dbmd-core 0.4.1

//! `assets` — the db.md asset layer.
//!
//! Raw binary assets (PDFs, recordings, large exports) belong to a store but
//! are too heavy for Git. A content file (the **wrapper**) declares one via an
//! `asset:` / `assets:` frontmatter key; this module records each in the
//! root-level `assets.jsonl` manifest: store-relative path, SHA-256, size,
//! media type, the declaring wrapper(s), and whether it is required for
//! byte-completeness.
//!
//! The manifest is a **pure projection** of (wrappers + asset files on disk):
//! every field is derivable, so a [`scan`] where the bytes are present
//! reproduces it byte-for-byte, exactly like `index.jsonl`. db.md never
//! transports the bytes and never names a storage provider; that is the
//! VibeCraft layer's job, keyed off the SHA-256. This module never shells out
//! to git and never touches the network.
//!
//! Four operations — one write, three reads:
//!   - [`scan`]   (write) discover declared assets, hash present files, rewrite the manifest
//!   - [`verify`] (read)  prove the local store is byte-complete for required assets
//!   - [`status`] (read)  report present / missing without failing
//!   - [`paths`]  (read)  the store-relative path list (for an ignore mechanism)
//!
//! Path safety: every declared path is validated store-relative (no `..`, no
//! absolute, no escape) via [`crate::store::ensure_path_within_store`] wherever
//! a path is read or resolved, so a poisoned manifest can never make `scan`
//! hash, or a restore write, outside the store.

use std::collections::{BTreeMap, BTreeSet};
use std::fmt::Write as _;
use std::io::Read as _;
use std::path::{Component, Path, PathBuf};

use serde::{Deserialize, Serialize};
use serde_norway::Value;
use sha2::{Digest, Sha256};

use crate::parser;
use crate::store::{self, Store};
use crate::write_atomic;

/// The manifest file name at the store root.
pub const MANIFEST_FILE: &str = "assets.jsonl";

/// One asset record — one line of `assets.jsonl`.
///
/// Every field is derivable from the store (wrapper frontmatter + the file on
/// disk), so the manifest rebuilds byte-for-byte. Field declaration order is
/// the canonical JSON key order; `wrappers` is always a sorted list (never a
/// bare string) so serialization is deterministic.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct AssetRecord {
    /// Store-relative path of the raw bytes, forward-slash, with extension. The
    /// record key. May differ from `wrappers` (the wrapper is the `.md`).
    pub path: String,
    /// Lowercase-hex SHA-256 of the bytes: the integrity check and the provider
    /// blob key. May repeat across records (identical bytes at two paths).
    pub sha256: String,
    /// Size in bytes.
    pub bytes: u64,
    /// Best-effort MIME type derived from the path extension.
    pub media_type: String,
    /// Store-relative path(s) of the content file(s) that declare this asset,
    /// sorted ascending. Usually one.
    pub wrappers: Vec<String>,
    /// Whether the asset is required for byte-completeness (default `true`;
    /// `false` only when every declaration marks it optional).
    pub required: bool,
}

/// A single `asset:` / `assets:` declaration read from a wrapper's frontmatter.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Declaration {
    /// The raw store-relative path string as written in frontmatter.
    pub path: String,
    /// Whether this declaration marks the asset required (bare string and
    /// object-without-`required` default to `true`).
    pub required: bool,
}

// ─────────────────────────────────────────────────────────────────────────────
// Reports (serialized directly in `--json`; the CLI renders the text form)
// ─────────────────────────────────────────────────────────────────────────────

/// Result of [`scan`].
#[derive(Debug, Serialize)]
pub struct ScanReport {
    pub manifest: String,
    pub cataloged: usize,
    pub hashed: usize,
    pub preserved: usize,
    pub bytes: u64,
    pub wrote: bool,
    pub dry_run: bool,
    pub warnings: Vec<String>,
    pub untracked: Vec<String>,
}

/// One asset's local state, used by [`status`] and [`verify`].
#[derive(Debug, Serialize)]
pub struct AssetState {
    pub path: String,
    pub sha256: String,
    pub bytes: u64,
    pub required: bool,
    /// `present` / `missing` (status); `ok` / `missing` / `corrupt` (verify).
    pub state: String,
}

