export const dynamic = "force-dynamic";

import type { Metadata } from "next";
import Link from "next/link";
import { notFound } from "next/navigation";
import { getProseChapter, getProseChapters } from "@/lib/api";
import { ogForChapter, extractQuoteFromHl, buildOgMeta } from "@/lib/og";
import { BOOK_NAMES } from "@/lib/constants";
import { PageHeader } from "@/components/layout/page-header";
import { JsonLd } from "@/components/seo/json-ld";
import { articleJsonLd } from "@/lib/jsonld";
import { Card, CardContent } from "@/components/ui/card";
import { buttonVariants } from "@/components/ui/button";
import { ChevronLeft, ChevronRight } from "lucide-react";
import { cn } from "@/lib/utils";
import { MobileNav, type MobileNavGroup } from "@/components/layout/mobile-nav";
import { FindInPage } from "@/components/layout/find-in-page";

export async function generateMetadata({
  params,
  searchParams,
}: {
  params: Promise<{ volume: string; slug: string }>;
  searchParams: Promise<Record<string, string | string[] | undefined>>;
}): Promise<Metadata> {
  const { volume, slug } = await params;
  const sp = await searchParams;
  const vol = parseInt(volume);
  const chapter = !isNaN(vol) ? await getProseChapter("kb", vol, slug) : null;
  const hlQuote = extractQuoteFromHl(sp, chapter?.paragraphs);
  if (hlQuote) {
    return buildOgMeta({
      title: BOOK_NAMES["kb"],
      detail: chapter ? `Volume ${vol} — ${chapter.title}` : `Volume ${vol}`,
      quote: hlQuote,
    });
  }
  return ogForChapter(
    "kb",
    chapter ? `Volume ${vol} — ${chapter.title}` : `Volume ${vol}`,
  );
}

export default async function KbChapterPage({
  params,
}: {
  params: Promise<{ volume: string; slug: string }>;
}) {
  const { volume, slug } = await params;
  const vol = parseInt(volume);
  if (isNaN(vol) || vol < 1 || vol > 2) notFound();

  const chapter = await getProseChapter("kb", vol, slug);
  if (!chapter) notFound();

  // Fetch all chapters/segments in this volume for sidebar + prev/next
  const allChapters = await getProseChapters("kb", vol);
  const currentIdx = allChapters.findIndex((ch) => ch.slug === slug);

  const prev = currentIdx > 0 ? allChapters[currentIdx - 1] : null;
  const next =
    currentIdx < allChapters.length - 1 ? allChapters[currentIdx + 1] : null;

  const chapterLabel =
    chapter.type === "chapter" && chapter.chapter != null
      ? `Chapter ${chapter.chapter}`
      : null;

  return (
    <div className="min-h-screen bg-background">
      <JsonLd data={articleJsonLd({ path: `/books/kb/${vol}/${slug}`, headline: chapter.title, description: chapter.paragraphs?.[0], isPartOf: "Kṛṣṇa, The Supreme Personality of Godhead" })} />
      <PageHeader sticky>
        <Link
          href={`/books/kb/${vol}`}
          className="text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          &larr; Volume {vol}
        </Link>
        <div className="mt-3 flex items-start justify-between gap-3">
          <h1 className="text-2xl font-bold text-foreground">
            {chapterLabel && (
              <span className="text-primary">{chapterLabel}: </span>
            )}
            {chapter.title}
          </h1>
          <FindInPage targetId="book-content" className="shrink-0 mt-0.5" />
        </div>
      </PageHeader>

      <div className="max-w-5xl mx-auto flex">
        {/* Left sidebar — chapter index */}
        <ChapterSidebar
          chapters={allChapters}
          currentSlug={slug}
          volume={vol}
        />

        {/* Main content */}
        <main className="flex-1 min-w-0 px-6 py-8 space-y-8">
          {/* Top navigation */}
          <ChapterNav
            prev={prev}
            next={next}
            volume={vol}
            chapters={allChapters}
            currentSlug={slug}
          />

          {/* Chapter content */}
          <Card id="book-content">
            <CardContent className="py-8 px-6 sm:px-8">
              <div className="space-y-4">
                {chapter.paragraphs.map((paragraph, i) => (
                  <div
                    key={i}
                    className="text-base text-foreground leading-relaxed"
                    dangerouslySetInnerHTML={{ __html: paragraph }}
                  />
                ))}
              </div>
            </CardContent>
          </Card>

