add ability to get donation links from channel

extractor/src/main/java/org/schabi/newpipe/extractor/channel/ChannelExtractor.java

@@ -45,4 +45,5 @@ public abstract class ChannelExtractor extends ListExtractor<StreamInfoItem> {
     public abstract String getFeedUrl() throws ParsingException;
     public abstract long getSubscriberCount() throws ParsingException;
     public abstract String getDescription() throws ParsingException;
+    public abstract String[] getDonationLinks() throws ParsingException;
 }

extractor/src/main/java/org/schabi/newpipe/extractor/channel/ChannelInfo.java

@@ -92,6 +92,11 @@ public class ChannelInfo extends ListInfo<StreamInfoItem> {
         } catch (Exception e) {
             info.addError(e);
         }
+        try {
+            info.setDonationLinks(extractor.getDonationLinks());
+        } catch (Exception e) {
+            info.addError(e);
+        }
 
         return info;
     }
@@ -101,6 +106,7 @@ public class ChannelInfo extends ListInfo<StreamInfoItem> {
     private String feedUrl;
     private long subscriberCount = -1;
     private String description;
+    private String[] donationLinks;
 
     public String getAvatarUrl() {
         return avatarUrl;
@@ -141,4 +147,12 @@ public class ChannelInfo extends ListInfo<StreamInfoItem> {
     public void setDescription(String description) {
         this.description = description;
     }
+
+    public String[] getDonationLinks() {
+        return donationLinks;
+    }
+
+    public void setDonationLinks(String[] donationLinks) {
+        this.donationLinks = donationLinks;
+    }
 }

extractor/src/main/java/org/schabi/newpipe/extractor/services/soundcloud/SoundcloudChannelExtractor.java

@@ -133,4 +133,9 @@ public class SoundcloudChannelExtractor extends ChannelExtractor {
 
         return new InfoItemsPage<>(collector, nextPageUrl);
     }
+
+    @Override
+    public String[] getDonationLinks() {
+        return new String[0];
+    }
 }

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

@@ -4,12 +4,14 @@ package org.schabi.newpipe.extractor.services.youtube;
 import com.grack.nanojson.JsonObject;
 import com.grack.nanojson.JsonParser;
 import com.grack.nanojson.JsonParserException;
+import com.sun.org.apache.xerces.internal.xs.StringList;
 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
 import org.schabi.newpipe.extractor.Downloader;
 import org.schabi.newpipe.extractor.NewPipe;
 import org.schabi.newpipe.extractor.StreamingService;
+import org.schabi.newpipe.extractor.UrlIdHandler;
 import org.schabi.newpipe.extractor.channel.ChannelExtractor;
 import org.schabi.newpipe.extractor.exceptions.ExtractionException;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
@@ -20,6 +22,7 @@ import org.schabi.newpipe.extractor.utils.Utils;
 
 import javax.annotation.Nonnull;
 import java.io.IOException;
+import java.util.ArrayList;
 
 /*
  * Created by Christian Schabesberger on 25.07.16.
@@ -181,6 +184,27 @@ public class YoutubeChannelExtractor extends ChannelExtractor {
         return new InfoItemsPage<>(collector, getNextPageUrlFromAjaxPage(ajaxJson, pageUrl));
     }
 
+    @Override
+    public String[] getDonationLinks() throws ParsingException {
+        try {
+            ArrayList<String> links = new ArrayList<>();
+            Element linkHolder = doc.select("div[id=\"links-holder\"]").first();
+            if(linkHolder == null) {
+                // this occures if no links are embeded into the channel
+                return new String[0];
+            }
+            for(Element a : linkHolder.select("a")) {
+                System.err.println(a.attr("abs:href"));
+                links.add(a.attr("abs:href"));
+            }
+            String[] retLinks = new String[links.size()];
+            retLinks = links.toArray(retLinks);
+            return retLinks;
+        } catch (Exception e) {
+            throw new ParsingException("Could not get donation links", e);
+        }
+    }
+
     private String getNextPageUrlFromAjaxPage(final JsonObject ajaxJson, final String pageUrl)
         throws ParsingException {
         String loadMoreHtmlDataRaw = ajaxJson.getString("load_more_widget_html");

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

@@ -103,6 +103,11 @@ public class YoutubeChannelExtractorTest {
         public void testSubscriberCount() throws Exception {
             assertTrue("Wrong subscriber count", extractor.getSubscriberCount() >= 0);
         }
+
+        @Test
+        public void testChannelDonation() throws Exception {
+            assertTrue(extractor.getDonationLinks().length != 0);
+        }
     }
 
     public static class Kurzgesagt implements BaseChannelExtractorTest {
@@ -205,6 +210,11 @@ public class YoutubeChannelExtractorTest {
         public void testSubscriberCount() throws Exception {
             assertTrue("Wrong subscriber count", extractor.getSubscriberCount() >= 5e6);
         }
+
+        @Test
+        public void testChannelDonation() throws Exception {
+            assertTrue(extractor.getDonationLinks().length == 0);
+        }
     }
 
     public static class CaptainDisillusion implements BaseChannelExtractorTest {
@@ -389,6 +399,11 @@ public class YoutubeChannelExtractorTest {
         public void testSubscriberCount() throws Exception {
             assertTrue("Wrong subscriber count", extractor.getSubscriberCount() >= 50);
         }
+
+        @Test
+        public void testChannelDonation() throws Exception {
+            assertTrue(extractor.getDonationLinks().length == 0);
+        }
     }
 };