oxios-kernel 1.5.1

//! Auto-meta detection: cheap heuristics on marker files (RFC-025 §Auto-Meta).
//!
//! Seeds [`MountMeta`](super::MountMeta) from filesystem markers, then the
//! agent refines it during enrichment. Detection runs at drift-detection time
//! (cheap `stat` + tiny reads), not on every message.

use std::path::Path;
use std::time::{Duration, UNIX_EPOCH};

use super::MountMeta;

/// Marker files that imply a language / stack. Checked against a Mount's
/// primary path.
const MARKERS: &[(&str, &str)] = &[
    ("Cargo.toml", "rust"),
    ("package.json", "typescript"),
    ("go.mod", "go"),
    ("pyproject.toml", "python"),
    ("requirements.txt", "python"),
    ("setup.py", "python"),
    ("pom.xml", "java"),
    ("build.gradle", "java"),
    ("build.gradle.kts", "kotlin"),
    ("Gemfile", "ruby"),
    ("composer.json", "php"),
    ("mix.exs", "elixir"),
    ("CMakeLists.txt", "cpp"),
    ("Makefile", "c"),
];

/// Docs/agent markers — recorded but don't imply a language.
const DOC_MARKERS: &[&str] = &[
    "AGENTS.md",
    "CLAUDE.md",
    ".cursorrules",
    "README.md",
    "GEMINI.md",
    ".windsurfrules",
];

/// Structure hints from top-level directories.
const STRUCTURE_HINTS: &[(&str, &str)] = &[
    ("crates", "cargo-workspace"),
    ("packages", "monorepo"),
    ("apps", "monorepo"),
    ("libs", "monorepo"),
];

/// Detect [`MountMeta`] from the filesystem at `path`.
///
/// This is a **draft** — the agent refines it during enrichment. We never make
/// an LLM call here; everything is cheap `stat`/`read` on small files.
pub fn detect_meta(path: &Path) -> MountMeta {
    let mut meta = MountMeta::default();

    let mut found_languages: Vec<String> = Vec::new();
    let mut found_markers: Vec<String> = Vec::new();

    // Language + stack markers.
    for (marker, lang) in MARKERS {
        let marker_path = path.join(marker);
        if marker_path.is_file() {
            if !found_languages.contains(&lang.to_string()) {
                found_languages.push(lang.to_string());
            }
            found_markers.push(marker.to_string());

            // Extract stack hints for well-known markers.
            extract_stack(marker, &marker_path, &mut meta.stack);
        }
    }

    // Doc / agent markers (no language, but recorded + seed summary).
    for marker in DOC_MARKERS {
        let marker_path = path.join(marker);
        if marker_path.is_file() {
            found_markers.push(marker.to_string());
            // AGENTS.md / README.md seed the summary (first paragraph).
            if (marker == &"AGENTS.md" || marker == &"README.md")
                && meta.summary.is_empty()
                && let Ok(content) = std::fs::read_to_string(&marker_path)
            {
                meta.summary = first_meaningful_line(&content);
            }
        }
    }

    // Structure hints.
    for (dir, hint) in STRUCTURE_HINTS {
        if path.join(dir).is_dir() && !meta.stack.contains(&hint.to_string()) {
            meta.stack.push(hint.to_string());
        }
    }

    meta.languages = found_languages;
    meta.markers = found_markers;

    // If no summary yet, derive one from languages.
    if meta.summary.is_empty() && !meta.languages.is_empty() {
        meta.summary = meta.languages.join(" + ");
    }

    meta
}

/// Compute the set of marker files to watch for drift, given a path.
///
/// Returns `(path, mtime)` pairs for existing markers — this is the snapshot
/// the drift detector compares against on the next session.
pub fn snapshot_markers(path: &Path) -> Vec<(std::path::PathBuf, std::time::SystemTime)> {
    let all: Vec<&str> = MARKERS
        .iter()
        .map(|(m, _)| *m)
        .chain(DOC_MARKERS.iter().copied())
        .collect();

    all.into_iter()
        .filter_map(|m| {
            let p = path.join(m);
            p.metadata()
                .and_then(|md| md.modified())
                .ok()
                // Truncate to whole seconds so the freshly-read mtime matches
                // the precision stored in the DB (u64 seconds). Without this,
                // drift would fire on every restart: the DB reconstructs a
                // whole-second SystemTime, but a fresh `stat()` yields
                // nanosecond precision.
                .map(|t| {
                    let truncated = t
                        .duration_since(UNIX_EPOCH)
                        .map(|d| UNIX_EPOCH + Duration::from_secs(d.as_secs()))
                        .unwrap_or(t);
                    (p, truncated)
                })
        })
        .collect()
}

