import type { Product, Sku } from "@vmall/shared";

/**
 * Cheapest active SKU, preferring one that is in stock. A pure helper over a
 * `Product`, so it lives here rather than in the fixed-data module.
 */
export function lowestSku(product: Product): Sku | null {
  const active = (product.skus ?? []).filter((sku) => sku.active && sku.stock > 0);
  return (
    active.reduce<Sku | null>(
      (low, sku) => (low === null || sku.price_minor < low.price_minor ? sku : low),
      null,
    ) ?? (product.skus ?? []).find((sku) => sku.active) ?? null
  );
}