cargo_anatomy/

lib.rs

//! Utilities for analyzing Rust crates and computing package metrics.
//!
//! The library parses Rust source files and builds a dependency graph of the
//! types that appear within a crate. From this graph a number of classic
//! software metrics are derived, such as efferent/afferent coupling and
//! relational cohesion. These building blocks are used by the accompanying
//! `cargo-anatomy` binary, but the functions are generic enough to be consumed
//! by other tools as well.
use log::{debug, info};
use serde::{Deserialize, Serialize};
use std::collections::{HashMap, HashSet};
use std::fs;
use std::io;
use std::panic::Location;
use syn::{visit::Visit, File};
use walkdir::WalkDir;

/// Wrap an error with file and line information.
///
/// This helper is mainly used by the [`loc_try!`] macro so that any propagated
/// error retains its originating call site, which simplifies debugging.
///
/// # Examples
///
/// ```
/// use cargo_anatomy::error_with_location;
///
/// fn might_fail() -> Result<(), Box<dyn std::error::Error>> {
///     Err(error_with_location("boom"))
/// }
/// ```
#[track_caller]
pub fn error_with_location<E>(err: E) -> Box<dyn std::error::Error>
where
    E: std::fmt::Display,
{
    let loc = Location::caller();
    Box::new(io::Error::other(format!(
        "{} at {}:{}",
        err,
        loc.file(),
        loc.line()
    )))
}

/// Try expression and attach location info on error.
///
/// This macro behaves similarly to the `?` operator but ensures that any error
/// returned is first wrapped with [`error_with_location`]. It is primarily
/// intended for internal use.
#[macro_export]
macro_rules! loc_try {
    ($expr:expr) => {
        match $expr {
            Ok(val) => val,
            Err(err) => {
                return Err($crate::error_with_location(err));
            }
        }
    };
}

fn has_test_attr(attrs: &[syn::Attribute]) -> bool {
    attrs.iter().any(|a| {
        if a.path().is_ident("test") {
            true
        } else if a.path().is_ident("cfg") {
            match &a.meta {
                syn::Meta::List(l) => l.tokens.to_string().contains("test"),
                _ => false,
            }
        } else {
            false
        }
    })
}

/// Represents the kind of item defined within a crate.
///
/// The variants correspond to common Rust constructs that can participate in
/// dependency relationships.
#[derive(Debug, Serialize, Clone)]
pub enum ClassKind {
    /// A `struct` definition.
    Struct,
    /// An `enum` definition.
    Enum,
    /// A `trait` definition.
    Trait,
    /// A `type` alias.
    TypeAlias,
    /// A `macro_rules!` or other macro definition.
    Macro,
}

/// Metadata about a type defined in a crate.
#[derive(Debug, Serialize, Clone)]
pub struct ClassInfo {
    /// Name of the item as it appears in source.
    pub name: String,
    /// Kind of the item.
    pub kind: ClassKind,
}

/// Specifies whether a crate belongs to the current workspace or is an
/// external dependency.
#[derive(Debug, Serialize, Clone, Copy, PartialEq, Eq)]
pub enum CrateKind {
    /// The crate lives in the workspace being analysed.
    Workspace,
    /// The crate is an external dependency.
    External,
}

/// Quantitative metrics describing the coupling and cohesion of a crate.
///
/// Values are derived from the relationships between types and follow the
/// definitions popularised by Robert C. Martin. Each field is documented with
/// the formula used to compute it.
#[derive(Debug, Serialize, Clone)]
pub struct Metrics {
    /// Number of internal type relationships.
    pub r: usize,
    /// Total number of type definitions.
    pub n: usize,
    /// Relational cohesion calculated as `(r + 1) / n`.
    pub h: f64,
    /// Afferent coupling – external types depending on this crate.
    pub ca: usize,
    /// Efferent coupling – this crate's types depending on other workspace crates.
    pub ce: usize,
    /// Abstraction ratio of traits to total types.
    pub a: f64,
    /// Instability ratio `ce / (ce + ca)`.
    pub i: f64,
    /// Distance from the main sequence.
    pub d: f64,
    /// Normalised distance from the main sequence.
    pub d_prime: f64,
}

/// Qualitative evaluation of a crate's level of abstraction.
#[derive(Debug, Serialize, Clone)]
#[serde(rename_all = "lowercase")]
pub enum AbstractionEval {
    /// More than the configured fraction of items are traits.
    Abstract,
    /// A mix of concrete and abstract items.
    Mixed,
    /// Dominated by concrete types.
    Concrete,
}

/// Qualitative evaluation of relational cohesion.
#[derive(Debug, Serialize, Clone)]
#[serde(rename_all = "lowercase")]
pub enum CohesionEval {
    /// Cohesion exceeds the configured high threshold.
    High,
    /// Cohesion does not exceed the high threshold.
    Low,
}

/// Qualitative evaluation of stability based on dependency ratios.
#[derive(Debug, Serialize, Clone)]
#[serde(rename_all = "lowercase")]
pub enum StabilityEval {
    /// Few outgoing dependencies, considered stable.
    Stable,
    /// Balance of incoming and outgoing dependencies.
    Moderate,
    /// Many outgoing dependencies, considered unstable.
    Unstable,
}

/// Qualitative evaluation of the normalised distance from the main sequence.
#[derive(Debug, Serialize, Clone)]
#[serde(rename_all = "lowercase")]
pub enum DistanceEval {
    /// Falls within the good range near the main sequence.
    Good,
    /// Neither particularly good nor problematic.
    Balanced,
    /// Far from the main sequence on the stable side.
    Painful,
    /// Far from the main sequence on the unstable side.
    Useless,
}

/// Human readable evaluation for a set of metrics.
#[derive(Debug, Serialize, Clone)]
pub struct Evaluation {
    /// Result of evaluating abstraction.
    pub a: AbstractionEval,
    /// Result of evaluating cohesion.
    pub h: CohesionEval,
    /// Result of evaluating instability.
    pub i: StabilityEval,
    /// Result of evaluating distance from the main sequence.
    pub d_prime: DistanceEval,
}

/// Metrics accompanied by their qualitative evaluation, used for output.
#[derive(Debug, Serialize, Clone)]
pub struct MetricsResult {
    /// Raw quantitative metrics.
    pub metrics: Metrics,
    /// Human readable evaluation of those metrics.
    pub evaluation: Evaluation,
}

/// Groups together threshold values used when evaluating metrics.
#[derive(Debug, Clone, Deserialize, Serialize, Default)]
pub struct EvaluationThresholds {
    /// Thresholds governing abstraction classification.
    #[serde(default)]
    pub abstraction: AbstractionThresholds,
    /// Thresholds for relational cohesion.
    #[serde(default)]
    pub cohesion: CohesionThresholds,
    /// Thresholds for stability.
    #[serde(default)]
    pub instability: InstabilityThresholds,
    /// Thresholds for distance from the main sequence.
    #[serde(default)]
    pub distance: DistanceThresholds,
}

/// Top-level structure for configuration files.
#[derive(Debug, Clone, Deserialize, Serialize, Default)]
pub struct Config {
    /// Threshold configuration for metric evaluation.
    #[serde(default)]
    pub evaluation: EvaluationThresholds,
}

/// Thresholds used when categorising a crate as abstract or concrete.
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct AbstractionThresholds {
    /// Minimum ratio of traits considered abstract.
    #[serde(default = "default_abstract_min")]
    pub abstract_min: f64,
    /// Maximum ratio of traits considered concrete.
    #[serde(default = "default_concrete_max")]
    pub concrete_max: f64,
}

fn default_abstract_min() -> f64 {
    0.7
}

fn default_concrete_max() -> f64 {
    0.3
}

impl Default for AbstractionThresholds {
    fn default() -> Self {
        Self {
            abstract_min: default_abstract_min(),
            concrete_max: default_concrete_max(),
        }
    }
}

/// Thresholds used to evaluate relational cohesion.
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct CohesionThresholds {
    /// Values greater than this are considered highly cohesive.
    #[serde(default = "default_high_gt")]
    pub high_gt: f64,
}

fn default_high_gt() -> f64 {
    1.0
}

impl Default for CohesionThresholds {
    fn default() -> Self {
        Self {
            high_gt: default_high_gt(),
        }
    }
}

/// Thresholds used to categorise crate stability.
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct InstabilityThresholds {
    /// Minimum ratio considered unstable.
    #[serde(default = "default_unstable_min")]
    pub unstable_min: f64,
    /// Maximum ratio considered stable.
    #[serde(default = "default_stable_max")]
    pub stable_max: f64,
}

fn default_unstable_min() -> f64 {
    0.7
}

fn default_stable_max() -> f64 {
    0.3
}

impl Default for InstabilityThresholds {
    fn default() -> Self {
        Self {
            unstable_min: default_unstable_min(),
            stable_max: default_stable_max(),
        }
    }
}

/// Thresholds for evaluating distance from the main sequence.
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct DistanceThresholds {
    /// Maximum normalised distance considered good.
    #[serde(default = "default_good_max")]
    pub good_max: f64,
    /// Minimum normalised distance considered bad.
    #[serde(default = "default_bad_min")]
    pub bad_min: f64,
}

fn default_good_max() -> f64 {
    0.4
}

fn default_bad_min() -> f64 {
    0.6
}

impl Default for DistanceThresholds {
    fn default() -> Self {
        Self {
            good_max: default_good_max(),
            bad_min: default_bad_min(),
        }
    }
}

/// Evaluate a set of metrics using the library's default thresholds.
///
/// This is a convenience wrapper around [`evaluate_metrics_with`].
/// Thresholds loosely follow the metrics described in Robert C. Martin's
/// *Agile Software Development*.
pub fn evaluate_metrics(m: &Metrics) -> Evaluation {
    evaluate_metrics_with(m, &EvaluationThresholds::default())
}

/// Evaluate metrics using custom thresholds.
pub fn evaluate_metrics_with(m: &Metrics, t: &EvaluationThresholds) -> Evaluation {
    let a_label = if m.a >= t.abstraction.abstract_min {
        AbstractionEval::Abstract
    } else if m.a <= t.abstraction.concrete_max {
        AbstractionEval::Concrete
    } else {
        AbstractionEval::Mixed
    };

    let h_label = if m.h > t.cohesion.high_gt {
        CohesionEval::High
    } else {
        CohesionEval::Low
    };

    let i_label = if m.i >= t.instability.unstable_min {
        StabilityEval::Unstable
    } else if m.i <= t.instability.stable_max {
        StabilityEval::Stable
    } else {
        StabilityEval::Moderate
    };

    let d_label = if m.d_prime <= t.distance.good_max {
        DistanceEval::Good
    } else if m.d_prime >= t.distance.bad_min {
        if m.a + m.i - 1.0 >= 0.0 {
            DistanceEval::Useless
        } else {
            DistanceEval::Painful
        }
    } else {
        DistanceEval::Balanced
    };