/// Result of [`status`].
#[derive(Debug, Serialize)]
pub struct StatusReport {
    pub total: usize,
    pub present: usize,
    pub missing: usize,
    pub required_missing: usize,
    pub optional_missing: usize,
    pub bytes_total: u64,
    pub bytes_missing: u64,
    pub assets: Vec<AssetState>,
}

/// Result of [`verify`].
#[derive(Debug, Serialize)]
pub struct VerifyReport {
    pub mode: String,
    pub checked: usize,
    pub ok: usize,
    pub missing: Vec<String>,
    pub corrupt: Vec<String>,
    pub complete: bool,
}

// ─────────────────────────────────────────────────────────────────────────────
// Manifest read / write
// ─────────────────────────────────────────────────────────────────────────────

/// Read `assets.jsonl` into records, deduped by path (last line wins) and
/// sorted by path ascending. A missing manifest is an empty store, not an
/// error. A malformed line is an `InvalidData` error (the CLI surfaces it;
/// [`crate::validate`] flags it leniently as `ASSET_MANIFEST_MALFORMED`).
pub fn read_manifest(store: &Store) -> crate::Result<Vec<AssetRecord>> {
    let abs = store.root.join(MANIFEST_FILE);
    if !abs.exists() {
        return Ok(Vec::new());
    }
    let text = std::fs::read_to_string(&abs)?;
    let mut by_path: BTreeMap<String, AssetRecord> = BTreeMap::new();
    for (i, line) in text.lines().enumerate() {
        if line.trim().is_empty() {
            continue;
        }
        let rec: AssetRecord = serde_json::from_str(line).map_err(|e| {
            std::io::Error::new(
                std::io::ErrorKind::InvalidData,
                format!("{MANIFEST_FILE} line {}: {e}", i + 1),
            )
        })?;
        by_path.insert(rec.path.clone(), rec);
    }
    Ok(by_path.into_values().collect())
}

/// Write the manifest atomically (temp + fsync + rename, via [`write_atomic`]),
/// records sorted by path ascending. An empty record set removes the file.
pub fn write_manifest(store: &Store, records: &[AssetRecord]) -> crate::Result<()> {
    let abs = store.root.join(MANIFEST_FILE);
    if records.is_empty() {
        if abs.exists() {
            std::fs::remove_file(&abs)?;
        }
        return Ok(());
    }
    let mut sorted = records.to_vec();
    sorted.sort_by(|a, b| a.path.cmp(&b.path));
    let mut out = String::new();
    for rec in &sorted {
        let line = serde_json::to_string(rec).expect("AssetRecord serializes");
        out.push_str(&line);
        out.push('\n');
    }
    write_atomic(&abs, out.as_bytes())?;
    Ok(())
}

// ─────────────────────────────────────────────────────────────────────────────
// scan (write) — rebuild the manifest from wrapper declarations
// ─────────────────────────────────────────────────────────────────────────────

/// Walk every content file, read its `asset`/`assets` declarations, hash the
/// present files, and (re)write the manifest. The manifest is a projection: a
/// path no longer declared by any wrapper drops out. Bytes absent locally but
/// previously cataloged are preserved (the eviction / disk-relief case) since
/// they cannot be re-hashed. `dry_run` computes without writing; `untracked`
/// additionally reports non-markdown files under `sources/` that no wrapper
/// declares. Never writes when nothing changed (keeps the Git diff and the
/// `--dry-run`-then-scan idempotent).
pub fn scan(store: &Store, dry_run: bool, untracked: bool) -> crate::Result<ScanReport> {
    // Tolerate a malformed existing manifest here: scan rebuilds from the files,
    // so a corrupt prior file is simply replaced. We still read it (best effort)
    // to preserve hashes for evicted (absent-but-cataloged) assets.
    let existing_by_path: BTreeMap<String, AssetRecord> = read_manifest(store)
        .unwrap_or_default()
        .into_iter()
        .map(|r| (r.path.clone(), r))
        .collect();

