import type { ProductListQuery } from '@sport/api-client';

/**
 * Parses listing filters out of a Next.js `searchParams` object.
 *
 * Kept deliberately permissive: unknown or malformed values are dropped rather
 * than rejected, because a listing page reached from a stale bookmark should
 * render products, not an error. The API re-validates everything anyway
 * (@sport/validation), so this is convenience, not enforcement.
 */
export type RawSearchParams = Record<string, string | string[] | undefined>;

const SORTS = ['newest', 'price_asc', 'price_desc', 'best_selling', 'relevance'] as const;

export function parseListingParams(params: RawSearchParams): ProductListQuery {
  return {
    q: single(params['q']),
    colors: list(params['colors']),
    sizes: list(params['sizes']),
    brandSlugs: list(params['brandSlugs']),
    categorySlug: single(params['category']),
    onSale: single(params['onSale']) === 'true' ? true : undefined,
    sort: parseSort(single(params['sort'])),
    // Present only when someone followed the "load more" link without
    // JavaScript, or a crawler did. The client path appends in place and never
    // puts a cursor in the address bar.
    cursor: single(params['cursor']),
  };
}

function single(value: string | string[] | undefined): string | undefined {
  const raw = Array.isArray(value) ? value[0] : value;
  return raw && raw.length > 0 ? raw : undefined;
}

/** Accepts both `?colors=a,b` and repeated `?colors=a&colors=b`. */
function list(value: string | string[] | undefined): string[] | undefined {
  if (!value) return undefined;

  const items = (Array.isArray(value) ? value : [value])
    .flatMap((entry) => entry.split(','))
    .map((entry) => entry.trim())
    .filter(Boolean);

  return items.length > 0 ? items : undefined;
}

function parseSort(value: string | undefined): ProductListQuery['sort'] {
  return SORTS.includes(value as (typeof SORTS)[number])
    ? (value as ProductListQuery['sort'])
    : undefined;
}