fallow_engine/health/

hotspots.rs

#![allow(
    clippy::print_stderr,
    reason = "human stderr notes (no-git, bot patterns, CODEOWNERS) preserved verbatim from the CLI health path"
)]

use fallow_output::{ClockProvenance, ClockSource, FileHealthScore, HotspotEntry, HotspotSummary};

use super::HealthOptions;
use super::ownership::{OwnershipContext, compile_bot_globs, compute_ownership};

/// Detect test/mock path conventions. Kept as a simple substring scan
/// against forward-slash normalized paths so it works uniformly on the
/// relative paths we use for display.
fn is_test_path(relative: &std::path::Path) -> bool {
    let s = relative.to_string_lossy().replace('\\', "/");
    s.contains("/__tests__/")
        || s.contains("/__mocks__/")
        || s.contains("/test/")
        || s.contains("/tests/")
        || s.contains(".test.")
        || s.contains(".spec.")
}

/// Result of fetching churn data, including cache hit/miss info and timing.
pub struct ChurnFetchResult {
    pub result: crate::churn::ChurnResult,
    pub since: crate::churn::SinceDuration,
    pub cache_hit: bool,
    pub git_log_ms: f64,
}

/// Focused inputs for target-level churn evidence.
///
/// This reuses the health hotspot churn cache without running project parsing,
/// file scoring, or any other health section.
pub struct TargetChurnOptions<'a> {
    /// Project root containing the git repository.
    pub root: &'a std::path::Path,
    /// Normalized project-relative path of the file to fetch churn for.
    pub target: &'a std::path::Path,
    /// Directory holding the shared hotspot churn cache.
    pub cache_dir: std::path::PathBuf,
    /// Bypass the churn cache and re-run `git log`.
    pub no_cache: bool,
    /// Churn lookback window (`90d`, `6m`, `1y`, or an ISO date); `None` uses
    /// the default window.
    pub since: Option<&'a str>,
    /// Minimum commit count for the target to qualify as churn evidence.
    pub min_commits: Option<u32>,
}

/// Qualifying target-level churn returned by the focused health API.
#[derive(Debug)]
pub struct TargetChurnEvidence {
    /// Per-file churn metrics from git history.
    pub file: crate::churn::FileChurn,
    /// The lookback window the churn was measured over.
    pub since: crate::churn::SinceDuration,
    /// The commit-count threshold the target met to qualify.
    pub min_commits: u32,
    /// True when the repository is a shallow clone, so churn counts may
    /// undercount actual history.
    pub shallow_clone: bool,
}

/// Result states that do not represent a churn-analysis failure.
#[derive(Debug)]
pub enum TargetChurnOutcome {
    /// The target met the churn threshold; evidence is attached.
    Found(TargetChurnEvidence),
    /// The target was analyzed but did not meet the commit threshold.
    NoQualifyingChurn {
        /// Commits observed for the target, when it appeared in history.
        observed_commits: Option<u32>,
        /// The lookback window the churn was measured over.
        since: crate::churn::SinceDuration,
        /// The commit-count threshold that was not met.
        min_commits: u32,
        /// True when the repository is a shallow clone, so churn counts may
        /// undercount actual history.
        shallow_clone: bool,
    },
    /// Churn could not be measured at all (for example: not a git repository).
    Unavailable {
        /// Human-readable reason churn analysis was unavailable.
        message: String,
    },
}

/// Analyze git churn for one normalized project-relative target.
///
/// The call is intentionally independent of the full health pipeline. Missing
/// git is an explicit unavailable outcome, while a failed git analysis remains
/// an error so callers can preserve partial-evidence warnings.
pub fn analyze_target_churn(
    options: &TargetChurnOptions<'_>,
) -> Result<TargetChurnOutcome, String> {
    analyze_target_churn_with(
        options,
        crate::churn::is_git_repo,
        crate::churn::analyze_churn_cached,
    )
}

fn analyze_target_churn_with<GitAvailable, Analyze>(
    options: &TargetChurnOptions<'_>,
    git_available: GitAvailable,
    analyze: Analyze,
) -> Result<TargetChurnOutcome, String>
where
    GitAvailable: FnOnce(&std::path::Path) -> bool,
    Analyze: FnOnce(
        &std::path::Path,
        &crate::churn::SinceDuration,
        &std::path::Path,
        bool,
    ) -> Option<(crate::churn::ChurnResult, bool)>,
{
    if !git_available(options.root) {
        return Ok(TargetChurnOutcome::Unavailable {
            message: "git repository unavailable at project root".to_string(),
        });
    }

    let since = crate::churn::parse_since(options.since.unwrap_or("6m"))?;
    let min_commits = options.min_commits.unwrap_or(3);
    let Some((result, _cache_hit)) =
        analyze(options.root, &since, &options.cache_dir, options.no_cache)
    else {
        return Err("git churn analysis failed".to_string());
    };
    let shallow_clone = result.shallow_clone;
    let target = options.root.join(options.target);
    let file = result.files.get(&target).cloned();

    let observed_commits = file.as_ref().map(|file| file.commits);
    if let Some(file) = file
        && file.commits >= min_commits
    {
        return Ok(TargetChurnOutcome::Found(TargetChurnEvidence {
            file,
            since,
            min_commits,
            shallow_clone,
        }));
    }

