import { getPostBySlug, getPostSlugs } 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 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';

const slugify = (text: React.ReactNode): 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: React.ComponentPropsWithoutRef<'h1'>) => <h1 {...props} id={slugify(props.children)} className="mt-12 scroll-mt-24 font-sans text-[2rem] font-medium leading-tight tracking-[-0.05em] text-ink sm:text-[2.5rem]" />,
    h2: (props: React.ComponentPropsWithoutRef<'h2'>) => <h2 {...props} id={slugify(props.children)} className="mt-14 scroll-mt-24 font-sans text-[1.65rem] font-medium leading-tight tracking-[-0.05em] text-ink sm:text-[2rem]" />,
    h3: (props: React.ComponentPropsWithoutRef<'h3'>) => <h3 {...props} id={slugify(props.children)} className="mt-10 scroll-mt-24 font-sans text-[1.22rem] font-medium tracking-[-0.03em] text-ink sm:text-[1.42rem]" />,
    p: (props: React.ComponentPropsWithoutRef<'p'>) => <p {...props} className="mb-6 text-[1.02rem] leading-[1.85] text-ink-soft" />,
    ul: (props: React.ComponentPropsWithoutRef<'ul'>) => <ul {...props} className="mb-6 list-disc space-y-2 pl-5 text-[0.98rem] leading-8 text-ink-soft marker:text-accent" />,
    ol: (props: React.ComponentPropsWithoutRef<'ol'>) => <ol {...props} className="mb-6 list-decimal space-y-2 pl-5 text-[0.98rem] leading-8 text-ink-soft marker:text-accent" />,
    blockquote: (props: React.ComponentPropsWithoutRef<'blockquote'>) => <blockquote {...props} className="my-10 border-l border-line-strong pl-5 text-[1.05rem] italic leading-8 text-ink-soft" />,
    code: (props: React.ComponentPropsWithoutRef<'code'>) => <code {...props} className="rounded bg-paper-strong px-1.5 py-0.5 font-mono text-[0.9em] text-ink" />,
    pre: (props: React.ComponentPropsWithoutRef<'pre'>) => <pre {...props} className="my-8 overflow-x-auto rounded-[1rem] border border-line bg-[#161412] p-5 text-sm text-paper shadow-[0_16px_40px_rgba(17,16,15,0.12)]" />,
    a: (props: React.ComponentPropsWithoutRef<'a'>) => <a {...props} className="font-medium text-ink underline decoration-line-strong underline-offset-4 transition-colors hover:text-accent hover:decoration-accent" />,
    SideNote,
    Citation,
    Bibliography,
};

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

export function generateStaticParams() {
    return getPostSlugs()
        .filter((slug) => slug.endsWith('.mdx'))
        .map((slug) => ({ slug: slug.replace(/\.mdx$/, '') }));
}

export async function generateMetadata({ params }: Props) {
    const { slug } = await params;
    try {
        const { metadata } = getPostBySlug(slug);
        return {
            title: metadata.title,
            description: metadata.description,
            openGraph: {
                title: metadata.title,
                description: metadata.description,
                type: 'article' as const,
                publishedTime: metadata.date,
            },
            twitter: {
                card: 'summary' as const,
                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();
    }

    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 };
    });
    const tags = Array.isArray(post.metadata.tags) ? post.metadata.tags : [];

    return (
        <div className="page-frame py-20 sm:py-24">
            <div className="mx-auto max-w-[78rem] xl:grid xl:grid-cols-[11rem_minmax(0,44rem)] xl:gap-x-10">
                <aside className="hidden xl:block">
                    <div className="sticky top-24">
                        <TableOfContents headings={headings} />
                    </div>
                </aside>

                <article className="w-full">
                    <header className="mb-8 space-y-4 border-b border-line pb-8">
                        <div className="flex flex-wrap items-center gap-x-4 gap-y-2 text-[0.72rem] font-mono uppercase tracking-[0.14em] text-muted-strong">
                            <time dateTime={post.metadata.date}>
                                {format(new Date(post.metadata.date), 'MMMM d, yyyy')}
                            </time>
                            {tags.map((tag: string) => (
                                <span key={tag}>{tag}</span>
                            ))}
                        </div>

                        <h1 className="max-w-[38rem] text-balance font-sans text-[clamp(2.7rem,5.8vw,4.4rem)] font-medium leading-[0.94] tracking-[-0.08em] text-ink">
                            {post.metadata.title}
                        </h1>

                        <p className="max-w-[34rem] text-[1.04rem] leading-8 text-muted">
                            {post.metadata.description}
                        </p>
                    </header>

                    <MobileTableOfContents headings={headings} />

                    <div className="essay-prose relative mt-8 max-w-none xl:max-w-[44rem]">
                        <MDXRemote
                            source={post.content}
                            components={components}
                            options={{
                                mdxOptions: {
                                    rehypePlugins: [
                                        [rehypeAutolinkHeadings, { behavior: 'wrap' }]
                                    ]
                                }
                            }}
                        />
                    </div>

                    <div className="mt-14 flex items-center justify-between border-t border-line pt-6 text-sm text-muted">
                        <Link href="/blog" className="transition-colors hover:text-ink">
                            &larr; Back to all posts
                        </Link>
                        <a href="#" className="transition-colors hover:text-ink">
                            Scroll to top &uarr;
                        </a>
                    </div>
                </article>
            </div>
        </div>
    );
}
