import type { Metadata } from "next";
import Link from "next/link";
import { notFound } from "next/navigation";
import { POSTS, getPost, formatDate } from "../posts";
import { Breadcrumb } from "@/components/marketing/Breadcrumb";
import {
  blogPostingSchema,
  breadcrumbSchema,
  jsonLdScript,
} from "@/lib/seo";

// Turn a heading string into a URL-safe anchor ID
function slugifyHeading(heading: string): string {
  return heading
    .toLowerCase()
    .replace(/[^a-z0-9\s-]/g, "")
    .replace(/\s+/g, "-")
    .replace(/-+/g, "-")
    .trim();
}

export function generateStaticParams() {
  return POSTS.map((p) => ({ slug: p.slug }));
}

export async function generateMetadata({
  params,
}: {
  params: Promise<{ slug: string }>;
}): Promise<Metadata> {
  const { slug } = await params;
  const post = getPost(slug);
  if (!post) return {};
  const url = `/blog/${post.slug}`;
  return {
    title: post.title,
    description: post.excerpt,
    alternates: { canonical: url },
    openGraph: {
      type: "article",
      url,
      siteName: "Tia",
      locale: "en_IN",
      title: post.title,
      description: post.excerpt,
      publishedTime: post.date,
      modifiedTime: post.date,
      authors: [post.author],
      section: post.category,
      // Uses the per-post opengraph-image.tsx in this segment.
    },
    twitter: {
      card: "summary_large_image",
      title: post.title,
      description: post.excerpt,
    },
  };
}

export default async function BlogPostPage({
  params,
}: {
  params: Promise<{ slug: string }>;
}) {
  const { slug } = await params;
  const post = getPost(slug);
  if (!post) notFound();

  // Extract headings for TOC
  const headings = post.sections.filter((s) => s.heading).map((s) => ({
    text: s.heading!,
    id: slugifyHeading(s.heading!),
  }));

  // Other posts (exclude current)
  const otherPosts = POSTS.filter((p) => p.slug !== slug).slice(0, 3);

  return (
    <div className="min-h-screen bg-white">
      {/* Structured data — BlogPosting + breadcrumb trail */}
      <script
        type="application/ld+json"
        dangerouslySetInnerHTML={jsonLdScript([
          blogPostingSchema(post),
          breadcrumbSchema([
            { name: "Home", path: "/" },
            { name: "Blog", path: "/blog" },
            { name: post.title, path: `/blog/${post.slug}` },
          ]),
        ])}
      />
      {/* Post hero / header */}
      <div className="bg-gradient-to-br from-rose-50 to-pink-50 border-b border-rose-100">
        <div className="max-w-6xl mx-auto px-5 pt-10 pb-10">
          <div className="max-w-2xl">
            <div className="flex flex-wrap items-center gap-2 mb-5">
              <span className={`text-xs font-semibold px-2.5 py-0.5 rounded-full ${post.categoryColor}`}>
                {post.category}
              </span>
              <span className="text-xs text-gray-400">{formatDate(post.date)}</span>
              <span className="text-xs text-gray-400">·</span>
              <span className="text-xs text-gray-400">{post.readTime}</span>
            </div>

            <h1 className="text-3xl sm:text-4xl font-bold text-gray-900 leading-tight mb-4">
              {post.emoji} {post.title}
            </h1>
            <p className="text-lg text-gray-500 leading-relaxed">{post.excerpt}</p>

            <div className="mt-5 text-sm text-gray-400">
              By <span className="text-gray-600 font-medium">{post.author}</span>
            </div>
          </div>
        </div>
      </div>

      {/* Breadcrumb — between hero and content */}
      <div className="max-w-6xl mx-auto px-5 pt-5 pb-1">
        <Breadcrumb
          items={[
            { label: "Home", href: "/" },
            { label: "Blog", href: "/blog" },
            { label: post.title },
          ]}
        />
      </div>

      {/* 3-column body */}
      <div className="max-w-6xl mx-auto px-5 py-6">
        <div className="grid grid-cols-1 lg:grid-cols-[220px_minmax(0,1fr)_200px] gap-10">

          {/* ── LEFT SIDEBAR: Table of Contents ── */}
          <aside className="hidden lg:block">
            <div className="sticky top-24">
              <p className="text-xs font-bold text-gray-400 uppercase tracking-widest mb-4">In this article</p>
              {headings.length > 0 ? (
                <ol className="flex flex-col gap-2">
                  {headings.map((h, i) => (
                    <li key={i}>
                      <a
                        href={`#${h.id}`}
                        className="group flex items-start gap-2 text-sm text-gray-500 hover:text-rose-600 transition-colors duration-150"
                      >
                        <span className="shrink-0 mt-0.5 w-4 h-4 rounded-full bg-rose-100 text-rose-500 text-[10px] flex items-center justify-center font-bold group-hover:bg-rose-200 transition-colors duration-150">
                          {i + 1}
                        </span>
                        <span className="leading-snug">{h.text}</span>
                      </a>
                    </li>
                  ))}
                </ol>
              ) : (
                <p className="text-xs text-gray-400">No sections</p>
              )}

              <div className="mt-8 pt-6 border-t border-gray-100">
                <Link
                  href="/blog"
                  className="flex items-center gap-1.5 text-sm text-rose-500 hover:text-rose-700 font-medium transition-colors"
                >
                  ← All articles
                </Link>
              </div>
            </div>
          </aside>