    // Aggregate declarations across all content files: path -> (wrappers, required).
    let mut wrappers_by_path: BTreeMap<String, BTreeSet<String>> = BTreeMap::new();
    let mut required_by_path: BTreeMap<String, bool> = BTreeMap::new();
    let mut declared_paths: BTreeSet<String> = BTreeSet::new();
    let mut warnings: Vec<String> = Vec::new();

    for rel in store.walk()? {
        let abs = store.abs_path(&rel);
        let (fm, _body) = match parser::read_file(&abs) {
            Ok(v) => v,
            Err(_) => continue, // unparseable / not a content file: skip
        };
        let wrapper = rel_to_string(&rel);
        for decl in declared_assets(&fm) {
            let norm = match normalize_asset_path(&decl.path) {
                Ok(n) => n,
                Err(e) => {
                    warnings.push(format!("{wrapper}: {e}"));
                    continue;
                }
            };
            if is_markdown(&norm) {
                warnings.push(format!(
                    "{wrapper}: asset path points at a markdown content file ({norm}); skipped"
                ));
                continue;
            }
            wrappers_by_path
                .entry(norm.clone())
                .or_default()
                .insert(wrapper.clone());
            let req = required_by_path.entry(norm.clone()).or_insert(false);
            *req = *req || decl.required;
            declared_paths.insert(norm);
        }
    }

    // Build records.
    let mut records: Vec<AssetRecord> = Vec::new();
    let mut hashed = 0usize;
    let mut preserved = 0usize;
    for (path, wrappers) in &wrappers_by_path {
        let required = *required_by_path.get(path).unwrap_or(&true);
        let wrappers: Vec<String> = wrappers.iter().cloned().collect();

        // Belt-and-suspenders containment check before any disk read.
        let abs = match store::ensure_path_within_store(&store.root, &store.root.join(path)) {
            Ok(p) => p,
            Err(_) => {
                warnings.push(format!("{path}: escapes the store root; skipped"));
                continue;
            }
        };

        if abs.is_dir() {
            warnings.push(format!("{path}: is a directory, not a file; skipped"));
            continue;
        }
        if abs.is_file() {
            let (sha256, bytes) = sha256_file(&abs)?;
            records.push(AssetRecord {
                path: path.clone(),
                sha256,
                bytes,
                media_type: media_type_for(path),
                wrappers,
                required,
            });
            hashed += 1;
        } else if let Some(prev) = existing_by_path.get(path) {
            // Evicted: bytes gone locally but previously cataloged. Preserve the
            // committed hash/size (we cannot re-hash what is not here).
            records.push(AssetRecord {
                path: path.clone(),
                sha256: prev.sha256.clone(),
                bytes: prev.bytes,
                media_type: media_type_for(path),
                wrappers,
                required,
            });
            preserved += 1;
        } else {
            warnings.push(format!(
                "{path}: declared but absent and never cataloged; cannot hash (skipped)"
            ));
        }
    }
    records.sort_by(|a, b| a.path.cmp(&b.path));

    let bytes: u64 = records.iter().map(|r| r.bytes).sum();
    let cataloged = records.len();

    let untracked_list = if untracked {
        find_untracked(store, &declared_paths)?
    } else {
        Vec::new()
    };

    // Only write when the canonical content actually changed.
    let mut wrote = false;
    if !dry_run {
        let current = read_manifest(store).unwrap_or_default();
        if current != records {
            write_manifest(store, &records)?;
            wrote = true;
        }
    }

    Ok(ScanReport {
        manifest: MANIFEST_FILE.to_string(),
        cataloged,
        hashed,
        preserved,
        bytes,
        wrote,
        dry_run,
        warnings,
        untracked: untracked_list,
    })
}

// ─────────────────────────────────────────────────────────────────────────────
// verify (read) — byte-completeness gate
// ─────────────────────────────────────────────────────────────────────────────

/// Check that every required asset (plus optional, under `include_optional`) is
/// present locally and matches the manifest. `quick` = presence + size only
/// (fast); otherwise a full SHA-256 re-hash. This is a SWEEP (O(asset bytes) in
/// deep mode), never a loop op. `complete` is true iff nothing is missing or
/// corrupt in the considered set.
pub fn verify(store: &Store, include_optional: bool, quick: bool) -> crate::Result<VerifyReport> {
    let records = read_manifest(store)?;
    let mut missing = Vec::new();
    let mut corrupt = Vec::new();
    let mut checked = 0usize;

    for rec in &records {
        if !rec.required && !include_optional {
            continue;
        }
        checked += 1;
        let abs = match store::ensure_path_within_store(&store.root, &store.root.join(&rec.path)) {
            Ok(p) => p,
            Err(_) => {
                // A manifest path that escapes the store is not restorable here.
                corrupt.push(rec.path.clone());
                continue;
            }
        };
        if !abs.is_file() {
            missing.push(rec.path.clone());
            continue;
        }
        if quick {
            let len = std::fs::metadata(&abs)?.len();
            if len != rec.bytes {
                corrupt.push(rec.path.clone());
            }
        } else {
            let (sha, bytes) = sha256_file(&abs)?;
            if sha != rec.sha256 || bytes != rec.bytes {
                corrupt.push(rec.path.clone());
            }
        }
    }