    Evaluation {
        a: a_label,
        h: h_label,
        i: i_label,
        d_prime: d_label,
    }
}

/// Detailed analysis results for a single crate.
#[derive(Debug, Serialize, Clone)]
pub struct CrateDetail {
    /// Whether the crate is part of the workspace or external.
    pub kind: CrateKind,
    /// Raw metrics computed for the crate.
    pub metrics: Metrics,
    /// Qualitative evaluation of the metrics.
    pub evaluation: Evaluation,
    /// All types defined within the crate.
    pub classes: Vec<ClassInfo>,
    /// Mapping of type names to the types they depend on within the crate.
    pub internal_depends_on: HashMap<String, Vec<String>>,
    /// Inverse mapping of [`internal_depends_on`].
    pub internal_depended_by: HashMap<String, Vec<String>>,
    /// External dependencies keyed by crate and type.
    pub external_depends_on: HashMap<String, HashMap<String, Vec<String>>>,
    /// External dependents keyed by crate and type.
    pub external_depended_by: HashMap<String, HashMap<String, Vec<String>>>,
}

/// Traverse parsed syntax trees and collect all type definitions, counting traits.
///
/// Returns a mapping from type name to [`ClassKind`] together with the number of
/// trait definitions encountered. Items marked as tests are ignored.
pub fn collect_defined(files: &[File]) -> (HashMap<String, ClassKind>, usize) {
    fn visit_items(
        items: &[syn::Item],
        defined: &mut HashMap<String, ClassKind>,
        abstract_count: &mut usize,
    ) {
        for item in items {
            match item {
                syn::Item::Struct(item) if !has_test_attr(&item.attrs) => {
                    defined.insert(item.ident.to_string(), ClassKind::Struct);
                }
                syn::Item::Enum(item) if !has_test_attr(&item.attrs) => {
                    defined.insert(item.ident.to_string(), ClassKind::Enum);
                }
                syn::Item::Trait(item) if !has_test_attr(&item.attrs) => {
                    defined.insert(item.ident.to_string(), ClassKind::Trait);
                    *abstract_count += 1;
                }
                syn::Item::Type(item) if !has_test_attr(&item.attrs) => {
                    defined.insert(item.ident.to_string(), ClassKind::TypeAlias);
                }
                syn::Item::Macro(item) if !has_test_attr(&item.attrs) => {
                    if let Some(id) = &item.ident {
                        defined.insert(id.to_string(), ClassKind::Macro);
                    }
                }
                syn::Item::Mod(m) if !has_test_attr(&m.attrs) => {
                    if let Some((_, items)) = &m.content {
                        visit_items(items, defined, abstract_count);
                    }
                }
                _ => {}
            }
        }
    }

    let mut defined = HashMap::new();
    let mut abstract_count = 0usize;

    for file in files {
        if has_test_attr(&file.attrs) {
            continue;
        }
        visit_items(&file.items, &mut defined, &mut abstract_count);
    }
    (defined, abstract_count)
}
/// Map method names to their return types for each `impl` block or trait.
///
/// The returned map uses `(impl_name, method_name)` as the key where
/// `impl_name` is the type or trait that the method belongs to and the value
/// is the return type. Test code is ignored.
pub fn collect_methods(files: &[File]) -> HashMap<(String, String), String> {
    let mut map = HashMap::new();
    fn ret_ty(output: &syn::ReturnType, self_ty: &str) -> Option<String> {
        fn from_impl_trait(it: &syn::TypeImplTrait) -> Option<String> {
            for b in &it.bounds {
                if let syn::TypeParamBound::Trait(t) = b {
                    if let Some(seg) = t.path.segments.last() {
                        return Some(seg.ident.to_string());
                    }
                }
            }
            None
        }

        fn from_trait_object(obj: &syn::TypeTraitObject) -> Option<String> {
            for b in &obj.bounds {
                if let syn::TypeParamBound::Trait(t) = b {
                    if let Some(seg) = t.path.segments.last() {
                        return Some(seg.ident.to_string());
                    }
                }
            }
            None
        }

        fn from_path(p: &syn::Path, self_ty: &str) -> Option<String> {
            if let Some(last) = p.segments.last() {
                if let syn::PathArguments::AngleBracketed(args) = &last.arguments {
                    for arg in &args.args {
                        if let syn::GenericArgument::Type(t) = arg {
                            if let Some(name) = from_type(t, self_ty) {
                                return Some(name);
                            }
                        }
                    }
                }
            }
            p.segments.last().map(|s| {
                if s.ident == "Self" {
                    self_ty.to_string()
                } else {
                    s.ident.to_string()
                }
            })
        }

        fn from_type(ty: &syn::Type, self_ty: &str) -> Option<String> {
            match ty {
                syn::Type::Path(p) => from_path(&p.path, self_ty),
                syn::Type::Reference(r) => from_type(&r.elem, self_ty),
                syn::Type::ImplTrait(it) => from_impl_trait(it),
                syn::Type::TraitObject(obj) => from_trait_object(obj),
                syn::Type::Paren(p) => from_type(&p.elem, self_ty),
                syn::Type::Group(g) => from_type(&g.elem, self_ty),
                syn::Type::Ptr(p) => from_type(&p.elem, self_ty),
                _ => None,
            }
        }

        match output {
            syn::ReturnType::Type(_, ty) => from_type(ty, self_ty),
            _ => None,
        }
    }

    for file in files {
        if has_test_attr(&file.attrs) {
            continue;
        }
        for item in &file.items {
            match item {
                syn::Item::Impl(imp) if !has_test_attr(&imp.attrs) => {
                    if let syn::Type::Path(tp) = &*imp.self_ty {
                        if let Some(seg) = tp.path.segments.last() {
                            let self_ty = seg.ident.to_string();
                            for item in &imp.items {
                                if let syn::ImplItem::Fn(m) = item {
                                    if has_test_attr(&m.attrs) {
                                        continue;
                                    }
                                    if let Some(ret) = ret_ty(&m.sig.output, &self_ty) {
                                        map.insert((self_ty.clone(), m.sig.ident.to_string()), ret);
                                    }
                                }
                            }
                        }
                    }
                }
                syn::Item::Trait(t) if !has_test_attr(&t.attrs) => {
                    let trait_name = t.ident.to_string();
                    for item in &t.items {
                        if let syn::TraitItem::Fn(m) = item {
                            if has_test_attr(&m.attrs) {
                                continue;
                            }
                            if let Some(ret) = ret_ty(&m.sig.output, &trait_name) {
                                map.insert((trait_name.clone(), m.sig.ident.to_string()), ret);
                            }
                        }
                    }
                }
                _ => {}
            }
        }
    }

    map
}
/// Collect trait inheritance information for each trait.
///
/// Returns a map from trait name to the list of traits it declares as
/// supertraits. Test code is ignored.
pub fn collect_trait_bounds(files: &[File]) -> HashMap<String, Vec<String>> {
    let mut map = HashMap::new();
    for file in files {
        if has_test_attr(&file.attrs) {
            continue;
        }
        for item in &file.items {
            if let syn::Item::Trait(t) = item {
                if has_test_attr(&t.attrs) {
                    continue;
                }
                let name = t.ident.to_string();
                let mut bounds = Vec::new();
                for b in &t.supertraits {
                    if let syn::TypeParamBound::Trait(tb) = b {
                        if let Some(seg) = tb.path.segments.last() {
                            bounds.push(seg.ident.to_string());
                        }
                    }
                }
                map.insert(name, bounds);
            }
        }
    }
    map
}

/// Collect re-exported items from workspace crates.
///
/// Returns a map from the re-exported name to the originating crate and the
/// original identifier.
pub fn collect_reexports(
    files: &[File],
    workspace: &HashSet<String>,
) -> HashMap<String, (String, String)> {
    struct ReexportVisitor<'a> {
        workspace: &'a HashSet<String>,
        map: HashMap<String, (String, String)>,
    }

    fn handle_use_tree(
        tree: &syn::UseTree,
        first: Option<String>,
        workspace: &HashSet<String>,
        map: &mut HashMap<String, (String, String)>,
    ) {
        match tree {
            syn::UseTree::Path(p) => {
                let root = first.clone().unwrap_or_else(|| p.ident.to_string());
                handle_use_tree(&p.tree, Some(root), workspace, map);
            }
            syn::UseTree::Name(n) => {
                if let Some(r) = &first {
                    if workspace.contains(r) {
                        map.insert(n.ident.to_string(), (r.clone(), n.ident.to_string()));
                    }
                }
            }
            syn::UseTree::Rename(rn) => {
                let root = first
                    .as_ref()
                    .cloned()
                    .unwrap_or_else(|| rn.ident.to_string());
                if workspace.contains(&root) {
                    map.insert(rn.rename.to_string(), (root, rn.ident.to_string()));
                }
            }
            syn::UseTree::Group(g) => {
                for t in &g.items {
                    handle_use_tree(t, first.clone(), workspace, map);
                }
            }
            syn::UseTree::Glob(_) => {}
        }
    }

    impl<'ast> Visit<'ast> for ReexportVisitor<'_> {
        fn visit_item_mod(&mut self, i: &'ast syn::ItemMod) {
            if has_test_attr(&i.attrs) {
                return;
            }
            syn::visit::visit_item_mod(self, i);
        }

        fn visit_item_use(&mut self, i: &'ast syn::ItemUse) {
            if has_test_attr(&i.attrs) {
                return;
            }
            if matches!(i.vis, syn::Visibility::Inherited) {
                syn::visit::visit_item_use(self, i);
                return;
            }
            handle_use_tree(&i.tree, None, self.workspace, &mut self.map);
            syn::visit::visit_item_use(self, i);
        }
    }

    let mut visitor = ReexportVisitor {
        workspace,
        map: HashMap::new(),
    };

    for file in files {
        if has_test_attr(&file.attrs) {
            continue;
        }
        visitor.visit_file(file);
    }

    visitor.map
}
/// Parse all Rust source files belonging to the given package.
fn package_source_dirs(package: &cargo_metadata::Package) -> HashSet<std::path::PathBuf> {
    let manifest_dir = package.manifest_path.parent().unwrap();
    let mut dirs = HashSet::new();
    for target in &package.targets {
        if target.kind.iter().any(|k| {
            matches!(
                k,
                cargo_metadata::TargetKind::Lib | cargo_metadata::TargetKind::Bin
            )
        }) {
            if let Some(parent) = std::path::Path::new(&target.src_path).parent() {
                dirs.insert(parent.to_path_buf());
            }
        }
    }
    if dirs.is_empty() {
        dirs.insert(manifest_dir.join("src").into());
    }
    dirs
}

fn parse_dir(dir: &std::path::Path) -> Result<Vec<File>, Box<dyn std::error::Error>> {
    let mut files = Vec::new();
    for entry in WalkDir::new(dir) {
        let entry = crate::loc_try!(entry);
        if entry.file_type().is_file()
            && entry.path().extension().map(|s| s == "rs").unwrap_or(false)
        {
            if entry.path().components().any(|c| c.as_os_str() == "tests") {
                continue;
            }
            debug!("parsing {}", entry.path().display());
            let content = crate::loc_try!(fs::read_to_string(entry.path()));
            let file = crate::loc_try!(syn::parse_file(&content));
            files.push(file);
        }
    }
    Ok(files)
}