    Ok(TargetChurnOutcome::NoQualifyingChurn {
        observed_commits,
        since,
        min_commits,
        shallow_clone,
    })
}

/// Validate git prerequisites and return churn data for hotspot analysis.
///
/// Uses disk cache when available. Returns `None` if the repo is missing,
/// `--since` is malformed, or git analysis fails. A missing git repo is treated
/// as unavailable data rather than a hard error so combined-mode `--format
/// json` never emits a second JSON document alongside the combined report
/// (#294); a non-fatal note goes to stderr unless `--quiet` is set.
pub(super) fn fetch_churn_data(
    opts: &HealthOptions<'_>,
    cache_dir: &std::path::Path,
) -> Option<ChurnFetchResult> {
    // `--churn-file` imports change history from a normalized JSON file and
    // bypasses git entirely, so projects on a non-git VCS (Yandex Arc,
    // Mercurial, Perforce) still get hotspots / ownership. The file is
    // authoritative for the analysis window, so `--since` is NOT applied to
    // imported events; it would only mislabel the header, hence `imported_since`.
    if let Some(churn_file) = opts.churn_file {
        let resolved =
            crate::health::scoring::resolve_relative_to_root(churn_file, Some(opts.root));
        let t = std::time::Instant::now();
        let result = match crate::churn::analyze_churn_from_file(&resolved, opts.root) {
            Ok(r) => r,
            Err(e) => {
                // The up-front `health::validate_churn_file` gate already
                // emitted this error and aborted with exit 2 for a malformed
                // file, so reaching here means the file changed between the
                // gate and this re-read (a TOCTOU race). Skip silently rather
                // than emit a SECOND error document, which would break the
                // single-document `--format json` contract (#294).
                tracing::warn!("churn file became unreadable after validation: {e}");
                // The diagnostic is the channel a `--quiet --format json`
                // consumer has, and a silent skip there reports the hotspot
                // sections as zero rather than as unmeasured (issue #2734).
                super::diagnostics::record_health_diagnostic(
                    opts.root,
                    Some(&resolved),
                    fallow_types::workspace::WorkspaceDiagnosticKind::HotspotsSkipped {
                        cause: "churn-file-unreadable".to_owned(),
                    },
                );
                return None;
            }
        };
        return Some(ChurnFetchResult {
            result,
            since: imported_since(),
            cache_hit: false,
            git_log_ms: t.elapsed().as_secs_f64() * 1000.0,
        });
    }

    if !crate::churn::is_git_repo(opts.root) {
        if !opts.quiet {
            eprintln!("note: hotspot analysis skipped: no git repository found at project root");
        }
        // Outside the quiet guard: the note is for a human, the diagnostic is
        // for the consumer that runs fallow with `--quiet` (issue #2689).
        super::diagnostics::record_health_diagnostic(
            opts.root,
            None,
            fallow_types::workspace::WorkspaceDiagnosticKind::HotspotsSkipped {
                cause: "not-a-repository".to_owned(),
            },
        );
        return None;
    }

    let since_input = opts.since.unwrap_or("6m");
    if let Err(e) = crate::validate::validate_no_control_chars(since_input, "--since") {
        // A malformed `--since` degrades to "no churn, continue" like the
        // missing-git-repo branch above: route the error text to `tracing` and
        // emit NO second JSON document, preserving the single-document
        // `--format json` contract (#294). The diagnostic carries the cause, so
        // a consumer that never sees stderr still reads the hotspot sections as
        // unmeasured rather than as zero (issue #2734).
        tracing::warn!("hotspot analysis skipped: {e}");
        record_invalid_since(opts.root);
        return None;
    }
    let since = match crate::churn::parse_since(since_input) {
        Ok(s) => s,
        Err(e) => {
            tracing::warn!("hotspot analysis skipped: invalid --since: {e}");
            record_invalid_since(opts.root);
            return None;
        }
    };

    let t = std::time::Instant::now();
    let (churn_result, cache_hit) =
        crate::churn::analyze_churn_cached(opts.root, &since, cache_dir, opts.no_cache)?;
    let git_log_ms = t.elapsed().as_secs_f64() * 1000.0;

    Some(ChurnFetchResult {
        result: churn_result,
        since,
        cache_hit,
        git_log_ms,
    })
}

/// Record the two `--since` failures as one diagnostic.
///
/// Rejected-as-input and failed-to-parse are one fact to the reader of a report:
/// the window they asked for was not read, so the hotspot sections measured
/// nothing. The error text that distinguishes them stays on the `tracing` line
/// where it was already written.
fn record_invalid_since(root: &std::path::Path) {
    super::diagnostics::record_health_diagnostic(
        root,
        None,
        fallow_types::workspace::WorkspaceDiagnosticKind::HotspotsSkipped {
            cause: "invalid-since".to_owned(),
        },
    );
}

/// Header label for imported churn (`--churn-file`). The imported window is
/// whatever the wrapper exported, so reusing the `--since` duration ("since 6
/// months") would misdescribe it, and no cutoff is applied on the import path.
fn imported_since() -> crate::churn::SinceDuration {
    crate::churn::SinceDuration {
        window: crate::churn::ChurnWindow::Imported,
        display: "imported churn".to_string(),
    }
}

