import Link from "next/link";
import { PageHeader } from "@/components/page-header";
import { getAllBooks, type BookMeta } from "@/lib/api";
import { BooksGrid, type BookInfo } from "./books-grid";

type ChapterEntry = { totalVerses: number };
type CantoEntry = { totalChapters: number; chapters: ChapterEntry[] };
type LilaEntry = { totalChapters: number; chapters: ChapterEntry[] };

interface ChapterBookMeta extends BookMeta {
  totalChapters: number;
  chapters: ChapterEntry[];
}

interface SbMeta extends BookMeta {
  totalCantos: number;
  cantos: CantoEntry[];
}

interface CcMeta extends BookMeta {
  totalLilas: number;
  lilas: LilaEntry[];
}

function buildBookList(allBooks: BookMeta[]): BookInfo[] {
  const books: BookInfo[] = [];

  for (const data of allBooks) {
    const slug = data.book;
    const title = data.title as string;
    const author = data.author as string;

    if (slug === "bg") {
      const bg = data as ChapterBookMeta;
      const totalVerses = bg.chapters.reduce(
        (sum, ch) => sum + ch.totalVerses,
        0,
      );
      books.push({
        slug,
        title,
        author,
        description: `${bg.totalChapters} chapters`,
        contentDescription:
          "The essence of Vedic knowledge — Lord Kṛṣṇa's teachings to Arjuna on the battlefield of Kurukṣetra.",
        totalVerses,
        href: "/books/bg",
      });
    } else if (slug === "sb1962") {
      const sb62 = data as ChapterBookMeta;
      const totalVerses = sb62.chapters.reduce(
        (sum, ch) => sum + ch.totalVerses,
        0,
      );
      books.push({
        slug,
        title,
        author,
        description: `${sb62.totalChapters} chapters · First Canto`,
        contentDescription:
          (data as { description?: string }).description ||
          "The original 1962 Indian edition of the First Canto.",
        totalVerses,
        href: "/books/sb1962",
      });
    } else if (slug === "sb") {
      const sb = data as SbMeta;
      const totalChapters = sb.cantos.reduce(
        (sum, c) => sum + c.totalChapters,
        0,
      );
      const totalVerses = sb.cantos.reduce(
        (sum, c) => sum + c.chapters.reduce((s, ch) => s + ch.totalVerses, 0),
        0,
      );
      books.push({
        slug,
        title,
        author,
        description: `${sb.totalCantos} cantos, ${totalChapters} chapters`,
        contentDescription:
          "The ripened fruit of Vedic literature — the science of God in 18,000 verses.",
        totalVerses,
        href: "/books/sb",
      });
    } else if (slug === "cc") {
      const cc = data as CcMeta;
      const totalChapters = cc.lilas.reduce(
        (sum, l) => sum + l.totalChapters,
        0,
      );
      const totalVerses = cc.lilas.reduce(
        (sum, l) => sum + l.chapters.reduce((s, ch) => s + ch.totalVerses, 0),
        0,
      );
      books.push({
        slug,
        title,
        author,
        description: `${cc.totalLilas} līlās, ${totalChapters} chapters`,
        contentDescription:
          "The life and teachings of Lord Caitanya Mahāprabhu — the most complete theistic science.",
        totalVerses,
        href: "/books/cc",
      });
    } else {
      // Generic handler for all other books — pulls description from metadata
      const metaDesc = (data as { description?: string }).description || "";
      const totalChapters = (data as { totalChapters?: number }).totalChapters;
      const totalMantras = (data as { totalMantras?: number }).totalMantras;
      const totalTexts = (data as { totalTexts?: number }).totalTexts;
      const parts = (data as { parts?: unknown[] }).parts;
      const volumes = (data as { volumes?: unknown[] }).volumes;

      let badge = "";
      if (totalMantras) badge = `${totalMantras} mantras`;
      else if (totalTexts) badge = `${totalTexts} texts`;
      else if (totalChapters && volumes)
        badge = `${totalChapters} chapters · ${volumes.length} volumes`;
      else if (totalChapters && parts)
        badge = `${totalChapters} chapters · ${parts.length} parts`;
      else if (totalChapters) badge = `${totalChapters} chapters`;

      books.push({
        slug,
        title,
        author,
        description: badge,
        contentDescription: metaDesc,
        totalVerses: 0,
        href: `/books/${slug}`,
      });
    }
  }

  return books;
}

export default async function BooksPage() {
  const allBooks = await getAllBooks();
  const books = buildBookList(allBooks);

  return (
    <div className="min-h-screen bg-background">
      <PageHeader>
        <Link
          href="/"
          className="text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          &larr; Home
        </Link>
        <h1 className="mt-3 text-3xl font-bold text-foreground">Books</h1>
        <p className="mt-1 text-muted-foreground">
          Browse the books and teachings of Śrīla Prabhupāda
        </p>
      </PageHeader>

      <main className="max-w-5xl mx-auto px-6 py-8">
        <BooksGrid books={books} />
      </main>
    </div>
  );
}