ucm-ingest 0.1.3

//! Code parser — extracts entities and relationships from source code.
//!
//! Extracts functions, classes, structs, and import relationships using
//! language-specific pattern matching. Produces `UcmEvent` streams that
//! the graph projection applies to build the dependency graph.
//!
//! Supported languages: TypeScript, JavaScript, Rust, Python.
//!
//! **Edges produced:** Each file gets a `Module` entity. Functions/structs
//! emit `DependsOn` edges to their module. Import statements emit `Imports`
//! edges from the importing module to the imported symbol. This gives the
//! BFS traversal a complete path: `callerFn → callerModule → importedSymbol`.
//!
//! Production upgrade path: replace `extract_functions_*` with tree-sitter
//! grammars for sub-millisecond incremental re-parsing and error recovery.
//! The event API surface stays identical — only the extraction backend changes.

use std::collections::HashMap;
use std::path::Path;
use ucm_graph_core::edge::*;
use ucm_graph_core::entity::*;
use ucm_graph_core::event::*;

/// Maps Rust crate names (underscored, e.g. `ucm_graph_core`) to their `src/`
/// directory paths relative to the scan root (e.g. `ucm-core/src`).
/// Built by the CLI scanner from workspace `Cargo.toml` files.
pub type RustCrateMap = HashMap<String, String>;

/// The top-level Python package name for absolute import resolution.
/// e.g. for marimo, this is "marimo" — so `from marimo._runtime.dataflow import X`
/// resolves to `marimo/_runtime/dataflow.py`.
pub type PythonPackageRoot = Option<String>;

/// Parse source code and emit entity + dependency events.
///
/// # Arguments
/// - `file_path` — path relative to project root (used as entity ID component)
/// - `source`    — raw source text
/// - `language`  — "typescript", "javascript", "rust", or "python"
///
/// # Returns
/// Stream of `UcmEvent`s ready for `GraphProjection::apply_event`.
pub fn parse_source_code(file_path: &str, source: &str, language: &str) -> Vec<UcmEvent> {
    parse_source_code_with_context(file_path, source, language, &HashMap::new())
}

/// Parse source code with project context for cross-file edge resolution.
///
/// `crate_map` maps Rust crate names (underscored) to their src/ directory
/// paths relative to the scan root. For non-Rust languages this is ignored.
pub fn parse_source_code_with_context(
    file_path: &str,
    source: &str,
    language: &str,
    crate_map: &RustCrateMap,
) -> Vec<UcmEvent> {
    parse_source_code_full(file_path, source, language, crate_map, &None)
}

/// Parse source code with full context including Python package root.
pub fn parse_source_code_full(
    file_path: &str,
    source: &str,
    language: &str,
    crate_map: &RustCrateMap,
    python_package_root: &PythonPackageRoot,
) -> Vec<UcmEvent> {
    let mut events = Vec::new();

    // 1. Emit a module entity for this file so import edges have a valid source.
    let module_id = EntityId::local(file_path, "module");
    events.push(UcmEvent::new(EventPayload::EntityDiscovered {
        entity_id: module_id.clone(),
        kind: EntityKind::Module {
            language: language.to_string(),
            exports: vec![],
        },
        name: file_name_of(file_path),
        file_path: file_path.to_string(),
        language: language.to_string(),
        source: DiscoverySource::StaticAnalysis,
        line_range: None,
    }));

    // 2. Extract function/struct entities and wire them to the module.
    //    For Python, also extract class-method associations.
    if matches!(language, "python" | "py") {
        let py_entities = extract_python_entities(source);
        for ent in &py_entities {
            match ent {
                PythonEntity::Function {
                    name,
                    is_async,
                    line_start,
                    line_end,
                    class_name,
                } => {
                    let display_name = if let Some(cls) = class_name {
                        format!("{cls}.{name}")
                    } else {
                        name.clone()
                    };
                    let fn_id = EntityId::local(file_path, &display_name);
                    events.push(UcmEvent::new(EventPayload::EntityDiscovered {
                        entity_id: fn_id.clone(),
                        kind: EntityKind::Function {
                            is_async: *is_async,
                            parameter_count: 0,
                            return_type: None,
                        },
                        name: display_name.clone(),
                        file_path: file_path.to_string(),
                        language: language.to_string(),
                        source: DiscoverySource::StaticAnalysis,
                        line_range: Some((*line_start, *line_end)),
                    }));
                    events.push(UcmEvent::new(EventPayload::DependencyLinked {
                        source_entity: fn_id.clone(),
                        target_entity: module_id.clone(),
                        relation_type: RelationType::DependsOn,
                        confidence: 0.99,
                        source: DiscoverySource::StaticAnalysis,
                        description: format!("{display_name} is defined in {file_path}"),
                    }));
                    // If method belongs to a class, emit Contains edge
                    if let Some(cls) = class_name {
                        let class_id = EntityId::local(file_path, cls);
                        events.push(UcmEvent::new(EventPayload::DependencyLinked {
                            source_entity: class_id,
                            target_entity: fn_id,
                            relation_type: RelationType::Contains,
                            confidence: 0.99,
                            source: DiscoverySource::StaticAnalysis,
                            description: format!("{cls} contains method {name}"),
                        }));
                    }
                }
                PythonEntity::Class {
                    name,
                    line_num,
                    bases,
                } => {
                    let class_id = EntityId::local(file_path, name);
                    events.push(UcmEvent::new(EventPayload::EntityDiscovered {
                        entity_id: class_id.clone(),
                        kind: EntityKind::DataModel { fields: vec![] },
                        name: name.clone(),
                        file_path: file_path.to_string(),
                        language: language.to_string(),
                        source: DiscoverySource::StaticAnalysis,
                        line_range: Some((*line_num, line_num + 5)),
                    }));
                    events.push(UcmEvent::new(EventPayload::DependencyLinked {
                        source_entity: class_id.clone(),
                        target_entity: module_id.clone(),
                        relation_type: RelationType::DependsOn,
                        confidence: 0.99,
                        source: DiscoverySource::StaticAnalysis,
                        description: format!("{name} is defined in {file_path}"),
                    }));
                    // Emit Extends edges for each base class
                    for base in bases {
                        let base_id = EntityId::local(file_path, base);
                        events.push(UcmEvent::new(EventPayload::DependencyLinked {
                            source_entity: class_id.clone(),
                            target_entity: base_id,
                            relation_type: RelationType::Extends,
                            confidence: 0.90,
                            source: DiscoverySource::StaticAnalysis,
                            description: format!("{name} extends {base}"),
                        }));
                    }
                }
            }
        }
    } else {
        let functions = match language {
            "rust" | "rs" => extract_functions_rust(source),
            _ => extract_functions_ts(source),
        };