/// Find the maximum weighted-commits and complexity-density across eligible files.
///
/// Used to normalize hotspot scores into the 0-100 range.
fn compute_normalization_maxima(
    file_scores: &[FileHealthScore],
    churn_files: &rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn>,
    min_commits: u32,
) -> (f64, f64) {
    let mut max_weighted: f64 = 0.0;
    let mut max_density: f64 = 0.0;
    for score in file_scores {
        if let Some(churn) = churn_files.get(&score.path)
            && churn.commits >= min_commits
        {
            max_weighted = max_weighted.max(churn.weighted_commits);
            max_density = max_density.max(score.complexity_density);
        }
    }
    (max_weighted, max_density)
}

/// Check whether a file should be excluded from hotspot results
/// based on workspace filter and ignore patterns.
fn is_excluded_from_hotspots(
    path: &std::path::Path,
    root: &std::path::Path,
    ignore_set: &globset::GlobSet,
    ws_roots: Option<&[std::path::PathBuf]>,
) -> bool {
    if let Some(ws) = ws_roots
        && !ws.iter().any(|r| path.starts_with(r))
    {
        return true;
    }
    if !ignore_set.is_empty() {
        let relative = path.strip_prefix(root).unwrap_or(path);
        if ignore_set.is_match(relative) {
            return true;
        }
    }
    false
}

/// Compute a normalized hotspot score from churn and complexity data.
///
/// Both inputs are normalized against their respective maxima so the result
/// falls in the 0-100 range (rounded to one decimal).
fn compute_hotspot_score(
    weighted_commits: f64,
    max_weighted: f64,
    complexity_density: f64,
    max_density: f64,
) -> f64 {
    let norm_churn = if max_weighted > 0.0 {
        weighted_commits / max_weighted
    } else {
        0.0
    };
    let norm_complexity = if max_density > 0.0 {
        complexity_density / max_density
    } else {
        0.0
    };
    (norm_churn * norm_complexity * 100.0 * 10.0).round() / 10.0
}

pub(super) struct HotspotComputationInput<'a> {
    pub(super) opts: &'a HealthOptions<'a>,
    pub(super) config: &'a fallow_config::ResolvedConfig,
    pub(super) file_scores: &'a [FileHealthScore],
    pub(super) ignore_set: &'a globset::GlobSet,
    pub(super) ws_roots: Option<&'a [std::path::PathBuf]>,
    pub(super) churn_fetch: ChurnFetchResult,
}

/// Compute hotspot entries by combining pre-fetched churn data with file health scores.
pub(super) fn compute_hotspots(
    input: HotspotComputationInput<'_>,
) -> (Vec<HotspotEntry>, Option<HotspotSummary>) {
    let HotspotComputationInput {
        opts,
        config,
        file_scores,
        ignore_set,
        ws_roots,
        churn_fetch,
    } = input;
    let churn_result = churn_fetch.result;
    let since = churn_fetch.since;

    let shallow_clone = churn_result.shallow_clone;
    warn_shallow_clone(opts, shallow_clone);
    warn_unpinned_clock(opts, churn_result.clock);

    let min_commits = opts.min_commits.unwrap_or(3);
    let (max_weighted, max_density) =
        compute_normalization_maxima(file_scores, &churn_result.files, min_commits);

    let ownership_cfg = &config.health.ownership;
    let bot_globs_owned = load_ownership_bot_globs(opts, ownership_cfg);
    let codeowners_owned = load_ownership_codeowners(opts, &config.root);
    // Staleness is measured against the run clock, not the system clock, so
    // `stale_days` and the thresholds it feeds (owner-active, drift minimum
    // file age) do not flip between two runs over the same commit.
    let now_secs = churn_result.clock.epoch_secs();
    let ownership_ctx = bot_globs_owned.as_ref().map(|bot_globs| OwnershipContext {
        author_pool: &churn_result.author_pool,
        bot_globs,
        codeowners: codeowners_owned.as_ref(),
        email_mode: opts.ownership_emails.unwrap_or(ownership_cfg.email_mode),
        now_secs,
    });

    let (mut hotspot_entries, files_excluded) = collect_hotspot_entries(&HotspotEntryCtx {
        file_scores,
        root: &config.root,
        ignore_set,
        ws_roots,
        churn_files: &churn_result.files,
        min_commits,
        max_weighted,
        max_density,
        ownership_ctx: ownership_ctx.as_ref(),
    });

    hotspot_entries.sort_by(|a, b| {
        b.score
            .partial_cmp(&a.score)
            .unwrap_or(std::cmp::Ordering::Equal)
    });

    let files_analyzed = hotspot_entries.len();
    let summary = HotspotSummary {
        since: since.display,
        min_commits,
        files_analyzed,
        files_excluded,
        shallow_clone,
        clock: Some(clock_provenance(churn_result.clock)),
    };

    if let Some(top) = opts.top {
        hotspot_entries.truncate(top);
    }

    (hotspot_entries, Some(summary))
}

/// Describe the run clock on the wire, so a JSON consumer can tell a
/// reproducible churn number from a drifting one.
///
/// [`warn_unpinned_clock`] says the same thing on stderr, where `--quiet`
/// removes it and a machine consumer never sees it at all.
fn clock_provenance(clock: crate::clock::AnalysisClock) -> ClockProvenance {
    ClockProvenance {
        source: match clock.source() {
            crate::clock::AnalysisClockSource::Environment => ClockSource::Environment,
            crate::clock::AnalysisClockSource::HeadCommit => ClockSource::HeadCommit,
            crate::clock::AnalysisClockSource::WallClock => ClockSource::WallClock,
        },
        epoch_secs: clock.epoch_secs(),
        reproducible: clock.is_reproducible(),
    }
}