/// Parse all Rust source files belonging to the given package.
///
/// Every library or binary target's source directory is scanned (or `src/` when
/// no targets declare a path) and any `.rs` files found are parsed into
/// [`syn::File`] structures. Files located under a `tests` directory are skipped
/// since Cargo treats integration tests as separate crates.
/// Returns the parsed files.
pub fn parse_package(
    package: &cargo_metadata::Package,
) -> Result<Vec<File>, Box<dyn std::error::Error>> {
    info!("reading crate {}", package.name);
    let mut files = Vec::new();
    for dir in package_source_dirs(package) {
        files.extend(parse_dir(&dir)?);
    }
    Ok(files)
}
/// Parse a package's source files and compute metrics.
///
/// The provided `workspace_types` should contain class names from all crates in
/// the workspace so that internal and external references are classified
/// correctly. Returns the computed [`Metrics`] for the package.
pub fn analyze_package(
    package: &cargo_metadata::Package,
    workspace_types: &HashSet<String>,
) -> Result<Metrics, Box<dyn std::error::Error>> {
    let files = crate::loc_try!(parse_package(package));
    Ok(analyze_files(&files, workspace_types))
}
/// Analyze parsed files to produce package metrics.
///
/// `workspace_types` should contain all type names defined in the workspace so
/// references can be counted as internal or external.
pub fn analyze_files(files: &[File], workspace_types: &HashSet<String>) -> Metrics {
    debug!("collecting definitions from {} files", files.len());
    let (defined, abstract_count) = collect_defined(files);

    let class_count = defined.len();

    let mut visitor = RefVisitor {
        defined: &defined,
        workspace: workspace_types,
        internal: 0,
        external: 0,
    };
    for file in files {
        visitor.visit_file(file);
    }

    let n = class_count;
    let r = visitor.internal;
    let ca = 0usize; // not computed in this function
    let ce = visitor.external;

    let h = if n > 0 {
        (r as f64 + 1.0) / n as f64
    } else {
        0.0
    };
    let a = if n > 0 {
        abstract_count as f64 / n as f64
    } else {
        0.0
    };
    let i = if ca + ce > 0 {
        ce as f64 / (ca + ce) as f64
    } else {
        0.0
    };
    let d_prime = (a + i - 1.0).abs();
    let d = d_prime / 2f64.sqrt();

    debug!(
        "metrics: N={} R={} Ca={} Ce={} A={:.3} I={:.3} D={:.3} D'={:.3}",
        n, r, ca, ce, a, i, d, d_prime
    );

    Metrics {
        r,
        n,
        h,
        ca,
        ce,
        a,
        i,
        d,
        d_prime,
    }
}

/// Analyse multiple crates together so cross-crate dependencies can be counted.
///
/// Each tuple contains the crate name and its parsed source files.
/// Only the [`Metrics`] for each crate are returned.
pub fn analyze_workspace(crates: &[(String, Vec<File>)]) -> HashMap<String, Metrics> {
    analyze_workspace_with_thresholds(crates, &EvaluationThresholds::default())
}

/// Analyse multiple crates together using custom evaluation thresholds.
///
/// Returns only the [`Metrics`] for each crate.
pub fn analyze_workspace_with_thresholds(
    crates: &[(String, Vec<File>)],
    t: &EvaluationThresholds,
) -> HashMap<String, Metrics> {
    analyze_workspace_details_with_thresholds(crates, t)
        .into_iter()
        .map(|(k, v)| (k, v.metrics))
        .collect()
}

/// Produce full [`CrateDetail`] information for multiple crates.
///
/// This performs a deeper analysis than [`analyze_workspace`] by tracking
/// type-level dependencies between crates.
pub fn analyze_workspace_details(crates: &[(String, Vec<File>)]) -> HashMap<String, CrateDetail> {
    analyze_workspace_details_with_thresholds(crates, &EvaluationThresholds::default())
}

/// Produce full [`CrateDetail`] information for multiple crates using custom thresholds.
pub fn analyze_workspace_details_with_thresholds(
    crates: &[(String, Vec<File>)],
    t: &EvaluationThresholds,
) -> HashMap<String, CrateDetail> {
    debug!("analysing {} crates", crates.len());

    let workspace_crates: HashSet<String> = crates.iter().map(|(name, _)| name.clone()).collect();

    let mut crate_defined = HashMap::new();
    let mut crate_abstract = HashMap::new();
    let mut crate_reexports: HashMap<String, HashMap<String, (String, String)>> = HashMap::new();
    let mut method_map: HashMap<(String, String), String> = HashMap::new();
    let mut trait_bounds: HashMap<String, Vec<String>> = HashMap::new();

    for (name, files) in crates {
        let (defined, abstract_count) = collect_defined(files);
        let methods = collect_methods(files);
        let bounds = collect_trait_bounds(files);
        let reexports = collect_reexports(files, &workspace_crates);
        method_map.extend(methods);
        for (k, v) in bounds {
            trait_bounds.insert(k, v);
        }
        crate_defined.insert(name.clone(), defined);
        crate_abstract.insert(name.clone(), abstract_count);
        crate_reexports.insert(name.clone(), reexports);
    }

    let mut internal_refs: HashMap<String, HashMap<String, HashSet<String>>> = HashMap::new();
    let mut external_refs: HashMap<String, HashMap<String, HashMap<String, HashSet<String>>>> =
        HashMap::new();

    for (name, files) in crates {
        let defined = crate_defined.get(name).unwrap();
        let mut visitor = DetailVisitor {
            current: None,
            defined,
            crate_name: name,
            workspace_crates: &workspace_crates,
            all_defined: &crate_defined,
            reexports: &crate_reexports,
            imports: HashMap::new(),
            internal: HashMap::new(),
            external: HashMap::new(),
            methods: &method_map,
            trait_bounds: &trait_bounds,
        };
        for f in files {
            visitor.visit_file(f);
        }
        internal_refs.insert(name.clone(), visitor.internal);
        external_refs.insert(name.clone(), visitor.external);
    }

    let mut internal_rev: HashMap<String, HashMap<String, HashSet<String>>> = HashMap::new();
    for (crate_name, map) in &internal_refs {
        for (from, tos) in map {
            for to in tos {
                internal_rev
                    .entry(crate_name.clone())
                    .or_default()
                    .entry(to.clone())
                    .or_default()
                    .insert(from.clone());
            }
        }
    }

    let mut external_rev: HashMap<String, HashMap<String, HashMap<String, HashSet<String>>>> =
        HashMap::new();
    for (src_crate, map) in &external_refs {
        for (from, crates_map) in map {
            for (target_crate, types) in crates_map {
                for ty in types {
                    external_rev
                        .entry(target_crate.clone())
                        .or_default()
                        .entry(ty.clone())
                        .or_default()
                        .entry(src_crate.clone())
                        .or_default()
                        .insert(from.clone());
                }
            }
        }
    }

    let mut result = HashMap::new();
    for (name, _) in crates {
        let n = crate_defined.get(name).map(|s| s.len()).unwrap_or(0);
        let r = internal_refs
            .get(name)
            .map(|m| m.values().map(|s| s.len()).sum())
            .unwrap_or(0);

        let mut ce_set = HashSet::new();
        if let Some(map) = external_refs.get(name) {
            for crate_map in map.values() {
                for (c, types) in crate_map {
                    for ty in types {
                        ce_set.insert(format!("{}::{}", c, ty));
                    }
                }
            }
        }
        let ce = ce_set.len();

        let mut ca_set = HashSet::new();
        if let Some(map) = external_rev.get(name) {
            for crate_map in map.values() {
                for (c, from_set) in crate_map {
                    for src in from_set {
                        ca_set.insert(format!("{}::{}", c, src));
                    }
                }
            }
        }
        let ca = ca_set.len();

        let a_count = *crate_abstract.get(name).unwrap_or(&0);
        let h = if n > 0 {
            (r as f64 + 1.0) / n as f64
        } else {
            0.0
        };
        let a = if n > 0 {
            a_count as f64 / n as f64
        } else {
            0.0
        };
        let i = if ca + ce > 0 {
            ce as f64 / (ca + ce) as f64
        } else {
            0.0
        };
        let d_prime = (a + i - 1.0).abs();
        let d = d_prime / 2f64.sqrt();

        let classes = crate_defined
            .get(name)
            .unwrap()
            .iter()
            .map(|(n, k)| ClassInfo {
                name: n.clone(),
                kind: k.clone(),
            })
            .collect();

        let to_vec_map = |map: &HashMap<String, HashSet<String>>| {
            map.iter()
                .filter(|(k, _)| *k != DetailVisitor::ROOT_ITEM)
                .map(|(k, v)| {
                    (
                        k.clone(),
                        v.iter()
                            .filter(|t| *t != DetailVisitor::ROOT_ITEM)
                            .cloned()
                            .collect::<Vec<_>>(),
                    )
                })
                .filter(|(_, v): &(_, Vec<String>)| !v.is_empty())
                .collect::<HashMap<_, _>>()
        };

        let to_vec_nested = |map: &HashMap<String, HashMap<String, HashSet<String>>>| {
            map.iter()
                .filter(|(k, _)| *k != DetailVisitor::ROOT_ITEM)
                .map(|(k, v)| {
                    (
                        k.clone(),
                        v.iter()
                            .filter(|(k2, _)| *k2 != DetailVisitor::ROOT_ITEM)
                            .map(|(k2, set)| {
                                (
                                    k2.clone(),
                                    set.iter()
                                        .filter(|t| *t != DetailVisitor::ROOT_ITEM)
                                        .cloned()
                                        .collect::<Vec<_>>(),
                                )
                            })
                            .filter(|(_, v)| !v.is_empty())
                            .collect::<HashMap<_, _>>(),
                    )
                })
                .filter(|(_, v)| !v.is_empty())
                .collect::<HashMap<_, _>>()
        };

        result.insert(name.clone(), {
            let metrics = Metrics {
                r,
                n,
                h,
                ca,
                ce,
                a,
                i,
                d,
                d_prime,
            };
            CrateDetail {
                kind: CrateKind::Workspace,
                metrics: metrics.clone(),
                evaluation: evaluate_metrics_with(&metrics, t),
                classes,
                internal_depends_on: to_vec_map(internal_refs.get(name).unwrap_or(&HashMap::new())),
                internal_depended_by: to_vec_map(internal_rev.get(name).unwrap_or(&HashMap::new())),
                external_depends_on: to_vec_nested(
                    external_refs.get(name).unwrap_or(&HashMap::new()),
                ),
                external_depended_by: to_vec_nested(
                    external_rev.get(name).unwrap_or(&HashMap::new()),
                ),
            }
        });
    }

    result
}

/// Detect cycles in the crate dependency graph.
///
/// The returned vector contains one entry per cycle; each entry is a list of
/// crate names in the order they appear in the cycle. Internally uses
/// Tarjan's strongly connected components algorithm.
pub fn dependency_cycles(details: &HashMap<String, CrateDetail>) -> Vec<Vec<String>> {
    // Build adjacency list of crate -> crates it depends on
    let mut graph: HashMap<String, HashSet<String>> = HashMap::new();
    for (name, detail) in details {
        let entry = graph.entry(name.clone()).or_default();
        for map in detail.external_depends_on.values() {
            for krate in map.keys() {
                entry.insert(krate.clone());
            }
        }
    }

    let graph: HashMap<String, Vec<String>> = graph
        .into_iter()
        .map(|(k, v)| (k, v.into_iter().collect()))
        .collect();