          {/* ── CENTER: Article body ── */}
          <article className="min-w-0">
            <div className="space-y-10">
              {post.sections.map((section, i) => (
                <div key={i}>
                  {section.heading && (
                    <h2
                      id={slugifyHeading(section.heading)}
                      className="text-xl font-bold text-gray-900 mb-4 mt-2 scroll-mt-28"
                    >
                      {section.heading}
                    </h2>
                  )}

                  {section.paragraphs?.map((p, j) => (
                    <p key={j} className="text-gray-600 leading-relaxed mb-4">
                      {p}
                    </p>
                  ))}

                  {section.table && (
                    <div className="overflow-x-auto mb-4 rounded-xl border border-gray-100">
                      <table className="w-full text-sm border-collapse">
                        <thead>
                          <tr className="bg-rose-50">
                            {section.table.headers.map((h, j) => (
                              <th
                                key={j}
                                className="text-left px-4 py-3 font-semibold text-gray-700 border-b border-rose-100"
                              >
                                {h}
                              </th>
                            ))}
                          </tr>
                        </thead>
                        <tbody>
                          {section.table.rows.map((row, j) => (
                            <tr key={j} className="border-b border-gray-50 last:border-0 hover:bg-gray-50">
                              {row.map((cell, k) => (
                                <td key={k} className="px-4 py-3 text-gray-600">
                                  {cell}
                                </td>
                              ))}
                            </tr>
                          ))}
                        </tbody>
                      </table>
                    </div>
                  )}

                  {section.list && (
                    <ul className="space-y-2.5 mb-4">
                      {section.list.map((item, j) => (
                        <li key={j} className="flex items-start gap-3 text-sm text-gray-600">
                          <span className="mt-1.5 w-1.5 h-1.5 rounded-full bg-rose-400 shrink-0" />
                          <span>
                            {item.label && (
                              <span className="font-semibold text-gray-800">{item.label}: </span>
                            )}
                            {item.text}
                          </span>
                        </li>
                      ))}
                    </ul>
                  )}

                  {section.callout && (
                    <div className="bg-rose-50 border border-rose-100 rounded-xl p-5 flex gap-3 items-start mb-4">
                      <span className="text-xl shrink-0 mt-0.5">{section.callout.emoji}</span>
                      <p className="text-sm text-rose-800 leading-relaxed">{section.callout.text}</p>
                    </div>
                  )}
                </div>
              ))}
            </div>

            {/* Article footer CTA */}
            <div className="mt-14 pt-10 border-t border-gray-100">
              <div className="bg-gradient-to-br from-rose-50 to-pink-50 rounded-2xl p-8 text-center border border-rose-100">
                <div className="text-3xl mb-3">🌸</div>
                <h3 className="text-xl font-bold text-gray-900 mb-2">Try Tia — free during early access</h3>
                <p className="text-gray-500 text-sm mb-6 max-w-sm mx-auto">
                  Log feeds, track vaccinations, and build a digital heirloom for your child. Built for Indian families.
                </p>
                <Link
                  href="/login"
                  className="inline-flex items-center gap-2 bg-rose-500 hover:bg-rose-600 text-white text-sm font-semibold px-7 py-3 rounded-full transition-colors duration-200"
                >
                  Get started →
                </Link>
              </div>

              {/* Back link — visible on mobile too */}
              <div className="mt-8 flex items-center justify-between">
                <Link
                  href="/blog"
                  className="inline-flex items-center gap-1.5 text-sm font-medium text-rose-600 hover:text-rose-700 transition-colors"
                >
                  ← All articles
                </Link>
                <span className="text-xs text-gray-400">
                  {formatDate(post.date)} · {post.readTime}
                </span>
              </div>
            </div>
          </article>

          {/* ── RIGHT SIDEBAR: More articles + categories ── */}
          <aside className="hidden lg:block">
            <div className="sticky top-24 space-y-8">

              {/* More articles */}
              <div>
                <p className="text-xs font-bold text-gray-400 uppercase tracking-widest mb-4">More articles</p>
                <div className="flex flex-col gap-4">
                  {otherPosts.map((p) => (
                    <Link
                      key={p.slug}
                      href={`/blog/${p.slug}`}
                      className="group flex items-start gap-2.5"
                    >
                      <span className="text-lg shrink-0 mt-0.5">{p.emoji}</span>
                      <div className="min-w-0">
                        <p className="text-xs text-gray-700 group-hover:text-rose-600 leading-snug font-medium transition-colors duration-150 line-clamp-2">
                          {p.title}
                        </p>
                        <p className="text-xs text-gray-400 mt-0.5">{p.readTime}</p>
                      </div>
                    </Link>
                  ))}
                </div>
              </div>

              <div className="border-t border-gray-100" />

              {/* Category badge */}
              <div>
                <p className="text-xs font-bold text-gray-400 uppercase tracking-widest mb-3">Filed under</p>
                <span className={`text-xs font-semibold px-2.5 py-1 rounded-full ${post.categoryColor}`}>
                  {post.category}
                </span>
              </div>

              <div className="border-t border-gray-100" />

              {/* CTA */}
              <div className="bg-rose-50 rounded-xl p-5 border border-rose-100 text-center">
                <div className="text-2xl mb-2">🌸</div>
                <p className="text-sm font-semibold text-gray-800 mb-1">Free early access</p>
                <p className="text-xs text-gray-500 mb-4 leading-relaxed">
                  Built for Indian families. No ads, no data selling.
                </p>
                <Link
                  href="/login"
                  className="inline-block w-full text-center bg-rose-500 hover:bg-rose-600 text-white text-xs font-semibold px-4 py-2.5 rounded-full transition-colors duration-200"
                >
                  Get started →
                </Link>
              </div>

            </div>
          </aside>

        </div>
      </div>
    </div>
  );
}