import superjson from "superjson";
import {
  appendSetCookies,
  ensureSpotifyAccessToken,
} from "../helpers/spotifyServer";
import type {
  OutputType,
  SpotifyArtistAlbum,
} from "./spotify-artist-albums_GET.schema";

type ImageRef = { url?: string };
type SpotifyArtist = {
  id?: string;
  name?: string;
  images?: ImageRef[];
  external_urls?: { spotify?: string };
};

type SpotifyAlbum = {
  id?: string;
  name?: string;
  album_type?: string;
  release_date?: string;
  total_tracks?: number;
  images?: ImageRef[];
  external_urls?: { spotify?: string };
};

type AlbumPage = {
  items?: SpotifyAlbum[];
  total?: number;
  offset?: number;
  limit?: number;
  next?: string | null;
};

async function spotifyGet<T>(url: string, token: string) {
  const response = await fetch(url, {
    headers: { Authorization: "Bearer " + token },
  });
  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;
}

function firstImage(images?: ImageRef[]) {
  return images?.find((entry) => entry.url)?.url;
}

export async function handle(request: Request) {
  try {
    const url = new URL(request.url);
    const artistId = url.searchParams.get("artistId")?.trim();
    const offset = Math.max(0, Number(url.searchParams.get("offset") || 0) || 0);
    if (!artistId) {
      return new Response(
        superjson.stringify({ error: "Artist ID is required." }),
        { status: 400 },
      );
    }

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

    const token = session.accessToken;
    const [artist, page] = await Promise.all([
      spotifyGet<SpotifyArtist>(
        "https://api.spotify.com/v1/artists/" + encodeURIComponent(artistId),
        token,
      ),
      spotifyGet<AlbumPage>(
        "https://api.spotify.com/v1/artists/" +
          encodeURIComponent(artistId) +
          "/albums?include_groups=album,single,compilation&limit=50&offset=" +
          offset,
        token,
      ),
    ]);

    if (!artist.id) {
      throw new Error("Spotify did not return the requested artist.");
    }

    const seen = new Set<string>();
    const albums: SpotifyArtistAlbum[] = [];
    for (const album of page.items || []) {
      if (!album.id || seen.has(album.id)) continue;
      seen.add(album.id);
      albums.push({
        id: album.id,
        name: album.name || "Untitled release",
        albumType: album.album_type,
        releaseDate: album.release_date,
        totalTracks: album.total_tracks,
        imageUrl: firstImage(album.images),
        externalUrl: album.external_urls?.spotify,
      });
    }

    const output: OutputType = {
      artist: {
        id: artist.id,
        name: artist.name || "Unknown artist",
        imageUrl: firstImage(artist.images),
        externalUrl: artist.external_urls?.spotify,
      },
      albums,
      total: page.total,
      nextOffset: page.next
        ? offset + (page.limit || 50)
        : undefined,
    };

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