        for (name, is_async, line_start, line_end) in functions {
            let fn_id = EntityId::local(file_path, &name);
            events.push(UcmEvent::new(EventPayload::EntityDiscovered {
                entity_id: fn_id.clone(),
                kind: EntityKind::Function {
                    is_async,
                    parameter_count: 0,
                    return_type: None,
                },
                name: name.clone(),
                file_path: file_path.to_string(),
                language: language.to_string(),
                source: DiscoverySource::StaticAnalysis,
                line_range: Some((line_start, line_end)),
            }));
            // fn → module: "this function lives in this module"
            events.push(UcmEvent::new(EventPayload::DependencyLinked {
                source_entity: fn_id,
                target_entity: module_id.clone(),
                relation_type: RelationType::DependsOn,
                confidence: 0.99,
                source: DiscoverySource::StaticAnalysis,
                description: format!("{name} is defined in {file_path}"),
            }));
        }

        // 3. Extract class / struct entities.
        let structs = match language {
            "rust" | "rs" => extract_structs_rust(source),
            _ => extract_classes_ts(source),
        };

        for (name, line_num) in structs {
            let struct_id = EntityId::local(file_path, &name);
            events.push(UcmEvent::new(EventPayload::EntityDiscovered {
                entity_id: struct_id.clone(),
                kind: EntityKind::DataModel { fields: vec![] },
                name: name.clone(),
                file_path: file_path.to_string(),
                language: language.to_string(),
                source: DiscoverySource::StaticAnalysis,
                line_range: Some((line_num, line_num + 5)),
            }));
            events.push(UcmEvent::new(EventPayload::DependencyLinked {
                source_entity: struct_id,
                target_entity: module_id.clone(),
                relation_type: RelationType::DependsOn,
                confidence: 0.99,
                source: DiscoverySource::StaticAnalysis,
                description: format!("{name} is defined in {file_path}"),
            }));
        }
    }

    // 4. Extract API routes (TypeScript/JS only).
    if matches!(language, "typescript" | "javascript" | "ts" | "js") {
        for (method, route, _handler, line_num) in extract_routes_ts(source) {
            let route_id = EntityId::local(file_path, &format!("{method}:{route}"));
            events.push(UcmEvent::new(EventPayload::EntityDiscovered {
                entity_id: route_id.clone(),
                kind: EntityKind::ApiEndpoint {
                    method: method.clone(),
                    route: route.clone(),
                    handler: String::new(),
                },
                name: format!("{method} {route}"),
                file_path: file_path.to_string(),
                language: language.to_string(),
                source: DiscoverySource::StaticAnalysis,
                line_range: Some((line_num, line_num)),
            }));
            events.push(UcmEvent::new(EventPayload::DependencyLinked {
                source_entity: route_id,
                target_entity: module_id.clone(),
                relation_type: RelationType::DependsOn,
                confidence: 0.99,
                source: DiscoverySource::StaticAnalysis,
                description: format!("{method} {route} is defined in {file_path}"),
            }));
        }
    }

    // 5. Extract imports → module:file imports symbol.
    //    module_id → imported symbol entity.
    //    When the imported symbol changes, BFS propagates to this module,
    //    then to all functions/structs that DependsOn this module.
    let imports = match language {
        "rust" | "rs" => extract_imports_rust(source, file_path, crate_map),
        "python" | "py" => extract_imports_python(source, file_path, python_package_root),
        _ => extract_imports_ts(source, file_path),
    };

    for (symbols, from_path, line_num) in imports {
        for symbol in &symbols {
            events.push(UcmEvent::new(EventPayload::DependencyLinked {
                source_entity: module_id.clone(),
                target_entity: EntityId::local(&from_path, symbol),
                relation_type: RelationType::Imports,
                confidence: 0.95,
                source: DiscoverySource::StaticAnalysis,
                description: format!("import {symbol} from '{from_path}' at line {line_num}"),
            }));
        }
    }

    events
}

// ── TypeScript / JavaScript ───────────────────────────────────────────────────

fn extract_functions_ts(source: &str) -> Vec<(String, bool, usize, usize)> {
    let mut out = Vec::new();
    for (i, line) in source.lines().enumerate() {
        let t = line.trim();
        let is_async = t.contains("async");
        if let Some(name) = ts_function_name(t) {
            out.push((name, is_async, i + 1, i + 20));
        }
    }
    out
}

fn ts_function_name(line: &str) -> Option<String> {
    for pat in &["function ", "async function "] {
        if let Some(pos) = line.find(pat) {
            let after = &line[pos + pat.len()..];
            let name: String = after
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            if !name.is_empty() {
                return Some(name);
            }
        }
    }
    // const name = ( or const name = async (
    if line.starts_with("const ") || line.starts_with("export const ") {
        let rest = line
            .strip_prefix("export const ")
            .unwrap_or_else(|| line.strip_prefix("const ").unwrap_or(line));
        if let Some(eq) = rest.find('=') {
            let name: String = rest[..eq]
                .trim()
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            let after_eq = &rest[eq..];
            if !name.is_empty() && (after_eq.contains('(') || after_eq.contains("=>")) {
                return Some(name);
            }
        }
    }
    None
}

