nobat724_front/app/blog/[slug]/page.js

import { cache } from "react";
import BlogPage from "@/components/blog";
import Layout from "@/components/layout/StLayout";
import { notFound } from "next/navigation";
import { fetchReq } from "@/lib/req";
import { getStateInfo } from "@/lib/getStateInfo";
import { getEntityOrigin } from "@/lib/getCanonicalUrl";
import { extractEntityCityId, findCityById } from "@/lib/domainHelpers";
import { safeJsonLd } from "@/lib/sanitize";
import { normalizeBlog, imageUrl } from "@/helper";

const FALLBACK_IMG = "/assets/images/og-image.png";
const API_URL = process.env.NEXT_PUBLIC_API_URL;

const getBlog = cache(async (slug) => {
  const res = await fetch(`${API_URL}/api/v1/blog/${slug}`, {
    next: { revalidate: 3600, tags: [`blog-${slug}`] },
  });
  if (res.status === 404 || res.status === 400) return null;
  if (!res.ok) throw new Error(`Failed to fetch blog: ${res.status}`);
  const json = await res.json();
  return json?.data?.data ?? null;
});

export async function generateMetadata({ params }) {
  const { slug } = await params;
  const { matchedCity } = await getStateInfo();
  const siteName = matchedCity?.site_name || "نوبت 724";

  const blog = await getBlog(slug);
  if (!blog) notFound();

  try {

    const title = `${blog.title} | ${siteName}`;
    const rawText = (blog.summary || blog.body || "")
      .replace(/<[^>]*>/g, "")
      .trim();
    const description = rawText.slice(0, 160) || blog.title;
    const image = blog.image_url ? imageUrl(blog.image_url) : FALLBACK_IMG;

    // C1-b — پست شهریافته به دامنهٔ همان شهر canonical می‌شود؛
    // پست سراسری (بدون شهر) روی دامنهٔ جاری self-canonical می‌ماند.
    const origin = await getEntityOrigin(extractEntityCityId(blog));

    return {
      title,
      description,
      alternates: { canonical: `${origin}/blog/${slug}` },
      openGraph: {
        title,
        description,
        type: "article",
        ...(blog.created_at && {
          publishedTime: new Date(blog.created_at * 1000).toISOString(),
        }),
        images: [image],
      },
      twitter: {
        card: "summary_large_image",
        title,
        description,
        images: [image],
      },
    };
  } catch (error) {
    console.error(`[blog/${slug}] generateMetadata failed:`, error);
    return {};
  }
}

async function Blog({ params }) {
  const { slug } = await params;

  const blog = normalizeBlog(await getBlog(slug));
  if (!blog) notFound();

  const blogCityId = extractEntityCityId(blog);
  const blogCity = findCityById(blogCityId);
  const origin = await getEntityOrigin(blogCityId);

  let relatedBlogs = [];
  const relatedResponse = await fetchReq(
    `${API_URL}/api/v1/blogs?page=1&limit=6`
  );
  relatedBlogs = (relatedResponse?.data || [])
    .filter((b) => b.uuid !== blog?.uuid)
    .slice(0, 4)
    .map(normalizeBlog);

  const jsonLd = blog
    ? {
        "@context": "https://schema.org",
        "@type": "Article",
        headline: blog.title,
        ...(blog.images?.[0]?.url && { image: imageUrl(blog.images[0].url) }),
        ...(blog.created && {
          datePublished: new Date(blog.created * 1000).toISOString(),
        }),
        ...(blog.author && { author: { "@type": "Person", name: blog.author } }),
        // پست شهریافته حوزهٔ جغرافیایی‌اش را اعلام می‌کند؛ پست سراسری این فیلد را ندارد.
        ...(blogCity && {
          spatialCoverage: { "@type": "Place", name: blogCity.name },
        }),
      }
    : null;

  const breadcrumbJsonLd = blog
    ? {
        "@context": "https://schema.org",
        "@type": "BreadcrumbList",
        itemListElement: [
          { "@type": "ListItem", position: 1, name: "خانه", item: origin },
          { "@type": "ListItem", position: 2, name: "مقالات", item: `${origin}/blogs` },
          { "@type": "ListItem", position: 3, name: blog.title },
        ],
      }
    : null;

  return (
    <>
      {jsonLd && (
        <script
          type="application/ld+json"
          dangerouslySetInnerHTML={{ __html: safeJsonLd(jsonLd) }}
        />
      )}
      {breadcrumbJsonLd && (
        <script
          type="application/ld+json"
          dangerouslySetInnerHTML={{ __html: safeJsonLd(breadcrumbJsonLd) }}
        />
      )}
      <Layout>
        <BlogPage blog={blog} blogs={relatedBlogs} cityName={blogCity?.name} />
      </Layout>
    </>
  );
}

export default Blog;