    let ok = checked - missing.len() - corrupt.len();
    let complete = missing.is_empty() && corrupt.is_empty();
    Ok(VerifyReport {
        mode: if quick { "quick" } else { "deep" }.to_string(),
        checked,
        ok,
        missing,
        corrupt,
        complete,
    })
}

// ─────────────────────────────────────────────────────────────────────────────
// status (read) — non-failing presence report
// ─────────────────────────────────────────────────────────────────────────────

/// Report which cataloged assets are present locally and how many bytes remain
/// to restore. Never fails on a missing asset (that is `verify`'s job); it does
/// fail on a malformed manifest.
pub fn status(store: &Store) -> crate::Result<StatusReport> {
    let records = read_manifest(store)?;
    let mut present = 0usize;
    let mut missing = 0usize;
    let mut required_missing = 0usize;
    let mut optional_missing = 0usize;
    let mut bytes_total = 0u64;
    let mut bytes_missing = 0u64;
    let mut assets = Vec::with_capacity(records.len());

    for rec in &records {
        bytes_total += rec.bytes;
        // Resolve through the same containment guard `scan` and `verify` use:
        // the module contract is that the guard applies "wherever a path is read
        // or resolved", and an unguarded `is_file()` here let a poisoned/hand-
        // edited manifest path (`../outside.txt`) report `present` (and count its
        // bytes) while `verify` reported it `corrupt` — two read commands on the
        // same store disagreeing, plus a path-existence oracle outside the store.
        // An escaping record is treated as not-present (missing), matching verify.
        let is_present = store::ensure_path_within_store(&store.root, &store.root.join(&rec.path))
            .map(|p| p.is_file())
            .unwrap_or(false);
        let state = if is_present {
            present += 1;
            "present"
        } else {
            missing += 1;
            bytes_missing += rec.bytes;
            if rec.required {
                required_missing += 1;
            } else {
                optional_missing += 1;
            }
            "missing"
        };
        assets.push(AssetState {
            path: rec.path.clone(),
            sha256: rec.sha256.clone(),
            bytes: rec.bytes,
            required: rec.required,
            state: state.to_string(),
        });
    }

    Ok(StatusReport {
        total: records.len(),
        present,
        missing,
        required_missing,
        optional_missing,
        bytes_total,
        bytes_missing,
        assets,
    })
}

// ─────────────────────────────────────────────────────────────────────────────
// paths (read) — the VCS-neutral path list
// ─────────────────────────────────────────────────────────────────────────────

/// The cataloged asset paths, sorted ascending. The VCS-neutral list a harness
/// feeds into a `.gitignore` managed block or a sync-service exclude. db.md
/// itself never writes any ignore file.
pub fn paths(store: &Store) -> crate::Result<Vec<String>> {
    Ok(read_manifest(store)?.into_iter().map(|r| r.path).collect())
}

// ─────────────────────────────────────────────────────────────────────────────
// Declaration parsing (shared with `validate`)
// ─────────────────────────────────────────────────────────────────────────────

/// Read all `asset:` / `assets:` declarations from a parsed frontmatter.
///
/// `asset: <path>` is a single required declaration. `assets:` is a list whose
/// items are either a bare path string (required) or a `{ path, required }`
/// mapping. Both keys may be present.
pub fn declared_assets(fm: &parser::Frontmatter) -> Vec<Declaration> {
    let mut out = Vec::new();
    if let Some(v) = fm.get("asset") {
        collect_declarations(&v, &mut out);
    }
    if let Some(v) = fm.get("assets") {
        collect_declarations(&v, &mut out);
    }
    out
}