/// Extract stack keywords from a marker file's contents.
///
/// Reads only the marker file (small), scans for dependency names. Keeps the
/// result bounded — at most ~8 entries.
fn extract_stack(marker: &str, path: &Path, stack: &mut Vec<String>) {
    let Ok(content) = std::fs::read_to_string(path) else {
        return;
    };
    let push = |stack: &mut Vec<String>, s: &str| {
        if s.len() >= 2 && !stack.iter().any(|e| e.eq_ignore_ascii_case(s)) {
            stack.push(s.to_string());
        }
    };

    match marker {
        "Cargo.toml" => {
            // Track the current TOML section so we only extract crate names
            // from dependency sections. Without this, fields from `[package]`
            // (name, edition, authors, license, …) leak into the stack.
            let mut current_section = String::new();
            let dep_sections = ["dependencies", "dev-dependencies", "build-dependencies"];

            for line in content.lines() {
                let trimmed = line.trim();
                // Track section headers like `[dependencies]` or
                // `[dependencies.serde]` (also `[workspace.dependencies]`).
                if trimmed.starts_with('[') && trimmed.ends_with(']') {
                    current_section = trimmed
                        .trim_start_matches('[')
                        .trim_end_matches(']')
                        .to_string();
                    // Dotted-table form: `[dependencies.serde]` or
                    // `[workspace.dependencies.serde]` — the trailing segment
                    // after the dependency-section name is the crate name.
                    if let Some(suffix) =
                        crate_suffix_of_dep_section(&current_section, &dep_sections)
                    {
                        let crate_name = suffix.split('.').next().unwrap_or(suffix);
                        push(stack, crate_name);
                    }
                    continue;
                }
                // For *bare* dependency sections (e.g. `[dependencies]`),
                // the `=` keys are crate names. Dotted tables were handled
                // above via their section header; their sub-keys (version,
                // path, features, …) must not be pushed.
                let is_bare_dep_section = dep_sections.iter().any(|ds| {
                    current_section == *ds || current_section == format!("workspace.{ds}")
                });
                if !is_bare_dep_section {
                    continue;
                }
                if let Some(eq_pos) = trimmed.find('=') {
                    let name = trimmed[..eq_pos].trim();
                    if !name.is_empty() {
                        push(stack, name);
                    }
                }
            }
        }
        "package.json" => {
            // Parse JSON, pull keys from dependencies + devDependencies.
            if let Ok(val) = serde_json::from_str::<serde_json::Value>(&content) {
                for key in &["dependencies", "devDependencies", "peerDependencies"] {
                    if let Some(obj) = val.get(key).and_then(|v| v.as_object()) {
                        for dep in obj.keys() {
                            push(stack, dep);
                        }
                    }
                }
            }
        }
        "go.mod" => {
            // Lines like `\tgithub.com/foo/bar v1.2.3`.
            for line in content.lines() {
                let trimmed = line.trim();
                if trimmed.starts_with("require ") || trimmed.contains(" v") {
                    let parts: Vec<&str> = trimmed.split_whitespace().collect();
                    for part in parts {
                        if part.contains('/') && part.contains('.') && !part.starts_with("require")
                        {
                            // Take the last path segment as the stack name.
                            if let Some(name) = part.rsplit('/').next() {
                                push(stack, name);
                            }
                        }
                    }
                }
            }
        }
        "pyproject.toml" | "requirements.txt" => {
            for line in content.lines() {
                let trimmed = line.trim();
                if trimmed.is_empty() || trimmed.starts_with('#') || trimmed.starts_with('[') {
                    continue;
                }
                let name = trimmed
                    .split(['=', '<', '>', ';', '[', ' '])
                    .next()
                    .unwrap_or("")
                    .trim();
                if !name.is_empty() {
                    push(stack, name);
                }
            }
        }
        _ => {}
    }

    // Bound the stack list.
    stack.truncate(8);
}

/// If `section` (a normalized TOML header without brackets, e.g.
/// `dependencies.serde` or `workspace.dependencies.serde`) names a *dotted*
/// dependency table, return the substring after the dependency-section prefix
/// (the crate name, possibly dotted). Returns `None` for bare sections like
/// `dependencies` and for non-dependency sections like `package`.
fn crate_suffix_of_dep_section<'a>(section: &'a str, dep_sections: &[&str]) -> Option<&'a str> {
    for ds in dep_sections {
        if let Some(rest) = section.strip_prefix(&format!("{ds}.")) {
            return Some(rest);
        }
        if let Some(rest) = section.strip_prefix(&format!("workspace.{ds}.")) {
            return Some(rest);
        }
    }
    None
}

/// Take the first non-heading, non-empty line as a summary seed.
fn first_meaningful_line(content: &str) -> String {
    for line in content.lines() {
        let trimmed = line.trim();
        if trimmed.is_empty() || trimmed.starts_with('#') || trimmed.starts_with("```") {
            continue;
        }
        // Strip markdown emphasis for a cleaner summary.
        let clean = trimmed.trim_start_matches('>').replace(['*', '`'], "");
        let clean = clean.trim();
        let capped = if clean.len() > 120 {
            &clean[..120]
        } else {
            clean
        };
        // Find a safe UTF-8 boundary.
        let mut end = capped.len();
        while end > 0 && !capped.is_char_boundary(end) {
            end -= 1;
        }
        let safe = &capped[..end];
        if clean.len() > 120 {
            return format!("{}…", safe);
        }
        return safe.to_string();
    }
    String::new()
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::fs;
    use tempfile::TempDir;

