import { prisma } from "@/lib/db";
import { topAlbums } from "@/lib/lastfm";
import { cached, normKey, CACHE_TTL } from "@/lib/apicache";
import { LIMIT, getLastfmCreds, parsePeriod, wantsRefresh } from "../_creds";

function albumKey(artist: string, album: string): string {
  return `${artist} ${album}`.trim().toLowerCase();
}

export async function GET(request: Request) {
  const creds = await getLastfmCreds();
  if (!creds) return Response.json({ error: "Last.fm not configured" }, { status: 400 });

  const url = new URL(request.url);
  const period = parsePeriod(url);
  const page = Number(url.searchParams.get("page")) || 1;

  // Cache ONLY the raw Last.fm payload; own-state (owned/wanted) is annotated live below.
  let result;
  try {
    result = await cached(
      `lfm-top-albums:${normKey(creds.username)}:${period}:${page}`,
      12 * CACHE_TTL.HOUR,
      () => topAlbums(creds.username, creds.apiKey, { period, page, limit: LIMIT }),
      { force: wantsRefresh(url) },
    );
  } catch (e) {
    return Response.json({ error: e instanceof Error ? e.message : "Last.fm request failed" }, { status: 502 });
  }

  const [libraryItems, monitoredReleases] = await Promise.all([
    prisma.libraryItem.findMany({ select: { artist: true, album: true } }),
    prisma.monitoredRelease.findMany({
      where: { OR: [{ monitored: true }, { currentQualityClass: { not: null } }] },
      select: { artistName: true, album: true },
    }),
  ]);
  const ownedKeys = new Set(libraryItems.map((r) => albumKey(r.artist, r.album)));
  const wantedKeys = new Set(monitoredReleases.map((r) => albumKey(r.artistName, r.album)));

  const albums = result.items.map((a) => {
    const key = albumKey(a.artist, a.name);
    const owned = ownedKeys.has(key);
    const wanted = wantedKeys.has(key);
    return { ...a, inLibrary: owned || wanted, owned, wanted };
  });

  return Response.json({ albums, totalPages: result.totalPages, page: result.page });
}