[Youtube] Add _ITEMS constants and improve code style

Move thumbnail id exctraction code to getThumbnailUrlFromId
Add test for "My mix" detection to service tests
Use ITEM_COUNT_UNKNOWN everywhere instead of -1 and add some tests

extractor/src/main/java/org/schabi/newpipe/extractor/services/media_ccc/extractors/infoItems/MediaCCCConferenceInfoItemExtractor.java

@@ -1,6 +1,8 @@
 package org.schabi.newpipe.extractor.services.media_ccc.extractors.infoItems;
 
 import com.grack.nanojson.JsonObject;
+
+import org.schabi.newpipe.extractor.ListExtractor;
 import org.schabi.newpipe.extractor.channel.ChannelInfoItemExtractor;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 
@@ -23,7 +25,7 @@ public class MediaCCCConferenceInfoItemExtractor implements ChannelInfoItemExtra
 
     @Override
     public long getStreamCount() {
-        return -1;
+        return ListExtractor.ITEM_COUNT_UNKNOWN;
     }
 
     @Override

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

@@ -2,6 +2,7 @@ package org.schabi.newpipe.extractor.services.youtube.extractors;
 
 import com.grack.nanojson.JsonObject;
 
+import org.schabi.newpipe.extractor.ListExtractor;
 import org.schabi.newpipe.extractor.channel.ChannelInfoItemExtractor;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 import org.schabi.newpipe.extractor.services.youtube.linkHandler.YoutubeChannelLinkHandlerFactory;
@@ -86,7 +87,7 @@ public class YoutubeChannelInfoItemExtractor implements ChannelInfoItemExtractor
         try {
             if (!channelInfoItem.has("videoCountText")) {
                 // Video count is not available, channel probably has no public uploads.
-                return -1;
+                return ListExtractor.ITEM_COUNT_UNKNOWN;
             }
 
             return Long.parseLong(Utils.removeNonDigitCharacters(getTextFromObject(

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

@@ -7,6 +7,8 @@ import com.grack.nanojson.JsonObject;
 import java.io.IOException;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+
+import org.schabi.newpipe.extractor.ListExtractor;
 import org.schabi.newpipe.extractor.StreamingService;
 import org.schabi.newpipe.extractor.downloader.Downloader;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
@@ -23,6 +25,7 @@ import org.schabi.newpipe.extractor.stream.StreamInfoItemsCollector;
  */
 public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
 
+
     private final static String CONTENTS = "contents";
     private final static String RESPONSE = "response";
     private final static String PLAYLIST = "playlist";
@@ -41,44 +44,25 @@ public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
         final String url = getUrl() + "&pbj=1";
         final JsonArray ajaxJson = getJsonResponse(url, getExtractorLocalization());
         JsonObject initialData = ajaxJson.getObject(3).getObject(RESPONSE);
-        try {
+        playlistData = initialData.getObject(CONTENTS).getObject(TWO_COLUMN_WATCH_NEXT_RESULTS)
-            playlistData = initialData.getObject(CONTENTS).getObject(TWO_COLUMNS_WATCH_NEXT_RESULTS)
+            .getObject(PLAYLIST).getObject(PLAYLIST);
-                .getObject(PLAYLIST).getObject(PLAYLIST);
-        } catch (NullPointerException e) {
-            throw new ExtractionException(e);
-        }
-
     }
 
     @Nonnull
     @Override
     public String getName() throws ParsingException {
-        try {
+        final String name = playlistData.getString("title");
-            final String name = playlistData.getString("title");
+        if (name == null) {
-            if (name != null) {
+            throw new ParsingException("Could not get playlist name");
-                return name;
-            } else {
-                return "";
-            }
-        } catch (Exception e) {
-            throw new ParsingException("Could not get playlist name", e);
         }
+        return name;
     }
 
     @Override
     public String getThumbnailUrl() throws ParsingException {
         try {
             final String playlistId = playlistData.getString("playlistId");
-            final String videoId;
+            return getThumbnailUrlFromId(playlistId);
-            if (playlistId.startsWith("RDMM")) {
-                videoId = playlistId.substring(4);
-            } else {
-                videoId = playlistId.substring(2);
-            }
-            if (videoId.isEmpty()) {
-                throw new ParsingException("");
-            }
-            return getThumbnailUrlFromId(videoId);
         } catch (Exception e) {
             throw new ParsingException("Could not get playlist thumbnail", e);
         }
@@ -97,20 +81,20 @@ public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
 
     @Override
     public String getUploaderName() {
-        //Youtube mix are auto-generated
+        //Youtube mix are auto-generated by YouTube
-        return "";
+        return "YouTube";
     }
 
