import superjson from "superjson";
import { appendSetCookies, ensureSpotifyAccessToken } from "../helpers/spotifyServer";
import type { OutputType, SpotifyPlaylistSummary } from "./spotify-playlists_GET.schema";

type SpotifyPlaylistPage = {
  items?: Array<{
    id?: string;
    name?: string;
    owner?: { display_name?: string; id?: string };
    collaborative?: boolean;
    images?: Array<{ url?: string }>;
    external_urls?: { spotify?: string };
    items?: { total?: number };
    tracks?: { total?: number };
  }>;
  next?: string | null;
};

async function spotifyGet<T>(url: string, accessToken: string) {
  const response = await fetch(url, {
    headers: { Authorization: `Bearer ${accessToken}` },
  });
  if (!response.ok) {
    const message = await response.text();
    throw new Error(`Spotify returned ${response.status}: ${message.slice(0, 220)}`);
  }
  return (await response.json()) as T;
}

export async function handle(request: Request) {
  try {
    const session = await ensureSpotifyAccessToken(request);
    if (!session.accessToken) {
      return new Response(superjson.stringify({ error: "Connect Spotify first." }), { status: 401 });
    }

    let next: string | null = "https://api.spotify.com/v1/me/playlists?limit=50";
    const playlists: SpotifyPlaylistSummary[] = [];

    while (next) {
      const page: SpotifyPlaylistPage = await spotifyGet<SpotifyPlaylistPage>(next, session.accessToken);
      for (const playlist of page.items ?? []) {
        if (!playlist.id) continue;
        playlists.push({
          id: playlist.id,
          name: playlist.name || "Untitled playlist",
          owner: playlist.owner?.display_name || playlist.owner?.id,
          ownerId: playlist.owner?.id,
          collaborative: Boolean(playlist.collaborative),
          imageUrl: playlist.images?.find((image) => image.url)?.url,
          total: playlist.items?.total ?? playlist.tracks?.total ?? 0,
          externalUrl: playlist.external_urls?.spotify,
        });
      }
      next = page.next || null;
    }

    const headers = new Headers({ "Content-Type": "application/json", "Cache-Control": "no-store" });
    appendSetCookies(headers, session.setCookies);
    return new Response(superjson.stringify({ playlists } satisfies OutputType), { headers });
  } catch (error) {
    const message = error instanceof Error ? error.message : "Unable to list Spotify playlists.";
    return new Response(superjson.stringify({ error: message }), { status: 500 });
  }
}