationUsage,
            &annot_name,
            start_line,
        );

        let graph_node = Node {
            id: id.clone(),
            kind: NodeKind::AnnotationUsage,
            name: annot_name.clone(),
            qualified_name,
            file_path: state.file_path.clone(),
            start_line,
            attrs_start_line: Self::compute_attrs_start_line(node),
            end_line,
            start_column,
            end_column,
            signature: Some(state.node_text(node).trim().to_string()),
            docstring: None,
            visibility: Visibility::Private,
            is_async: false,
            branches: 0,
            loops: 0,
            returns: 0,
            max_nesting: 0,
            unsafe_blocks: 0,
            unchecked_calls: 0,
            assertions: 0,
            updated_at: state.timestamp,
            parent_id: None,
        };
        state.nodes.push(graph_node);

        // Annotates unresolved ref.
        state.unresolved_refs.push(UnresolvedRef {
            from_node_id: id.clone(),
            reference_name: annot_name,
            reference_kind: EdgeKind::Annotates,
            line: start_line,
            column: start_column,
            file_path: state.file_path.clone(),
        });

        // Direct Annotates edge from the annotation to the target.
        state.edges.push(Edge {
            source: id,
            target: target_id.to_string(),
            kind: EdgeKind::Annotates,
            line: Some(start_line),
        });
    }

    /// Extract the name from a Rust `attribute_item` node.
    ///
    /// Trims `#[` and `]`, then takes everything before `(` as the name.
    /// E.g. `#[cfg(test)]` -> `cfg`, `#[inline]` -> `inline`.
    fn extract_annotation_name(state: &ExtractionState, node: TsNode<'_>) -> String {
        let text = state.node_text(node);
        let trimmed = text.trim();
        let inner = trimmed
            .strip_prefix("#[")
            .unwrap_or(trimmed)
            .strip_suffix(']')
            .unwrap_or(trimmed);
        inner.split('(').next().unwrap_or(inner).trim().to_string()
    }

    /// Build the final `ExtractionResult` from the accumulated state.
    fn build_result(state: ExtractionState, start: Instant) -> ExtractionResult {
        ExtractionResult {
            nodes: state.nodes,
            edges: state.edges,
            unresolved_refs: state.unresolved_refs,
            errors: state.errors,
            duration_ms: start.elapsed().as_millis() as u64,
        }
    }
}

impl crate::extraction::LanguageExtractor for RustExtractor {
    fn extensions(&self) -> &[&str] {
        &["rs"]
    }

    fn language_name(&self) -> &'static str {
        "Rust"
    }

    fn extract(&self, file_path: &str, source: &str) -> ExtractionResult {
        RustExtractor::extract(file_path, source)
    }
}