import { Types } from "mongoose";
import { Product } from "@/lib/server/models/Product";

/**
 * Two products with the same name (ignoring case) would be impossible to
 * tell apart on the terminal and in reports, so names are unique per
 * business — including deactivated products, which can be reactivated.
 */
export async function labelTakenError(
  businessId: Types.ObjectId | string,
  label: string,
  exceptId?: string
): Promise<string | null> {
  const filter: Record<string, unknown> = { businessId, label: label.trim() };
  if (exceptId) filter._id = { $ne: exceptId };
  const clash = await Product.findOne(filter).collation({ locale: "en", strength: 2 }).select("label isActive").lean();
  if (!clash) return null;
  return clash.isActive
    ? `A product called "${clash.label}" already exists.`
    : `A deactivated product called "${clash.label}" already exists. Reactivate it instead.`;
}