/// Read declarations from an already-parsed YAML mapping. Used by
/// [`crate::validate`], which holds the parsed mapping and need not re-read the
/// file. Equivalent to [`declared_assets`] but keyed off a raw map.
pub fn declarations_from_yaml_map(map: &BTreeMap<String, Value>) -> Vec<Declaration> {
    let mut out = Vec::new();
    if let Some(v) = map.get("asset") {
        collect_declarations(v, &mut out);
    }
    if let Some(v) = map.get("assets") {
        collect_declarations(v, &mut out);
    }
    out
}

fn collect_declarations(v: &Value, out: &mut Vec<Declaration>) {
    match v {
        Value::String(s) => out.push(Declaration {
            path: s.clone(),
            required: true,
        }),
        Value::Sequence(items) => {
            for item in items {
                match item {
                    Value::String(s) => out.push(Declaration {
                        path: s.clone(),
                        required: true,
                    }),
                    Value::Mapping(m) => {
                        let path = m
                            .get(Value::String("path".to_string()))
                            .and_then(|x| x.as_str())
                            .map(|s| s.to_string());
                        if let Some(path) = path {
                            let required = m
                                .get(Value::String("required".to_string()))
                                .and_then(|x| x.as_bool())
                                .unwrap_or(true);
                            out.push(Declaration { path, required });
                        }
                    }
                    _ => {}
                }
            }
        }
        _ => {}
    }
}

// ─────────────────────────────────────────────────────────────────────────────
// Helpers
// ─────────────────────────────────────────────────────────────────────────────

/// Normalize a declared asset path to a CANONICAL store-relative forward-slash
/// string, rejecting absolute paths and any `..` / root component. This is the
/// lexical guard; [`crate::store::ensure_path_within_store`] is the resolved-path
/// guard applied before any disk read.
///
/// The result is the record key, so it MUST be canonical: `./sources/x.pdf`,
/// `sources/x.pdf`, and `sources/./x.pdf` all denote the same file and must fold
/// to the same key `sources/x.pdf`. The path is rebuilt from `Normal` components
/// only (dropping `CurDir`); hostile `..`/root/prefix components are still hard
/// errors (never silently sanitized), so a leading `./` is normalized away while
/// a traversal attempt is rejected.
pub fn normalize_asset_path(raw: &str) -> Result<String, String> {
    let trimmed = raw.trim();
    if trimmed.is_empty() {
        return Err("empty asset path".to_string());
    }
    let p = Path::new(trimmed);
    if p.is_absolute() {
        return Err(format!("absolute asset path not allowed: {raw}"));
    }
    let mut normal: Vec<&std::ffi::OsStr> = Vec::new();
    for c in p.components() {
        match c {
            Component::ParentDir => return Err(format!("`..` not allowed in asset path: {raw}")),
            Component::Prefix(_) | Component::RootDir => {
                return Err(format!("asset path escapes the store: {raw}"))
            }
            // A `.` (CurDir) carries no path information — drop it so the key is
            // canonical and `./x` does not split into a second record from `x`.
            Component::CurDir => {}
            Component::Normal(seg) => normal.push(seg),
        }
    }
    if normal.is_empty() {
        // The path was only `.`/`./` — no actual target.
        return Err(format!("asset path names no file: {raw}"));
    }
    let joined: PathBuf = normal.into_iter().collect();
    Ok(joined.to_string_lossy().replace('\\', "/"))
}

fn is_markdown(path: &str) -> bool {
    Path::new(path)
        .extension()
        .and_then(|e| e.to_str())
        .map(|e| e.eq_ignore_ascii_case("md"))
        .unwrap_or(false)
}

fn rel_to_string(p: &Path) -> String {
    p.to_string_lossy().replace('\\', "/")
}

/// Stream the file through SHA-256 (constant memory) and return
/// `(lowercase-hex digest, byte length)`.
fn sha256_file(abs: &Path) -> std::io::Result<(String, u64)> {
    let mut f = std::fs::File::open(abs)?;
    let mut hasher = Sha256::new();
    let mut buf = [0u8; 65536];
    let mut total: u64 = 0;
    loop {
        let n = f.read(&mut buf)?;
        if n == 0 {
            break;
        }
        hasher.update(&buf[..n]);
        total += n as u64;
    }
    let digest = hasher.finalize();
    let mut hex = String::with_capacity(64);
    for b in digest.iter() {
        let _ = write!(hex, "{b:02x}");
    }
    Ok((hex, total))
}

