export const dynamic = "force-dynamic";

import type { Metadata } from "next";
import Link from "next/link";
import { notFound } from "next/navigation";
import {
  getSvaContent,
  getSvaSidebarItems,
  getNavigableItems,
  type SvaChapter,
  type SvaSidebarItem,
} from "@/lib/sva";
import { getProseChapter } 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";

// ---------------------------------------------------------------------------
// Metadata
// ---------------------------------------------------------------------------

export async function generateMetadata({
  params,
  searchParams,
}: {
  params: Promise<{ chapter: string }>;
  searchParams: Promise<Record<string, string | string[] | undefined>>;
}): Promise<Metadata> {
  const { chapter: slug } = await params;
  const sp = await searchParams;
  const chapter = await getProseChapter("sva", 0, slug);
  const hlQuote = extractQuoteFromHl(sp, chapter?.paragraphs);
  if (hlQuote) {
    return buildOgMeta({ title: BOOK_NAMES["sva"], quote: hlQuote });
  }
  return ogForChapter("sva", chapter?.title || "");
}

// ---------------------------------------------------------------------------
// Page
// ---------------------------------------------------------------------------

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

  const content = await getSvaContent(slug);
  if (!content) notFound();

  const sidebarItems = await getSvaSidebarItems();

  // Build a flat list of navigable items (skip "parent" type — they're labels, not pages)
  const navigableItems = getNavigableItems(sidebarItems);
  const currentIdx = navigableItems.findIndex((item) => item.slug === slug);

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

  // Determine if this is a sub-chapter (has parentChapter)
  const isSubChapter =
    "parentChapter" in content &&
    typeof (content as SvaChapter).parentChapter === "number";
  const parentChapterNum = isSubChapter
    ? (content as SvaChapter).parentChapter
    : null;

  return (
    <div className="min-h-screen bg-background">
      <JsonLd data={articleJsonLd({ path: `/books/sva/${slug}`, headline: content.title, description: content.paragraphs?.[0], isPartOf: "Songs of the Vaiṣṇava Ācāryas" })} />
      <PageHeader sticky>
        <Link
          href="/books/sva"
          className="text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          &larr; Songs of the Vaiṣṇava Ācāryas
        </Link>
        <div className="mt-3 flex items-start justify-between gap-3">
          <h1 className="text-2xl font-bold text-foreground">
            {parentChapterNum != null && (
              <span className="text-primary">Part {parentChapterNum}: </span>
            )}
            {content.title}
          </h1>
          <FindInPage targetId="book-content" className="shrink-0 mt-0.5" />
        </div>
      </PageHeader>

      <div className="max-w-5xl mx-auto flex">
        {/* Left sidebar */}
        <SvaSidebar items={sidebarItems} currentSlug={slug} />

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

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

          {/* Bottom navigation */}
          <SvaNav
            prev={prev}
            next={next}
            sidebarItems={sidebarItems}
            currentSlug={slug}
          />
        </main>
      </div>
    </div>
  );
}

// ---------------------------------------------------------------------------
// Sidebar
// ---------------------------------------------------------------------------

function SvaSidebar({
  items,
  currentSlug,
}: {
  items: SvaSidebarItem[];
  currentSlug: string;
}) {
  // Split items by section
  const frontMatter = items.filter((i) => i.type === "intro-segment");
  const parents = items.filter((i) => i.type === "parent");
  const subChapters = items.filter((i) => i.type === "sub-chapter");

  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">
      {/* Front Matter */}
      {frontMatter.length > 0 && (
        <>
          <h2 className="text-xs font-bold uppercase tracking-wider text-muted-foreground mb-3 px-2">
            Front Matter
          </h2>
          <nav className="flex flex-col gap-0.5 mb-4">
            {frontMatter.map((item) => (
              <SidebarLink
                key={item.slug}
                item={item}
                isActive={item.slug === currentSlug}
              />
            ))}
          </nav>
        </>
      )}

      {/* Parts — grouped by parent */}
      {parents.length > 0 && (
        <>
          <h2 className="text-xs font-bold uppercase tracking-wider text-muted-foreground mb-3 px-2">
            Songs
          </h2>
          <nav className="flex flex-col gap-0.5 mb-4">
            {parents.map((parent) => (
              <div key={parent.slug}>
                {/* Parent heading — not a link, just a bold label */}
                <div className="px-2 py-1.5 text-xs font-bold text-muted-foreground mt-3 first:mt-0">
                  {parent.label}
                </div>
                {/* Sub-chapters (songs) indented */}
                {subChapters
                  .filter((sub) => sub.parentChapter === parent.parentChapter)
                  .map((sub) => {
                    const isActive = sub.slug === currentSlug;
                    return (
                      <Link
                        key={sub.slug}
                        href={`/books/sva/${sub.slug}`}
                        className={cn(
                          "pl-4 px-2 py-1.5 rounded-md text-sm transition-colors truncate block",
                          isActive
                            ? "bg-primary/10 text-primary font-medium"
                            : "text-muted-foreground hover:bg-muted hover:text-foreground",
                        )}
                        title={sub.label}
                      >
                        {sub.label}
                      </Link>
                    );
                  })}
              </div>
            ))}
          </nav>
        </>
      )}
    </aside>
  );
}

function SidebarLink({
  item,
  isActive,
}: {
  item: SvaSidebarItem;
  isActive: boolean;
}) {
  return (
    <Link
      href={`/books/sva/${item.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={item.label}
    >
      {item.label}
    </Link>
  );
}

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

function SvaNav({
  prev,
  next,
  sidebarItems,
  currentSlug,
}: {
  prev: SvaSidebarItem | null;
  next: SvaSidebarItem | null;
  sidebarItems: SvaSidebarItem[];
  currentSlug: string;
}) {
  const mobileNavGroups: MobileNavGroup[] = [];

  const frontMatter = sidebarItems.filter((i) => i.type === "intro-segment");
  if (frontMatter.length > 0) {
    mobileNavGroups.push({
      title: "Front Matter",
      items: frontMatter.map((i) => ({
        slug: i.slug,
        label: i.label,
        href: `/books/sva/${i.slug}`,
        type: i.type,
      })),
    });
  }

  const chapterItems = sidebarItems.filter(
    (i) => i.type === "parent" || i.type === "sub-chapter",
  );
  if (chapterItems.length > 0) {
    mobileNavGroups.push({
      title: "Songs",
      items: chapterItems.map((i) => ({
        slug: i.slug,
        label: i.label,
        href: `/books/sva/${i.slug}`,
        type: i.type,
        parentChapter: i.parentChapter,
        isParent: i.type === "parent",
      })),
    });
  }

  return (
    <div className="flex items-center justify-between gap-3">
      <div className="flex items-center gap-2">
        <MobileNav
          groups={mobileNavGroups}
          currentSlug={currentSlug}
          bookTitle="Songs of the Vaiṣṇava Ācāryas"
        />
        {prev ? (
          <Link
            href={`/books/sva/${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.label}
            </span>
            <span className="sm:hidden">Previous</span>
          </Link>
        ) : (
          <div className="hidden lg:block" />
        )}
      </div>

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