/// Warn when churn numbers were measured against the wall clock.
///
/// The run clock normally comes from HEAD's committer timestamp, which makes
/// recency weighting and `stale_days` reproducible for one commit. `git log`
/// churn cannot reach this warning: if HEAD has no readable timestamp there is
/// no git history to analyze either. Imported churn (`--churn-file`) can, and
/// is the point of the warning, since it exists for projects whose history
/// lives in a non-git VCS.
fn warn_unpinned_clock(opts: &HealthOptions<'_>, clock: crate::clock::AnalysisClock) {
    if clock.is_reproducible() {
        return;
    }
    if !opts.quiet {
        eprintln!(
            "Warning: no commit timestamp available, so churn recency and \
             ownership staleness were measured against the wall clock and will \
             drift between runs. Set FALLOW_CLOCK_EPOCH to pin them."
        );
    }
    super::diagnostics::record_health_diagnostic(
        opts.root,
        None,
        fallow_types::workspace::WorkspaceDiagnosticKind::UnpinnedClock,
    );
}

/// Emit shallow-clone warnings (and the ownership-skew note) when relevant.
fn warn_shallow_clone(opts: &HealthOptions<'_>, shallow_clone: bool) {
    if !shallow_clone {
        return;
    }
    if !opts.quiet {
        eprintln!(
            "Warning: shallow clone detected. Hotspot analysis may be incomplete. \
             Use `git fetch --unshallow` for full history."
        );
        if opts.ownership {
            eprintln!(
                "Warning: shallow clones inflate single-author dominance, so \
                 ownership signals will be skewed."
            );
        }
    }
    super::diagnostics::record_health_diagnostic(
        opts.root,
        None,
        fallow_types::workspace::WorkspaceDiagnosticKind::ShallowClone {
            ownership_requested: opts.ownership,
        },
    );
}

/// Compile the bot-author glob set for ownership analysis, warning on a bad pattern.
fn load_ownership_bot_globs(
    opts: &HealthOptions<'_>,
    ownership_cfg: &fallow_config::OwnershipConfig,
) -> Option<globset::GlobSet> {
    opts.ownership.then(|| {
        compile_bot_globs(&ownership_cfg.bot_patterns).unwrap_or_else(|e| {
            if !opts.quiet {
                eprintln!("Warning: invalid bot pattern in health.ownership.botPatterns: {e}");
            }
            super::diagnostics::record_health_diagnostic(
                opts.root,
                None,
                fallow_types::workspace::WorkspaceDiagnosticKind::OwnershipUnavailable {
                    cause: "invalid-bot-pattern".to_owned(),
                    error: e.to_string(),
                },
            );
            globset::GlobSet::empty()
        })
    })
}

/// Load CODEOWNERS for ownership analysis, warning on a real parse error only.
fn load_ownership_codeowners(
    opts: &HealthOptions<'_>,
    root: &std::path::Path,
) -> Option<crate::codeowners::CodeOwners> {
    opts.ownership
        .then(|| match crate::codeowners::CodeOwners::load(root, None) {
            Ok(co) => Some(co),
            Err(e) => {
                // A project with no CODEOWNERS at all never asked for declared
                // owners, so it is not a degraded input and gets neither the
                // note nor the diagnostic.
                if !e.contains("no CODEOWNERS file found") {
                    if !opts.quiet {
                        eprintln!("Warning: failed to parse CODEOWNERS: {e}");
                    }
                    super::diagnostics::record_health_diagnostic(
                        root,
                        None,
                        fallow_types::workspace::WorkspaceDiagnosticKind::OwnershipUnavailable {
                            cause: "codeowners-parse-failed".to_owned(),
                            error: e,
                        },
                    );
                }
                None
            }
        })
        .flatten()
}

/// Read-only inputs for the per-file hotspot-entry loop.
struct HotspotEntryCtx<'a> {
    file_scores: &'a [FileHealthScore],
    root: &'a std::path::Path,
    ignore_set: &'a globset::GlobSet,
    ws_roots: Option<&'a [std::path::PathBuf]>,
    churn_files: &'a rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn>,
    min_commits: u32,
    max_weighted: f64,
    max_density: f64,
    ownership_ctx: Option<&'a OwnershipContext<'a>>,
}

/// Build hotspot entries for eligible files; returns the entries plus the count
/// of files excluded for not meeting the minimum-commits threshold.
fn collect_hotspot_entries(ctx: &HotspotEntryCtx<'_>) -> (Vec<HotspotEntry>, usize) {
    let mut hotspot_entries = Vec::new();
    let mut files_excluded: usize = 0;

    for score in ctx.file_scores {
        if is_excluded_from_hotspots(&score.path, ctx.root, ctx.ignore_set, ctx.ws_roots) {
            continue;
        }

        let Some(churn) = ctx.churn_files.get(&score.path) else {
            continue;
        };
        if churn.commits < ctx.min_commits {
            files_excluded += 1;
            continue;
        }

        let relative = score.path.strip_prefix(ctx.root).unwrap_or(&score.path);
        let ownership = ctx
            .ownership_ctx
            .and_then(|own| compute_ownership(churn, relative, own));

        hotspot_entries.push(HotspotEntry {
            path: score.path.clone(),
            score: compute_hotspot_score(
                churn.weighted_commits,
                ctx.max_weighted,
                score.complexity_density,
                ctx.max_density,
            ),
            commits: churn.commits,
            weighted_commits: churn.weighted_commits,
            lines_added: churn.lines_added,
            lines_deleted: churn.lines_deleted,
            complexity_density: score.complexity_density,
            fan_in: score.fan_in,
            trend: churn.trend,
            ownership,
            is_test_path: is_test_path(relative),
        });
    }