fn extract_classes_ts(source: &str) -> Vec<(String, usize)> {
    let mut out = Vec::new();
    for (i, line) in source.lines().enumerate() {
        let t = line.trim();
        if t.contains("class ") && t.contains('{') {
            if let Some(after) = t.split("class ").nth(1) {
                let name: String = after
                    .chars()
                    .take_while(|c| c.is_alphanumeric() || *c == '_')
                    .collect();
                if !name.is_empty() {
                    out.push((name, i + 1));
                }
            }
        }
    }
    out
}

fn extract_routes_ts(source: &str) -> Vec<(String, String, String, usize)> {
    let mut out = Vec::new();
    for (i, line) in source.lines().enumerate() {
        let t = line.trim();
        for method in &["get", "post", "put", "delete", "patch"] {
            for prefix in &[format!("app.{method}("), format!("router.{method}(")] {
                if t.contains(prefix.as_str()) {
                    if let Some(route) = ts_route_path(t) {
                        out.push((method.to_uppercase(), route, String::new(), i + 1));
                    }
                }
            }
        }
    }
    out
}

fn ts_route_path(line: &str) -> Option<String> {
    let after = line.split('(').nth(1)?;
    let q = if after.contains('\'') { '\'' } else { '"' };
    let parts: Vec<&str> = after.split(q).collect();
    if parts.len() >= 2 {
        Some(parts[1].to_string())
    } else {
        None
    }
}

/// Returns `(symbols, resolved_path, line_number)` for TypeScript imports.
fn extract_imports_ts(source: &str, current_file: &str) -> Vec<(Vec<String>, String, usize)> {
    let mut out = Vec::new();
    let dir = parent_dir(current_file);
    for (i, line) in source.lines().enumerate() {
        let t = line.trim();
        if t.starts_with("import ") && t.contains("from ") {
            let symbols = ts_import_symbols(t);
            if let Some(raw_path) = ts_import_path(t) {
                // Only follow relative imports — node_modules won't be in the graph.
                if raw_path.starts_with("./") || raw_path.starts_with("../") {
                    let resolved = resolve_path(&dir, &raw_path, &["ts", "tsx", "js"]);
                    if !symbols.is_empty() {
                        out.push((symbols, resolved, i + 1));
                    }
                }
            }
        }
    }
    out
}

fn ts_import_symbols(line: &str) -> Vec<String> {
    if let (Some(s), Some(e)) = (line.find('{'), line.find('}')) {
        return line[s + 1..e]
            .split(',')
            .map(|s| {
                s.trim()
                    .split(" as ")
                    .next()
                    .unwrap_or("")
                    .trim()
                    .to_string()
            })
            .filter(|s| !s.is_empty())
            .collect();
    }
    // default import: import Foo from ...
    let after = line.strip_prefix("import ").unwrap_or("");
    let name: String = after
        .chars()
        .take_while(|c| c.is_alphanumeric() || *c == '_')
        .collect();
    if !name.is_empty() && name != "type" {
        vec![name]
    } else {
        vec![]
    }
}

fn ts_import_path(line: &str) -> Option<String> {
    let after = line.split("from ").nth(1)?;
    let q = if after.contains('\'') { '\'' } else { '"' };
    let parts: Vec<&str> = after.split(q).collect();
    if parts.len() >= 2 {
        Some(parts[1].to_string())
    } else {
        None
    }
}

// ── Rust ─────────────────────────────────────────────────────────────────────

fn extract_functions_rust(source: &str) -> Vec<(String, bool, usize, usize)> {
    let mut out = Vec::new();
    for (i, line) in source.lines().enumerate() {
        let t = line.trim();
        // Skip test functions and doc comments
        if t.starts_with("//") || t.starts_with("#[test") {
            continue;
        }
        if let Some(name) = rust_fn_name(t) {
            let is_async = t.contains("async ");
            out.push((name, is_async, i + 1, i + 30));
        }
    }
    out
}

fn rust_fn_name(line: &str) -> Option<String> {
    // Strip visibility and qualifiers
    let stripped = line
        .trim_start_matches("pub(crate) ")
        .trim_start_matches("pub(super) ")
        .trim_start_matches("pub ")
        .trim_start_matches("async ")
        .trim_start_matches("unsafe ")
        .trim_start_matches("extern \"C\" ");
    if let Some(rest) = stripped.strip_prefix("fn ") {
        let name: String = rest
            .chars()
            .take_while(|c| c.is_alphanumeric() || *c == '_')
            .collect();
        if !name.is_empty() {
            return Some(name);
        }
    }
    None
}

fn extract_structs_rust(source: &str) -> Vec<(String, usize)> {
    let mut out = Vec::new();
    for (i, line) in source.lines().enumerate() {
        let t = line.trim();
        let stripped = t
            .trim_start_matches("pub(crate) ")
            .trim_start_matches("pub ");
        if let Some(rest) = stripped.strip_prefix("struct ") {
            let name: String = rest
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            if !name.is_empty() {
                out.push((name, i + 1));
            }
        } else if let Some(rest) = stripped.strip_prefix("enum ") {
            let name: String = rest
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            if !name.is_empty() {
                out.push((name, i + 1));
            }
        } else if let Some(rest) = stripped.strip_prefix("trait ") {
            let name: String = rest
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            if !name.is_empty() {
                out.push((name, i + 1));
            }
        }
    }
    out
}

/// Extract Rust `use` imports and resolve them to file paths that match scanned entity IDs.
///
/// Handles three import forms:
/// 1. `use crate::module::Symbol`   → resolves relative to current crate's `src/` root
/// 2. `use super::module::Symbol`   → resolves relative to parent module directory
/// 3. `use sibling_crate::mod::Sym` → looks up crate name in `crate_map`
///
/// Symbols imported from `std` and other external crates (not in crate_map) are skipped.
fn extract_imports_rust(
    source: &str,
    current_file: &str,
    crate_map: &RustCrateMap,
) -> Vec<(Vec<String>, String, usize)> {
    let mut out = Vec::new();