    #[allow(clippy::too_many_arguments)]
    fn strongconnect(
        v: &String,
        index: &mut usize,
        stack: &mut Vec<String>,
        indices: &mut HashMap<String, usize>,
        lowlink: &mut HashMap<String, usize>,
        on_stack: &mut HashSet<String>,
        graph: &HashMap<String, Vec<String>>,
        result: &mut Vec<Vec<String>>,
    ) {
        indices.insert(v.clone(), *index);
        lowlink.insert(v.clone(), *index);
        *index += 1;
        stack.push(v.clone());
        on_stack.insert(v.clone());

        if let Some(neigh) = graph.get(v) {
            for w in neigh {
                if !indices.contains_key(w) {
                    strongconnect(w, index, stack, indices, lowlink, on_stack, graph, result);
                    let lw = *lowlink.get(w).unwrap();
                    let lv = *lowlink.get(v).unwrap();
                    if lw < lv {
                        lowlink.insert(v.clone(), lw);
                    }
                } else if on_stack.contains(w) {
                    let iw = *indices.get(w).unwrap();
                    let lv = *lowlink.get(v).unwrap();
                    if iw < lv {
                        lowlink.insert(v.clone(), iw);
                    }
                }
            }
        }

        if indices.get(v) == lowlink.get(v) {
            let mut scc = Vec::new();
            while let Some(w) = stack.pop() {
                on_stack.remove(&w);
                scc.push(w.clone());
                if &w == v {
                    break;
                }
            }
            if scc.len() > 1 {
                scc.reverse();
                result.push(scc);
            }
        }
    }

    let mut index = 0usize;
    let mut stack = Vec::new();
    let mut indices: HashMap<String, usize> = HashMap::new();
    let mut lowlink: HashMap<String, usize> = HashMap::new();
    let mut on_stack: HashSet<String> = HashSet::new();
    let mut result_vec = Vec::new();

    for v in graph.keys() {
        if !indices.contains_key(v) {
            strongconnect(
                v,
                &mut index,
                &mut stack,
                &mut indices,
                &mut lowlink,
                &mut on_stack,
                &graph,
                &mut result_vec,
            );
        }
    }

    result_vec
}

struct RefVisitor<'a> {
    defined: &'a HashMap<String, ClassKind>,
    workspace: &'a HashSet<String>,
    internal: usize,
    external: usize,
}

impl<'ast> Visit<'ast> for RefVisitor<'_> {
    fn visit_path(&mut self, node: &'ast syn::Path) {
        if let Some(seg) = node.segments.last() {
            let name = seg.ident.to_string();
            if self.defined.contains_key(&name) {
                self.internal += 1;
            } else if self.workspace.contains(&name) {
                self.external += 1;
            }
        }
        syn::visit::visit_path(self, node);
    }
}

struct DetailVisitor<'a> {
    current: Option<String>,
    defined: &'a HashMap<String, ClassKind>,
    crate_name: &'a str,
    workspace_crates: &'a HashSet<String>,
    all_defined: &'a HashMap<String, HashMap<String, ClassKind>>,
    reexports: &'a HashMap<String, HashMap<String, (String, String)>>,
    /// Map of imported identifiers to their originating crate and original name.
    ///
    /// The key is the local identifier introduced by a `use` statement. The
    /// value is a tuple of `(root crate, original identifier)` where either
    /// element may be `None` if it cannot be resolved.
    imports: HashMap<String, (Option<String>, Option<String>)>,
    internal: HashMap<String, HashSet<String>>, // from -> to
    external: HashMap<String, HashMap<String, HashSet<String>>>, // from -> crate -> types
    methods: &'a HashMap<(String, String), String>,
    trait_bounds: &'a HashMap<String, Vec<String>>,
}

impl<'ast> Visit<'ast> for DetailVisitor<'_> {
    fn visit_file(&mut self, i: &'ast syn::File) {
        if has_test_attr(&i.attrs) {
            return;
        }
        syn::visit::visit_file(self, i);
    }
    fn visit_item_struct(&mut self, i: &'ast syn::ItemStruct) {
        if has_test_attr(&i.attrs) {
            return;
        }
        let name = i.ident.to_string();
        self.current = Some(name);
        syn::visit::visit_item_struct(self, i);
        self.current = None;
    }
    fn visit_item_enum(&mut self, i: &'ast syn::ItemEnum) {
        if has_test_attr(&i.attrs) {
            return;
        }
        let name = i.ident.to_string();
        self.current = Some(name);
        syn::visit::visit_item_enum(self, i);
        self.current = None;
    }
    fn visit_item_trait(&mut self, i: &'ast syn::ItemTrait) {
        if has_test_attr(&i.attrs) {
            return;
        }
        let name = i.ident.to_string();
        self.current = Some(name);
        syn::visit::visit_item_trait(self, i);
        self.current = None;
    }
    fn visit_item_type(&mut self, i: &'ast syn::ItemType) {
        if has_test_attr(&i.attrs) {
            return;
        }
        let name = i.ident.to_string();
        self.current = Some(name);
        syn::visit::visit_item_type(self, i);
        self.current = None;
    }
    fn visit_item_const(&mut self, i: &'ast syn::ItemConst) {
        if has_test_attr(&i.attrs) {
            return;
        }
        let name = i.ident.to_string();
        self.current = Some(name);
        syn::visit::visit_item_const(self, i);
        self.current = None;
    }
    fn visit_item_static(&mut self, i: &'ast syn::ItemStatic) {
        if has_test_attr(&i.attrs) {
            return;
        }
        let name = i.ident.to_string();
        self.current = Some(name);
        syn::visit::visit_item_static(self, i);
        self.current = None;
    }
    fn visit_item_impl(&mut self, i: &'ast syn::ItemImpl) {
        if has_test_attr(&i.attrs) {
            return;
        }
        if let syn::Type::Path(tp) = &*i.self_ty {
            if let Some(seg) = tp.path.segments.last() {
                let name = seg.ident.to_string();
                if self.defined.contains_key(&name) {
                    self.current = Some(name);
                    syn::visit::visit_item_impl(self, i);
                    self.current = None;
                    return;
                }
            }
        }
        syn::visit::visit_item_impl(self, i);
    }
    fn visit_item_fn(&mut self, i: &'ast syn::ItemFn) {
        if has_test_attr(&i.attrs) {
            return;
        }
        let name = i.sig.ident.to_string();
        self.current = Some(name);
        syn::visit::visit_item_fn(self, i);
        self.current = None;
    }
    fn visit_item_mod(&mut self, i: &'ast syn::ItemMod) {
        if has_test_attr(&i.attrs) {
            return;
        }
        syn::visit::visit_item_mod(self, i);
    }
    fn visit_item_use(&mut self, i: &'ast syn::ItemUse) {
        fn handle(
            tree: &syn::UseTree,
            first: Option<String>,
            ws: &HashSet<String>,
            all_def: &HashMap<String, HashMap<String, ClassKind>>,
            map: &mut HashMap<String, (Option<String>, Option<String>)>,
        ) {
            match tree {
                syn::UseTree::Path(p) => {
                    let root = first.clone().unwrap_or_else(|| p.ident.to_string());
                    handle(&p.tree, Some(root), ws, all_def, map);
                }
                syn::UseTree::Name(n) => {
                    // When `first` is `None`, the use statement is importing a
                    // crate without an alias (e.g. `use foo;`). In this case
                    // `path_root` can resolve the crate directly, so we only
                    // track names when they appear as part of a path with a
                    // prefix.
                    if let Some(r) = &first {
                        if ws.contains(r) {
                            map.insert(
                                n.ident.to_string(),
                                (Some(r.clone()), Some(n.ident.to_string())),
                            );
                        } else {
                            map.insert(n.ident.to_string(), (None, None));
                        }
                    }
                }
                syn::UseTree::Rename(rn) => {
                    let root = first
                        .as_ref()
                        .cloned()
                        .unwrap_or_else(|| rn.ident.to_string());
                    if ws.contains(&root) {
                        map.insert(
                            rn.rename.to_string(),
                            (Some(root), Some(rn.ident.to_string())),
                        );
                    } else {
                        map.insert(rn.rename.to_string(), (None, None));
                    }
                }
                syn::UseTree::Group(g) => {
                    for t in &g.items {
                        handle(t, first.clone(), ws, all_def, map);
                    }
                }
                syn::UseTree::Glob(_) => {
                    if let Some(r) = &first {
                        if ws.contains(r) {
                            if let Some(defs) = all_def.get(r) {
                                for name in defs.keys() {
                                    map.insert(name.clone(), (Some(r.clone()), Some(name.clone())));
                                }
                            }
                        }
                    }
                }
            }
        }

        handle(
            &i.tree,
            None,
            self.workspace_crates,
            self.all_defined,
            &mut self.imports,
        );
        syn::visit::visit_item_use(self, i);
    }
    fn visit_path(&mut self, node: &'ast syn::Path) {
        if let Some(seg) = node.segments.last() {
            let name = seg.ident.to_string();
            let root = self.path_root(node);
            self.record_use(name, root);
        }
        syn::visit::visit_path(self, node);
    }

