export const dynamic = "force-dynamic";

import type { Metadata } from "next";
import fs from "fs";
import path from "path";
import Link from "next/link";
import { PageHeader } from "@/components/layout/page-header";
import { FindInPage } from "@/components/layout/find-in-page";
import { notFound } from "next/navigation";
import {
  getBookMeta,
  getSingleVerse,
  getChapterVerseIndex,
  type VerseIndexEntry,
  type VerseRecord,
} from "@/lib/api";
import { ogForVerse, extractQuoteFromHl, buildOgMeta } from "@/lib/og";
import { ChapterViewer } from "@/app/(app)/(reader)/books/chapter-viewer";
import type { MobileNavGroup } from "@/components/layout/mobile-nav";

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

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

// Fallback functions that read from local JSON when DB is empty
async function getMetaWithFallback() {
  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;
  }
}

async function getVerseIndexWithFallback(
  chapter: number,
): Promise<VerseIndexEntry[]> {
  const index = await getChapterVerseIndex("nbs", null, chapter);
  if (index.length > 0) return index;

  // Fallback: read verse files from local JSON
  const versesDir = path.join(
    NBS_JSON_DIR,
    "chapters",
    String(chapter).padStart(2, "0"),
    "verses",
  );
  if (!fs.existsSync(versesDir)) return [] as VerseIndexEntry[];

  const files = fs
    .readdirSync(versesDir)
    .filter((f) => f.endsWith(".json"))
    .sort();
  return files.map((f): VerseIndexEntry => {
    const v = JSON.parse(fs.readFileSync(path.join(versesDir, f), "utf-8"));
    return {
      verse: v.verse,
      verseEnd: v.verse_end || null,
      reference: v.reference,
    };
  });
}

async function getVerseWithFallback(
  chapter: number,
  verse: number,
): Promise<VerseRecord | null> {
  const v = await getSingleVerse("nbs", null, chapter, verse);
  if (v) return v;

  // Fallback: read from local JSON
  const versesDir = path.join(
    NBS_JSON_DIR,
    "chapters",
    String(chapter).padStart(2, "0"),
    "verses",
  );
  if (!fs.existsSync(versesDir)) return null;

  const files = fs
    .readdirSync(versesDir)
    .filter((f) => f.endsWith(".json"))
    .sort();
  for (const f of files) {
    const data = JSON.parse(fs.readFileSync(path.join(versesDir, f), "utf-8"));
    if (data.verse === verse) {
      return {
        id: `nbs-${chapter}-${verse}`,
        book: "nbs",
        division: null,
        chapter: data.chapter,
        verse: data.verse,
        verseEnd: data.verse_end || null,
        reference: data.reference,
        bookTitle: data.book_title,
        devanagari: data.devanagari,
        bengali: null,
        transliteration: data.transliteration,
        synonyms: data.synonyms,
        translation: data.translation,
        purport: data.purport,
      };
    }
  }
  return null;
}

export async function generateMetadata({
  params,
  searchParams,
}: {
  params: Promise<{ chapter: string; verse: string }>;
  searchParams: Promise<Record<string, string | string[] | undefined>>;
}): Promise<Metadata> {
  const { chapter, verse } = await params;
  const sp = await searchParams;
  const v = await getSingleVerse(
    "nbs",
    null,
    parseInt(chapter),
    parseInt(verse),
  );
  const paragraphs = v ? [v.translation, ...v.purport] : undefined;
  const quote = extractQuoteFromHl(sp, paragraphs);
  if (quote) {
    return buildOgMeta({
      title: "Nārada-bhakti-sūtra",
      detail: `Chapter ${chapter}, Verse ${verse}`,
      quote,
    });
  }
  return ogForVerse("nbs", {
    chapter: parseInt(chapter),
    verse: parseInt(verse),
  });
}

export default async function VersePage({
  params,
}: {
  params: Promise<{ chapter: string; verse: string }>;
}) {
  const { chapter, verse: verseParam } = await params;

  const nbsMeta = await getMetaWithFallback();
  if (!nbsMeta) notFound();

  const chapterInfo = nbsMeta.chapters?.find(
    (c) => c.number === parseInt(chapter),
  );
  if (!chapterInfo?.title) notFound();

  const title: string = chapterInfo.title;

  const verseIndex = await getVerseIndexWithFallback(parseInt(chapter));
  if (verseIndex.length === 0) notFound();

  const requestedVerse = parseInt(verseParam);
  const verse = await getVerseWithFallback(parseInt(chapter), requestedVerse);
  if (!verse) notFound();

  // Build mobile nav groups — verses for the current chapter
  const mobileNavGroups: MobileNavGroup[] = [
    {
      title: "Verses",
      items: verseIndex.map((v) => ({
        slug: String(v.verse),
        label: v.verseEnd
          ? `Verse ${chapter}.${v.verse}–${v.verseEnd}`
          : `Verse ${chapter}.${v.verse}`,
        href: `/books/nbs/${chapter}/${v.verse}`,
        type: "verse",
      })),
    },
  ];

  return (
    <div className="min-h-screen bg-background">
      <PageHeader sticky>
        <Link
          href="/books/nbs"
          className="text-sm text-muted-foreground hover:text-foreground"
        >
          &larr; Nārada-bhakti-sūtra
        </Link>
        <div className="mt-2 flex items-start justify-between gap-3">
          <h1 className="text-2xl font-bold text-foreground">
            Chapter {chapter}: {title}
          </h1>
          <FindInPage targetId="book-content" className="shrink-0 mt-0.5" />
        </div>
      </PageHeader>

      <div className="max-w-5xl mx-auto flex">
        <ChapterViewer
          initialVerse={verse}
          initialVerseNum={requestedVerse}
          verseIndex={verseIndex.map((v) => ({
            verse: v.verse,
            verseEnd: v.verseEnd ?? undefined,
            reference: v.reference,
          }))}
          book="nbs"
          division={null}
          chapter={parseInt(chapter)}
          basePath={`/books/nbs/${chapter}`}
          showBengali={false}
          mobileNavGroups={mobileNavGroups}
          mobileNavBookTitle={`Chapter ${chapter}: ${title}`}
        />
      </div>
    </div>
  );
}