// Deriving a Team's URL slug from a game-written name (TEAMS.md §2.1).
//
// A slug is derived ONCE, at create, and then frozen for the life of the row —
// like `name`, and for the same reason: the Team page URL has to stay stable, and
// a rename is an archive plus a create rather than an edit.

const MAX_SLUG = 180 // the column is 191; leaves room for a -NN suffix

/**
 * Reduce a name to a URL-safe stem.
 *
 * Diacritics are folded rather than stripped so "Ünderdark" becomes "underdark"
 * and not "nderdark". A name made entirely of characters that do not survive —
 * which a guild name genuinely can be, since the game accepts far more than a URL
 * does — leaves an empty stem, and the caller substitutes a stable fallback
 * rather than minting a Team with no address.
 */
function slugify(name) {
  return String(name || '')
    .normalize('NFKD')
    .replace(/[̀-ͯ]/g, '')
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, MAX_SLUG)
    .replace(/-+$/g, '')
}

/**
 * A slug not already taken, given the ones that are.
 *
 * `taken` must include ARCHIVED teams' slugs, not only active ones. The unique
 * key constrains active rows alone, so the database would allow a new Team to
 * take a retired Team's slug — and §2.2 promises the retired one stays readable
 * at that address, which is what a bookmark or an old Discord link resolves to.
 */
function uniqueSlug(name, taken, { fallback = 'team' } = {}) {
  const base = slugify(name) || fallback
  const used = new Set(taken)
  if (!used.has(base)) return base
  // Bounded rather than unbounded: a suffix search that cannot terminate is worse
  // than a slug with an id in it, and 999 same-named teams is already absurd.
  for (let n = 2; n <= 999; n++) {
    const candidate = `${base}-${n}`
    if (!used.has(candidate)) return candidate
  }
  return `${base}-${Date.now().toString(36)}`
}

module.exports = { slugify, uniqueSlug, MAX_SLUG }