    fn visit_expr_call(&mut self, node: &'ast syn::ExprCall) {
        if let syn::Expr::Path(p) = &*node.func {
            if p.path.segments.len() >= 2 {
                let func = p.path.segments.last().unwrap().ident.to_string();
                let ty = p.path.segments[p.path.segments.len() - 2].ident.to_string();
                let root = self.path_root(&p.path);
                self.record_use(ty.clone(), root.clone());
                let _ = self.methods.get(&(ty, func));
            } else if let Some(seg) = p.path.segments.last() {
                let name = seg.ident.to_string();
                let root = self.path_root(&p.path);
                self.record_use(name, root);
            }
        }
        syn::visit::visit_expr_call(self, node);
    }

    fn visit_expr_macro(&mut self, node: &'ast syn::ExprMacro) {
        if let Some(seg) = node.mac.path.segments.last() {
            let name = seg.ident.to_string();
            let root = self.path_root(&node.mac.path);
            self.record_use(name, root);
        }
        syn::visit::visit_expr_macro(self, node);
    }

    fn visit_item_macro(&mut self, i: &'ast syn::ItemMacro) {
        if i.ident.is_none() {
            if let Some(seg) = i.mac.path.segments.last() {
                let name = seg.ident.to_string();
                let root = self.path_root(&i.mac.path);
                self.record_use(name, root);
            }
        }
        syn::visit::visit_item_macro(self, i);
    }

    fn visit_expr_method_call(&mut self, node: &'ast syn::ExprMethodCall) {
        if let Some((receiver_ty, root)) = self.infer_expr_type(&node.receiver) {
            self.record_use(receiver_ty, root);
        }
        syn::visit::visit_expr_method_call(self, node);
    }
}

impl<'a> DetailVisitor<'a> {
    fn path_root(&self, path: &syn::Path) -> Option<String> {
        if let Some(first) = path.segments.first() {
            let ident = first.ident.to_string();
            match ident.as_str() {
                "crate" | "self" | "super" => Some(self.crate_name.to_string()),
                _ => {
                    if self.workspace_crates.contains(&ident) {
                        Some(ident)
                    } else if let Some((Some(root), _)) = self.imports.get(&ident) {
                        Some(root.clone())
                    } else {
                        None
                    }
                }
            }
        } else {
            None
        }
    }

    const ROOT_ITEM: &'static str = "__crate_root";

    fn record_use(&mut self, name: String, root: Option<String>) {
        let current = self
            .current
            .clone()
            .unwrap_or_else(|| Self::ROOT_ITEM.to_string());

        if name == current {
            return;
        }

        match root {
            Some(ref r) if r == self.crate_name => {
                if self.defined.contains_key(&name) {
                    self.internal
                        .entry(current.clone())
                        .or_default()
                        .insert(name);
                } else if let Some((target_crate, target_name)) = self
                    .reexports
                    .get(self.crate_name)
                    .and_then(|m| m.get(&name))
                    .cloned()
                {
                    if self.workspace_crates.contains(&target_crate) {
                        self.external
                            .entry(current.clone())
                            .or_default()
                            .entry(target_crate)
                            .or_default()
                            .insert(target_name);
                    }
                }
            }
            Some(ref r) => {
                if self.workspace_crates.contains(r) {
                    let lookup = if let Some((_, Some(orig))) = self.imports.get(&name) {
                        orig
                    } else {
                        &name
                    };
                    if self
                        .all_defined
                        .get(r)
                        .is_some_and(|d| d.contains_key(lookup))
                    {
                        self.external
                            .entry(current.clone())
                            .or_default()
                            .entry(r.clone())
                            .or_default()
                            .insert(lookup.to_string());
                    } else if let Some((target_crate, target_name)) =
                        self.reexports.get(r).and_then(|m| m.get(lookup)).cloned()
                    {
                        if self.workspace_crates.contains(&target_crate) {
                            self.external
                                .entry(current.clone())
                                .or_default()
                                .entry(target_crate)
                                .or_default()
                                .insert(target_name);
                        }
                    }
                }
            }
            None => {
                if self.defined.contains_key(&name) {
                    self.internal
                        .entry(current.clone())
                        .or_default()
                        .insert(name);
                } else if let Some((Some(import_root), orig)) = self.imports.get(&name).cloned() {
                    let lookup = orig.unwrap_or(name.clone());
                    if self
                        .all_defined
                        .get(&import_root)
                        .is_some_and(|d| d.contains_key(&lookup))
                    {
                        self.external
                            .entry(current.clone())
                            .or_default()
                            .entry(import_root.clone())
                            .or_default()
                            .insert(lookup);
                    } else if let Some((target_crate, target_name)) = self
                        .reexports
                        .get(&import_root)
                        .and_then(|m| m.get(&lookup))
                        .cloned()
                    {
                        if self.workspace_crates.contains(&target_crate) {
                            self.external
                                .entry(current.clone())
                                .or_default()
                                .entry(target_crate)
                                .or_default()
                                .insert(target_name);
                        }
                    }
                }
            }
        }
    }
    fn infer_from_call(&self, call: &syn::ExprCall) -> Option<(String, Option<String>)> {
        if let syn::Expr::Path(p) = &*call.func {
            if p.path.segments.len() >= 2 {
                let func = p.path.segments.last().unwrap().ident.to_string();
                let ty = p.path.segments[p.path.segments.len() - 2].ident.to_string();
                if let Some(ret) = self.methods.get(&(ty.clone(), func.clone())) {
                    let root = self.path_root(&p.path);
                    return Some((ret.clone(), root));
                }
            }
            if let Some(seg) = p.path.segments.last() {
                let name = seg.ident.to_string();
                if self.defined.contains_key(&name)
                    || self.all_defined.values().any(|d| d.contains_key(&name))
                {
                    let root = self.path_root(&p.path);
                    return Some((name, root));
                }
            }
        }
        None
    }

    fn infer_from_method_call(&self, mc: &syn::ExprMethodCall) -> Option<(String, Option<String>)> {
        if let Some((receiver_ty, root)) = self.infer_expr_type(&mc.receiver) {
            if let Some(ret) = self
                .methods
                .get(&(receiver_ty.clone(), mc.method.to_string()))
            {
                return Some((ret.clone(), root));
            }
            if let Some(bounds) = self.trait_bounds.get(&receiver_ty) {
                let mut found = None;
                for b in bounds {
                    if let Some(ret) = self.methods.get(&(b.clone(), mc.method.to_string())) {
                        if found.is_some() {
                            return None;
                        }
                        found = Some(ret.clone());
                    }
                }
                if let Some(ret) = found {
                    return Some((ret, None));
                }
            }
            return Some((receiver_ty, root));
        }
        let mut ret = None;
        for ((_, name), r) in self.methods.iter() {
            if name == &mc.method.to_string() {
                if ret.is_some() {
                    return None;
                }
                ret = Some(r.clone());
            }
        }
        ret.map(|r| (r, None))
    }

    fn infer_from_path(&self, p: &syn::ExprPath) -> Option<(String, Option<String>)> {
        if p.path.segments.len() == 1 && p.path.segments[0].ident == "self" {
            return self
                .current
                .as_ref()
                .map(|c| (c.clone(), Some(self.crate_name.to_string())));
        }
        if let Some(seg) = p.path.segments.last() {
            let name = seg.ident.to_string();
            if self.defined.contains_key(&name)
                || self.all_defined.values().any(|d| d.contains_key(&name))
            {
                let root = self.path_root(&p.path);
                return Some((name, root));
            }
        }
        None
    }

    fn infer_expr_type(&self, expr: &syn::Expr) -> Option<(String, Option<String>)> {
        match expr {
            syn::Expr::Call(call) => self.infer_from_call(call),
            syn::Expr::MethodCall(mc) => self.infer_from_method_call(mc),
            syn::Expr::Path(p) => self.infer_from_path(p),
            _ => None,
        }
    }
}

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

    #[test]
    fn simple_metrics() {
        let src = r#"
            pub struct A {
                b: B,
                map: std::collections::HashMap<String, String>,
            }
            pub struct B;
            pub trait MyTrait {
                fn do_it(&self, a: A);
            }
        "#;
        let file: syn::File = syn::parse_str(src).unwrap();
        let defs = collect_defined(&[file.clone()]);
        let workspace: HashSet<String> = defs.0.keys().cloned().collect();
        let metrics = analyze_files(&[file], &workspace);
        assert_eq!(metrics.n, 3);
        assert_eq!(metrics.ca, 0);
        assert_eq!(metrics.ce, 0); // HashMap is outside workspace
        assert!((metrics.h - ((2.0 + 1.0) / 3.0)).abs() < 1e-6);
        assert!((metrics.a - (1.0 / 3.0)).abs() < 1e-6);
        // With no cross-crate dependencies, instability is defined as zero
        assert!(metrics.i.abs() < 1e-6);
    }

    #[test]
    fn cross_crate_metrics() {
        let src_a = "pub struct A;";
        let src_b = "pub struct B { a: crate_a::A }";
        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];
        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(a_info.metrics.ca, 1);
        assert_eq!(a_info.metrics.ce, 0);
        assert_eq!(b_info.metrics.ce, 1);

        assert_eq!(
            b_info
                .external_depends_on
                .get("B")
                .and_then(|m| m.get("crate_a"))
                .map(|v| v.contains(&"A".to_string()))
                .unwrap_or(false),
            true
        );
        assert_eq!(
            a_info
                .external_depended_by
                .get("A")
                .and_then(|m| m.get("crate_b"))
                .map(|v| v.contains(&"B".to_string()))
                .unwrap_or(false),
            true
        );
    }

    #[test]
    fn detailed_info() {
        let src_a = "pub struct A;";
        let src_b = "pub struct B { a: crate_a::A }";
        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];
        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        assert_eq!(a_info.classes.len(), 1);
        assert_eq!(a_info.classes[0].name, "A");
        assert!(a_info
            .external_depended_by
            .get("A")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"B".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn trait_bound_dependency() {
        let src_a = "pub trait Foo {}";
        let src_b = "use crate_a::Foo; pub struct Bar<U: Foo>(U);";

