import { getPostBySlug } from '@/lib/mdx';
import { MDXRemote } from 'next-mdx-remote/rsc';
import Link from 'next/link';
import { notFound } from 'next/navigation';
import { format } from 'date-fns';
import rehypeSlug from 'rehype-slug';
import rehypeAutolinkHeadings from 'rehype-autolink-headings';
import { TableOfContents } from '@/components/mdx/TableOfContents';
import { SideNote } from '@/components/mdx/SideNote';
import { Citation, Bibliography } from '@/components/mdx/Citation';
import { MobileTableOfContents } from '@/components/mdx/MobileTableOfContents';

// Utility to ensure consistent IDs
const slugify = (text: any): string => {
    if (!text) return '';
    const str = typeof text === 'string' ? text : String(text);
    return str
        .toLowerCase()
        .replace(/[^a-z0-9]+/g, '-')
        .replace(/^-+|-+$/g, '');
};

const components = {
    h1: (props: any) => <h1 {...props} id={slugify(props.children)} className="text-3xl font-bold mt-8 mb-4 text-zinc-900 dark:text-zinc-50 scroll-mt-24" />,
    h2: (props: any) => <h2 {...props} id={slugify(props.children)} className="text-2xl font-bold mt-8 mb-4 text-zinc-900 dark:text-zinc-50 scroll-mt-24" />,
    h3: (props: any) => <h3 {...props} id={slugify(props.children)} className="text-xl font-bold mt-6 mb-3 text-zinc-900 dark:text-zinc-50 scroll-mt-24" />,
    p: (props: any) => <p {...props} className="mb-4 leading-relaxed text-zinc-700 dark:text-zinc-300" />,
    ul: (props: any) => <ul {...props} className="list-disc pl-5 mb-4 space-y-2 text-zinc-700 dark:text-zinc-300" />,
    ol: (props: any) => <ol {...props} className="list-decimal pl-5 mb-4 space-y-2 text-zinc-700 dark:text-zinc-300" />,
    blockquote: (props: any) => <blockquote {...props} className="border-l-4 border-zinc-200 dark:border-zinc-700 pl-4 italic my-6 text-zinc-600 dark:text-zinc-400" />,
    code: (props: any) => <code {...props} className="bg-zinc-100 dark:bg-zinc-800 text-pink-600 dark:text-pink-400 px-1 py-0.5 rounded text-sm font-mono" />,
    pre: (props: any) => <pre {...props} className="bg-zinc-900 dark:bg-zinc-900 text-zinc-100 p-4 rounded-lg overflow-x-auto my-6 text-sm font-mono" />,
    a: (props: any) => <a {...props} className="text-zinc-900 dark:text-zinc-100 underline decoration-zinc-300 dark:decoration-zinc-700 hover:decoration-zinc-900 dark:hover:decoration-zinc-100 transition-all font-medium" />,
    SideNote,
    Citation,
    Bibliography,
};

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

export async function generateMetadata({ params }: Props) {
    const { slug } = await params;
    try {
        const { metadata } = getPostBySlug(slug);
        return {
            title: metadata.title,
            description: metadata.description,
        };
    } catch {
        return {
            title: 'Post Not Found',
        };
    }
}

export default async function BlogPost({ params }: Props) {
    const { slug } = await params;

    let post;
    try {
        post = getPostBySlug(slug);
    } catch {
        notFound();
    }

    // Extract headings for TOC
    const headingLines = post.content.match(/^#{2,3}\s+(.+)$/gm) || [];
    const headings = headingLines.map((line) => {
        const level = line.match(/^#+/)?.[0].length || 2;
        const text = line.replace(/^#+\s+/, '').trim();
        const id = slugify(text);
        return { id, text, level };
    });

    return (
        <div className="max-w-7xl mx-auto px-6 py-24 animate-fade-in relative">

            <div className="grid grid-cols-1 xl:grid-cols-[250px_1fr] gap-12">
                {/* Left Column: TOC */}
                <aside className="hidden xl:block">
                    <div className="sticky top-32">
                        <TableOfContents headings={headings} />
                    </div>
                </aside>

                {/* Right Column: Content */}
                <article className="max-w-3xl mx-auto xl:mx-0 w-full">

                    {/* Mobile TOC */}
                    <MobileTableOfContents headings={headings} />

                    <header className="mb-12 text-center sm:text-left">
                        <div className="flex items-center gap-3 text-sm text-zinc-400 dark:text-zinc-500 mb-4 justify-center sm:justify-start">
                            <time dateTime={post.metadata.date}>
                                {format(new Date(post.metadata.date), 'MMMM d, yyyy')}
                            </time>
                            <span className="w-1 h-1 rounded-full bg-zinc-300 dark:bg-zinc-700" />
                            <div className="flex gap-2">
                                {Array.isArray(post.metadata.tags) && post.metadata.tags.map((tag: string) => (
                                    <span key={tag} className="text-xs uppercase tracking-wider">{tag}</span>
                                ))}
                            </div>
                        </div>

                        <h1 className="text-4xl sm:text-5xl font-bold tracking-tight text-zinc-900 dark:text-zinc-50 mb-6 leading-tight">
                            {post.metadata.title}
                        </h1>

                        <p className="text-xl text-zinc-500 dark:text-zinc-400 font-light leading-relaxed">
                            {post.metadata.description}
                        </p>
                    </header>

                    <div className="prose prose-zinc dark:prose-invert prose-lg max-w-none relative">
                        <MDXRemote
                            source={post.content}
                            components={components}
                            options={{
                                mdxOptions: {
                                    rehypePlugins: [
                                        [rehypeAutolinkHeadings, { behavior: 'wrap' }]
                                    ]
                                }
                            }}
                        />
                    </div>

                    <div className="mt-16 pt-8 border-t border-zinc-200 dark:border-zinc-800 flex justify-between items-center text-sm text-zinc-500">
                        <Link href="/blog" className="hover:text-zinc-900 dark:hover:text-zinc-100 transition-colors">
                            &larr; Back to all posts
                        </Link>
                        <a href="#" className="hover:text-zinc-900 dark:hover:text-zinc-100 transition-colors">
                            Scroll to top &uarr;
                        </a>
                    </div>
                </article>
            </div>
        </div>
    );
}