import { NextRequest, NextResponse } from "next/server";
import { assertLocalRequest } from "@/lib/api/localOnly";
import { listImages, countImages } from "@/lib/db/queries";
import { resolveSort } from "@/lib/sortServer";
import { parseFilterCriteria, statusToFlags } from "@/lib/filters";
import { getAppSetting } from "@/lib/db/appSettings";
import type { LibraryView } from "@/components/grid/ViewToggle";

export const runtime = "nodejs";
export const dynamic = "force-dynamic";

/**
 * Paginated covers feed for client-side infinite-scroll appends.
 * Mirrors the SSR filter shape in app/page.tsx — every filter the
 * grid supports (letter, search, sort, marks, multi-select tabs)
 * resolves through the same listImages/countImages path.
 */
export async function GET(req: NextRequest) {
  const blocked = assertLocalRequest(req);
  if (blocked) return blocked;

  const sp = req.nextUrl.searchParams;
  // Ape Object.fromEntries for plain access matching page params.
  const params: Record<string, string | string[] | undefined> = {};
  for (const [k, v] of sp.entries()) {
    const cur = params[k];
    if (cur == null) params[k] = v;
    else if (Array.isArray(cur)) cur.push(v);
    else params[k] = [cur, v];
  }

  const criteria = parseFilterCriteria(params);
  const sort = await resolveSort(typeof params.sort === "string" ? params.sort : undefined);
  const rawLetter = (typeof params.letter === "string" ? params.letter : "").toUpperCase();
  const letter = rawLetter === "#" ? "#" : (/^[A-Z]$/.test(rawLetter) ? rawLetter : null);
  const search = (typeof params.q === "string" ? params.q.trim() : "") || undefined;
  // view is purely a presentational hint; included for symmetry but
  // doesn't affect query.
  void (params.view === "portrait" ? "portrait" : "landscape" as LibraryView);

  const rawPage = typeof params.page === "string" ? Number(params.page) : NaN;
  const page = Number.isFinite(rawPage) && rawPage >= 1 ? Math.floor(rawPage) : 1;

  const filterOpts = {
    sort,
    letter: letter ?? undefined,
    search,
    ...statusToFlags(criteria.status),
    marks: criteria.marks,
    actressIds: criteria.ids.actresses,
    actressMode: criteria.mode.actresses,
    studioIds: criteria.ids.studios,
    seriesIds: criteria.ids.series,
    genreIds: criteria.ids.genres,
    genreMode: criteria.mode.genres,
    collectionIds: criteria.ids.collections,
    collectionMode: criteria.mode.collections,
    tagIds: criteria.ids.tags,
    tagMode: criteria.mode.tags,
    categoryIds: criteria.ids.categories,
    categoryMode: criteria.mode.categories,
  };

  const PAGE_SIZE = Math.max(25, Math.min(500, getAppSetting("coverPageSize") ?? 100));
  const totalCount = countImages(filterOpts);
  const totalPages = Math.max(1, Math.ceil(totalCount / PAGE_SIZE));
  const effectivePage = Math.min(page, totalPages);
  const offset = (effectivePage - 1) * PAGE_SIZE;
  const items = listImages({ ...filterOpts, limit: PAGE_SIZE, offset });

  return NextResponse.json(
    { items, page: effectivePage, totalPages, totalCount, hasMore: effectivePage < totalPages },
    { headers: { "Cache-Control": "no-store" } },
  );
}