[YouTube] Support new playlist layout

This new layout doesn't provide author thumbnails and is completely different
for metadata, so the code to get them has been refactored.

The code of learning playlists video count check has been also removed, as it
seems to be not relevant anymore (the video count seems to be returned for
these playlists with both layouts).

Finally, unneeded overrides of subchannel methods, which don't apply to the
YouTube service, have been removed.

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubePlaylistExtractor.java

@@ -44,16 +44,19 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 public class YoutubePlaylistExtractor extends PlaylistExtractor {
-    // Minimum size of the stats array in the browse response which includes the streams count
-    private static final int STATS_ARRAY_WITH_STREAMS_COUNT_MIN_SIZE = 2;
-
     // Names of some objects in JSON response frequently used in this class
     private static final String PLAYLIST_VIDEO_RENDERER = "playlistVideoRenderer";
     private static final String PLAYLIST_VIDEO_LIST_RENDERER = "playlistVideoListRenderer";
+    private static final String SIDEBAR = "sidebar";
     private static final String VIDEO_OWNER_RENDERER = "videoOwnerRenderer";
 
     private JsonObject browseResponse;
+
     private JsonObject playlistInfo;
+    private JsonObject uploaderInfo;
+    private JsonObject playlistHeader;
+
+    private boolean isNewPlaylistInterface;
 
     public YoutubePlaylistExtractor(final StreamingService service,
                                     final ListLinkHandler linkHandler) {
@@ -73,48 +76,86 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
 
         browseResponse = getJsonPostResponse("browse", body, localization);
         YoutubeParsingHelper.defaultAlertsCheck(browseResponse);
-
+        isNewPlaylistInterface = checkIfResponseIsNewPlaylistInterface();
-        playlistInfo = getPlaylistInfo();
     }
 
+    /**
+     * Whether the playlist response is using only the new playlist design.
+     *
+     * <p>
+     * This new response changes how metadata is returned, and does not provide author thumbnails.
+     * </p>
+     *
+     * <p>
+     * The new response can be detected by checking whether a header JSON object is returned in the
+     * browse response (the old returns instead a sidebar one).
+     * </p>
+     *
+     * <p>
+     * This new playlist UI is currently A/B tested.
+     * </p>
+     *
+     * @return Whether the playlist response is using only the new playlist design
+     */
+    private boolean checkIfResponseIsNewPlaylistInterface() {
+        // The "old" playlist UI can be also returned with the new one
+        return browseResponse.has("header") && !browseResponse.has(SIDEBAR);
+    }
+
+    @Nonnull
     private JsonObject getUploaderInfo() throws ParsingException {
-        final JsonArray items = browseResponse.getObject("sidebar")
+        if (uploaderInfo == null) {
-                .getObject("playlistSidebarRenderer")
+            uploaderInfo = browseResponse.getObject(SIDEBAR)
-                .getArray("items");
-
-        JsonObject videoOwner = items.getObject(1)
-                .getObject("playlistSidebarSecondaryInfoRenderer")
-                .getObject("videoOwner");
-        if (videoOwner.has(VIDEO_OWNER_RENDERER)) {
-            return videoOwner.getObject(VIDEO_OWNER_RENDERER);
-        }
-
-        // we might want to create a loop here instead of using duplicated code
-        videoOwner = items.getObject(items.size())
-                .getObject("playlistSidebarSecondaryInfoRenderer")
-                .getObject("videoOwner");
-        if (videoOwner.has(VIDEO_OWNER_RENDERER)) {
-            return videoOwner.getObject(VIDEO_OWNER_RENDERER);
-        }
-        throw new ParsingException("Could not get uploader info");
-    }
-
-    private JsonObject getPlaylistInfo() throws ParsingException {
-        try {
-            return browseResponse.getObject("sidebar")
                     .getObject("playlistSidebarRenderer")
                     .getArray("items")
-                    .getObject(0)
+                    .stream()
-                    .getObject("playlistSidebarPrimaryInfoRenderer");
+                    .filter(JsonObject.class::isInstance)
-        } catch (final Exception e) {
+                    .map(JsonObject.class::cast)
-            throw new ParsingException("Could not get PlaylistInfo", e);
+                    .filter(item -> item.getObject("playlistSidebarSecondaryInfoRenderer")
+                            .getObject("videoOwner")
+                            .has(VIDEO_OWNER_RENDERER))
+                    .map(item -> item.getObject("playlistSidebarSecondaryInfoRenderer")
+                            .getObject("videoOwner")
+                            .getObject(VIDEO_OWNER_RENDERER))
+                    .findFirst()
+                    .orElseThrow(() -> new ParsingException("Could not get uploader info"));
         }
+
+        return uploaderInfo;
+    }
+
+    @Nonnull
+    private JsonObject getPlaylistInfo() throws ParsingException {
+        if (playlistInfo == null) {
+            playlistInfo = browseResponse.getObject(SIDEBAR)
+                    .getObject("playlistSidebarRenderer")
+                    .getArray("items")
+                    .stream()
+                    .filter(JsonObject.class::isInstance)
+                    .map(JsonObject.class::cast)
+                    .filter(item -> item.has("playlistSidebarPrimaryInfoRenderer"))
+                    .map(item -> item.getObject("playlistSidebarPrimaryInfoRenderer"))
+                    .findFirst()
+                    .orElseThrow(() -> new ParsingException("Could not get playlist info"));
+        }
+
+        return playlistInfo;
+    }
+
+    @Nonnull
+    private JsonObject getPlaylistHeader() {
+        if (playlistHeader == null) {
+            playlistHeader = browseResponse.getObject("header")
+                    .getObject("playlistHeaderRenderer");
+        }
+
+        return playlistHeader;
     }
 
