[YouTube] Differentiate genre mixes from normal mixes

Note: genre mixes already worked, now they are just considered as such in various video id extraction and in related items
Note 2: now extracting a mix id from a *normal* youtube mix id will fail if the video id wouldn't be exactly 11 characters long

Author: Stypox

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeParsingHelper.java

@@ -13,6 +13,7 @@
 import org.schabi.newpipe.extractor.exceptions.*;
 import org.schabi.newpipe.extractor.localization.ContentCountry;
 import org.schabi.newpipe.extractor.localization.Localization;
+import org.schabi.newpipe.extractor.playlist.PlaylistInfo;
 import org.schabi.newpipe.extractor.stream.Description;
 import org.schabi.newpipe.extractor.utils.JsonUtils;
 import org.schabi.newpipe.extractor.utils.Parser;
@@ -246,7 +247,8 @@ public static OffsetDateTime parseDateFrom(final String textualUploadDate)
      * @return Whether given id belongs to a YouTube Mix
      */
     public static boolean isYoutubeMixId(@Nonnull final String playlistId) {
-        return playlistId.startsWith("RD") && !isYoutubeMusicMixId(playlistId);
+        return playlistId.startsWith("RD")
+                && !isYoutubeMusicMixId(playlistId);
     }
 
     /**
@@ -282,28 +284,57 @@ public static boolean isYoutubeChannelMixId(@Nonnull final String playlistId) {
     }
 
     /**
-     * @return the video id extracted from the playlist id for Mixes
-     * @throws ParsingException If the playlistId is a Channel Mix or not a mix.
+     * Checks if the given playlist id is a YouTube Genre Mix (auto-generated playlist)
+     * Ids from a YouTube Genre Mix start with "RDGMEM"
+     *
+     * @return Whether given id belongs to a YouTube Genre Mix
+     */
+    public static boolean isYoutubeGenreMixId(@Nonnull final String playlistId) {
+        return playlistId.startsWith("RDGMEM");
+    }
+
+    /**
+     * @param playlistId the playlist id to parse
+     * @return the {@link PlaylistInfo.PlaylistType} extracted from the playlistId (mix playlist
+     *         types included)
+     * @throws ParsingException if the playlistId is null or empty, if the playlistId is not a mix,
+     *                          if it is a mix but it's not based on a specific stream (this is the
+     *                          case for channel or genre mixes)
      */
     @Nonnull
-    public static String extractVideoIdFromMixId(@Nonnull final String playlistId)
+    public static String extractVideoIdFromMixId(final String playlistId)
             throws ParsingException {
-        if (isYoutubeMyMixId(playlistId)) {
+        if (isNullOrEmpty(playlistId)) {
+            throw new ParsingException("Video id could not be determined from empty playlist id");
+
+        } else if (isYoutubeMyMixId(playlistId)) {
             return playlistId.substring(4);
 
         } else if (isYoutubeMusicMixId(playlistId)) {
             return playlistId.substring(6);
 
         } else if (isYoutubeChannelMixId(playlistId)) {
-            // Channel mix are build with RMCM{channelId}, so videoId can't be determined
-            throw new ParsingException("Video id could not be determined from mix id: "
+            // Channel mixes are of the form RMCM{channelId}, so videoId can't be determined
+            throw new ParsingException("Video id could not be determined from channel mix id: "
+                    + playlistId);
+
+        } else if (isYoutubeGenreMixId(playlistId)) {
+            // Genre mixes are of the form RDGMEM{garbage}, so videoId can't be determined
+            throw new ParsingException("Video id could not be determined from genre mix id: "
                     + playlistId);
 
         } else if (isYoutubeMixId(playlistId)) { // normal mix
+            if (playlistId.length() != 13) {
+                // Stream YouTube mixes are of the form RD{videoId}, but if videoId is not exactly
+                // 11 characters then it can't be a video id, hence we are dealing with a different
+                // type of mix (e.g. genre mixes handled above, of the form RDGMEM{garbage})
+                throw new ParsingException("Video id could not be determined from mix id: "
+                    + playlistId);
+            }
             return playlistId.substring(2);
 
         } else { // not a mix
-            throw new ParsingException("Video id could not be determined from mix id: "
+            throw new ParsingException("Video id could not be determined from playlist id: "
                     + playlistId);
         }
     }

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

@@ -3,6 +3,7 @@
 import static org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper.getTextFromObject;
 import static org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper.getThumbnailUrlFromInfoItem;
 import static org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper.isYoutubeChannelMixId;
+import static org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper.isYoutubeGenreMixId;
 import static org.schabi.newpipe.extractor.services.youtube.YoutubeParsingHelper.isYoutubeMusicMixId;
 import static org.schabi.newpipe.extractor.utils.Utils.isNullOrEmpty;
 
@@ -74,8 +75,11 @@ public PlaylistInfo.PlaylistType getPlaylistType() throws ParsingException {
                 return PlaylistInfo.PlaylistType.MIX_MUSIC;
             } else if (isYoutubeChannelMixId(mixPlaylistId)) {
                 return PlaylistInfo.PlaylistType.MIX_CHANNEL;
+            } else if (isYoutubeGenreMixId(mixPlaylistId)) {
+                return PlaylistInfo.PlaylistType.MIX_GENRE;
             } else {
                 // either a normal mix based on a stream, or a "my mix" (still based on a stream)
+                // note: if YouTube introduces even more types of mixes, they will default to this
                 return PlaylistInfo.PlaylistType.MIX_STREAM;
             }
         } catch (final MalformedURLException e) {