    (hotspot_entries, files_excluded)
}

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

    fn target_churn_options(root: &std::path::Path) -> TargetChurnOptions<'_> {
        TargetChurnOptions {
            root,
            target: std::path::Path::new("src/app.ts"),
            cache_dir: root.join(".fallow"),
            no_cache: true,
            since: None,
            min_commits: None,
        }
    }

    fn churn_result(root: &std::path::Path, commits: u32) -> crate::churn::ChurnResult {
        let path = root.join("src/app.ts");
        let mut files = rustc_hash::FxHashMap::default();
        files.insert(
            path.clone(),
            crate::churn::FileChurn {
                path,
                commits,
                weighted_commits: 2.5,
                lines_added: 20,
                lines_deleted: 5,
                trend: crate::churn::ChurnTrend::Accelerating,
                authors: rustc_hash::FxHashMap::default(),
            },
        );
        crate::churn::ChurnResult {
            files,
            shallow_clone: false,
            author_pool: Vec::new(),
            clock: crate::clock::AnalysisClock::pinned(1_788_782_400),
        }
    }

    #[test]
    fn target_churn_returns_only_the_requested_qualifying_file() {
        let root = std::path::Path::new("/project");
        let options = target_churn_options(root);

        let outcome = analyze_target_churn_with(
            &options,
            |_| true,
            |_, _, _, _| Some((churn_result(root, 4), false)),
        )
        .unwrap();

        let TargetChurnOutcome::Found(evidence) = outcome else {
            panic!("expected qualifying churn evidence");
        };
        assert_eq!(evidence.file.path, root.join("src/app.ts"));
        assert_eq!(evidence.file.commits, 4);
        assert_eq!(evidence.min_commits, 3);
        assert_eq!(evidence.since.display, "6 months");
    }

    #[test]
    fn target_churn_distinguishes_no_qualifying_history() {
        let root = std::path::Path::new("/project");
        let options = target_churn_options(root);

        let outcome = analyze_target_churn_with(
            &options,
            |_| true,
            |_, _, _, _| Some((churn_result(root, 2), false)),
        )
        .unwrap();

        assert!(matches!(
            outcome,
            TargetChurnOutcome::NoQualifyingChurn {
                observed_commits: Some(2),
                min_commits: 3,
                ..
            }
        ));
    }

    #[test]
    fn target_churn_distinguishes_git_unavailable() {
        let root = std::path::Path::new("/project");
        let options = target_churn_options(root);

        let outcome = analyze_target_churn_with(
            &options,
            |_| false,
            |_, _, _, _| panic!("churn analysis must not run without git"),
        )
        .unwrap();

        assert!(matches!(outcome, TargetChurnOutcome::Unavailable { .. }));
    }

    #[test]
    fn target_churn_surfaces_analysis_failure() {
        let root = std::path::Path::new("/project");
        let options = target_churn_options(root);

        let error = analyze_target_churn_with(&options, |_| true, |_, _, _, _| None)
            .expect_err("failed git analysis must remain explicit");

        assert!(error.contains("git churn analysis failed"));
    }

    #[test]
    fn hotspot_score_both_maxima_zero() {
        assert!((compute_hotspot_score(0.0, 0.0, 0.0, 0.0)).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_max_weighted_zero() {
        assert!((compute_hotspot_score(5.0, 0.0, 0.5, 1.0)).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_max_density_zero() {
        assert!((compute_hotspot_score(5.0, 10.0, 0.0, 0.0)).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_equal_normalization() {
        let score = compute_hotspot_score(10.0, 10.0, 2.0, 2.0);
        assert!((score - 100.0).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_half_values() {
        let score = compute_hotspot_score(5.0, 10.0, 1.0, 2.0);
        assert!((score - 25.0).abs() < f64::EPSILON);
    }

    #[test]
    fn excluded_no_filters() {
        let path = std::path::Path::new("/project/src/foo.ts");
        let root = std::path::Path::new("/project");
        let ignore_set = globset::GlobSet::empty();

        assert!(!is_excluded_from_hotspots(path, root, &ignore_set, None));
    }

    #[test]
    fn excluded_workspace_filter_mismatch() {
        let path = std::path::Path::new("/project/packages/b/src/foo.ts");
        let root = std::path::Path::new("/project");
        let ws_roots = [std::path::PathBuf::from("/project/packages/a")];
        let ignore_set = globset::GlobSet::empty();

        assert!(is_excluded_from_hotspots(
            path,
            root,
            &ignore_set,
            Some(&ws_roots)
        ));
    }

