lean-ctx 3.9.19

use std::collections::{HashMap, HashSet};
use std::path::{Path, PathBuf};

use ignore::WalkBuilder;

use crate::core::tokens::count_tokens;

struct Entry {
    depth: usize,
    name: String,
    is_dir: bool,
    path: PathBuf,
}

/// Generates a compact directory tree body with the raw tree token count.
pub fn handle(
    path: &str,
    depth: usize,
    show_hidden: bool,
    respect_gitignore: bool,
) -> (String, usize) {
    let requested_root = Path::new(path);
    let walk_root = crate::core::walk_filter::explicit_walk_root(requested_root);
    let root = walk_root.as_path();

    if root.is_file() {
        let parent = root
            .parent()
            .map_or(path.to_string(), |parent| parent.display().to_string());
        return (
            format!(
                "ERROR: '{path}' is a file, not a directory. Use path=\"{parent}\" for the containing directory."
            ),
            0,
        );
    }
    if !root.is_dir() {
        return (
            format!("ERROR: {path} does not exist or is not a directory"),
            0,
        );
    }

    if let Some(err) = crate::tools::walk_guard::deny_unsafe_walk_root(path) {
        return (err, 0);
    }

    let (entries, raw_tokens) = collect_entries(root, depth, show_hidden, respect_gitignore);
    let body = render_compact_tree(root, &entries);
    if body.trim().is_empty() {
        return (format!("{path}/ (empty directory, depth={depth})"), 0);
    }

    (body, raw_tokens)
}

fn collect_entries(
    root: &Path,
    max_depth: usize,
    show_hidden: bool,
    respect_gitignore: bool,
) -> (Vec<Entry>, usize) {
    let mut entries = Vec::new();
    let mut raw_tokens = 0;
    let newline_tokens = count_tokens("\n");

    let walker = WalkBuilder::new(root)
        .hidden(!show_hidden)
        .git_ignore(respect_gitignore)
        .git_global(respect_gitignore)
        .git_exclude(respect_gitignore)
        .require_git(false)
        .max_depth(Some(max_depth))
        .sort_by_file_name(std::cmp::Ord::cmp)
        .filter_entry(move |entry| {
            if respect_gitignore {
                crate::core::walk_filter::keep_entry(entry)
            } else {
                crate::core::cloud_files::keep_entry(entry)
            }
        })
        .build();

    for entry in walker.filter_map(std::result::Result::ok) {
        if entry.depth() == 0 {
            continue;
        }

        let depth = entry.depth();
        let name = entry.file_name().to_string_lossy().to_string();
        let is_dir = entry
            .file_type()
            .is_some_and(|file_type| file_type.is_dir());
        let path = entry.into_path();
        let relative_path = path
            .strip_prefix(root)
            .unwrap_or(path.as_path())
            .to_string_lossy();

        if !entries.is_empty() {
            raw_tokens += newline_tokens;
        }
        raw_tokens += count_tokens(&relative_path);

        entries.push(Entry {
            depth,
            name,
            is_dir,
            path,
        });
    }

    (entries, raw_tokens)
}

fn render_compact_tree(root: &Path, entries: &[Entry]) -> String {
    let mut lines = Vec::new();

    let mut dir_file_counts: HashMap<&Path, usize> = HashMap::new();
    for entry in entries {
        if !entry.is_dir
            && let Some(parent) = entry.path.parent()
        {
            *dir_file_counts.entry(parent).or_default() += 1;
        }
    }

    let (hive_summaries, hive_skipped) = detect_hive_partitions(entries, &dir_file_counts);
    if let Some(summary) = hive_summaries.get(root) {
        let root_name = root.file_name().map_or_else(
            || root.display().to_string(),
            |name| name.to_string_lossy().to_string(),
        );
        lines.push(format!("{root_name}/ ({summary})"));
    }

