export const dynamic = "force-dynamic";

import type { Metadata } from "next";
import Link from "next/link";
import { notFound } from "next/navigation";
import { getBookMeta } from "@/lib/api";
import { ogForBook } from "@/lib/og";
import { PageHeader } from "@/components/layout/page-header";
import { JsonLd } from "@/components/seo/json-ld";
import { bookJsonLd } from "@/lib/jsonld";
import { Card, CardContent } from "@/components/ui/card";
import { ExtractedVerseCount } from "../extracted-verse-count";
import fs from "fs";
import path from "path";

export function generateMetadata(): Metadata {
  return ogForBook("nbs");
}

type NbsMeta = {
  book: string;
  title: string;
  author: string;
  year?: number;
  description?: string;
  totalChapters: number;
  chapters: { number: number; title: string; totalVerses: number }[];
};

type NbsIntroSegment = {
  slug: string;
  title: string;
  type: string;
  book: string;
  order: number;
  paragraphs: string[];
};

const NBS_JSON_DIR = path.join(process.cwd(), "lib", "jsons", "books", "nbs");

async function getMetaWithFallback(): Promise<NbsMeta | null> {
  const meta = await getBookMeta("nbs");
  if (meta) return meta as unknown as NbsMeta;

  const introPath = path.join(NBS_JSON_DIR, "intro.json");
  if (!fs.existsSync(introPath)) return null;
  try {
    return JSON.parse(fs.readFileSync(introPath, "utf-8")) as NbsMeta;
  } catch {
    return null;
  }
}

function getLocalIntroSegments(): NbsIntroSegment[] {
  const introDir = path.join(NBS_JSON_DIR, "intro");
  if (!fs.existsSync(introDir)) return [];

  const results: NbsIntroSegment[] = [];
  const files = ["introduction.json"];
  for (const file of files) {
    const filePath = path.join(introDir, file);
    if (fs.existsSync(filePath)) {
      try {
        results.push(
          JSON.parse(fs.readFileSync(filePath, "utf-8")) as NbsIntroSegment,
        );
      } catch {
        // skip
      }
    }
  }
  return results.sort((a, b) => a.order - b.order);
}

export default async function NbsPage() {
  const meta = await getMetaWithFallback();
  if (!meta) notFound();

  const introSegments = getLocalIntroSegments();
  const introduction = introSegments.find((s) => s.slug === "introduction");

  return (
    <div className="min-h-screen bg-background">
      <JsonLd data={bookJsonLd({ path: "/books/nbs", name: "Nārada-bhakti-sūtra" })} />
      <PageHeader>
        <Link
          href="/books"
          className="text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          &larr; Books
        </Link>
        <h1 className="mt-3 text-3xl font-bold text-foreground">
          {meta.title}
        </h1>
        <p className="mt-1 text-muted-foreground">{meta.author}</p>
        {meta.description && (
          <p className="mt-2 text-sm text-muted-foreground">
            {meta.description}
          </p>
        )}
      </PageHeader>

      <main className="max-w-5xl mx-auto px-6 py-8 space-y-8">
        {/* Front Matter */}
        {introduction && (
          <div>
            <h2 className="text-sm font-bold uppercase tracking-wider text-muted-foreground mb-3">
              Front Matter
            </h2>
            <Card className="divide-y divide-border">
              <CardContent className="p-0">
                <ul className="divide-y divide-border">
                  <li>
                    <Link
                      href="/books/nbs/intro-introduction"
                      className="flex flex-col sm:flex-row sm:items-center sm:justify-between px-5 py-4 gap-1 sm:gap-0 hover:bg-muted transition-colors"
                    >
                      <p className="font-medium text-foreground">
                        {introduction.title}
                      </p>
                      <span className="text-sm text-muted-foreground sm:shrink-0 sm:ml-4">
                      </span>
                    </Link>
                  </li>
                </ul>
              </CardContent>
            </Card>
          </div>
        )}

        {/* Chapters */}
        <div>
          <h2 className="text-sm font-bold uppercase tracking-wider text-muted-foreground mb-3">
            Chapters
          </h2>
          <Card className="divide-y divide-border py-0">
            <CardContent className="p-0">
              <ul className="divide-y divide-border">
                {meta.chapters.map((ch) => (
                  <li key={ch.number}>
                    <Link
                      href={`/books/nbs/${ch.number}`}
                      className="flex flex-col sm:flex-row sm:items-center sm:justify-between px-5 py-4 gap-1 sm:gap-0 hover:bg-muted transition-colors"
                    >
                      <div>
                        <span className="text-sm text-primary font-medium">
                          Chapter {ch.number}
                        </span>
                        <p className="font-medium text-foreground">
                          {ch.title}
                        </p>
                      </div>
                      <span className="text-sm text-muted-foreground sm:shrink-0 sm:ml-4">
                        <ExtractedVerseCount count={ch.totalVerses} />
                      </span>
                    </Link>
                  </li>
                ))}
              </ul>
            </CardContent>
          </Card>
        </div>
      </main>
    </div>
  );
}