/// Best-effort MIME type from the path extension. Defaults to
/// `application/octet-stream`. This is deterministic (extension-driven), so it
/// does not break the manifest's rebuild equivalence.
fn media_type_for(path: &str) -> String {
    let ext = Path::new(path)
        .extension()
        .and_then(|e| e.to_str())
        .unwrap_or("")
        .to_ascii_lowercase();
    let mt = match ext.as_str() {
        "pdf" => "application/pdf",
        "png" => "image/png",
        "jpg" | "jpeg" => "image/jpeg",
        "gif" => "image/gif",
        "webp" => "image/webp",
        "svg" => "image/svg+xml",
        "tiff" | "tif" => "image/tiff",
        "mp4" => "video/mp4",
        "mov" => "video/quicktime",
        "webm" => "video/webm",
        "mkv" => "video/x-matroska",
        "mp3" => "audio/mpeg",
        "wav" => "audio/wav",
        "m4a" => "audio/mp4",
        "flac" => "audio/flac",
        "zip" => "application/zip",
        "gz" | "tgz" => "application/gzip",
        "tar" => "application/x-tar",
        "csv" => "text/csv",
        "tsv" => "text/tab-separated-values",
        "json" => "application/json",
        "xml" => "application/xml",
        "txt" => "text/plain",
        "vtt" => "text/vtt",
        "srt" => "application/x-subrip",
        "html" | "htm" => "text/html",
        "epub" => "application/epub+zip",
        "docx" => "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
        "xlsx" => "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
        "pptx" => "application/vnd.openxmlformats-officedocument.presentationml.presentation",
        "doc" => "application/msword",
        "xls" => "application/vnd.ms-excel",
        "ppt" => "application/vnd.ms-powerpoint",
        _ => "application/octet-stream",
    };
    mt.to_string()
}

/// Non-markdown files under `sources/` that no wrapper declares (the
/// un-wrappered-drop worklist). Walks the raw filesystem (so it sees files an
/// ignore mechanism would hide), skips `index.*` sidecars and hidden entries.
fn find_untracked(store: &Store, declared: &BTreeSet<String>) -> crate::Result<Vec<String>> {
    let sources = store.root.join("sources");
    if !sources.is_dir() {
        return Ok(Vec::new());
    }
    let mut out = Vec::new();
    for entry in walkdir::WalkDir::new(&sources)
        .into_iter()
        .filter_entry(|e| !is_hidden(e.file_name().to_str().unwrap_or("")))
    {
        let entry = match entry {
            Ok(e) => e,
            Err(_) => continue,
        };
        if !entry.file_type().is_file() {
            continue;
        }
        let name = entry.file_name().to_str().unwrap_or("");
        if is_markdown(name) || name == "index.jsonl" {
            continue;
        }
        let rel = match entry.path().strip_prefix(&store.root) {
            Ok(r) => rel_to_string(r),
            Err(_) => continue,
        };
        if !declared.contains(&rel) {
            out.push(rel);
        }
    }
    out.sort();
    Ok(out)
}

fn is_hidden(name: &str) -> bool {
    name.starts_with('.') && name != "." && name != ".."
}

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

    /// Regression (adversarial review): `normalize_asset_path` must fold a
    /// leading/interior `.` (CurDir) into the canonical key, so `./sources/x.pdf`
    /// and `sources/x.pdf` are ONE record (not duplicated, byte-double-counted,
    /// and falsely reported untracked). Traversal / absolute / root stay hard
    /// errors — folding must never silently sanitize a hostile path.
    #[test]
    fn normalize_asset_path_folds_curdir_and_rejects_traversal() {
        assert_eq!(
            normalize_asset_path("./sources/x.pdf").unwrap(),
            "sources/x.pdf"
        );
        assert_eq!(
            normalize_asset_path("sources/x.pdf").unwrap(),
            "sources/x.pdf"
        );
        assert_eq!(
            normalize_asset_path("sources/./x.pdf").unwrap(),
            "sources/x.pdf"
        );
        assert_eq!(
            normalize_asset_path("sources/x.pdf/").unwrap(),
            "sources/x.pdf"
        );

        // Hostile / structural inputs are still rejected, not sanitized.
        assert!(normalize_asset_path("../outside.txt").is_err());
        assert!(normalize_asset_path("sources/../../etc/passwd").is_err());
        assert!(normalize_asset_path("/abs/x.pdf").is_err());
        // A `.`-only path (or empty) names no file.
        assert!(normalize_asset_path(".").is_err());
        assert!(normalize_asset_path("./").is_err());
        assert!(normalize_asset_path("").is_err());
    }
}