    for entry in entries {
        if hive_skipped.contains(&entry.path) {
            continue;
        }
        let indent = "  ".repeat(entry.depth.saturating_sub(1));
        if entry.is_dir {
            if let Some(summary) = hive_summaries.get(&entry.path) {
                lines.push(format!("{indent}{}/ ({summary})", entry.name));
            } else {
                let count = dir_file_counts
                    .get(entry.path.as_path())
                    .copied()
                    .unwrap_or(0);
                lines.push(format!("{indent}{}/ ({count})", entry.name));
            }
        } else {
            lines.push(format!("{indent}{}", entry.name));
        }
    }

    lines.join("\n")
}

/// Detects Hive-partitioned directories and returns summaries plus paths to omit.
fn detect_hive_partitions(
    entries: &[Entry],
    dir_file_counts: &HashMap<&Path, usize>,
) -> (HashMap<PathBuf, String>, HashSet<PathBuf>) {
    let mut children_by_parent: HashMap<&Path, Vec<&Entry>> = HashMap::new();
    for entry in entries.iter().filter(|entry| entry.is_dir) {
        if let Some(parent) = entry.path.parent() {
            children_by_parent.entry(parent).or_default().push(entry);
        }
    }

    let mut summaries = HashMap::new();
    let mut skipped = HashSet::new();
    for (parent, children) in children_by_parent {
        let Some(key) = children
            .first()
            .and_then(|entry| hive_partition_key(&entry.name))
        else {
            continue;
        };
        if children.len() < 3
            || children
                .iter()
                .any(|entry| hive_partition_key(&entry.name) != Some(key))
        {
            continue;
        }

        let file_count = children
            .iter()
            .map(|entry| {
                dir_file_counts
                    .get(entry.path.as_path())
                    .copied()
                    .unwrap_or(0)
            })
            .sum::<usize>();
        summaries.insert(
            parent.to_path_buf(),
            format!(
                "hive: {key}=* — {} partitions, {file_count} files",
                children.len()
            ),
        );
        for entry in entries {
            if children
                .iter()
                .any(|child| entry.path.starts_with(&child.path))
            {
                skipped.insert(entry.path.clone());
            }
        }
    }

    (summaries, skipped)
}

fn hive_partition_key(name: &str) -> Option<&str> {
    let (key, value) = name.split_once('=')?;
    if value.is_empty() {
        return None;
    }

    let mut chars = key.chars();
    let first = chars.next()?;
    if !(first.is_ascii_alphabetic() || first == '_')
        || !chars.all(|character| character.is_ascii_alphanumeric() || character == '_')
    {
        return None;
    }
    Some(key)
}

#[cfg(test)]
mod tests {
    use super::{collect_entries, count_tokens, handle, render_compact_tree};

    /// Builds a deterministic source-tree fixture so the assertions do not
    /// depend on the live repository size or platform path separators (the live
    /// repo coupling previously made this test tip over its token threshold on
    /// Windows as the codebase grew).
    fn make_fixture() -> tempfile::TempDir {
        let dir = tempfile::tempdir().unwrap();
        let root = dir.path();
        let files = [
            "Cargo.toml",
            "README.md",
            "src/main.rs",
            "src/lib.rs",
            "src/core/mod.rs",
            "src/core/engine.rs",
            "src/core/util.rs",
            "src/tools/mod.rs",
            "src/tools/reader.rs",
            "tests/integration.rs",
            "tests/smoke.rs",
        ];
        for rel in files {
            let p = root.join(rel);
            std::fs::create_dir_all(p.parent().unwrap()).unwrap();
            std::fs::write(&p, "// fixture\n").unwrap();
        }
        dir
    }

    #[test]
    fn tree_derives_body_and_raw_tokens_from_one_entry_set() {
        let dir = make_fixture();
        let root = dir.path();
        let (entries, expected_raw_tokens) = collect_entries(root, 3, false, true);

        let (body, raw_tokens) = handle(&root.to_string_lossy(), 3, false, true);

        assert_eq!(body, render_compact_tree(root, &entries));
        assert_eq!(raw_tokens, expected_raw_tokens);
    }

