"""Library scanning and the stable per-book id shared across progress.py,
blocks.py, and remote.py."""

from __future__ import annotations

import hashlib
from pathlib import Path


def _book_id(path: Path) -> str:
    # Identifies a book by its resolved path for now. Once the sync API exists,
    # this should switch to whatever stable id diora assigns server-side.
    return hashlib.sha256(str(path.resolve()).encode()).hexdigest()[:16]


def scan_library(library_dir: Path) -> list[Path]:
    if not library_dir.exists():
        return []
    return sorted(library_dir.rglob("*.epub"))