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(a_info.metrics.ca, 1);
        assert_eq!(b_info.metrics.ce, 1);

        assert!(b_info
            .external_depends_on
            .get("Bar")
            .and_then(|m| m.get("crate_a"))
            .map(|v| v.contains(&"Foo".to_string()))
            .unwrap_or(false));
        assert!(a_info
            .external_depended_by
            .get("Foo")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"Bar".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn reexported_dependency_counts_as_external() {
        let src_infra = r#"
            pub mod repo {
                pub struct HashDB;
            }
        "#;
        let src_sample = r#"
            pub mod repository {
                pub use infra::repo::HashDB;
            }
        "#;
        let src_app = r#"
            use sample::repository::HashDB;

            pub struct App(HashDB);
        "#;

        let file_infra: syn::File = syn::parse_str(src_infra).unwrap();
        let file_sample: syn::File = syn::parse_str(src_sample).unwrap();
        let file_app: syn::File = syn::parse_str(src_app).unwrap();

        let crates = vec![
            ("infra".to_string(), vec![file_infra.clone()]),
            ("sample".to_string(), vec![file_sample.clone()]),
            ("app".to_string(), vec![file_app.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let app_info = info.get("app").unwrap();

        assert_eq!(app_info.metrics.ce, 1);
        assert!(app_info
            .external_depends_on
            .get("App")
            .and_then(|m| m.get("infra"))
            .map(|v| v.contains(&"HashDB".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn unique_counts() {
        let src_a = "pub struct A;";
        let src_b = "pub struct B { a1: crate_a::A, a2: crate_a::A }";
        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];
        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);

        assert!(b_info
            .external_depends_on
            .get("B")
            .and_then(|m| m.get("crate_a"))
            .map(|v| v.len() == 1 && v.contains(&"A".to_string()))
            .unwrap_or(false));
        assert!(a_info
            .external_depended_by
            .get("A")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.len() == 1 && v.contains(&"B".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn same_name_internal_external_dependency() {
        let src_a = "pub struct Foo;";
        let src_b = "pub struct Foo; pub struct Bar { ext: crate_a::Foo, int: Foo }";

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let b_info = info.get("crate_b").unwrap();

        assert!(b_info
            .internal_depends_on
            .get("Bar")
            .map(|v| v.contains(&"Foo".to_string()))
            .unwrap_or(false));
        assert!(b_info
            .external_depends_on
            .get("Bar")
            .and_then(|m| m.get("crate_a"))
            .map(|v| v.contains(&"Foo".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn method_call_dependency() {
        let src_a = r#"
            pub struct Dao;
            impl Dao {
                pub fn new() -> Self { Dao }
                pub fn delete(&self) {}
            }
        "#;
        let src_b = r#"
            pub struct Use;
            impl Use {
                pub fn run() {
                    crate_a::Dao::new().delete();
                }
            }
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);

        assert!(b_info
            .external_depends_on
            .get("Use")
            .and_then(|m| m.get("crate_a"))
            .map(|v| v.contains(&"Dao".to_string()))
            .unwrap_or(false));
        assert!(a_info
            .external_depended_by
            .get("Dao")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"Use".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn chained_method_call_dependency() {
        let src_a = r#"
            pub struct Dao;
            pub trait HaveDao {
                fn dao(&self) -> Dao;
            }
            impl Dao {
                pub fn delete(&self) {}
            }
        "#;
        let src_b = r#"
            use crate_a::{Dao, HaveDao};
            pub struct Use<D: HaveDao> { inner: D }
            impl<D: HaveDao> Use<D> {
                pub fn run(&self) {
                    self.inner.dao().delete();
                }
            }
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 2);
        assert_eq!(b_info.metrics.ca, 0);
        assert_eq!(a_info.metrics.ca, 1);

        let b_deps = b_info
            .external_depends_on
            .get("Use")
            .and_then(|m| m.get("crate_a"))
            .cloned()
            .unwrap_or_default();
        assert!(b_deps.contains(&"Dao".to_string()));
        assert!(b_deps.contains(&"HaveDao".to_string()));

        assert!(a_info
            .external_depended_by
            .get("Dao")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"Use".to_string()))
            .unwrap_or(false));
        assert!(a_info
            .external_depended_by
            .get("HaveDao")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"Use".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn dyn_trait_return() {
        let src_a = r#"
            pub trait Dao { fn delete(&self); }
            pub trait HaveDao { fn dao(&self) -> Box<dyn Dao>; }
        "#;
        let src_b = r#"
            use crate_a::{Dao, HaveDao};
            pub struct Use<D: HaveDao> { inner: D }
            impl<D: HaveDao> Use<D> {
                pub fn run(&self) {
                    self.inner.dao().delete();
                }
            }
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 2);
        assert_eq!(a_info.metrics.ca, 1);

        let b_deps = b_info
            .external_depends_on
            .get("Use")
            .and_then(|m| m.get("crate_a"))
            .cloned()
            .unwrap_or_default();
        assert!(b_deps.contains(&"Dao".to_string()));
        assert!(b_deps.contains(&"HaveDao".to_string()));

        assert!(a_info
            .external_depended_by
            .get("Dao")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"Use".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn ignore_non_workspace_crate() {
        let src_a = "pub struct Tx;";
        let src_b = "use tx_rs::Tx; pub struct Use { t: Tx }";
        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 0);
        assert_eq!(a_info.metrics.ca, 0);
        assert!(b_info.external_depends_on.is_empty());
        assert!(a_info.external_depended_by.is_empty());
    }

    #[test]
    fn struct_usage_in_trait() {
        let src_a = r#"
            pub struct Paycheck;
            impl Paycheck { pub fn new() -> Self { Paycheck } }
        "#;
        let src_c = "pub struct Paycheck;";
        let src_b = r#"
            use crate_a::Paycheck;
            pub trait Payday {
                fn run(&self) {
                    self.run_tx(|_| {
                        let _ = Paycheck::new();
                    });
                }
                fn run_tx<F>(&self, f: F) where F: FnOnce(i32) {}
            }
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();
        let file_c: syn::File = syn::parse_str(src_c).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
            ("crate_c".to_string(), vec![file_c.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert!(b_info
            .external_depends_on
            .get("Payday")
            .and_then(|m| m.get("crate_a"))
            .map(|v| v.contains(&"Paycheck".to_string()))
            .unwrap_or(false));
        assert!(a_info
            .external_depended_by
            .get("Paycheck")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"Payday".to_string()))
            .unwrap_or(false));
    }
    #[test]
    fn r_counts_unique_edges() {
        let src = "pub struct B; pub struct A { b1: B, b2: B }";
        let file: syn::File = syn::parse_str(src).unwrap();
        let crates = vec![("crate_a".to_string(), vec![file.clone()])];
        let info = analyze_workspace_details(&crates);
        let a = info.get("crate_a").unwrap();
        assert_eq!(a.metrics.r, 1);
        let deps = a.internal_depends_on.get("A").cloned().unwrap_or_default();
        assert_eq!(deps.len(), 1);
        assert!(deps.contains(&"B".to_string()));
    }

    #[test]
    fn r_multiple_edges() {
        let src = "pub struct B; pub struct C { b1: B, b2: B } pub struct A { b: B, c: C }";
        let file: syn::File = syn::parse_str(src).unwrap();
        let crates = vec![("crate_a".to_string(), vec![file.clone()])];
        let info = analyze_workspace_details(&crates);
        let a = info.get("crate_a").unwrap();
        assert_eq!(a.metrics.r, 3);
        let a_deps = a.internal_depends_on.get("A").cloned().unwrap_or_default();
        let c_deps = a.internal_depends_on.get("C").cloned().unwrap_or_default();
        assert!(a_deps.contains(&"B".to_string()));
        assert!(c_deps.contains(&"B".to_string()));
    }

    #[test]
    fn r_counts_method_body() {
        let src = "pub struct B; pub struct A; impl A { fn make() -> B { B } }";
        let file: syn::File = syn::parse_str(src).unwrap();
        let crates = vec![("crate_a".to_string(), vec![file.clone()])];
        let info = analyze_workspace_details(&crates);
        let a = info.get("crate_a").unwrap();
        assert_eq!(a.metrics.r, 1);
        let deps = a.internal_depends_on.get("A").cloned().unwrap_or_default();
        assert_eq!(deps.len(), 1);
        assert!(deps.contains(&"B".to_string()));
    }

    #[test]
    fn free_function_dependency() {
        let src_a = "pub struct Helper;";
        let src_b = "use crate_a::Helper; fn main() { let _ = Helper; }";
        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);

        assert!(b_info
            .external_depends_on
            .get("main")
            .and_then(|m| m.get("crate_a"))
            .map(|v| v.contains(&"Helper".to_string()))
            .unwrap_or(false));
        assert!(a_info
            .external_depended_by
            .get("Helper")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"main".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn async_function_dependency() {
        let src_a = "pub struct Helper;";
        let src_b = "use crate_a::Helper; async fn run() { let _ = Helper; }";
        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);

        assert!(b_info
            .external_depends_on
            .get("run")
            .and_then(|m| m.get("crate_a"))
            .map(|v| v.contains(&"Helper".to_string()))
            .unwrap_or(false));
        assert!(a_info
            .external_depended_by
            .get("Helper")
            .and_then(|m| m.get("crate_b"))
            .map(|v| v.contains(&"run".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn module_metrics() {
        let root = r#"
            mod foo;
            pub mod bar;

            pub struct Root {
                f: foo::Foo,
                b: bar::Bar,
            }
        "#;
        let foo = "pub struct Foo;";
        let bar = "pub struct Bar;";

        let file_root: syn::File = syn::parse_str(root).unwrap();
        let file_foo: syn::File = syn::parse_str(foo).unwrap();
        let file_bar: syn::File = syn::parse_str(bar).unwrap();

        let defs = collect_defined(&[file_root.clone(), file_foo.clone(), file_bar.clone()]);
        let workspace: HashSet<String> = defs.0.keys().cloned().collect();
        let metrics = analyze_files(&[file_root, file_foo, file_bar], &workspace);

        assert_eq!(metrics.n, 3);
        assert_eq!(metrics.r, 2);
        assert_eq!(metrics.ce, 0);
        assert_eq!(metrics.ca, 0);
    }

    #[test]
    fn inline_module_metrics() {
        let src = r#"
            mod foo {
                pub struct Foo;
            }
            pub mod bar {
                pub struct Bar;
            }

            pub struct Root {
                f: foo::Foo,
                b: bar::Bar,
            }
        "#;

        let file: syn::File = syn::parse_str(src).unwrap();
        let defs = collect_defined(&[file.clone()]);
        let workspace: HashSet<String> = defs.0.keys().cloned().collect();
        let metrics = analyze_files(&[file], &workspace);

        assert_eq!(metrics.n, 3);
        assert_eq!(metrics.r, 2);
        assert_eq!(metrics.ce, 0);
        assert_eq!(metrics.ca, 0);
    }

    #[test]
    fn macro_dependencies() {
        let src_a = r#"
            #[macro_export]
            macro_rules! my_macro {
                () => {};
            }
        "#;
        let src_b = r#"
            pub struct Use;
            impl Use {
                pub fn run() {
                    crate_a::my_macro!();
                }
            }
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);
    }

    #[test]
    fn glob_import_dependency() {
        let src_a = r#"
            pub struct Foo;
        "#;
        let src_b = r#"
            use crate_a::*;
            pub struct Use(Foo);
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);
    }

    #[test]
    fn top_level_macro_invocation() {
        let src_a = r#"
            #[macro_export]
            macro_rules! my_macro {
                () => {};
            }
        "#;
        let src_b = r#"
            use crate_a::*;
            my_macro!();
            fn main() {}
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);
    }

