import { XMLBuilder } from 'fast-xml-parser';

export async function generateMetaCatalogFeed(req: Request, res: Response) {
  const products = await db.products.findAll({
    where: { status: 'active', availableForSale: true },
    include: ['variants', 'images'],
  });

  const items = products.flatMap((p) =>
    p.variants.map((v) => ({
      id: v.sku,                    // Use SKU as the catalog item ID — must be stable
      title: p.name,
      description: p.description.slice(0, 9999),
      availability: v.inventory > 0 ? 'in stock' : 'out of stock',
      condition: 'new',
      price: `${(v.priceInCents / 100).toFixed(2)} USD`,
      link: `${process.env.STORE_URL}/products/${p.slug}?variant=${v.id}`,
      image_link: p.images[0]?.url,
      brand: p.brand ?? process.env.STORE_NAME,
      google_product_category: p.googleProductCategory,
      item_group_id: p.id,          // Required: groups variants together in Meta
      color: v.color,
      size: v.size,
    }))
  );

  const builder = new XMLBuilder({ arrayNodeName: 'item', ignoreAttributes: false });
  const xml = builder.build({ rss: { channel: { item: items } } });

  res.setHeader('Content-Type', 'application/xml');
  res.setHeader('Cache-Control', 'public, max-age=3600');
  res.send(xml);
}

// Push individual product updates immediately when price or inventory changes
async function pushProductUpdateToMeta(variantSku: string, inventory: number, priceInCents: number) {
  await fetch(`https://graph.facebook.com/v18.0/${process.env.META_CATALOG_ID}/items_batch`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      access_token: process.env.META_ACCESS_TOKEN,
      item_type: 'PRODUCT_ITEM',
      requests: [{
        method: 'UPDATE',
        retailer_id: variantSku,
        data: {
          availability: inventory > 0 ? 'in stock' : 'out of stock',
          price: `${(priceInCents / 100).toFixed(2)} USD`,
        },
      }],
    }),
  });
}