     @Nonnull
     @Override
     public String getName() throws ParsingException {
-        final String name = getTextFromObject(playlistInfo.getObject("title"));
+        final String name = getTextFromObject(getPlaylistInfo().getObject("title"));
         if (!isNullOrEmpty(name)) {
             return name;
         }
@@ -127,13 +168,24 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
     @Nonnull
     @Override
     public String getThumbnailUrl() throws ParsingException {
-        String url = playlistInfo.getObject("thumbnailRenderer")
+        String url;
-                .getObject("playlistVideoThumbnailRenderer")
+        if (isNewPlaylistInterface) {
-                .getObject("thumbnail")
+            url = getPlaylistHeader().getObject("playlistHeaderBanner")
-                .getArray("thumbnails")
+                    .getObject("heroPlaylistThumbnailRenderer")
-                .getObject(0)
+                    .getObject("thumbnail")
-                .getString("url");
+                    .getArray("thumbnails")
+                    .getObject(0)
+                    .getString("url");
+        } else {
+            url = getPlaylistInfo().getObject("thumbnailRenderer")
+                    .getObject("playlistVideoThumbnailRenderer")
+                    .getObject("thumbnail")
+                    .getArray("thumbnails")
+                    .getObject(0)
+                    .getString("url");
+        }
 
+        // This data structure is returned in both layouts
         if (isNullOrEmpty(url)) {
             url = browseResponse.getObject("microformat")
                     .getObject("microformatDataRenderer")
@@ -153,7 +205,12 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
     @Override
     public String getUploaderUrl() throws ParsingException {
         try {
-            return getUrlFromNavigationEndpoint(getUploaderInfo().getObject("navigationEndpoint"));
+            return getUrlFromNavigationEndpoint(isNewPlaylistInterface
+                    ? getPlaylistHeader().getObject("ownerText")
+                    .getArray("runs")
+                    .getObject(0)
+                    .getObject("navigationEndpoint")
+                    : getUploaderInfo().getObject("navigationEndpoint"));
         } catch (final Exception e) {
             throw new ParsingException("Could not get playlist uploader url", e);
         }
@@ -162,7 +219,9 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
     @Override
     public String getUploaderName() throws ParsingException {
         try {
-            return getTextFromObject(getUploaderInfo().getObject("title"));
+            return getTextFromObject(isNewPlaylistInterface
+                    ? getPlaylistHeader().getObject("ownerText")
+                    : getUploaderInfo().getObject("title"));
         } catch (final Exception e) {
             throw new ParsingException("Could not get playlist uploader name", e);
         }
@@ -170,6 +229,11 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
 