          {/* Bottom navigation */}
          <ChapterNav
            prev={prev}
            next={next}
            volume={vol}
            chapters={allChapters}
            currentSlug={slug}
          />
        </main>
      </div>
    </div>
  );
}

// ---------------------------------------------------------------------------
// Sidebar — chapter index
// ---------------------------------------------------------------------------

type SidebarChapter = {
  slug: string;
  title: string;
  type: string;
  chapter: number | null;
};

function ChapterSidebar({
  chapters,
  currentSlug,
  volume,
}: {
  chapters: SidebarChapter[];
  currentSlug: string;
  volume: number;
}) {
  return (
    <aside className="hidden lg:block w-56 shrink-0 sticky top-[89px] self-start max-h-[calc(100vh-89px)] overflow-y-auto py-8 pr-4">
      <h2 className="text-xs font-bold uppercase tracking-wider text-muted-foreground mb-3 px-2">
        Chapters
      </h2>
      <nav className="flex flex-col gap-0.5">
        {chapters.map((ch) => {
          const isActive = ch.slug === currentSlug;
          const label =
            ch.type === "chapter" && ch.chapter != null
              ? `${ch.chapter}. ${ch.title}`
              : ch.title;

          return (
            <Link
              key={ch.slug}
              href={`/books/kb/${volume}/${ch.slug}`}
              className={cn(
                "px-2 py-1.5 rounded-md text-sm transition-colors truncate",
                isActive
                  ? "bg-primary/10 text-primary font-medium"
                  : "text-muted-foreground hover:bg-muted hover:text-foreground",
              )}
              title={label}
            >
              {label}
            </Link>
          );
        })}
      </nav>
    </aside>
  );
}

// ---------------------------------------------------------------------------
// Prev / Next navigation
// ---------------------------------------------------------------------------

type NavChapter = {
  slug: string;
  title: string;
  type: string;
  chapter: number | null;
};

function ChapterNav({
  prev,
  next,
  volume,
  chapters,
  currentSlug,
}: {
  prev: NavChapter | null;
  next: NavChapter | null;
  volume: number;
  chapters: SidebarChapter[];
  currentSlug: string;
}) {
  const mobileNavGroups: MobileNavGroup[] = [];

  const introItems = chapters.filter((i) => i.type !== "chapter");
  if (introItems.length > 0) {
    mobileNavGroups.push({
      title: "Front Matter",
      items: introItems.map((i) => ({
        slug: i.slug,
        label: i.title,
        href: `/books/kb/${volume}/${i.slug}`,
        type: i.type,
      })),
    });
  }

  const chapterItems = chapters.filter((i) => i.type === "chapter");
  if (chapterItems.length > 0) {
    mobileNavGroups.push({
      title: "Chapters",
      items: chapterItems.map((i) => ({
        slug: i.slug,
        label: i.chapter != null ? `${i.chapter}. ${i.title}` : i.title,
        href: `/books/kb/${volume}/${i.slug}`,
        type: i.type,
      })),
    });
  }

  return (
    <div className="flex items-center justify-between gap-3">
      <div className="flex items-center gap-2">
        <MobileNav
          groups={mobileNavGroups}
          currentSlug={currentSlug}
          bookTitle={`Kṛṣṇa Book — Volume ${volume}`}
        />
        {prev ? (
          <Link
            href={`/books/kb/${volume}/${prev.slug}`}
            className={cn(
              buttonVariants({ variant: "outline", size: "sm" }),
              "gap-1.5",
            )}
          >
            <ChevronLeft className="size-4" />
            <span className="hidden sm:inline truncate max-w-[180px]">
              {prev.type === "chapter" && prev.chapter != null
                ? `Ch. ${prev.chapter}`
                : prev.title}
            </span>
            <span className="sm:hidden">Previous</span>
          </Link>
        ) : (
          <div className="hidden lg:block" />
        )}
      </div>

      {next ? (
        <Link
          href={`/books/kb/${volume}/${next.slug}`}
          className={cn(
            buttonVariants({ variant: "outline", size: "sm" }),
            "gap-1.5",
          )}
        >
          <span className="hidden sm:inline truncate max-w-[180px]">
            {next.type === "chapter" && next.chapter != null
              ? `Ch. ${next.chapter}`
              : next.title}
          </span>
          <span className="sm:hidden">Next</span>
          <ChevronRight className="size-4" />
        </Link>
      ) : (
        <div />
      )}
    </div>
  );
}