import type { Metadata } from "next";
import Link from "next/link";
import { notFound } from "next/navigation";
import { BlogCoverImage } from "@/components/BlogCoverImage";
import { ContentPageShell } from "@/components/ContentPageShell";
import { HtmlContent } from "@/components/HtmlContent";
import {
  ApiNotFoundError,
  authorName,
  formatFaDate,
  getBlog,
  getBlogCoverImage,
} from "@/lib/api";

type BlogDetailPageProps = {
  params: Promise<{ slug: string }>;
};

function stripLeadingCoverImage(html: string, cover: string | null): string {
  if (!html) return html;

  let next = html.replace(
    /^\s*<p[^>]*>\s*<img[^>]*>\s*<\/p>/i,
    "",
  );

  if (cover) {
    const escaped = cover.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
    next = next.replace(
      new RegExp(
        `<p[^>]*>\\s*<img[^>]*src=["']${escaped}["'][^>]*>\\s*<\\/p>`,
        "i",
      ),
      "",
    );
  }

  return next.trim();
}

export async function generateMetadata({
  params,
}: BlogDetailPageProps): Promise<Metadata> {
  const { slug } = await params;

  try {
    const blog = await getBlog(slug);
    return {
      title: `${blog.title} | مشکی`,
      description: blog.abstract ?? undefined,
      alternates: { canonical: `/blog/${blog.slug}` },
      openGraph: {
        title: blog.title,
        description: blog.abstract ?? undefined,
        type: "article",
      },
    };
  } catch {
    return { title: "مقاله | مشکی" };
  }
}

export default async function BlogDetailPage({ params }: BlogDetailPageProps) {
  const { slug } = await params;

  let blog;
  try {
    blog = await getBlog(slug);
  } catch (error) {
    if (error instanceof ApiNotFoundError) notFound();
    throw error;
  }

  const cover = getBlogCoverImage(blog);
  const date = formatFaDate(blog.publishedAt);
  const author = authorName(blog.author);
  const category = blog.categoryName;
  const bodyHtml = blog.mainTextHtml
    ? stripLeadingCoverImage(blog.mainTextHtml, cover)
    : null;
  const titleEn = category || "Blog";

  return (
    <ContentPageShell flushTop>
      <article className="pb-20 lg:pb-28">
        <div className="page-title-band mb-8 md:mb-10">
          <div className="relative mx-auto max-w-7xl px-5 pb-10 pt-[calc(var(--header-height)+0.15rem)] lg:px-8 lg:pb-12 lg:pt-[calc(var(--header-height)+0.3rem)]">
            <p
              aria-hidden
              className="latin pointer-events-none absolute inset-x-5 top-[calc(var(--header-height)+1.75rem)] z-0 text-[clamp(1.75rem,5.5vw,3.75rem)] font-light uppercase leading-none tracking-[0.05em] text-ink/[0.07] lg:inset-x-8 lg:top-[calc(var(--header-height)+1.95rem)]"
            >
              {titleEn}
            </p>

            <div className="reveal relative z-10">
              <nav
                aria-label="مسیر صفحه"
                className="mb-3 flex flex-wrap items-center gap-1.5 text-xs text-muted"
              >
                <Link href="/blog" className="link-hover">
                  مقالات
                </Link>
                {category ? (
                  <>
                    <span aria-hidden className="text-line">
                      /
                    </span>
                    <span className="latin uppercase tracking-[0.14em]">
                      {category}
                    </span>
                  </>
                ) : null}
                <span aria-hidden className="text-line">
                  /
                </span>
                <span className="line-clamp-1 text-ink-soft">{blog.title}</span>
              </nav>

              <h1 className="whitespace-normal text-[clamp(1.35rem,3.8vw,2.5rem)] font-normal leading-tight tracking-tight text-ink">
                {blog.title}
              </h1>

              {blog.abstract ? (
                <p className="mt-2 text-justify text-sm leading-7 text-muted md:text-base">
                  {blog.abstract}
                </p>
              ) : null}
            </div>
          </div>
        </div>

        <div className="mx-auto max-w-3xl px-5 lg:px-8">
          {cover ? (
            <div className="mb-5 overflow-hidden rounded-2xl">
              <BlogCoverImage
                src={cover}
                alt={blog.title}
                className="mx-auto max-h-[28rem]"
              />
            </div>
          ) : null}

          {(date || author) ? (
            <div className="mb-8 flex items-center justify-between gap-4 border-b border-line/70 pb-5 text-xs text-muted">
              {author ? <span>نویسنده: {author}</span> : <span />}
              {date ? (
                <time dateTime={blog.publishedAt ?? undefined}>{date}</time>
              ) : null}
            </div>
          ) : cover ? (
            <div className="mb-8 border-b border-line/70" />
          ) : null}

          {bodyHtml ? (
            <div className="reveal">
              <HtmlContent html={bodyHtml} />
            </div>
          ) : null}
        </div>
      </article>
    </ContentPageShell>
  );
}