    #[test]
    fn const_dependency() {
        let src_a = r#"
            pub enum Buz { X }
        "#;
        let src_b = r#"
            pub const FOO: &crate_a::Buz = &crate_a::Buz::X;
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);
    }

    #[test]
    fn import_const_dependency() {
        let src_a = r#"
            pub mod foo {
                pub enum Foo { A }
            }
        "#;
        let src_c = r#"
            use crate_a::foo;
            pub const X: foo::Foo = foo::Foo::A;
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_c: syn::File = syn::parse_str(src_c).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_c".to_string(), vec![file_c.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let c_info = info.get("crate_c").unwrap();

        assert_eq!(c_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);
    }

    #[test]
    fn evaluate_metrics_thresholds() {
        let m = Metrics {
            r: 0,
            n: 0,
            h: 1.1,
            ca: 0,
            ce: 0,
            a: 0.8,
            i: 0.8,
            d: 0.0,
            d_prime: 0.7,
        };
        let eval = evaluate_metrics(&m);
        assert!(matches!(eval.a, AbstractionEval::Abstract));
        assert!(matches!(eval.h, CohesionEval::High));
        assert!(matches!(eval.i, StabilityEval::Unstable));
        assert!(matches!(eval.d_prime, DistanceEval::Useless));

        let m = Metrics {
            r: 0,
            n: 0,
            h: 0.8,
            ca: 0,
            ce: 0,
            a: 0.2,
            i: 0.2,
            d: 0.0,
            d_prime: 0.7,
        };
        let eval = evaluate_metrics(&m);
        assert!(matches!(eval.a, AbstractionEval::Concrete));
        assert!(matches!(eval.h, CohesionEval::Low));
        assert!(matches!(eval.i, StabilityEval::Stable));
        assert!(matches!(eval.d_prime, DistanceEval::Painful));

        let m = Metrics {
            r: 0,
            n: 0,
            h: 1.0,
            ca: 0,
            ce: 0,
            a: 0.5,
            i: 0.5,
            d: 0.0,
            d_prime: 0.5,
        };
        let eval = evaluate_metrics(&m);
        assert!(matches!(eval.a, AbstractionEval::Mixed));
        assert!(matches!(eval.h, CohesionEval::Low));
        assert!(matches!(eval.i, StabilityEval::Moderate));
        assert!(matches!(eval.d_prime, DistanceEval::Balanced));

        let m = Metrics {
            r: 0,
            n: 0,
            h: 1.0,
            ca: 0,
            ce: 0,
            a: 0.5,
            i: 0.5,
            d: 0.0,
            d_prime: 0.3,
        };
        let eval = evaluate_metrics(&m);
        assert!(matches!(eval.d_prime, DistanceEval::Good));
    }

    #[test]
    fn detects_two_crate_cycle() {
        let src_a = "use crate_b::B; pub struct A(B);";
        let src_b = "use crate_a::A; pub struct B(A);";

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a]),
            ("crate_b".to_string(), vec![file_b]),
        ];

        let info = analyze_workspace_details(&crates);
        let cycles = dependency_cycles(&info);
        assert_eq!(cycles.len(), 1);
        let cyc = &cycles[0];
        assert!(cyc.contains(&"crate_a".to_string()));
        assert!(cyc.contains(&"crate_b".to_string()));
    }

    #[test]
    fn detects_three_crate_cycle() {
        let src_a = "use crate_b::B; pub struct A(B);";
        let src_b = "use crate_c::C; pub struct B(C);";
        let src_c = "use crate_a::A; pub struct C(A);";

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();
        let file_c: syn::File = syn::parse_str(src_c).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a]),
            ("crate_b".to_string(), vec![file_b]),
            ("crate_c".to_string(), vec![file_c]),
        ];

        let info = analyze_workspace_details(&crates);
        let cycles = dependency_cycles(&info);
        assert_eq!(cycles.len(), 1);
        let cyc = &cycles[0];
        assert!(cyc.contains(&"crate_a".to_string()));
        assert!(cyc.contains(&"crate_b".to_string()));
        assert!(cyc.contains(&"crate_c".to_string()));
    }

    #[test]
    fn unrelated_crate_not_included() {
        let src_a = "use crate_b::B; pub struct A(B);";
        let src_b = "use crate_a::A; pub struct B(A);";
        let src_c = "pub struct C;";

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();
        let file_c: syn::File = syn::parse_str(src_c).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a]),
            ("crate_b".to_string(), vec![file_b]),
            ("crate_c".to_string(), vec![file_c]),
        ];

        let info = analyze_workspace_details(&crates);
        let cycles = dependency_cycles(&info);
        assert_eq!(cycles.len(), 1);
        let cyc = &cycles[0];
        assert!(cyc.contains(&"crate_a".to_string()));
        assert!(cyc.contains(&"crate_b".to_string()));
        assert!(!cyc.contains(&"crate_c".to_string()));
    }

    #[test]
    fn detects_cycle_via_method_calls() {
        let src_a = r#"
            pub struct A;
            impl A {
                pub fn call_b() {
                    crate_b::B::bar();
                }
                pub fn bar() {}
            }
        "#;
        let src_b = r#"
            pub struct B;
            impl B {
                pub fn bar() {
                    crate_a::A::call_b();
                }
            }
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a]),
            ("crate_b".to_string(), vec![file_b]),
        ];

        let info = analyze_workspace_details(&crates);
        let cycles = dependency_cycles(&info);
        assert_eq!(cycles.len(), 1);
        let cyc = &cycles[0];
        assert!(cyc.contains(&"crate_a".to_string()));
        assert!(cyc.contains(&"crate_b".to_string()));
    }

    #[test]
    fn parse_package_ignores_tests_dir() {
        use cargo_metadata::MetadataCommand;
        let dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(dir.path().join("pkg/src")).unwrap();
        std::fs::create_dir_all(dir.path().join("pkg/tests")).unwrap();
        std::fs::write(
            dir.path().join("pkg/Cargo.toml"),
            "[package]\nname = \"pkg\"\nversion = \"0.1.0\"\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("pkg/src/lib.rs"), "pub struct Foo;\n").unwrap();
        std::fs::write(
            dir.path().join("pkg/tests/integration.rs"),
            "pub struct Bar;\n",
        )
        .unwrap();
        let metadata = MetadataCommand::new()
            .no_deps()
            .current_dir(dir.path().join("pkg"))
            .exec()
            .unwrap();
        let package = metadata.packages.first().unwrap();
        let files = parse_package(package).unwrap();
        assert_eq!(files.len(), 1);
    }

    #[test]
    fn lib_and_main_dependency() {
        use cargo_metadata::MetadataCommand;
        let dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(dir.path().join("dep/src")).unwrap();
        std::fs::write(
            dir.path().join("dep/Cargo.toml"),
            "[package]\nname = \"dep\"\nversion = \"0.1.0\"\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("dep/src/lib.rs"), "pub struct Dep;\n").unwrap();

        std::fs::create_dir_all(dir.path().join("app/src")).unwrap();
        std::fs::write(
            dir.path().join("app/Cargo.toml"),
            "[package]\nname = \"app\"\nversion = \"0.1.0\"\n[dependencies]\ndep = { path = \"../dep\" }\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("app/src/lib.rs"), "pub struct App;\n").unwrap();
        std::fs::write(
            dir.path().join("app/src/main.rs"),
            "use dep::Dep; fn main() { let _ = Dep; }\n",
        )
        .unwrap();

        std::fs::write(
            dir.path().join("Cargo.toml"),
            "[workspace]\nmembers = [\"app\", \"dep\"]\n",
        )
        .unwrap();

        let metadata = MetadataCommand::new()
            .no_deps()
            .current_dir(dir.path())
            .exec()
            .unwrap();
        let mut crates = Vec::new();
        for pkg in &metadata.packages {
            crates.push((pkg.name.as_str().to_string(), parse_package(pkg).unwrap()));
        }

        let info = analyze_workspace_details(&crates);
        assert_eq!(info["app"].metrics.ce, 1);
        assert_eq!(info["dep"].metrics.ca, 1);
    }

    #[test]
    fn path_dep_import_dependency() {
        use cargo_metadata::MetadataCommand;
        let dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(dir.path().join("a/src")).unwrap();
        std::fs::create_dir_all(dir.path().join("b/c/src")).unwrap();
        std::fs::create_dir_all(dir.path().join("b/src")).unwrap();

        std::fs::write(
            dir.path().join("a/Cargo.toml"),
            "[package]\nname = \"a\"\nversion = \"0.1.0\"\nedition = \"2024\"\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("a/src/lib.rs"), "pub mod foo;\n").unwrap();
        std::fs::write(
            dir.path().join("a/src/foo.rs"),
            "#[derive(Debug)]\npub enum Foo { A }\n",
        )
        .unwrap();

        std::fs::write(
            dir.path().join("b/Cargo.toml"),
            "[package]\nname = \"b\"\nversion = \"0.1.0\"\nedition = \"2024\"\n\n[dependencies]\na = { path = \"../a\" }\nc = { path = \"./c\" }\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("b/src/lib.rs"), "pub use c;\n").unwrap();

        std::fs::write(
            dir.path().join("b/c/Cargo.toml"),
            "[package]\nname = \"c\"\nversion = \"0.1.0\"\nedition = \"2024\"\n\n[dependencies]\na = { path = \"../../a\" }\n",
        )
        .unwrap();
        std::fs::write(
            dir.path().join("b/c/src/lib.rs"),
            "use a::foo;\npub const X: foo::Foo = foo::Foo::A;\n",
        )
        .unwrap();

        std::fs::write(
            dir.path().join("Cargo.toml"),
            "[workspace]\nmembers = [\"a\", \"b\"]\nresolver = \"3\"\n",
        )
        .unwrap();

        let metadata = MetadataCommand::new()
            .no_deps()
            .current_dir(dir.path())
            .exec()
            .unwrap();
        let mut crates = Vec::new();
        for pkg in &metadata.packages {
            crates.push((pkg.name.as_str().to_string(), parse_package(pkg).unwrap()));
        }

        let info = analyze_workspace_details(&crates);
        assert_eq!(info["c"].metrics.ce, 1);
        assert_eq!(info["a"].metrics.ca, 1);
    }

