Add the ability to subscribe on wikivoyage saved articles updates

OsmAnd/src/net/osmand/plus/wikivoyage/data/WikivoyageLocalDataHelper.java

@@ -25,6 +25,12 @@ public class WikivoyageLocalDataHelper {
 	private TLongObjectHashMap<WikivoyageSearchHistoryItem> historyMap;
 	private List<WikivoyageArticle> savedArticles;
 
+	private Listener listener;
+
+	public void setListener(Listener listener) {
+		this.listener = listener;
+	}
+
 	private WikivoyageLocalDataHelper(OsmandApplication app) {
 		dbHelper = new WikivoyageLocalDataDbHelper(app);
 		historyMap = dbHelper.getAllHistoryMap();
@@ -99,6 +105,7 @@ public class WikivoyageLocalDataHelper {
 			saved.content = article.getPartialContent();
 			savedArticles.add(saved);
 			dbHelper.addSavedArticle(saved);
+			notifySavedUpdated();
 		}
 	}
 
@@ -107,6 +114,7 @@ public class WikivoyageLocalDataHelper {
 		if (savedArticle != null) {
 			savedArticles.remove(savedArticle);
 			dbHelper.removeSavedArticle(savedArticle);
+			notifySavedUpdated();
 		}
 	}
 
@@ -114,6 +122,12 @@ public class WikivoyageLocalDataHelper {
 		return getArticle(article.cityId, article.lang) != null;
 	}
 
+	private void notifySavedUpdated() {
+		if (listener != null) {
+			listener.savedArticlesUpdated();
+		}
+	}
+
 	@Nullable
 	private WikivoyageArticle getArticle(long cityId, String lang) {
 		for (WikivoyageArticle article : savedArticles) {
@@ -124,6 +138,11 @@ public class WikivoyageLocalDataHelper {
 		return null;
 	}
 
+	public interface Listener {
+
+		void savedArticlesUpdated();
+	}
+
 	private static class WikivoyageLocalDataDbHelper {
 
 		private static final int DB_VERSION = 2;