    // Infer current crate's src root from file path.
    // e.g. "ucm-core/src/graph.rs" → crate_src_root = "ucm-core/src"
    //      "ucm-api/src/main.rs"   → crate_src_root = "ucm-api/src"
    let crate_src_root = infer_crate_src_root(current_file);
    // e.g. "ucm-core/src/graph.rs" → file_in_crate = "graph.rs"
    let file_in_crate = current_file
        .strip_prefix(&format!("{crate_src_root}/"))
        .unwrap_or(current_file);

    for (i, line) in source.lines().enumerate() {
        let t = line.trim();
        if !t.starts_with("use ") {
            continue;
        }
        let rest = &t[4..]; // strip "use "

        // Determine target src root + module path based on import prefix
        let (target_src_root, rest_after_prefix) = if let Some(r) = rest.strip_prefix("crate::") {
            // use crate::foo::Bar → resolve from own crate root
            (crate_src_root.clone(), r)
        } else if let Some(r) = rest.strip_prefix("super::") {
            // use super::foo::Bar → resolve from parent module dir
            let parent = rust_parent_module_dir(&crate_src_root, file_in_crate);
            (parent, r)
        } else if let Some(r) = rest.strip_prefix("self::") {
            // use self::foo::Bar → resolve from current module dir
            let current_dir = rust_current_module_dir(&crate_src_root, file_in_crate);
            (current_dir, r)
        } else {
            // Could be a sibling crate import: use ucm_graph_core::graph::UcmGraph
            // Extract the first segment and look it up in crate_map
            let first_segment = rest.split("::").next().unwrap_or("");
            if let Some(sibling_root) = crate_map.get(first_segment) {
                let after = rest
                    .strip_prefix(first_segment)
                    .and_then(|s| s.strip_prefix("::"))
                    .unwrap_or("");
                (sibling_root.clone(), after)
            } else {
                // External crate (std, serde, etc.) — skip
                continue;
            }
        };

        // Parse module_path::Symbol or module::{A, B, C}
        let cleaned = rest_after_prefix.trim_end_matches(';');
        let (module_segments, symbols) = if cleaned.contains('{') {
            // use crate::foo::{A, B, C}
            let brace_start = cleaned.find('{').unwrap_or(cleaned.len());
            let prefix = cleaned[..brace_start].trim_end_matches("::");
            let inner = cleaned
                .get(brace_start + 1..)
                .and_then(|s| s.split('}').next())
                .unwrap_or("");
            let syms: Vec<String> = inner
                .split(',')
                .map(|s| {
                    s.trim()
                        .split(" as ")
                        .next()
                        .unwrap_or("")
                        .trim()
                        .to_string()
                })
                .filter(|s| !s.is_empty() && s != "*")
                .collect();
            (prefix.to_string(), syms)
        } else {
            // use crate::foo::bar::Baz → module=foo::bar, symbol=Baz
            let parts: Vec<&str> = cleaned.split("::").collect();
            if parts.len() < 2 {
                // Just `use crate::module;` — module itself is the symbol
                if parts.len() == 1 && !parts[0].is_empty() && parts[0] != "*" {
                    // Importing a module as a whole: target is module.rs#module
                    let mod_name = parts[0].to_string();
                    let file_path = format!("{target_src_root}/{mod_name}.rs");
                    out.push((vec!["module".to_string()], file_path, i + 1));
                }
                continue;
            }
            let symbol = parts.last().unwrap().to_string();
            if symbol == "*" {
                continue;
            }
            let mod_parts = &parts[..parts.len() - 1];
            (mod_parts.join("::"), vec![symbol])
        };

        if symbols.is_empty() {
            continue;
        }

        // Convert module::path to file path: foo::bar → {target_src_root}/foo/bar.rs
        // Also try foo/bar/mod.rs convention (but .rs is more common)
        let module_file_path = if module_segments.is_empty() {
            // Direct import from crate root: use crate::Symbol → lib.rs or main.rs
            // Best guess: target the src root's lib.rs
            format!("{target_src_root}/lib.rs")
        } else {
            format!(
                "{target_src_root}/{}.rs",
                module_segments.replace("::", "/")
            )
        };

        out.push((symbols, module_file_path, i + 1));
    }
    out
}

/// Infer the crate src root from a file path.
/// "ucm-core/src/graph.rs" → "ucm-core/src"
/// "src/main.rs" → "src"
/// "crates/ucm-core/src/entity.rs" → "crates/ucm-core/src"
fn infer_crate_src_root(file_path: &str) -> String {
    // Find the last occurrence of "/src/" and take everything up to and including "src"
    if let Some(pos) = file_path.rfind("/src/") {
        file_path[..pos + 4].to_string()
    } else if file_path.starts_with("src/") {
        "src".to_string()
    } else {
        // Fallback: use parent directory
        parent_dir(file_path)
    }
}

/// Get the parent module directory for `super::` resolution.
/// crate_src_root="ucm-core/src", file_in_crate="graph.rs" → "ucm-core/src"
/// crate_src_root="ucm-core/src", file_in_crate="sub/module.rs" → "ucm-core/src"
fn rust_parent_module_dir(crate_src_root: &str, file_in_crate: &str) -> String {
    let dir = parent_dir(file_in_crate);
    if dir.is_empty() {
        // Already at crate root — super points to crate root
        crate_src_root.to_string()
    } else {
        // Go one level up
        let parent = parent_dir(&dir);
        if parent.is_empty() {
            crate_src_root.to_string()
        } else {
            format!("{crate_src_root}/{parent}")
        }
    }
}

/// Get the current module directory for `self::` resolution.
fn rust_current_module_dir(crate_src_root: &str, file_in_crate: &str) -> String {
    let dir = parent_dir(file_in_crate);
    if dir.is_empty() {
        crate_src_root.to_string()
    } else {
        format!("{crate_src_root}/{dir}")
    }
}

// ── Python ───────────────────────────────────────────────────────────────────

/// A Python entity extracted with indentation awareness.
#[derive(Debug)]
enum PythonEntity {
    Function {
        name: String,
        is_async: bool,
        line_start: usize,
        line_end: usize,
        /// If this function is a method, the enclosing class name.
        class_name: Option<String>,
    },
    Class {
        name: String,
        line_num: usize,
        /// Base class names from `class Foo(Bar, Baz):`.
        bases: Vec<String>,
    },
}

