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

type ArtistRef = { name?: string };
type ImageRef = { url?: string };

type TrackObject = {
  id?: string;
  name?: string;
  uri?: string;
  duration_ms?: number;
  track_number?: number;
  disc_number?: number;
  artists?: ArtistRef[];
  external_urls?: { spotify?: string };
};

type TrackPage = {
  items?: TrackObject[];
  next?: string | null;
};

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

function artistNames(values?: ArtistRef[]) {
  return (values || []).map((entry) => entry.name).filter(Boolean).join(", ");
}

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

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 normalizeTrack(track: TrackObject): SpotifyAlbumTrack | undefined {
  if (!track.id) return undefined;
  return {
    id: track.id,
    name: track.name || "Untitled track",
    artist: artistNames(track.artists) || "Unknown artist",
    uri: track.uri,
    durationMs: track.duration_ms || 0,
    trackNumber: track.track_number,
    discNumber: track.disc_number,
    externalUrl: track.external_urls?.spotify,
  };
}

export async function handle(request: Request) {
  try {
    const url = new URL(request.url);
    const albumId = url.searchParams.get("albumId")?.trim();
    if (!albumId) {
      return new Response(
        superjson.stringify({ error: "Album 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 album = await spotifyGet<SpotifyAlbum>(
      "https://api.spotify.com/v1/albums/" + encodeURIComponent(albumId),
      token,
    );
    if (!album.id) {
      throw new Error("Spotify did not return the requested album.");
    }

    const tracks: SpotifyAlbumTrack[] = [];
    for (const item of album.tracks?.items || []) {
      const normalized = normalizeTrack(item);
      if (normalized) tracks.push(normalized);
    }

    let next = album.tracks?.next || null;
    while (next) {
      const page = await spotifyGet<TrackPage>(next, token);
      for (const item of page.items || []) {
        const normalized = normalizeTrack(item);
        if (normalized) tracks.push(normalized);
      }
      next = page.next || null;
    }

    const output: OutputType = {
      album: {
        id: album.id,
        name: album.name || "Untitled album",
        artist: artistNames(album.artists) || "Unknown artist",
        releaseDate: album.release_date,
        totalTracks: album.total_tracks,
        imageUrl: firstImage(album.images),
        externalUrl: album.external_urls?.spotify,
      },
      tracks,
    };

    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 Spotify album.";
    return new Response(superjson.stringify({ error: message }), { status: 500 });
  }
}