fFix(youtube): recover source URL for background media cache on direct mpv open (#132)

src/main/runtime/youtube-media-cache-playback.ts

@@ -0,0 +1,179 @@
+import type { YoutubeMediaCacheMode } from '../../types/integrations';
+import { isYoutubeMediaPath } from './youtube-playback';
+
+type PlaylistEntry = {
+  filename: string;
+  current: boolean;
+  playing: boolean;
+};
+
+export interface YoutubeMediaCachePlaybackRuntimeDeps {
+  getMediaCacheConfig: () => {
+    mode: YoutubeMediaCacheMode;
+    maxHeight?: number;
+  };
+  requestMpvProperty?: (name: string) => Promise<unknown>;
+  startYoutubeMediaCache: (
+    url: string,
+    options: {
+      mode: YoutubeMediaCacheMode;
+      maxHeight?: number;
+    },
+  ) => void;
+  logWarn: (message: string) => void;
+}
+
+function trimToNonEmptyString(value: unknown): string | null {
+  if (typeof value !== 'string') {
+    return null;
+  }
+  const trimmed = value.trim();
+  return trimmed.length > 0 ? trimmed : null;
+}
+
+function normalizePlaylistIndex(value: unknown): number | null {
+  return typeof value === 'number' && Number.isInteger(value) && value >= 0 ? value : null;
+}
+
+function isGoogleVideoStreamPath(mediaPath: string): boolean {
+  try {
+    const parsed = new URL(mediaPath);
+    const host = parsed.hostname.toLowerCase();
+    return host === 'googlevideo.com' || host.endsWith('.googlevideo.com');
+  } catch {
+    return false;
+  }
+}
+
+function normalizePlaylistEntries(raw: unknown): PlaylistEntry[] {
+  if (!Array.isArray(raw)) {
+    return [];
+  }
+  return raw.map((entry) => {
+    const item = (entry ?? {}) as {
+      filename?: unknown;
+      current?: unknown;
+      playing?: unknown;
+    };
+    return {
+      filename: trimToNonEmptyString(item.filename) ?? '',
+      current: item.current === true,
+      playing: item.playing === true,
+    };
+  });
+}
+
+function resolvePlaylistEntry(
+  playlist: PlaylistEntry[],
+  playingPosValue: unknown,
+): PlaylistEntry | null {
+  if (playlist.length === 0) {
+    return null;
+  }
+
+  const playingPos = normalizePlaylistIndex(playingPosValue);
+  if (playingPos !== null && playingPos < playlist.length) {
+    return playlist[playingPos] ?? null;
+  }
+
+  return playlist.find((entry) => entry.current || entry.playing) ?? null;
+}
+
+async function requestMpvPropertySafely(
+  deps: YoutubeMediaCachePlaybackRuntimeDeps,
+  name: string,
+): Promise<unknown> {
+  if (!deps.requestMpvProperty) {
+    return null;
+  }
+  try {
+    return await deps.requestMpvProperty(name);
+  } catch {
+    return null;
+  }
+}
+
+async function resolveYoutubeSourceFromPlaylist(
+  deps: YoutubeMediaCachePlaybackRuntimeDeps,
+): Promise<string | null> {
+  const [playingPosValue, playlistValue] = await Promise.all([
+    requestMpvPropertySafely(deps, 'playlist-playing-pos'),
+    requestMpvPropertySafely(deps, 'playlist'),
+  ]);
+  const playlistEntry = resolvePlaylistEntry(
+    normalizePlaylistEntries(playlistValue),
+    playingPosValue,
+  );
+  return playlistEntry?.filename && isYoutubeMediaPath(playlistEntry.filename)
+    ? playlistEntry.filename
+    : null;
+}
+
+async function resolveYoutubeSourceUrl(
+  deps: YoutubeMediaCachePlaybackRuntimeDeps,
+  mediaPath: string,
+): Promise<string | null> {
+  const directPath = trimToNonEmptyString(mediaPath);
+  if (directPath && isYoutubeMediaPath(directPath)) {
+    return directPath;
+  }
+  if (!directPath || !isGoogleVideoStreamPath(directPath)) {
+    return null;
+  }
+  return await resolveYoutubeSourceFromPlaylist(deps);
+}
+
+export function createYoutubeMediaCachePlaybackRuntime(deps: YoutubeMediaCachePlaybackRuntimeDeps) {
+  let activeYoutubeSourceUrl: string | null = null;
+  let activeYoutubeSourceUrlPromise: Promise<string | null> | null = null;
+  let generation = 0;
+
+  const handleMediaPathChange = async (mediaPath: string): Promise<void> => {
+    const currentGeneration = ++generation;
+    const config = deps.getMediaCacheConfig();
+    if (config.mode !== 'background') {
+      activeYoutubeSourceUrl = null;
+      activeYoutubeSourceUrlPromise = Promise.resolve(null);
+      return;
+    }
+
+    if (!isYoutubeMediaPath(mediaPath)) {
+      activeYoutubeSourceUrl = null;
+    }
+
+    const sourceUrlPromise = resolveYoutubeSourceUrl(deps, mediaPath);
+    activeYoutubeSourceUrlPromise = sourceUrlPromise.then((sourceUrl) =>
+      currentGeneration === generation ? sourceUrl : null,
+    );
+
+    const sourceUrl = await sourceUrlPromise;
+    if (currentGeneration !== generation) {
+      return;
+    }
+
+    activeYoutubeSourceUrl = sourceUrl;
+    if (!sourceUrl) {
+      return;
+    }
+
+    try {
+      deps.startYoutubeMediaCache(sourceUrl, {
+        mode: config.mode,
+        maxHeight: config.maxHeight,
+      });
+    } catch (error) {
+      deps.logWarn(
+        `Failed to start YouTube media cache: ${
+          error instanceof Error ? error.message : String(error)
+        }`,
+      );
+    }
+  };
+
+  return {
+    getActiveYoutubeSourceUrl: async (): Promise<string | null> =>
+      activeYoutubeSourceUrlPromise ?? activeYoutubeSourceUrl,
+    getActiveYoutubeSourceUrlSnapshot: (): string | null => activeYoutubeSourceUrl,
+    handleMediaPathChange,
+  };
+}