    #[test]
    fn external_crate_alias() {
        use cargo_metadata::MetadataCommand;
        let dir = tempfile::tempdir().unwrap();
        let external = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(external.path().join("src")).unwrap();
        std::fs::write(
            external.path().join("Cargo.toml"),
            "[package]\nname = \"foo_bar\"\nversion = \"0.1.0\"\n",
        )
        .unwrap();
        std::fs::write(external.path().join("src/lib.rs"), "pub struct FooBar;\n").unwrap();

        std::fs::create_dir(dir.path().join("app")).unwrap();
        std::fs::create_dir(dir.path().join("app/src")).unwrap();
        std::fs::write(
            dir.path().join("app/Cargo.toml"),
            format!(
                "[package]\nname = \"app\"\nversion = \"0.1.0\"\n[dependencies]\nfoo_bar = {{ path = \"{}\" }}\n",
                external.path().display()
            ),
        )
        .unwrap();
        std::fs::write(
            dir.path().join("app/src/lib.rs"),
            "use foo_bar as foo; pub struct App { d: foo::FooBar }\n",
        )
        .unwrap();

        std::fs::write(
            dir.path().join("Cargo.toml"),
            "[workspace]\nmembers = [\"app\"]\n",
        )
        .unwrap();

        let metadata_app = MetadataCommand::new()
            .no_deps()
            .current_dir(dir.path().join("app"))
            .exec()
            .unwrap();
        let app_pkg = metadata_app.packages.first().unwrap();
        let app_files = parse_package(app_pkg).unwrap();

        let metadata_dep = MetadataCommand::new()
            .no_deps()
            .current_dir(external.path())
            .exec()
            .unwrap();
        let dep_pkg = metadata_dep.packages.first().unwrap();
        let dep_files = parse_package(dep_pkg).unwrap();

        let crates = vec![
            ("app".to_string(), app_files),
            ("foo_bar".to_string(), dep_files),
        ];

        let info = analyze_workspace_details(&crates);
        let app = info.get("app").unwrap();
        let dep = info.get("foo_bar").unwrap();
        assert_eq!(app.metrics.ce, 1);
        assert_eq!(dep.metrics.ca, 1);
        assert_eq!(dep.metrics.ce, 0);
        assert!(app
            .external_depends_on
            .get("App")
            .and_then(|m| m.get("foo_bar"))
            .map(|v| v.contains(&"FooBar".to_string()))
            .unwrap_or(false));
    }

    #[test]
    fn type_alias_dependency() {
        use cargo_metadata::MetadataCommand;
        let dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(dir.path().join("a/src")).unwrap();
        std::fs::write(
            dir.path().join("a/Cargo.toml"),
            "[package]\nname = \"a\"\nversion = \"0.1.0\"\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("a/src/lib.rs"), "pub struct Cache;\n").unwrap();

        std::fs::create_dir_all(dir.path().join("b/src")).unwrap();
        std::fs::write(
            dir.path().join("b/Cargo.toml"),
            "[package]\nname = \"b\"\nversion = \"0.1.0\"\n\n[[bin]]\nname = \"b\"\n",
        )
        .unwrap();
        std::fs::write(
            dir.path().join("b/src/main.rs"),
            "use a::Cache as CacheImpl; fn main() { let _ = CacheImpl; }\n",
        )
        .unwrap();

        std::fs::write(
            dir.path().join("Cargo.toml"),
            "[workspace]\nmembers = [\"b\", \"a\"]\n",
        )
        .unwrap();

        let metadata = MetadataCommand::new()
            .no_deps()
            .current_dir(dir.path())
            .exec()
            .unwrap();
        let mut crates = Vec::new();
        for pkg in &metadata.packages {
            crates.push((pkg.name.as_str().to_string(), parse_package(pkg).unwrap()));
        }

        let info = analyze_workspace_details(&crates);
        assert_eq!(info["b"].metrics.ce, 1);
        assert_eq!(info["a"].metrics.ca, 1);
    }

    #[test]
    fn bin_target_dependency() {
        use cargo_metadata::MetadataCommand;
        let dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(dir.path().join("dep/src")).unwrap();
        std::fs::write(
            dir.path().join("dep/Cargo.toml"),
            "[package]\nname = \"dep\"\nversion = \"0.1.0\"\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("dep/src/lib.rs"), "pub struct Dep;\n").unwrap();

        std::fs::create_dir_all(dir.path().join("app/src/bin")).unwrap();
        std::fs::write(
            dir.path().join("app/Cargo.toml"),
            "[package]\nname = \"app\"\nversion = \"0.1.0\"\n[dependencies]\ndep = { path = \"../dep\" }\n\n[[bin]]\nname = \"cli\"\npath = \"src/bin/cli.rs\"\n",
        )
        .unwrap();
        std::fs::write(dir.path().join("app/src/lib.rs"), "pub struct App;\n").unwrap();
        std::fs::write(
            dir.path().join("app/src/bin/cli.rs"),
            "use dep::Dep; fn main() { let _ = Dep; }\n",
        )
        .unwrap();

        std::fs::write(
            dir.path().join("Cargo.toml"),
            "[workspace]\nmembers = [\"app\", \"dep\"]\n",
        )
        .unwrap();

        let metadata = MetadataCommand::new()
            .no_deps()
            .current_dir(dir.path())
            .exec()
            .unwrap();
        let mut crates = Vec::new();
        for pkg in &metadata.packages {
            crates.push((pkg.name.as_str().to_string(), parse_package(pkg).unwrap()));
        }

        let info = analyze_workspace_details(&crates);
        assert_eq!(info["app"].metrics.ce, 1);
        assert_eq!(info["dep"].metrics.ca, 1);
    }

    #[test]
    fn path_root_resolves_special_paths() {
        let defined = std::collections::HashMap::new();
        let mut ws = std::collections::HashSet::new();
        ws.insert("my_crate".to_string());
        let visitor = DetailVisitor {
            current: None,
            defined: &defined,
            crate_name: "my_crate",
            workspace_crates: &ws,
            all_defined: &std::collections::HashMap::new(),
            reexports: &std::collections::HashMap::new(),
            imports: std::collections::HashMap::new(),
            internal: std::collections::HashMap::new(),
            external: std::collections::HashMap::new(),
            methods: &std::collections::HashMap::new(),
            trait_bounds: &std::collections::HashMap::new(),
        };
        let p: syn::Path = syn::parse_str("self::Foo").unwrap();
        assert_eq!(visitor.path_root(&p), Some("my_crate".to_string()));
        let p: syn::Path = syn::parse_str("super::bar::Baz").unwrap();
        assert_eq!(visitor.path_root(&p), Some("my_crate".to_string()));
        let p: syn::Path = syn::parse_str("crate::Foo").unwrap();
        assert_eq!(visitor.path_root(&p), Some("my_crate".to_string()));
    }

    #[test]
    fn infer_expr_type_special_paths() {
        use std::collections::{HashMap, HashSet};
        let mut defined = HashMap::new();
        defined.insert("Foo".to_string(), ClassKind::Struct);
        let mut ws = HashSet::new();
        ws.insert("my_crate".to_string());
        let visitor = DetailVisitor {
            current: Some("Current".to_string()),
            defined: &defined,
            crate_name: "my_crate",
            workspace_crates: &ws,
            all_defined: &HashMap::new(),
            reexports: &HashMap::new(),
            imports: HashMap::new(),
            internal: HashMap::new(),
            external: HashMap::new(),
            methods: &HashMap::new(),
            trait_bounds: &HashMap::new(),
        };
        let e: syn::Expr = syn::parse_str("self").unwrap();
        assert_eq!(
            visitor.infer_expr_type(&e),
            Some(("Current".to_string(), Some("my_crate".to_string())))
        );
        let e: syn::Expr = syn::parse_str("self::Foo").unwrap();
        assert_eq!(
            visitor.infer_expr_type(&e),
            Some(("Foo".to_string(), Some("my_crate".to_string())))
        );
        let e: syn::Expr = syn::parse_str("super::Foo").unwrap();
        assert_eq!(
            visitor.infer_expr_type(&e),
            Some(("Foo".to_string(), Some("my_crate".to_string())))
        );
        let e: syn::Expr = syn::parse_str("crate::Foo").unwrap();
        assert_eq!(
            visitor.infer_expr_type(&e),
            Some(("Foo".to_string(), Some("my_crate".to_string())))
        );
    }

    #[test]
    fn detects_multiple_cycles() {
        let src_a = "use crate_b::B; pub struct A(B);";
        let src_b = "use crate_a::A; pub struct B(A);";
        let src_c = "use crate_d::D; pub struct C(D);";
        let src_d = "use crate_c::C; pub struct D(C);";

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();
        let file_c: syn::File = syn::parse_str(src_c).unwrap();
        let file_d: syn::File = syn::parse_str(src_d).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a]),
            ("crate_b".to_string(), vec![file_b]),
            ("crate_c".to_string(), vec![file_c]),
            ("crate_d".to_string(), vec![file_d]),
        ];

        let info = analyze_workspace_details(&crates);
        let mut cycles = dependency_cycles(&info);
        cycles.sort_by(|a, b| a[0].cmp(&b[0]));
        assert_eq!(cycles.len(), 2);
        assert!(cycles[0].contains(&"crate_a".to_string()));
        assert!(cycles[0].contains(&"crate_b".to_string()));
        assert!(cycles[1].contains(&"crate_c".to_string()));
        assert!(cycles[1].contains(&"crate_d".to_string()));
    }

    #[test]
    fn detects_no_cycles() {
        let src_a = "use crate_b::B; pub struct A(B);";
        let src_b = "pub struct B;";
        let src_c = "use crate_b::B; pub struct C(B);";

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();
        let file_c: syn::File = syn::parse_str(src_c).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a]),
            ("crate_b".to_string(), vec![file_b]),
            ("crate_c".to_string(), vec![file_c]),
        ];

        let info = analyze_workspace_details(&crates);
        let cycles = dependency_cycles(&info);
        assert!(cycles.is_empty());
    }

    #[test]
    fn where_clause_dependency() {
        let src_a = "pub trait Foo {}";
        let src_b = r#"
            use crate_a::Foo;
            pub fn bar<T>(_: T)
            where
                T: Foo,
            {}
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);
    }

    #[test]
    fn macro_method_generic_dependency() {
        let src_a = "pub struct A<T, E>(T, std::marker::PhantomData<E>);";
        let src_b = r#"
            use crate_a::A;

            pub struct B(A<u8, u8>);

            macro_rules! impl_invoke {
                ($that:expr, $req:expr) => {
                    $that.invoke($req)
                };
            }

            impl B {
                fn invoke(&self, _req: ()) -> () {
                    ()
                }
            }

            fn get_foo(b: &B, req: ()) -> () {
                impl_invoke!(b, req)
            }
        "#;

        let file_a: syn::File = syn::parse_str(src_a).unwrap();
        let file_b: syn::File = syn::parse_str(src_b).unwrap();

        let crates = vec![
            ("crate_a".to_string(), vec![file_a.clone()]),
            ("crate_b".to_string(), vec![file_b.clone()]),
        ];

        let info = analyze_workspace_details(&crates);
        let a_info = info.get("crate_a").unwrap();
        let b_info = info.get("crate_b").unwrap();

        assert_eq!(b_info.metrics.ce, 1);
        assert_eq!(a_info.metrics.ca, 1);
    }
}