    #[test]
    fn excluded_workspace_filter_match() {
        let path = std::path::Path::new("/project/packages/a/src/foo.ts");
        let root = std::path::Path::new("/project");
        let ws_roots = [std::path::PathBuf::from("/project/packages/a")];
        let ignore_set = globset::GlobSet::empty();

        assert!(!is_excluded_from_hotspots(
            path,
            root,
            &ignore_set,
            Some(&ws_roots)
        ));
    }

    #[test]
    fn excluded_matching_glob() {
        let path = std::path::Path::new("/project/src/generated/types.ts");
        let root = std::path::Path::new("/project");
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("src/generated/**").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(is_excluded_from_hotspots(path, root, &ignore_set, None));
    }

    #[test]
    fn excluded_non_matching_glob() {
        let path = std::path::Path::new("/project/src/components/Button.tsx");
        let root = std::path::Path::new("/project");
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("src/generated/**").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(!is_excluded_from_hotspots(path, root, &ignore_set, None));
    }

    #[test]
    fn normalization_maxima_empty_input() {
        let scores: Vec<FileHealthScore> = vec![];
        let churn_files = rustc_hash::FxHashMap::default();

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 3);
        assert!((max_w).abs() < f64::EPSILON);
        assert!((max_d).abs() < f64::EPSILON);
    }

    #[test]
    fn normalization_maxima_single_file() {
        let scores = vec![FileHealthScore {
            path: std::path::PathBuf::from("/src/foo.ts"),
            fan_in: 0,
            fan_out: 0,
            dead_code_ratio: 0.0,
            complexity_density: 0.75,
            maintainability_index: 80.0,
            total_cyclomatic: 15,
            total_cognitive: 10,
            function_count: 3,
            lines: 20,
            crap_max: 0.0,
            crap_above_threshold: 0,
            crap_exempted: 0,
            crap_effective_threshold: None,
        }];
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/foo.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/foo.ts"),
                commits: 5,
                weighted_commits: 4.2,
                lines_added: 100,
                lines_deleted: 20,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 3);
        assert!((max_w - 4.2).abs() < f64::EPSILON);
        assert!((max_d - 0.75).abs() < f64::EPSILON);
    }

    /// Hotspot ranking is churn times complexity density and consults no CRAP
    /// thresholds, so an exemption that clears the risk tag and the coverage
    /// target must leave hotspot inputs untouched (issue #2228).
    #[test]
    fn normalization_maxima_ignore_crap_exemption_fields() {
        let base = FileHealthScore {
            path: std::path::PathBuf::from("/src/foo.ts"),
            fan_in: 0,
            fan_out: 0,
            dead_code_ratio: 0.0,
            complexity_density: 0.75,
            maintainability_index: 80.0,
            total_cyclomatic: 15,
            total_cognitive: 10,
            function_count: 3,
            lines: 20,
            crap_max: 110.0,
            crap_above_threshold: 2,
            crap_exempted: 0,
            crap_effective_threshold: None,
        };
        let exempt = FileHealthScore {
            crap_above_threshold: 0,
            crap_exempted: 2,
            crap_effective_threshold: Some(500.0),
            ..base.clone()
        };
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/foo.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/foo.ts"),
                commits: 5,
                weighted_commits: 4.2,
                lines_added: 100,
                lines_deleted: 20,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let flagged = compute_normalization_maxima(&[base], &churn_files, 3);
        let exempted = compute_normalization_maxima(&[exempt], &churn_files, 3);
        assert_eq!(flagged, exempted);
    }

    #[test]
    fn normalization_maxima_below_min_commits() {
        let scores = vec![FileHealthScore {
            path: std::path::PathBuf::from("/src/foo.ts"),
            fan_in: 0,
            fan_out: 0,
            dead_code_ratio: 0.0,
            complexity_density: 0.75,
            maintainability_index: 80.0,
            total_cyclomatic: 15,
            total_cognitive: 10,
            function_count: 3,
            lines: 20,
            crap_max: 0.0,
            crap_above_threshold: 0,
            crap_exempted: 0,
            crap_effective_threshold: None,
        }];
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/foo.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/foo.ts"),
                commits: 2, // below min_commits=3
                weighted_commits: 4.2,
                lines_added: 100,
                lines_deleted: 20,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 3);
        assert!((max_w).abs() < f64::EPSILON);
        assert!((max_d).abs() < f64::EPSILON);
    }

    #[test]
    fn normalization_maxima_all_zeros() {
        let scores = vec![FileHealthScore {
            path: std::path::PathBuf::from("/src/foo.ts"),
            fan_in: 0,
            fan_out: 0,
            dead_code_ratio: 0.0,
            complexity_density: 0.0,
            maintainability_index: 100.0,
            total_cyclomatic: 0,
            total_cognitive: 0,
            function_count: 1,
            lines: 10,
            crap_max: 0.0,
            crap_above_threshold: 0,
            crap_exempted: 0,
            crap_effective_threshold: None,
        }];
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/foo.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/foo.ts"),
                commits: 5,
                weighted_commits: 0.0,
                lines_added: 0,
                lines_deleted: 0,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 3);
        assert!((max_w).abs() < f64::EPSILON);
        assert!((max_d).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_high_churn_low_complexity() {
        let score = compute_hotspot_score(10.0, 10.0, 0.1, 1.0);
        assert!((score - 10.0).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_low_churn_high_complexity() {
        let score = compute_hotspot_score(1.0, 10.0, 2.0, 2.0);
        assert!((score - 10.0).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_rounding() {
        let score = compute_hotspot_score(1.0, 3.0, 1.0, 3.0);
        assert!((score - 11.1).abs() < f64::EPSILON);
    }

