// File: src/app/sitemap.xml/route.js
// Serves a valid XML sitemap at /sitemap.xml with correct headers.

export const revalidate = 86400; // re-generate once per day

function ensureSite() {
  const raw =
    process.env.NEXT_PUBLIC_SITE_URL?.replace(/\/$/, "") ||
    "http://localhost:3000";
  return raw;
}

function urlEntry(loc, {
  lastmod = new Date().toISOString(),
  changefreq = "weekly",
  priority = 0.7,
} = {}) {
  // escape minimal entities
  const esc = (s) => String(s)
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;");
  return `
  <url>
    <loc>${esc(loc)}</loc>
    <lastmod>${esc(lastmod)}</lastmod>
    <changefreq>${changefreq}</changefreq>
    <priority>${priority}</priority>
  </url>`;
}

export async function GET() {
  const site = ensureSite();
  const now = new Date().toISOString();

  // --- Edit the lists below anytime to add/remove routes ---

  // Core
  const core = ["/", "/pricing", "/order", "/reviews", "/contact"];

  // Learn & tools
  const learn = [
    "/learn-more",
    "/design-list",
    "/card-3d",
    "/nfc-check",
    "/nfc-profile-style",
  ];

  // Programs & offers
  const programs = [
    "/affiliate-referral-program-bangladesh",
    "/become-nfc-reseller-bangladesh",
    "/business-offer",
    "/nfc-qr-profile-package-bangladesh",              // Package 3
    "/nfc-store-owner-full-branded-setup-bangladesh",  // Package 4
  ];

  // Blog
  const blog = [
    "/blog/nfc-smart-visiting-card-bangladesh-guide",
    "/blog/medical-profile-subscription-bangladesh",
  ];

  // Legal / policy
  const legal = [
    "/privacy-policy",
    "/terms-and-condition",
    "/cookie-policy",
    "/refund-policy",
  ];

  // Build XML
  let body = `<?xml version="1.0" encoding="UTF-8"?>\n`;
  body += `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">\n`;

  const add = (paths, opts) => {
    for (const p of paths) {
      body += urlEntry(`${site}${p}`, { lastmod: now, ...(opts || {}) });
    }
  };

  add(core,    { changefreq: "daily",   priority: 1.0 });
  add(learn,   { changefreq: "weekly",  priority: 0.7 });
  add(programs,{ changefreq: "weekly",  priority: 0.8 });
  add(blog,    { changefreq: "monthly", priority: 0.6 });
  add(legal,   { changefreq: "yearly",  priority: 0.3 });

  /* ── Optional: append dynamic URLs (e.g., public profiles) ──
  try {
    const res = await fetch(
      `${process.env.NEXT_PUBLIC_API_BASE}/public-slugs`,
      { next: { revalidate: 86400 } }
    );
    if (res.ok) {
      const slugs = await res.json(); // e.g. ["bismillahithouse.com", "john-doe"]
      for (const s of slugs) {
        body += urlEntry(`${site}/p/${s}`, { lastmod: now, changefreq: "weekly", priority: 0.5 });
      }
    }
  } catch {}
  ───────────────────────────────────────────────────────────── */

  body += `\n</urlset>`;

  return new Response(body, {
    status: 200,
    headers: {
      "Content-Type": "application/xml; charset=utf-8",
      "Cache-Control": "public, max-age=0, s-maxage=86400, stale-while-revalidate=3600",
    },
  });
}