     @Override
     public String getUploaderAvatarUrl() {
-        //Youtube mix are auto-generated
+        //Youtube mix are auto-generated by YouTube
         return "";
     }
 
     @Override
     public long getStreamCount() {
         // Auto-generated playlist always start with 25 videos and are endless
-        return 25;
+        return ListExtractor.ITEM_COUNT_INFINITE;
     }
 
     @Nonnull
@@ -135,7 +119,7 @@ public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
 
     @Override
     public InfoItemsPage<StreamInfoItem> getPage(final String pageUrl)
-        throws ExtractionException, IOException {
+            throws ExtractionException, IOException {
         if (pageUrl == null || pageUrl.isEmpty()) {
             throw new ExtractionException(
                 new IllegalArgumentException("Page url is empty or null"));
@@ -145,7 +129,7 @@ public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
         final JsonArray ajaxJson = getJsonResponse(pageUrl, getExtractorLocalization());
         playlistData =
             ajaxJson.getObject(3).getObject(RESPONSE).getObject(CONTENTS)
-                .getObject(TWO_COLUMNS_WATCH_NEXT_RESULTS).getObject(PLAYLIST)
+                .getObject(TWO_COLUMN_WATCH_NEXT_RESULTS).getObject(PLAYLIST)
                 .getObject(PLAYLIST);
         final JsonArray streams = playlistData.getArray(CONTENTS);
         //Because continuation requests are created with the last video of previous request as start
@@ -155,8 +139,8 @@ public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
     }
 
     private void collectStreamsFrom(
-        @Nonnull StreamInfoItemsCollector collector,
+            @Nonnull StreamInfoItemsCollector collector,
-        @Nullable JsonArray streams) {
+            @Nullable JsonArray streams) {
         collector.reset();
 
         if (streams == null) {
@@ -176,7 +160,16 @@ public class YoutubeMixPlaylistExtractor extends PlaylistExtractor {
         }
     }
 
-    private String getThumbnailUrlFromId(String videoId) {
+    private String getThumbnailUrlFromId(String playlistId) throws ParsingException {
+        final String videoId;
+        if (playlistId.startsWith("RDMM")) {
+            videoId = playlistId.substring(4);
+        } else {
+            videoId = playlistId.substring(2);
+        }
+        if (videoId.isEmpty()) {
+            throw new ParsingException("videoId is empty");
+        }
         return "https://i.ytimg.com/vi/" + videoId + "/hqdefault.jpg";
     }
 }

extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeMixPlaylistExtractorTest.java

@@ -93,6 +93,11 @@ public class YoutubeMixPlaylistExtractorTest {
         public void getStreamCount() throws Exception {
             assertEquals(ListExtractor.ITEM_COUNT_INFINITE, extractor.getStreamCount());
         }
+
+        @Test
+        public void getStreamCount() throws Exception {
+            assertEquals(ListExtractor.ITEM_COUNT_INFINITE, extractor.getStreamCount());
+        }
     }
 
     public static class MixWithIndex {
@@ -165,6 +170,11 @@ public class YoutubeMixPlaylistExtractorTest {
         public void getStreamCount() {
             assertEquals(ListExtractor.ITEM_COUNT_INFINITE, extractor.getStreamCount());
         }
+
+        @Test
+        public void getStreamCount() throws Exception {
+            assertEquals(ListExtractor.ITEM_COUNT_INFINITE, extractor.getStreamCount());
+        }
     }
 
     public static class MyMix {
@@ -319,5 +329,10 @@ public class YoutubeMixPlaylistExtractorTest {
         public void getStreamCount() throws Exception {
             assertEquals(ListExtractor.ITEM_COUNT_INFINITE, extractor.getStreamCount());
         }
+
+        @Test
+        public void getStreamCount() throws Exception {
+            assertEquals(ListExtractor.ITEM_COUNT_INFINITE, extractor.getStreamCount());
+        }
     }
 }

extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeServiceTest.java

@@ -75,7 +75,13 @@ public class YoutubeServiceTest {
         assertTrue(extractor instanceof YoutubeMixPlaylistExtractor);
 
         extractor = YouTube.getPlaylistExtractor(
-            "https://www.youtube.com/watch?v=" + videoId + "&list=RD" + videoId);
+            "https://www.youtube.com/watch?v=" + videoId + "&list=RDMM" + videoId);
+        assertTrue(extractor instanceof YoutubeMixPlaylistExtractor);
+
+        final String mixVideoId = "qHtzO49SDmk";
+
+        extractor = YouTube.getPlaylistExtractor(
+            "https://www.youtube.com/watch?v=" + mixVideoId + "&list=RD" + videoId);
         assertTrue(extractor instanceof YoutubeMixPlaylistExtractor);
     }
 }