    #[test]
    fn hotspot_score_very_small_values() {
        let score = compute_hotspot_score(0.01, 100.0, 0.001, 10.0);
        assert!((score).abs() < 0.1);
    }

    #[test]
    fn hotspot_score_weighted_exceeds_max() {
        let score = compute_hotspot_score(15.0, 10.0, 1.0, 2.0);
        assert!((score - 75.0).abs() < f64::EPSILON);
    }

    #[test]
    fn normalization_maxima_multiple_files_picks_max() {
        let scores = vec![
            FileHealthScore {
                path: std::path::PathBuf::from("/src/a.ts"),
                fan_in: 0,
                fan_out: 0,
                dead_code_ratio: 0.0,
                complexity_density: 0.5,
                maintainability_index: 80.0,
                total_cyclomatic: 10,
                total_cognitive: 5,
                function_count: 2,
                lines: 50,
                crap_max: 0.0,
                crap_above_threshold: 0,
                crap_exempted: 0,
                crap_effective_threshold: None,
            },
            FileHealthScore {
                path: std::path::PathBuf::from("/src/b.ts"),
                fan_in: 0,
                fan_out: 0,
                dead_code_ratio: 0.0,
                complexity_density: 1.2, // highest density
                maintainability_index: 60.0,
                total_cyclomatic: 30,
                total_cognitive: 20,
                function_count: 5,
                lines: 100,
                crap_max: 0.0,
                crap_above_threshold: 0,
                crap_exempted: 0,
                crap_effective_threshold: None,
            },
            FileHealthScore {
                path: std::path::PathBuf::from("/src/c.ts"),
                fan_in: 0,
                fan_out: 0,
                dead_code_ratio: 0.0,
                complexity_density: 0.8,
                maintainability_index: 70.0,
                total_cyclomatic: 20,
                total_cognitive: 15,
                function_count: 4,
                lines: 80,
                crap_max: 0.0,
                crap_above_threshold: 0,
                crap_exempted: 0,
                crap_effective_threshold: None,
            },
        ];
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/a.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/a.ts"),
                commits: 5,
                weighted_commits: 3.0,
                lines_added: 50,
                lines_deleted: 10,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );
        churn_files.insert(
            std::path::PathBuf::from("/src/b.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/b.ts"),
                commits: 10,
                weighted_commits: 8.5, // highest weighted
                lines_added: 200,
                lines_deleted: 50,
                trend: crate::churn::ChurnTrend::Accelerating,
                authors: rustc_hash::FxHashMap::default(),
            },
        );
        churn_files.insert(
            std::path::PathBuf::from("/src/c.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/c.ts"),
                commits: 7,
                weighted_commits: 5.0,
                lines_added: 100,
                lines_deleted: 30,
                trend: crate::churn::ChurnTrend::Cooling,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 3);
        assert!((max_w - 8.5).abs() < f64::EPSILON);
        assert!((max_d - 1.2).abs() < f64::EPSILON);
    }

    #[test]
    fn normalization_maxima_mixed_above_and_below_threshold() {
        let scores = vec![
            FileHealthScore {
                path: std::path::PathBuf::from("/src/frequent.ts"),
                fan_in: 0,
                fan_out: 0,
                dead_code_ratio: 0.0,
                complexity_density: 0.4,
                maintainability_index: 85.0,
                total_cyclomatic: 8,
                total_cognitive: 4,
                function_count: 2,
                lines: 40,
                crap_max: 0.0,
                crap_above_threshold: 0,
                crap_exempted: 0,
                crap_effective_threshold: None,
            },
            FileHealthScore {
                path: std::path::PathBuf::from("/src/rare.ts"),
                fan_in: 0,
                fan_out: 0,
                dead_code_ratio: 0.0,
                complexity_density: 2.0, // higher but excluded
                maintainability_index: 50.0,
                total_cyclomatic: 40,
                total_cognitive: 30,
                function_count: 8,
                lines: 200,
                crap_max: 0.0,
                crap_above_threshold: 0,
                crap_exempted: 0,
                crap_effective_threshold: None,
            },
        ];
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/frequent.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/frequent.ts"),
                commits: 10,
                weighted_commits: 7.0,
                lines_added: 150,
                lines_deleted: 40,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );
        churn_files.insert(
            std::path::PathBuf::from("/src/rare.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/rare.ts"),
                commits: 1, // below min_commits=5
                weighted_commits: 0.9,
                lines_added: 10,
                lines_deleted: 2,
                trend: crate::churn::ChurnTrend::Cooling,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 5);
        assert!((max_w - 7.0).abs() < f64::EPSILON);
        assert!((max_d - 0.4).abs() < f64::EPSILON);
    }