     @Override
     public String getUploaderAvatarUrl() throws ParsingException {
+        if (isNewPlaylistInterface) {
+            // The new playlist interface doesn't provide an uploader avatar
+            return "";
+        }
+
         try {
             final String url = getUploaderInfo()
                     .getObject("thumbnail")
@@ -191,44 +255,50 @@ public class YoutubePlaylistExtractor extends PlaylistExtractor {
 
     @Override
     public long getStreamCount() throws ParsingException {
-        try {
+        if (isNewPlaylistInterface) {
-            final JsonArray stats = playlistInfo.getArray("stats");
+            final String numVideosText =
-            // For unknown reasons, YouTube don't provide the stream count for learning playlists
+                    getTextFromObject(getPlaylistHeader().getObject("numVideosText"));
-            // on the desktop client but only the number of views and the playlist modified date
+            if (numVideosText != null) {
-            // On normal playlists, at least 3 items are returned: the number of videos, the number
+                try {
-            // of views and the playlist modification date
+                    return Long.parseLong(Utils.removeNonDigitCharacters(numVideosText));
-            // We can get it by using another client, however it seems we can't get the avatar
+                } catch (final NumberFormatException ignored) {
-            // uploader URL with another client than the WEB client
-            if (stats.size() > STATS_ARRAY_WITH_STREAMS_COUNT_MIN_SIZE) {
-                final String videosText = getTextFromObject(playlistInfo.getArray("stats")
-                        .getObject(0));
-                if (videosText != null) {
-                    return Long.parseLong(Utils.removeNonDigitCharacters(videosText));
                 }
             }
 
-            return ITEM_COUNT_UNKNOWN;
+            final String firstByLineRendererText = getTextFromObject(
-        } catch (final Exception e) {
+                    getPlaylistHeader().getArray("byline")
-            throw new ParsingException("Could not get video count from playlist", e);
+                            .getObject(0)
+                            .getObject("text"));
+
+            if (firstByLineRendererText != null) {
+                try {
+                    return Long.parseLong(Utils.removeNonDigitCharacters(firstByLineRendererText));
+                } catch (final NumberFormatException ignored) {
+                }
+            }
         }
-    }
 
-    @Nonnull
+        // These data structures are returned in both layouts
-    @Override
+        final JsonArray briefStats =
-    public String getSubChannelName() {
+                (isNewPlaylistInterface ? getPlaylistHeader() : getPlaylistInfo())
-        return "";
+                        .getArray("briefStats");
-    }
+        if (!briefStats.isEmpty()) {
+            final String briefsStatsText = getTextFromObject(briefStats.getObject(0));
+            if (briefsStatsText != null) {
+                return Long.parseLong(Utils.removeNonDigitCharacters(briefsStatsText));
+            }
+        }
 
-    @Nonnull
+        final JsonArray stats = (isNewPlaylistInterface ? getPlaylistHeader() : getPlaylistInfo())
-    @Override
+                .getArray("stats");
-    public String getSubChannelUrl() {
+        if (!stats.isEmpty()) {
-        return "";
+            final String statsText = getTextFromObject(stats.getObject(0));
-    }
+            if (statsText != null) {
+                return Long.parseLong(Utils.removeNonDigitCharacters(statsText));
+            }
+        }
 
-    @Nonnull
+        return ITEM_COUNT_UNKNOWN;
-    @Override
-    public String getSubChannelAvatarUrl() {
-        return "";
     }
 
     @Nonnull