/**
 * JSON-LD 提取器（schema.org/Product）
 *
 * Ozon 是 SSR 站点，商品页 HTML 里带 application/ld+json，
 * 是 DOM 之外最稳定的结构化来源（比哈希类名稳定一个数量级）。
 *
 * 参考实现（毛子ERP）也解析 application/ld+json 取 description / offers.url。
 */

export interface JsonLdProduct {
  title?: string;
  description?: string;
  brand?: string;
  sku?: string;
  price?: string;
  currency?: string;
  images: string[];
  rating?: string;
  reviewCount?: string;
}

function asString(v: unknown): string | undefined {
  if (typeof v === 'string') return v;
  if (typeof v === 'number') return String(v);
  return undefined;
}

function findProduct(node: unknown): any | null {
  if (Array.isArray(node)) {
    for (const item of node) {
      const r = findProduct(item);
      if (r) return r;
    }
    return null;
  }
  if (!node || typeof node !== 'object') return null;

  const obj = node as Record<string, unknown>;
  const type = obj['@type'];
  const types = Array.isArray(type) ? type : [type];
  if (types.some((t) => t === 'Product')) return obj;

  // @graph 包裹
  if (Array.isArray(obj['@graph'])) {
    for (const g of obj['@graph']) {
      const r = findProduct(g);
      if (r) return r;
    }
  }
  return null;
}

function collectImages(node: unknown, out: string[]): void {
  if (!node) return;
  if (typeof node === 'string') {
    if (/^(https?:)?\/\/.+/i.test(node) && !out.includes(node)) out.push(node);
    return;
  }
  if (Array.isArray(node)) {
    node.forEach((n) => collectImages(n, out));
    return;
  }
  if (typeof node === 'object') {
    for (const v of Object.values(node as Record<string, unknown>)) {
      collectImages(v, out);
    }
  }
}

export function extractJsonLd(): JsonLdProduct | null {
  try {
    const scripts = document.querySelectorAll('script[type="application/ld+json"]');
    for (const script of Array.from(scripts)) {
      const text = script.textContent?.trim();
      if (!text) continue;
      let data: unknown;
      try {
        data = JSON.parse(text);
      } catch {
        continue;
      }
      const product = findProduct(data);
      if (!product) continue;

      const offers = Array.isArray(product.offers) ? product.offers[0] : product.offers;
      const brandName = product.brand?.name ?? (typeof product.brand === 'string' ? product.brand : undefined);

      const images: string[] = [];
      if (product.image) collectImages(product.image, images);

      return {
        title: asString(product.name),
        description: asString(product.description),
        brand: asString(brandName),
        sku: asString(product.sku),
        price: asString(offers?.price),
        currency: asString(offers?.priceCurrency),
        images,
        rating: asString(product.aggregateRating?.ratingValue),
        reviewCount: asString(product.aggregateRating?.reviewCount),
      };
    }
  } catch (err) {
    console.warn('[JSON-LD] 提取失败:', err);
  }
  return null;
}