    #[test]
    fn normalization_maxima_file_score_without_churn() {
        let scores = vec![FileHealthScore {
            path: std::path::PathBuf::from("/src/no_churn.ts"),
            fan_in: 0,
            fan_out: 0,
            dead_code_ratio: 0.0,
            complexity_density: 5.0,
            maintainability_index: 30.0,
            total_cyclomatic: 100,
            total_cognitive: 80,
            function_count: 20,
            lines: 500,
            crap_max: 0.0,
            crap_above_threshold: 0,
            crap_exempted: 0,
            crap_effective_threshold: None,
        }];
        let churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 1);
        assert!((max_w).abs() < f64::EPSILON);
        assert!((max_d).abs() < f64::EPSILON);
    }

    #[test]
    fn normalization_maxima_min_commits_zero() {
        let scores = vec![FileHealthScore {
            path: std::path::PathBuf::from("/src/foo.ts"),
            fan_in: 0,
            fan_out: 0,
            dead_code_ratio: 0.0,
            complexity_density: 0.3,
            maintainability_index: 90.0,
            total_cyclomatic: 3,
            total_cognitive: 2,
            function_count: 1,
            lines: 10,
            crap_max: 0.0,
            crap_above_threshold: 0,
            crap_exempted: 0,
            crap_effective_threshold: None,
        }];
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/foo.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/foo.ts"),
                commits: 0,
                weighted_commits: 0.0,
                lines_added: 0,
                lines_deleted: 0,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 0);
        assert!((max_w).abs() < f64::EPSILON);
        assert!((max_d - 0.3).abs() < f64::EPSILON);
    }

    #[test]
    fn normalization_maxima_exactly_at_threshold() {
        let scores = vec![FileHealthScore {
            path: std::path::PathBuf::from("/src/foo.ts"),
            fan_in: 0,
            fan_out: 0,
            dead_code_ratio: 0.0,
            complexity_density: 1.5,
            maintainability_index: 65.0,
            total_cyclomatic: 25,
            total_cognitive: 18,
            function_count: 5,
            lines: 120,
            crap_max: 0.0,
            crap_above_threshold: 0,
            crap_exempted: 0,
            crap_effective_threshold: None,
        }];
        let mut churn_files: rustc_hash::FxHashMap<std::path::PathBuf, crate::churn::FileChurn> =
            rustc_hash::FxHashMap::default();
        churn_files.insert(
            std::path::PathBuf::from("/src/foo.ts"),
            crate::churn::FileChurn {
                path: std::path::PathBuf::from("/src/foo.ts"),
                commits: 3, // exactly at min_commits=3
                weighted_commits: 2.8,
                lines_added: 60,
                lines_deleted: 15,
                trend: crate::churn::ChurnTrend::Stable,
                authors: rustc_hash::FxHashMap::default(),
            },
        );

        let (max_w, max_d) = compute_normalization_maxima(&scores, &churn_files, 3);
        assert!((max_w - 2.8).abs() < f64::EPSILON);
        assert!((max_d - 1.5).abs() < f64::EPSILON);
    }

    #[test]
    fn excluded_workspace_and_glob_combined() {
        let path = std::path::Path::new("/project/packages/a/src/generated/types.ts");
        let root = std::path::Path::new("/project");
        let ws_roots = [std::path::PathBuf::from("/project/packages/a")];
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("**/generated/**").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(is_excluded_from_hotspots(
            path,
            root,
            &ignore_set,
            Some(&ws_roots)
        ));
    }

    #[test]
    fn excluded_workspace_match_but_glob_no_match() {
        let path = std::path::Path::new("/project/packages/a/src/index.ts");
        let root = std::path::Path::new("/project");
        let ws_roots = [std::path::PathBuf::from("/project/packages/a")];
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("**/generated/**").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(!is_excluded_from_hotspots(
            path,
            root,
            &ignore_set,
            Some(&ws_roots)
        ));
    }

    #[test]
    fn excluded_path_equals_root() {
        let path = std::path::Path::new("/project");
        let root = std::path::Path::new("/project");
        let ignore_set = globset::GlobSet::empty();

        assert!(!is_excluded_from_hotspots(path, root, &ignore_set, None));
    }

    #[test]
    fn excluded_path_outside_root() {
        let path = std::path::Path::new("/other/src/foo.ts");
        let root = std::path::Path::new("/project");
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("src/foo.ts").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(!is_excluded_from_hotspots(path, root, &ignore_set, None));
    }

    #[test]
    fn excluded_multiple_globs_first_matches() {
        let path = std::path::Path::new("/project/dist/bundle.js");
        let root = std::path::Path::new("/project");
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("dist/**").unwrap());
        builder.add(globset::Glob::new("node_modules/**").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(is_excluded_from_hotspots(path, root, &ignore_set, None));
    }

    #[test]
    fn excluded_multiple_globs_second_matches() {
        let path = std::path::Path::new("/project/node_modules/lodash/index.js");
        let root = std::path::Path::new("/project");
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("dist/**").unwrap());
        builder.add(globset::Glob::new("node_modules/**").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(is_excluded_from_hotspots(path, root, &ignore_set, None));
    }

    #[test]
    fn excluded_multiple_globs_none_matches() {
        let path = std::path::Path::new("/project/src/app.ts");
        let root = std::path::Path::new("/project");
        let mut builder = globset::GlobSetBuilder::new();
        builder.add(globset::Glob::new("dist/**").unwrap());
        builder.add(globset::Glob::new("node_modules/**").unwrap());
        let ignore_set = builder.build().unwrap();

        assert!(!is_excluded_from_hotspots(path, root, &ignore_set, None));
    }
}