// Validation for a user's synced Reader bookmarks and text highlights. The data comes
// from the browser, so everything is checked and malformed entries are dropped.
const COLOR = /^#[0-9a-fA-F]{3,8}$/;
const BOOKMARK_KEY = /^[1-3]?[A-Za-z]{2,3}-\d{1,3}-\d{1,3}$/; // e.g. "JHN-3-16", "1SA-3-5"
const BOOK = /^[1-3A-Za-z]{3}$/;
const MAX_BOOKMARKS = 5000;
const MAX_HIGHLIGHTS = 20000;

const int = (v, min, max) => Number.isInteger(v) && v >= min && v <= max;

// Returns { bookmarks, highlights } with only well-formed entries, or null when the body is
// not an object at all.
export function cleanMarks(body) {
  if (!body || typeof body !== 'object' || Array.isArray(body)) return null;

  const bookmarks = {};
  if (body.bookmarks && typeof body.bookmarks === 'object' && !Array.isArray(body.bookmarks)) {
    for (const [key, color] of Object.entries(body.bookmarks).slice(0, MAX_BOOKMARKS)) {
      if (BOOKMARK_KEY.test(key) && typeof color === 'string' && COLOR.test(color)) bookmarks[key] = color;
    }
  }

  const highlights = [];
  if (Array.isArray(body.highlights)) {
    const seen = new Set();
    for (const h of body.highlights.slice(0, MAX_HIGHLIGHTS)) {
      if (!h || typeof h !== 'object') continue;
      if (typeof h.id !== 'string' || h.id.length === 0 || h.id.length > 64 || seen.has(h.id)) continue;
      if (!BOOK.test(String(h.book)) || !int(h.chapter, 1, 200) || !int(h.verse, 1, 200)) continue;
      if (!int(h.startOffset, 0, 5000) || !int(h.endOffset, 1, 5000) || h.endOffset <= h.startOffset) continue;
      if (typeof h.color !== 'string' || !COLOR.test(h.color)) continue;
      seen.add(h.id);
      highlights.push({
        id: h.id, book: String(h.book).toUpperCase(), chapter: h.chapter, verse: h.verse,
        startOffset: h.startOffset, endOffset: h.endOffset, color: h.color,
      });
    }
  }
  return { bookmarks, highlights };
}