Add setting for lyric providers and add more providers

Fixes #335

src/settings/lyricssettingspage.h

@@ -0,0 +1,72 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2020, Jonas Kvinge <jonas@jkvinge.net>
+ *
+ * Strawberry 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.
+ *
+ * Strawberry 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
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef LYRICSSETTINGSPAGE_H
+#define LYRICSSETTINGSPAGE_H
+
+#include "config.h"
+
+#include <QObject>
+#include <QString>
+#include <QStringList>
+
+#include "settings/settingspage.h"
+
+class QListWidgetItem;
+
+class LyricsProvider;
+class SettingsDialog;
+class Ui_LyricsSettingsPage;
+
+class LyricsSettingsPage : public SettingsPage {
+  Q_OBJECT
+
+ public:
+  explicit LyricsSettingsPage(SettingsDialog *parent = nullptr);
+  ~LyricsSettingsPage();
+
+  static const char *kSettingsGroup;
+
+  void Load();
+  void Save();
+
+ private:
+  void NoProviderSelected();
+  void ProvidersMove(const int d);
+  void DisableAuthentication();
+  void DisconnectAuthentication(LyricsProvider *provider);
+  static bool ProviderCompareOrder(LyricsProvider *a, LyricsProvider *b);
+
+ private slots:
+  void CurrentItemChanged(QListWidgetItem *item_current, QListWidgetItem *item_previous);
+  void ItemSelectionChanged();
+  void ItemChanged(QListWidgetItem *item);
+  void ProvidersMoveUp();
+  void ProvidersMoveDown();
+  void AuthenticateClicked();
+  void LogoutClicked();
+  void AuthenticationSuccess();
+  void AuthenticationFailure(const QStringList &errors);
+
+ private:
+  Ui_LyricsSettingsPage *ui_;
+  bool provider_selected_;
+};
+
+#endif  // LYRICSSETTINGSPAGE_H