    #[test]
    fn test_detect_rust_project() {
        let dir = TempDir::new().unwrap();
        fs::write(
            dir.path().join("Cargo.toml"),
            "[package]\nname = \"oxios\"\n\n[dependencies]\ntokio = \"1\"\nserde = \"1\"\naxum = \"0.7\"\n",
        )
        .unwrap();
        fs::write(dir.path().join("AGENTS.md"), "# Oxios\nAgent OS in Rust.").unwrap();

        let meta = detect_meta(dir.path());
        assert!(meta.languages.contains(&"rust".to_string()));
        assert!(meta.markers.contains(&"Cargo.toml".to_string()));
        assert!(meta.markers.contains(&"AGENTS.md".to_string()));
        assert!(meta.stack.iter().any(|s| s == "tokio"));
        assert!(meta.stack.iter().any(|s| s == "axum"));
        assert!(!meta.summary.is_empty());
    }

    #[test]
    fn test_extract_stack_ignores_non_dependency_sections() {
        // RFC-025 fix: `[package]` fields must not leak into the stack.
        let dir = TempDir::new().unwrap();
        fs::write(
            dir.path().join("Cargo.toml"),
            [
                "[package]",
                "name = \"foo\"",
                "edition = \"2021\"",
                "authors = [\"a\"]",
                "description = \"desc\"",
                "license = \"MIT\"",
                "",
                "[dependencies]",
                "tokio = { version = \"1\", features = [\"full\"] }",
                "serde = \"1.0\"",
                "",
                "[dev-dependencies]",
                "pretty_assertions = \"1\"",
                "",
                "[dependencies.axum]",
                "version = \"0.7\"",
                "features = [\"json\"]",
            ]
            .join("\n"),
        )
        .unwrap();

        let meta = detect_meta(dir.path());
        // Real deps are captured (bare section + dotted table).
        assert!(
            meta.stack.iter().any(|s| s == "tokio"),
            "tokio missing: {meta:?}"
        );
        assert!(
            meta.stack.iter().any(|s| s == "serde"),
            "serde missing: {meta:?}"
        );
        assert!(
            meta.stack.iter().any(|s| s == "axum"),
            "dotted-table crate name missing: {meta:?}"
        );
        assert!(
            meta.stack.iter().any(|s| s == "pretty_assertions"),
            "dev-dep missing: {meta:?}"
        );
        // `[package]` fields must NOT appear.
        assert!(
            !meta.stack.iter().any(|s| s == "name"),
            "name leaked: {meta:?}"
        );
        assert!(
            !meta.stack.iter().any(|s| s == "edition"),
            "edition leaked: {meta:?}"
        );
        assert!(
            !meta.stack.iter().any(|s| s == "authors"),
            "authors leaked: {meta:?}"
        );
        // Dotted-table sub-keys must NOT appear.
        assert!(
            !meta.stack.iter().any(|s| s == "version"),
            "version leaked: {meta:?}"
        );
        assert!(
            !meta.stack.iter().any(|s| s == "features"),
            "features leaked: {meta:?}"
        );
    }

    #[test]
    fn test_detect_node_project() {
        let dir = TempDir::new().unwrap();
        fs::write(
            dir.path().join("package.json"),
            r#"{"dependencies": {"react": "^18", "next": "^14"}, "devDependencies": {"typescript": "^5"}}"#,
        )
        .unwrap();

        let meta = detect_meta(dir.path());
        assert!(meta.languages.contains(&"typescript".to_string()));
        assert!(meta.stack.iter().any(|s| s == "react"));
        assert!(meta.stack.iter().any(|s| s == "next"));
    }

    #[test]
    fn test_detect_empty_dir() {
        let dir = TempDir::new().unwrap();
        let meta = detect_meta(dir.path());
        assert!(meta.languages.is_empty());
        assert!(meta.markers.is_empty());
        assert!(meta.summary.is_empty());
    }

    #[test]
    fn test_structure_hints() {
        let dir = TempDir::new().unwrap();
        fs::create_dir(dir.path().join("crates")).unwrap();
        let meta = detect_meta(dir.path());
        assert!(meta.stack.contains(&"cargo-workspace".to_string()));
    }

    #[test]
    fn test_snapshot_markers() {
        let dir = TempDir::new().unwrap();
        fs::write(dir.path().join("Cargo.toml"), "[package]\nname = \"x\"").unwrap();
        let snap = snapshot_markers(dir.path());
        assert!(
            snap.iter()
                .any(|(p, _)| p.file_name().unwrap() == "Cargo.toml")
        );
        // Non-existent markers are excluded.
        assert!(
            !snap
                .iter()
                .any(|(p, _)| p.file_name().unwrap() == "package.json")
        );
    }

    #[test]
    fn test_first_meaningful_line() {
        assert_eq!(
            first_meaningful_line("# Title\n\nThis is the **summary**.\nMore."),
            "This is the summary."
        );
    }
}