PlaylistDAO: add getNextPlaylist(), to be used for History feature

src/library/dao/playlistdao.cpp

@@ -781,6 +781,26 @@ int PlaylistDAO::getPreviousPlaylist(const int currentPlaylistId, HiddenType hid
     return kInvalidPlaylistId;
 }
 
+int PlaylistDAO::getNextPlaylist(const int currentPlaylistId, HiddenType hidden) const {
+    QSqlQuery query(m_database);
+    query.prepare(QStringLiteral(
+            "SELECT max(id) as id FROM Playlists "
+            "WHERE id > :id AND hidden = :hidden"));
+    query.bindValue(":id", currentPlaylistId);
+    query.bindValue(":hidden", hidden);
+
+    if (!query.exec()) {
+        LOG_FAILED_QUERY(query);
+        return kInvalidPlaylistId;
+    }
+
+    // Get the id of the lowest playlist
+    if (query.next()) {
+        return query.value(query.record().indexOf("id")).toInt();
+    }
+    return kInvalidPlaylistId;
+}
+
 bool PlaylistDAO::copyPlaylistTracks(const int sourcePlaylistID, const int targetPlaylistID) {
     // Start the transaction
     ScopedTransaction transaction(m_database);

src/library/dao/playlistdao.h

@@ -112,6 +112,9 @@ class PlaylistDAO : public QObject, public virtual DAO {
     // Get the preceding playlist of currentPlaylistId with the HiddenType
     // hidden. Returns -1 if no such playlist exists.
     int getPreviousPlaylist(const int currentPlaylistId, HiddenType hidden) const;
+    // Get the following playlist of currentPlaylistId with the HiddenType
+    // hidden. Returns -1 if no such playlist exists.
+    int getNextPlaylist(const int currentPlaylistId, HiddenType hidden) const;
     // Append all the tracks in the source playlist to the target playlist.
     bool copyPlaylistTracks(const int sourcePlaylistID, const int targetPlaylistID);
     // Returns the number of tracks in the given playlist.