    #[test]
    fn tree_savings_are_reasonable() {
        let dir = make_fixture();
        let (output, original) = handle(&dir.path().to_string_lossy(), 3, false, true);
        let compact_tokens = count_tokens(&output);

        eprintln!("=== ctx_tree savings test ===");
        eprintln!("  original (raw) tokens: {original}");
        eprintln!("  compact tokens:        {compact_tokens}");
        eprintln!(
            "  savings:               {}",
            original.saturating_sub(compact_tokens)
        );

        assert!(original > 0, "raw tree should have some tokens");
        assert!(
            original < 2000,
            "raw tree for the fixture should be small, got {original}"
        );
        if original > compact_tokens {
            let ratio = (original - compact_tokens) as f64 / original as f64;
            eprintln!("  savings ratio:         {:.1}%", ratio * 100.0);
            assert!(
                ratio < 0.90,
                "savings ratio should be < 90% for same-depth comparison, got {:.1}%",
                ratio * 100.0
            );
        }
    }

    #[test]
    fn tree_refuses_home_directory_root() {
        // #356 class: never walk the whole home dir (macOS TCC prompts).
        let home = dirs::home_dir().expect("home dir in test env");
        let (output, tokens) = handle(home.to_string_lossy().as_ref(), 2, false, true);
        assert!(
            output.starts_with("ERROR:") && output.contains("refusing to scan"),
            "home root must be refused: {output}"
        );
        assert_eq!(tokens, 0);
    }

    #[test]
    fn tree_hides_node_modules_by_default_even_without_git() {
        // #400: vendor dirs are pruned by default; respect_gitignore=false is
        // the explicit escape hatch to look inside them.
        let tmp = tempfile::tempdir().expect("tempdir");
        std::fs::create_dir_all(tmp.path().join("node_modules/react")).expect("mkdir");
        std::fs::write(tmp.path().join("node_modules/react/index.js"), "x").expect("write");
        std::fs::create_dir_all(tmp.path().join("src")).expect("mkdir");
        std::fs::write(tmp.path().join("src/app.js"), "y").expect("write");
        let root = tmp.path().to_string_lossy().to_string();

        let (default_out, _) = handle(&root, 4, false, true);
        assert!(default_out.contains("src"), "src visible: {default_out}");
        assert!(
            !default_out.contains("node_modules"),
            "node_modules must be hidden by default: {default_out}"
        );

        let (opt_out, _) = handle(&root, 4, false, false);
        assert!(
            opt_out.contains("node_modules"),
            "respect_gitignore=false must reveal vendor dirs: {opt_out}"
        );
    }

    #[test]
    fn hive_partition_detection() {
        let dir = tempfile::tempdir().expect("tempdir");
        let root = dir.path();
        for year in 2020..=2024 {
            let partition = root.join(format!("year={year}"));
            std::fs::create_dir_all(&partition).expect("mkdir");
            std::fs::write(partition.join("data.parquet"), "fake").expect("write");
        }

        let (output, _) = handle(&root.display().to_string(), 3, false, false);
        assert!(output.contains("hive:"), "expected Hive summary: {output}");
        assert!(
            output.contains("5 partitions"),
            "expected partition count: {output}"
        );
        assert!(output.contains("5 files"), "expected file count: {output}");
        assert!(
            !output.contains("year=2020"),
            "partition was not collapsed: {output}"
        );
    }

    #[cfg(windows)]
    #[test]
    fn tree_walks_explicit_directory_reparse_root() {
        use std::os::windows::fs::symlink_dir;

        let tmp = tempfile::tempdir().expect("tempdir");
        let target = tmp.path().join("target");
        let link = tmp.path().join("junction");
        std::fs::create_dir_all(&target).expect("target");
        std::fs::write(target.join("visible.rs"), "fn visible() {}\n").expect("fixture");
        if symlink_dir(&target, &link).is_err() {
            // Windows hosts without Developer Mode cannot create this fixture.
            return;
        }
        let (out, _) = handle(&link.to_string_lossy(), 2, false, true);
        assert!(
            out.contains("visible.rs"),
            "junction root must be traversed: {out}"
        );
    }
}