[YouTube] Support new trending structure and filter recently trending section

This new structure allow us to filter easily Trending shorts and Recently
trending sections.

On the previous one, this Recently trending section is now filtered, by
checking whether sections have a title, which isn't the case for normal trends
contrary to the other ones.

This makes that the extractor returns now only the real 50 "Now" YouTube
trends.

Elements inside arrays are now extracted dynamically instead of only the ones
of the first index, using Java 8's Stream API.

The getInitialPage() method of YoutubeTrendingExtractor can now throw a
ParsingException if no selected tab (corresponding to the one of the trends
type extracted) has been found.

Finally, the licence header has been moved to the top of the file and updated.

Author: AudricV

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

@@ -1,26 +1,25 @@
-package org.schabi.newpipe.extractor.services.youtube.extractors;
-
 /*
  * Created by Christian Schabesberger on 12.08.17.
  *
  * Copyright (C) Christian Schabesberger 2018 <chris.schabesberger@mailbox.org>
- * YoutubeTrendingExtractor.java is part of NewPipe.
+ * YoutubeTrendingExtractor.java is part of NewPipe Extractor.
  *
- * NewPipe is free software: you can redistribute it and/or modify
+ * NewPipe Extractor is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
  *
- * NewPipe is distributed in the hope that it will be useful,
+ * NewPipe Extractor is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with NewPipe.  If not, see <http://www.gnu.org/licenses/>.
+ * along with NewPipe Extractor. If not, see <https://www.gnu.org/licenses/>.
  */
 
-import com.grack.nanojson.JsonArray;
+package org.schabi.newpipe.extractor.services.youtube.extractors;
+
 import com.grack.nanojson.JsonObject;
 import com.grack.nanojson.JsonWriter;
 
@@ -92,25 +91,66 @@ public String getName() throws ParsingException {
 
     @Nonnull
     @Override
-    public InfoItemsPage<StreamInfoItem> getInitialPage() {
+    public InfoItemsPage<StreamInfoItem> getInitialPage() throws ParsingException {
         final StreamInfoItemsCollector collector = new StreamInfoItemsCollector(getServiceId());
         final TimeAgoParser timeAgoParser = getTimeAgoParser();
-        final JsonArray itemSectionRenderers = initialData.getObject("contents")
-                .getObject("twoColumnBrowseResultsRenderer").getArray("tabs").getObject(0)
-                .getObject("tabRenderer").getObject("content").getObject("sectionListRenderer")
-                .getArray("contents");
-
-        for (final Object itemSectionRenderer : itemSectionRenderers) {
-            final JsonObject expandedShelfContentsRenderer = ((JsonObject) itemSectionRenderer)
-                    .getObject("itemSectionRenderer").getArray("contents").getObject(0)
-                    .getObject("shelfRenderer").getObject("content")
-                    .getObject("expandedShelfContentsRenderer");
-            for (final Object ul : expandedShelfContentsRenderer.getArray("items")) {
-                final JsonObject videoInfo = ((JsonObject) ul).getObject("videoRenderer");
-                collector.commit(new YoutubeStreamInfoItemExtractor(videoInfo, timeAgoParser));
-            }
+        final JsonObject tabContent = getTrendingTabContent();
+
+        if (tabContent.has("richGridRenderer")) {
+            tabContent.getObject("richGridRenderer")
+                    .getArray("contents")
+                    .stream()
+                    .filter(JsonObject.class::isInstance)
+                    .map(JsonObject.class::cast)
+                    // Filter Trending shorts and Recently trending sections
+                    .filter(content -> content.has("richItemRenderer"))
+                    .map(content -> content.getObject("richItemRenderer")
+                            .getObject("content")
+                            .getObject("videoRenderer"))
+                    .forEachOrdered(videoRenderer -> collector.commit(
+                            new YoutubeStreamInfoItemExtractor(videoRenderer, timeAgoParser)));
+        } else if (tabContent.has("sectionListRenderer")) {
+            tabContent.getObject("sectionListRenderer")
+                    .getArray("contents")
+                    .stream()
+                    .filter(JsonObject.class::isInstance)
+                    .map(JsonObject.class::cast)
+                    .flatMap(content -> content.getObject("itemSectionRenderer")
+                            .getArray("contents")
+                            .stream())
+                    .filter(JsonObject.class::isInstance)
+                    .map(JsonObject.class::cast)
+                    .map(content -> content.getObject("shelfRenderer"))
+                    // Filter Trending shorts and Recently trending sections which have a title,
+                    // contrary to normal trends
+                    .filter(shelfRenderer -> !shelfRenderer.has("title"))
+                    .flatMap(shelfRenderer -> shelfRenderer.getObject("content")
+                            .getObject("expandedShelfContentsRenderer")
+                            .getArray("items")
+                            .stream())
+                    .filter(JsonObject.class::isInstance)
+                    .map(JsonObject.class::cast)
+                    .map(item -> item.getObject("videoRenderer"))
+                    .forEachOrdered(videoRenderer -> collector.commit(
+                            new YoutubeStreamInfoItemExtractor(videoRenderer, timeAgoParser)));
         }
 
         return new InfoItemsPage<>(collector, null);
     }
+
+    private JsonObject getTrendingTabContent() throws ParsingException {
+        return initialData.getObject("contents")
+                .getObject("twoColumnBrowseResultsRenderer")
+                .getArray("tabs")
+                .stream()
+                .filter(JsonObject.class::isInstance)
+                .map(JsonObject.class::cast)
+                .map(tab -> tab.getObject("tabRenderer"))
+                .filter(tabRenderer -> tabRenderer.getBoolean("selected"))
+                .filter(tabRenderer -> tabRenderer.has("content"))
+                // There should be at most one tab selected
+                .findFirst()
+                .orElseThrow(() -> new ParsingException("Could not get \"Now\" trending tab"))
+                .getObject("content");
+    }
 }