/**
 * Reverse the word order of a name. "Aiba Reika" → "Reika Aiba".
 * For single-token names returns null (no useful reverse).
 */
export function reverseName(name: string): string | null {
  const tokens = name.trim().split(/\s+/).filter(Boolean);
  if (tokens.length < 2) return null;
  return tokens.slice().reverse().join(" ");
}

/**
 * Build the displayed alt-name list for an actress: always lead with the
 * word-order-reversed name (auto-generated, user can't remove), then any
 * user-typed alt names from the comma-separated `altNames` field, deduped
 * and excluding the actress's own canonical name.
 */
export function buildAltNameChips(name: string, altNamesField: string | null): Array<{ value: string; auto: boolean }> {
  const out: Array<{ value: string; auto: boolean }> = [];
  const seen = new Set<string>([name.trim().toLowerCase()]);

  const reversed = reverseName(name);
  if (reversed && !seen.has(reversed.toLowerCase())) {
    out.push({ value: reversed, auto: true });
    seen.add(reversed.toLowerCase());
  }

  if (altNamesField) {
    for (const raw of altNamesField.split(/[,、，]/)) {
      const v = raw.trim();
      if (!v) continue;
      const k = v.toLowerCase();
      if (seen.has(k)) continue;
      seen.add(k);
      out.push({ value: v, auto: false });
    }
  }
  return out;
}