/// Extract Python functions and classes with indentation-based class-method association.
fn extract_python_entities(source: &str) -> Vec<PythonEntity> {
    let mut out = Vec::new();
    let mut current_class: Option<(String, usize)> = None; // (name, indent_col)

    for (i, line) in source.lines().enumerate() {
        let trimmed = line.trim();
        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        let indent = line.len() - line.trim_start().len();

        // If we're inside a class and hit a line at or before the class indent
        // (that isn't blank), we've left the class body.
        if let Some((_, class_indent)) = &current_class {
            if indent <= *class_indent && !trimmed.is_empty() {
                current_class = None;
            }
        }

        // Detect class definition
        if let Some(rest) = trimmed.strip_prefix("class ") {
            let name: String = rest
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            if !name.is_empty() {
                let bases = parse_python_bases(rest);
                current_class = Some((name.clone(), indent));
                out.push(PythonEntity::Class {
                    name,
                    line_num: i + 1,
                    bases,
                });
                continue;
            }
        }

        // Detect function/method definition
        if let Some(rest) = trimmed
            .strip_prefix("async def ")
            .or_else(|| trimmed.strip_prefix("def "))
        {
            let is_async = trimmed.starts_with("async ");
            let name: String = rest
                .chars()
                .take_while(|c| c.is_alphanumeric() || *c == '_')
                .collect();
            if !name.is_empty() {
                let class_name = current_class
                    .as_ref()
                    .filter(|(_, ci)| indent > *ci)
                    .map(|(cn, _)| cn.clone());
                out.push(PythonEntity::Function {
                    name,
                    is_async,
                    line_start: i + 1,
                    line_end: i + 20,
                    class_name,
                });
            }
        }
    }
    out
}

/// Parse base classes from a class definition line.
/// `"Foo(Bar, Baz):"` → `["Bar", "Baz"]`
fn parse_python_bases(after_class_name: &str) -> Vec<String> {
    if let Some(paren_start) = after_class_name.find('(') {
        if let Some(paren_end) = after_class_name.find(')') {
            let inner = &after_class_name[paren_start + 1..paren_end];
            return inner
                .split(',')
                .map(|s| {
                    // Handle `metaclass=ABCMeta` style args — skip keyword args
                    let s = s.trim();
                    if s.contains('=') {
                        return String::new();
                    }
                    // Take just the last component of dotted names: `abc.ABC` → `ABC`
                    s.rsplit('.').next().unwrap_or("").trim().to_string()
                })
                .filter(|s| !s.is_empty())
                .collect();
        }
    }
    vec![]
}

/// Extract Python imports: relative (`from .mod import X`) and absolute (`from pkg.mod import X`).
fn extract_imports_python(
    source: &str,
    current_file: &str,
    package_root: &PythonPackageRoot,
) -> Vec<(Vec<String>, String, usize)> {
    let mut out = Vec::new();
    let dir = parent_dir(current_file);

    for (i, line) in source.lines().enumerate() {
        let t = line.trim();

        // Handle `from .module import Foo, Bar` (relative imports)
        if let Some(rest) = t.strip_prefix("from .") {
            if let Some(imp_pos) = rest.find(" import ") {
                let mod_part = &rest[..imp_pos];
                let imp_part = &rest[imp_pos + 8..];
                let symbols = parse_python_import_symbols(imp_part);
                // Resolve dots: `from ..foo import X` means go up two levels
                let dots = mod_part.chars().take_while(|c| *c == '.').count();
                let module_name = mod_part.trim_start_matches('.');
                let mut base = dir.clone();
                for _ in 0..dots {
                    base = parent_dir(&base);
                }
                let path = if module_name.is_empty() {
                    format!("{base}/__init__.py")
                } else {
                    format!("{base}/{}.py", module_name.replace('.', "/"))
                };
                if !symbols.is_empty() {
                    out.push((symbols, path, i + 1));
                }
            }
            continue;
        }

        // Handle `from package.sub.module import X, Y` (absolute imports)
        if let Some(rest) = t.strip_prefix("from ") {
            if let Some(imp_pos) = rest.find(" import ") {
                let mod_part = &rest[..imp_pos];
                let imp_part = &rest[imp_pos + 8..];

                // Only resolve if it matches the project's package root
                if let Some(pkg) = package_root {
                    if mod_part.starts_with(pkg.as_str()) {
                        let symbols = parse_python_import_symbols(imp_part);
                        // Strip package root prefix and convert dots to slashes:
                        // `marimo._runtime.dataflow` → `_runtime/dataflow.py`
                        // The package root maps to the scan directory itself.
                        let after_pkg = mod_part
                            .strip_prefix(pkg.as_str())
                            .unwrap_or(mod_part)
                            .trim_start_matches('.');
                        let path = if after_pkg.is_empty() {
                            "__init__.py".to_string()
                        } else {
                            format!("{}.py", after_pkg.replace('.', "/"))
                        };
                        if !symbols.is_empty() {
                            out.push((symbols, path, i + 1));
                        }
                    }
                }
            }
            continue;
        }

        // Handle `import package.sub.module` (bare absolute imports)
        if let Some(rest) = t.strip_prefix("import ") {
            if let Some(pkg) = package_root {
                // May have comma-separated: `import foo.bar, foo.baz`
                for mod_path in rest.split(',') {
                    let mod_path = mod_path.trim().split(" as ").next().unwrap_or("").trim();
                    if mod_path.starts_with(pkg.as_str()) {
                        let after_pkg = mod_path
                            .strip_prefix(pkg.as_str())
                            .unwrap_or(mod_path)
                            .trim_start_matches('.');
                        let path = if after_pkg.is_empty() {
                            "__init__.py".to_string()
                        } else {
                            format!("{}.py", after_pkg.replace('.', "/"))
                        };
                        out.push((vec!["module".to_string()], path, i + 1));
                    }
                }
            }
        }
    }
    out
}

