import { LoaderFunctionArgs } from "@remix-run/node";
import { getInternalApiUrl } from "~/utils/api-config";

interface ExploreProduct {
  id: string;
  updatedAt?: string;
}

interface PaginatedResponse {
  results: ExploreProduct[];
  next: string | null;
}

// Fetch all products with pagination
async function fetchAllProducts(apiBaseUrl: string): Promise<ExploreProduct[]> {
  const allProducts: ExploreProduct[] = [];
  let cursor: string | undefined = undefined;
  const maxPages = 50; // Safety limit to prevent infinite loops
  let pageCount = 0;

  try {
    while (pageCount < maxPages) {
      const url = cursor
        ? `${apiBaseUrl}/api/explore/v1/?cursor=${cursor}`
        : `${apiBaseUrl}/api/explore/v1/`;

      const response = await fetch(url);
      if (!response.ok) break;

      const data: PaginatedResponse = await response.json();
      allProducts.push(...data.results);

      if (!data.next) break;

      // Extract cursor from next URL
      const nextUrl = new URL(data.next);
      cursor = nextUrl.searchParams.get("cursor") || undefined;
      if (!cursor) break;

      pageCount++;
    }
  } catch (error) {
    console.error("Error fetching products for sitemap:", error);
  }

  return allProducts;
}

export async function loader({ request }: LoaderFunctionArgs) {
  const baseUrl = new URL(request.url).origin;
  const apiBaseUrl = getInternalApiUrl();

  const staticPages = [
    { path: "/", priority: "1.0", changefreq: "daily" },
    { path: "/explore", priority: "0.9", changefreq: "daily" },
    { path: "/login", priority: "0.5", changefreq: "monthly" },
    { path: "/profile", priority: "0.7", changefreq: "weekly" },
    { path: "/cart", priority: "0.6", changefreq: "daily" },
  ];

  // Fetch products from API
  const products = await fetchAllProducts(apiBaseUrl);

  const today = new Date().toISOString().split("T")[0];

  const staticUrls = staticPages
    .map(
      (page) => `  <url>
    <loc>${baseUrl}${page.path}</loc>
    <lastmod>${today}</lastmod>
    <changefreq>${page.changefreq}</changefreq>
    <priority>${page.priority}</priority>
  </url>`,
    )
    .join("\n");

  const productUrls = products
    .map((product) => {
      const lastmod = product.updatedAt
        ? new Date(product.updatedAt).toISOString().split("T")[0]
        : today;
      return `  <url>
    <loc>${baseUrl}/product/${product.id}</loc>
    <lastmod>${lastmod}</lastmod>
    <changefreq>weekly</changefreq>
    <priority>0.8</priority>
  </url>`;
    })
    .join("\n");

  const sitemap = `<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
${staticUrls}
${productUrls}
</urlset>`;

  return new Response(sitemap, {
    status: 200,
    headers: {
      "Content-Type": "application/xml",
      "Cache-Control": "public, max-age=3600", // Cache for 1 hour
    },
  });
}