streamyfin/utils/casting/castLoad.ts

/**
 * Unified Chromecast media loading.
 *
 * Owns the getStreamUrl → buildCastMediaInfo → loadMedia sequence that was
 * previously duplicated across PlayButton and the casting player. Builds the
 * device profile from detected capabilities and retries once with a forced
 * conservative profile when the receiver rejects the initial load (status 2100).
 */

import type { Api } from "@jellyfin/sdk";
import type { BaseItemDto } from "@jellyfin/sdk/lib/generated-client";
import type { RemoteMediaClient } from "react-native-google-cast";
import { buildChromecastProfile } from "@/utils/casting/buildProfile";
import {
  type ChromecastProfileMode,
  detectCapabilities,
} from "@/utils/casting/capabilities";
import { isLoadFailedError } from "@/utils/casting/castErrors";
import { buildCastMediaInfo } from "@/utils/casting/mediaInfo";
import { getStreamUrl } from "@/utils/jellyfin/media/getStreamUrl";

export interface CastLoadOptions {
  audioStreamIndex?: number;
  subtitleStreamIndex?: number;
  maxBitrate?: number;
  mediaSourceId?: string;
  startPositionMs?: number;
}

export interface CastLoadParams {
  client: RemoteMediaClient;
  /** Cast device — only `modelName` is read, for capability detection. */
  device: { modelName?: string } | null;
  api: Api;
  item: BaseItemDto;
  userId: string;
  profileMode: ChromecastProfileMode;
  /** Manual bitrate cap from settings, in bits per second. */
  maxBitrateSetting?: number;
  options?: CastLoadOptions;
}

export type CastLoadResult = { ok: true } | { ok: false; error: unknown };

/**
 * Resolve the default audio stream index for an item.
 * Fixes the previous `audioStreamIndex = 0` default, which selected the video stream.
 */
export const resolveDefaultAudioIndex = (
  item: BaseItemDto,
  mediaSourceId?: string,
): number | undefined => {
  const source = mediaSourceId
    ? item.MediaSources?.find((s) => s.Id === mediaSourceId)
    : item.MediaSources?.[0];
  if (source?.DefaultAudioStreamIndex != null) {
    return source.DefaultAudioStreamIndex;
  }
  const audio =
    item.MediaStreams?.find((s) => s.Type === "Audio" && s.IsDefault) ??
    item.MediaStreams?.find((s) => s.Type === "Audio");
  return audio?.Index ?? undefined;
};

const attemptLoad = async (
  params: CastLoadParams,
  caps: Parameters<typeof buildChromecastProfile>[0],
): Promise<void> => {
  const { api, item, userId, client, options } = params;
  const profile = buildChromecastProfile(caps);
  const audioStreamIndex =
    options?.audioStreamIndex ??
    resolveDefaultAudioIndex(item, options?.mediaSourceId);
  const startPositionMs = options?.startPositionMs ?? 0;

  const data = await getStreamUrl({
    api,
    item,
    userId,
    startTimeTicks: Math.floor(startPositionMs * 10000),
    deviceProfile: profile,
    audioStreamIndex,
    subtitleStreamIndex: options?.subtitleStreamIndex,
    maxStreamingBitrate: options?.maxBitrate,
    mediaSourceId: options?.mediaSourceId,
  });

  if (!data?.url) {
    throw new Error("getStreamUrl returned no URL");
  }

  await client.loadMedia({
    mediaInfo: buildCastMediaInfo({
      item,
      streamUrl: data.url,
      api,
      playSessionId: data.sessionId ?? undefined,
    }),
    startTime: startPositionMs / 1000,
  });
};

/**
 * Load media onto the connected Chromecast.
 * On a status-2100 rejection, retries once with a forced conservative profile.
 */
export const loadCastMedia = async (
  params: CastLoadParams,
): Promise<CastLoadResult> => {
  const caps = detectCapabilities(params.device, {
    profileMode: params.profileMode,
    maxBitrate: params.maxBitrateSetting,
  });

  try {
    await attemptLoad(params, caps);
    return { ok: true };
  } catch (error) {
    if (!isLoadFailedError(error)) {
      return { ok: false, error };
    }
    // Downgrade-on-failure: one retry with the safest possible profile.
    try {
      const fallback = detectCapabilities(params.device, {
        profileMode: "force-h264",
      });
      await attemptLoad(params, {
        ...fallback,
        maxVideoBitrate: 4_000_000,
        maxAudioChannels: 2,
      });
      return { ok: true };
    } catch (retryError) {
      return { ok: false, error: retryError };
    }
  }
};