/// Parse symbols from the `import X, Y as Z, W` part of a Python import.
fn parse_python_import_symbols(imp_part: &str) -> Vec<String> {
    // Handle parenthesized imports: `from x import (\n  A,\n  B\n)`
    let cleaned = imp_part.trim_start_matches('(').trim_end_matches(')');
    cleaned
        .split(',')
        .map(|s| {
            s.trim()
                .split(" as ")
                .next()
                .unwrap_or("")
                .trim()
                .to_string()
        })
        .filter(|s| !s.is_empty() && s != "*")
        .collect()
}

// ── Path utilities ────────────────────────────────────────────────────────────

fn parent_dir(file_path: &str) -> String {
    Path::new(file_path)
        .parent()
        .map(|p| p.to_string_lossy().to_string())
        .unwrap_or_default()
}

fn file_name_of(file_path: &str) -> String {
    Path::new(file_path)
        .file_name()
        .map(|n| n.to_string_lossy().to_string())
        .unwrap_or_else(|| file_path.to_string())
}

/// Resolve a relative import path (e.g., `"./auth/service"`) against the
/// directory of the importing file, appending `.ts` if no extension present.
///
/// Uses `PathBuf::join` + manual component normalization so that `../`
/// traversal works correctly even when `dir` is a single-level path
/// (e.g. `"fraud"` + `"../pipeline/rag"` → `"pipeline/rag.ts"`).
fn resolve_path(dir: &str, raw: &str, _extensions: &[&str]) -> String {
    use std::path::{Component, PathBuf};

    // Build base: treat empty dir as current directory.
    let base = if dir.is_empty() {
        PathBuf::from(".")
    } else {
        PathBuf::from(dir)
    };

    // Join and normalize away `.` and `..` manually.
    // PathBuf::join handles the concatenation; we then walk components to
    // resolve parent-dir traversal without touching the filesystem.
    let joined = base.join(raw);
    let mut parts: Vec<std::ffi::OsString> = Vec::new();
    for comp in joined.components() {
        match comp {
            Component::ParentDir => {
                parts.pop();
            }
            Component::CurDir => {}
            Component::RootDir => {} // drop any accidental leading /
            other => parts.push(other.as_os_str().to_owned()),
        }
    }
    let normalized: PathBuf = parts.iter().collect();
    let s = normalized.to_string_lossy();

    // Append .ts extension if the path has no extension (most TS imports omit it).
    if Path::new(s.as_ref()).extension().is_none() {
        format!("{s}.ts")
    } else {
        s.to_string()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_typescript_emits_module_entity() {
        let source = r#"
import { DatabaseClient } from './db/client';
export async function validateToken(token: string): Promise<boolean> {
    return true;
}
"#;
        let events = parse_source_code("src/auth/service.ts", source, "typescript");

        let entity_events: Vec<_> = events
            .iter()
            .filter(|e| matches!(&e.payload, EventPayload::EntityDiscovered { .. }))
            .collect();
        // module + validateToken
        assert!(
            entity_events.len() >= 2,
            "Expected module + function entities"
        );

        let dep_events: Vec<_> = events
            .iter()
            .filter(|e| matches!(&e.payload, EventPayload::DependencyLinked { .. }))
            .collect();
        // validateToken→module + module→DatabaseClient
        assert!(
            dep_events.len() >= 2,
            "Expected function→module + module→import edges"
        );
    }

    #[test]
    fn test_module_entity_is_discovered_before_import_edges() {
        let source = "import { Foo } from './foo';\nfunction bar() {}";
        let events = parse_source_code("src/main.ts", source, "typescript");

        // Module entity must appear before DependencyLinked so projection has it.
        let first_entity = events
            .iter()
            .position(|e| matches!(&e.payload, EventPayload::EntityDiscovered { .. }));
        let first_dep = events
            .iter()
            .position(|e| matches!(&e.payload, EventPayload::DependencyLinked { .. }));
        assert!(
            first_entity < first_dep,
            "EntityDiscovered must precede DependencyLinked"
        );
    }

    #[test]
    fn test_parse_rust_functions_and_structs() {
        let source = r#"
use crate::graph::UcmGraph;

pub struct GraphProjection;

impl GraphProjection {
    pub fn replay_all(events: &[UcmEvent]) -> UcmGraph {
        UcmGraph::new()
    }

    pub async fn apply_event(graph: &mut UcmGraph, event: &UcmEvent) {}
}
"#;
        let events = parse_source_code("src/projection.rs", source, "rust");

        let entities: Vec<_> = events
            .iter()
            .filter(|e| {
                matches!(
                    &e.payload,
                    EventPayload::EntityDiscovered {
                        kind: EntityKind::Function { .. },
                        ..
                    }
                )
            })
            .collect();
        assert!(
            entities.len() >= 2,
            "Should find replay_all and apply_event"
        );

        let structs: Vec<_> = events
            .iter()
            .filter(|e| {
                matches!(
                    &e.payload,
                    EventPayload::EntityDiscovered {
                        kind: EntityKind::DataModel { .. },
                        ..
                    }
                )
            })
            .collect();
        assert!(!structs.is_empty(), "Should find GraphProjection struct");
    }

    #[test]
    fn test_parse_rust_imports() {
        let source = r#"
use crate::entity::EntityId;
use crate::graph::UcmGraph;
use std::collections::HashMap;
"#;
        let empty_map = RustCrateMap::new();
        let imports = extract_imports_rust(source, "ucm-core/src/main.rs", &empty_map);
        // Only crate:: imports, skip std::
        assert_eq!(imports.len(), 2, "Should find 2 crate imports, skip std");
        assert!(imports
            .iter()
            .any(|(syms, _, _)| syms.contains(&"EntityId".to_string())));
        assert!(imports
            .iter()
            .any(|(syms, _, _)| syms.contains(&"UcmGraph".to_string())));

        // Verify resolved file paths
        let entity_import = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"EntityId".to_string()))
            .unwrap();
        assert_eq!(
            entity_import.1, "ucm-core/src/entity.rs",
            "crate::entity::EntityId should resolve to ucm-core/src/entity.rs"
        );

        let graph_import = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"UcmGraph".to_string()))
            .unwrap();
        assert_eq!(
            graph_import.1, "ucm-core/src/graph.rs",
            "crate::graph::UcmGraph should resolve to ucm-core/src/graph.rs"
        );
    }

