import fs from 'node:fs';
import path from 'node:path';

export function booksPath() {
  return (
    process.env.BOOKS_PATH ||
    path.join(process.env.FLEET_STATE_DIR || process.cwd(), 'data', 'books.json')
  );
}

export function loadInto(books) {
  const p = booksPath();
  if (!fs.existsSync(p)) return books;
  try {
    books.load(JSON.parse(fs.readFileSync(p, 'utf8')));
  } catch {
    /* keep empty */
  }
  return books;
}

export function saveFrom(books) {
  const p = booksPath();
  fs.mkdirSync(path.dirname(p), { recursive: true });
  const tmp = `${p}.tmp`;
  fs.writeFileSync(tmp, JSON.stringify(books.dump(), null, 2));
  fs.renameSync(tmp, p);
}