/**
 * Turns a Bandcamp page into a queue of streams for the site's own player.
 * `usePlayRichContent` calls it when a Bandcamp link is played in native mode,
 * and `streamSources.ts` again when the streams' signed URLs expire.
 *
 * @module
 */

import { API_URL } from "../../config/api.ts";
import type { PlayerItem } from "../../contexts/player/PlayerContext.ts";
import type { Tralbum, TralbumTrack } from "../../../shared/player.ts";

/**
 * Passed to {@link resolveBandcampQueue} by its callers and copied onto every
 * item of the queue, since the server's tracklist knows nothing of the dump.
 */
export interface BandcampContext {
  dumpHref?: string;
  /** Lets PlayerProvider fall back to Bandcamp's iframe if the streams fail. */
  embedUrl?: string;
  /** Used only if the page carries no album art of its own. */
  fallbackArtworkUrl?: string;
}

/**
 * Resolves the Bandcamp page `pageUrl` into one `stream` item per streamable
 * track, through `GET /api/bandcamp/tracks`, each carrying `ctx`. `force`
 * bypasses the server's cache, for re-resolving once the signed URLs expire.
 *
 * @throws {Error} When the request fails or the page has no streamable track.
 * Callers then fall back to the embed.
 */
export async function resolveBandcampQueue(
  pageUrl: string,
  ctx: BandcampContext = {},
  { force = false }: { force?: boolean } = {},
): Promise<PlayerItem[]> {
  const res = await fetch(
    `${API_URL}/api/bandcamp/tracks?url=${encodeURIComponent(pageUrl)}${
      force ? "&force=1" : ""
    }`,
  );
  if (!res.ok) throw new Error(`resolve failed: ${res.status}`);

  const body = await res.json() as { success: boolean; data?: Tralbum };
  const album = body.data;
  if (!body.success || !album) throw new Error("resolve returned no data");

  const items = album.tracks
    .filter((t): t is TralbumTrack & { streamUrl: string } =>
      t.streamable && typeof t.streamUrl === "string"
    )
    .map((t): PlayerItem => ({
      kind: "stream",
      streamUrl: t.streamUrl,
      type: "bandcamp",
      // The header and the tracklist name the track; the artist goes below.
      title: t.title,
      subtitle: album.artist,
      duration: t.duration,
      trackNum: t.trackNum,
      artworkUrl: album.artworkUrl ?? ctx.fallbackArtworkUrl,
      dumpHref: ctx.dumpHref,
      resolveUrl: album.sourceUrl,
      resolveIndex: t.index,
      resolvedAt: album.resolvedAt,
      embedUrl: ctx.embedUrl,
    }));

  if (items.length === 0) throw new Error("no streamable tracks");
  return items;
}