    #[test]
    fn test_rust_cross_crate_imports() {
        let source = r#"
use ucm_graph_core::graph::UcmGraph;
use ucm_graph_core::entity::{EntityId, EntityKind};
use ucm_ingest::code_parser;
use serde::Serialize;
"#;
        let mut crate_map = RustCrateMap::new();
        crate_map.insert("ucm_graph_core".to_string(), "ucm-core/src".to_string());
        crate_map.insert("ucm_ingest".to_string(), "ucm-ingest/src".to_string());

        let imports = extract_imports_rust(source, "ucm-api/src/main.rs", &crate_map);

        // Should find 3 imports (ucm_graph_core::graph, ucm_graph_core::entity, ucm_ingest::code_parser)
        // Should skip serde (not in crate_map)
        assert_eq!(
            imports.len(),
            3,
            "Should find 3 sibling crate imports, skip serde: got {imports:?}"
        );

        // Verify cross-crate resolution
        let graph_import = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"UcmGraph".to_string()))
            .unwrap();
        assert_eq!(graph_import.1, "ucm-core/src/graph.rs");

        let entity_import = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"EntityId".to_string()))
            .unwrap();
        assert_eq!(entity_import.1, "ucm-core/src/entity.rs");
        assert!(
            entity_import.0.contains(&"EntityKind".to_string()),
            "Should import both EntityId and EntityKind"
        );

        // Importing a module directly (no :: after module name → single segment after crate)
        let parser_import = imports
            .iter()
            .find(|(_, path, _)| path.contains("ucm-ingest"))
            .unwrap();
        assert_eq!(parser_import.1, "ucm-ingest/src/code_parser.rs");
    }

    #[test]
    fn test_parse_api_routes() {
        let source = r#"
app.get('/api/v1/users', getUsers);
app.post('/api/v1/auth/login', handleLogin);
"#;
        let events = parse_source_code("src/routes.ts", source, "typescript");
        let routes: Vec<_> = events
            .iter()
            .filter(|e| {
                matches!(
                    &e.payload,
                    EventPayload::EntityDiscovered {
                        kind: EntityKind::ApiEndpoint { .. },
                        ..
                    }
                )
            })
            .collect();
        assert_eq!(routes.len(), 2);
    }

    #[test]
    fn test_resolve_path_parent_traversal() {
        // fraud/agent.ts imports from ../pipeline/rag-pipeline
        // dir = "fraud", raw = "../pipeline/rag-pipeline"
        // expected = "pipeline/rag-pipeline.ts"  (NOT "/pipeline/rag-pipeline.ts")
        let result = resolve_path("fraud", "../pipeline/rag-pipeline", &["ts"]);
        assert_eq!(result, "pipeline/rag-pipeline.ts");

        // nested: src/fraud/agent.ts imports from ../pipeline/rag
        // dir = "src/fraud", raw = "../pipeline/rag"
        // expected = "src/pipeline/rag.ts"
        let result2 = resolve_path("src/fraud", "../pipeline/rag", &["ts"]);
        assert_eq!(result2, "src/pipeline/rag.ts");

        // same-dir import: fraud/agent.ts imports ./compliance-checker
        let result3 = resolve_path("fraud", "./compliance-checker", &["ts"]);
        assert_eq!(result3, "fraud/compliance-checker.ts");

        // file at root level: dir = "", raw = "./embedding-service"
        let result4 = resolve_path("", "./embedding-service", &["ts"]);
        assert_eq!(result4, "embedding-service.ts");
    }

    #[test]
    fn test_full_graph_has_edges() {
        // Simulate two files: auth.ts exports validateToken, middleware.ts imports it.
        let auth_src = "export async function validateToken() {}";
        let mid_src =
            "import { validateToken } from './auth';\nexport function authMiddleware() {}";

        use ucm_events::projection::GraphProjection;
        use ucm_graph_core::graph::UcmGraph;
        let mut graph = UcmGraph::new();
        for ev in parse_source_code("src/auth.ts", auth_src, "typescript") {
            GraphProjection::apply_event(&mut graph, &ev);
        }
        for ev in parse_source_code("src/middleware.ts", mid_src, "typescript") {
            GraphProjection::apply_event(&mut graph, &ev);
        }

        let stats = graph.stats();
        assert!(stats.entity_count >= 2, "Should have entities");
        assert!(
            stats.edge_count >= 1,
            "Should have at least one edge — this was the core bug"
        );
    }

    // ── Python parser tests ──────────────────────────────────────────────────

    #[test]
    fn test_python_absolute_imports() {
        let source = r#"
from marimo._runtime.dataflow import DirectedGraph
from marimo._ast.visitor import parse_cell
import os
import marimo._plugins.ui as ui
"#;
        let pkg_root = Some("marimo".to_string());
        let imports = extract_imports_python(source, "_runtime/runtime.py", &pkg_root);

        // Should find 3 imports: 2 `from` + 1 bare `import` matching package root
        assert_eq!(
            imports.len(),
            3,
            "Expected 3 marimo imports, got {imports:?}"
        );

        // Check first import resolves correctly (package root stripped)
        let dg_import = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"DirectedGraph".to_string()))
            .expect("Should find DirectedGraph import");
        assert_eq!(dg_import.1, "_runtime/dataflow.py");

        // Check second import
        let visitor_import = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"parse_cell".to_string()))
            .expect("Should find parse_cell import");
        assert_eq!(visitor_import.1, "_ast/visitor.py");

        // Check bare import
        let bare_import = imports
            .iter()
            .find(|(_, path, _)| path.contains("_plugins"))
            .expect("Should find bare marimo._plugins import");
        assert_eq!(bare_import.1, "_plugins/ui.py");
    }

