export const dynamic = "force-dynamic";

import type { Metadata } from "next";
import Link from "next/link";
import { redirect, notFound } from "next/navigation";
import { ChevronLeft, ChevronRight } from "lucide-react";
import { getBookMeta, getProseChapter, getChapterVerseIndex } from "@/lib/api";
import { CC_LILAS } from "@/lib/constants";
import { buildOgMeta } from "@/lib/og";
import { PageHeader } from "@/components/layout/page-header";
import { Card, CardContent } from "@/components/ui/card";
import { buttonVariants } from "@/components/ui/button";
import { FindInPage } from "@/components/layout/find-in-page";
import { MobileNav, type MobileNavGroup } from "@/components/layout/mobile-nav";
import { cn } from "@/lib/utils";

type ChapterInfo = { number: number; title: string; totalVerses: number };
type LilaInfo = {
  key: string;
  name: string;
  totalChapters: number;
  totalVerses: number;
  chapters: ChapterInfo[];
};
type VerseEntry = { verse: number; verseEnd?: number | null; reference: string };

export async function generateMetadata({
  params,
}: {
  params: Promise<{ lila: string; chapter: string }>;
}): Promise<Metadata> {
  const { lila, chapter } = await params;
  const lilaName = CC_LILAS[lila] || lila;
  return buildOgMeta({
    title: "Śrī Caitanya-caritāmṛta",
    detail: `${lilaName}, Chapter ${chapter}`,
  });
}

function verseLabel(v: VerseEntry): string {
  return v.verseEnd ? `${v.verse}–${v.verseEnd}` : String(v.verse);
}

// ---------------------------------------------------------------------------
// Top/bottom navigation — mirrors the verse pages' VerseNav: a Contents
// toggle (mobile) listing this chapter's verses, Previous/Next (chapter), and
// a "Chapter X of N" label.
// ---------------------------------------------------------------------------
function ChapterNav({
  lila,
  chapters,
  current,
  chapterTitle,
  verseIndex,
}: {
  lila: string;
  chapters: ChapterInfo[];
  current: number;
  chapterTitle: string;
  verseIndex: VerseEntry[];
}) {
  const idx = chapters.findIndex((c) => c.number === current);
  const prev = idx > 0 ? chapters[idx - 1] : null;
  const next = idx < chapters.length - 1 ? chapters[idx + 1] : null;

  // The contents drawer lists the active chapter's verses (same as the
  // verse-page sidebar) so the reader can jump straight in.
  const groups: MobileNavGroup[] = [
    {
      title: "Verses",
      items: verseIndex.map((v) => ({
        slug: String(v.verse),
        label: `Verse ${verseLabel(v)}`,
        href: `/books/cc/${lila}/${current}/${v.verse}`,
        type: "verse",
      })),
    },
  ];

  return (
    <div className="flex items-center justify-between gap-3">
      <div className="flex items-center gap-2">
        <MobileNav
          groups={groups}
          currentSlug=""
          bookTitle={`Chapter ${current}: ${chapterTitle}`}
        />
        {prev ? (
          <Link
            href={`/books/cc/${lila}/${prev.number}`}
            className={cn(buttonVariants({ variant: "outline", size: "sm" }), "gap-1.5")}
          >
            <ChevronLeft className="size-4" />
            <span className="hidden sm:inline">Previous</span>
          </Link>
        ) : (
          <div className="hidden lg:block" />
        )}
      </div>

      <span className="text-sm text-muted-foreground">
        Chapter {current} of {chapters.length}
      </span>

      {next ? (
        <Link
          href={`/books/cc/${lila}/${next.number}`}
          className={cn(buttonVariants({ variant: "outline", size: "sm" }), "gap-1.5")}
        >
          <span className="hidden sm:inline">Next</span>
          <ChevronRight className="size-4" />
        </Link>
      ) : (
        <div />
      )}
    </div>
  );
}

export default async function CcChapterPage({
  params,
}: {
  params: Promise<{ lila: string; chapter: string }>;
}) {
  const { lila, chapter } = await params;
  const chapterNum = parseInt(chapter);

  const [meta, summary, verseIndex] = await Promise.all([
    getBookMeta("cc"),
    getProseChapter("cc", 0, `${lila}-${chapterNum}`),
    getChapterVerseIndex("cc", lila, chapterNum),
  ]);

  if (!meta) notFound();
  const lilaInfo = (meta.lilas as LilaInfo[] | undefined)?.find(
    (l) => l.key === lila,
  );
  if (!lilaInfo) notFound();
  const chapterInfo = lilaInfo.chapters.find((ch) => ch.number === chapterNum);
  if (!chapterInfo) notFound();
  if (verseIndex.length === 0) notFound();

  const firstVerse = verseIndex[0].verse;

  // Chapters without a summary (e.g. Ādi 7) go straight to the verses.
  if (!summary || summary.paragraphs.length === 0) {
    redirect(`/books/cc/${lila}/${chapterNum}/${firstVerse}`);
  }

  return (
    <div className="min-h-screen bg-background">
      <PageHeader sticky>
        <Link
          href={`/books/cc/${lila}`}
          className="text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          &larr; {lilaInfo.name}
        </Link>
        <div className="mt-3 flex items-start justify-between gap-3">
          <h1 className="text-2xl font-bold text-foreground">
            Chapter {chapterNum}: {chapterInfo.title}
          </h1>
          <FindInPage targetId="book-content" className="shrink-0 mt-0.5" />
        </div>
      </PageHeader>

      <div className="max-w-5xl mx-auto flex">
        {/* Desktop sidebar — verses of the active chapter (matches the
            verse-page sidebar) so the reader can jump to any verse. */}
        <aside className="hidden lg:block w-64 shrink-0 sticky top-[89px] self-start max-h-[calc(100vh-165px)] overflow-y-auto py-8 pr-4">
          <h2 className="text-sm font-bold uppercase tracking-wider text-muted-foreground mb-3 px-2">
            Verses
          </h2>
          <nav className="grid grid-cols-3 gap-1">
            {verseIndex.map((v) => (
              <Link
                key={v.verse}
                href={`/books/cc/${lila}/${chapterNum}/${v.verse}`}
                className="px-2 py-1 rounded-md text-sm tabular-nums text-muted-foreground hover:bg-muted hover:text-foreground transition-colors"
              >
                {verseLabel(v)}
              </Link>
            ))}
          </nav>
        </aside>

        {/* Main — chapter summary */}
        <main className="flex-1 min-w-0 px-6 py-8 space-y-6">
          {/* Top navigation */}
          <ChapterNav
            lila={lila}
            chapters={lilaInfo.chapters}
            current={chapterNum}
            chapterTitle={chapterInfo.title}
            verseIndex={verseIndex}
          />

          <p className="text-sm font-bold uppercase tracking-wider text-muted-foreground">
            Chapter Summary
          </p>
          <Card id="book-content">
            <CardContent className="py-8 px-6 sm:px-8">
              <div className="space-y-4">
                {summary.paragraphs.map((paragraph, i) => (
                  <div
                    key={i}
                    className="text-base text-foreground leading-relaxed"
                    dangerouslySetInnerHTML={{ __html: paragraph }}
                  />
                ))}
              </div>
            </CardContent>
          </Card>

          {/* Bottom navigation */}
          <ChapterNav
            lila={lila}
            chapters={lilaInfo.chapters}
            current={chapterNum}
            chapterTitle={chapterInfo.title}
            verseIndex={verseIndex}
          />
        </main>
      </div>
    </div>
  );
}