    #[test]
    fn test_python_absolute_imports_skip_external() {
        let source = r#"
from marimo._runtime.dataflow import DirectedGraph
from typing import Optional
import json
from dataclasses import dataclass
"#;
        let pkg_root = Some("marimo".to_string());
        let imports = extract_imports_python(source, "marimo/test.py", &pkg_root);

        // Should only find 1 import (marimo), skip typing/json/dataclasses
        assert_eq!(
            imports.len(),
            1,
            "Should skip external imports, got {imports:?}"
        );
    }

    #[test]
    fn test_python_relative_imports_still_work() {
        let source = r#"
from .dataflow import DirectedGraph
from ..utils import serialize
"#;
        let pkg_root = Some("marimo".to_string());
        let imports = extract_imports_python(source, "marimo/_runtime/runtime.py", &pkg_root);

        assert_eq!(imports.len(), 2, "Should find 2 relative imports");
        let dg = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"DirectedGraph".to_string()))
            .unwrap();
        assert_eq!(dg.1, "marimo/_runtime/dataflow.py");

        let util = imports
            .iter()
            .find(|(s, _, _)| s.contains(&"serialize".to_string()))
            .unwrap();
        assert_eq!(util.1, "marimo/utils.py");
    }

    #[test]
    fn test_python_class_method_association() {
        let source = r#"
class DirectedGraph:
    def __init__(self):
        pass

    def add_edge(self, src, dst):
        pass

    async def traverse(self):
        pass

def standalone_function():
    pass
"#;
        let entities = extract_python_entities(source);

        // Should find: 1 class + 3 methods + 1 standalone function
        let classes: Vec<_> = entities
            .iter()
            .filter(|e| matches!(e, PythonEntity::Class { .. }))
            .collect();
        assert_eq!(classes.len(), 1, "Should find 1 class");

        let methods: Vec<_> = entities
            .iter()
            .filter(|e| {
                matches!(
                    e,
                    PythonEntity::Function {
                        class_name: Some(_),
                        ..
                    }
                )
            })
            .collect();
        assert_eq!(methods.len(), 3, "Should find 3 methods in DirectedGraph");

        let standalone: Vec<_> = entities
            .iter()
            .filter(|e| {
                matches!(
                    e,
                    PythonEntity::Function {
                        class_name: None,
                        ..
                    }
                )
            })
            .collect();
        assert_eq!(standalone.len(), 1, "Should find 1 standalone function");

        // Verify method names are associated with the class
        for m in &methods {
            if let PythonEntity::Function { class_name, .. } = m {
                assert_eq!(
                    class_name.as_deref(),
                    Some("DirectedGraph"),
                    "Method should belong to DirectedGraph"
                );
            }
        }
    }

    #[test]
    fn test_python_class_method_events() {
        let source = r#"
class MyClass:
    def my_method(self):
        pass
"#;
        let events = parse_source_code("test.py", source, "python");

        // Should have Contains edge from MyClass to MyClass.my_method
        let contains_edges: Vec<_> = events
            .iter()
            .filter(|e| {
                matches!(
                    &e.payload,
                    EventPayload::DependencyLinked {
                        relation_type: RelationType::Contains,
                        ..
                    }
                )
            })
            .collect();
        assert_eq!(
            contains_edges.len(),
            1,
            "Should have 1 Contains edge for class→method"
        );

        // Verify the method is named ClassName.method_name
        let method_entities: Vec<_> = events
            .iter()
            .filter_map(|e| {
                if let EventPayload::EntityDiscovered {
                    kind: EntityKind::Function { .. },
                    name,
                    ..
                } = &e.payload
                {
                    Some(name.clone())
                } else {
                    None
                }
            })
            .collect();
        assert!(
            method_entities.contains(&"MyClass.my_method".to_string()),
            "Method should be named MyClass.my_method, got {method_entities:?}"
        );
    }

    #[test]
    fn test_python_inheritance_edges() {
        let source = r#"
class Animal:
    pass

class Dog(Animal):
    pass

class GuideDog(Dog, Trainable):
    pass
"#;
        let entities = extract_python_entities(source);

        let classes: Vec<_> = entities
            .iter()
            .filter_map(|e| {
                if let PythonEntity::Class { name, bases, .. } = e {
                    Some((name.clone(), bases.clone()))
                } else {
                    None
                }
            })
            .collect();

        assert_eq!(classes.len(), 3);

        let animal = classes.iter().find(|(n, _)| n == "Animal").unwrap();
        assert!(animal.1.is_empty(), "Animal has no bases");

        let dog = classes.iter().find(|(n, _)| n == "Dog").unwrap();
        assert_eq!(dog.1, vec!["Animal"]);

        let guide = classes.iter().find(|(n, _)| n == "GuideDog").unwrap();
        assert_eq!(guide.1, vec!["Dog", "Trainable"]);
    }

    #[test]
    fn test_python_inheritance_events() {
        let source = r#"
class Base:
    pass

class Child(Base):
    pass
"#;
        let events = parse_source_code("test.py", source, "python");

        let extends_edges: Vec<_> = events
            .iter()
            .filter(|e| {
                matches!(
                    &e.payload,
                    EventPayload::DependencyLinked {
                        relation_type: RelationType::Extends,
                        ..
                    }
                )
            })
            .collect();
        assert_eq!(
            extends_edges.len(),
            1,
            "Should have 1 Extends edge (Child → Base)"
        );
    }

    #[test]
    fn test_python_no_package_root_skips_absolute() {
        let source = "from marimo._runtime import foo\nimport json\n";
        let no_pkg: PythonPackageRoot = None;
        let imports = extract_imports_python(source, "test.py", &no_pkg);
        assert!(
            imports.is_empty(),
            "Without package root, absolute imports should be skipped"
        );
    }

    #[test]
    fn test_python_metaclass_skipped_in_bases() {
        let source = "class Foo(Bar, metaclass=ABCMeta):\n    pass\n";
        let entities = extract_python_entities(source);
        if let Some(PythonEntity::Class { bases, .. }) = entities.first() {
            assert_eq!(bases, &["Bar"], "metaclass= arg should be skipped");
        } else {
            panic!("Expected a class entity");
        }
    }
}