Add Subsonic scrobble support (#545)

* add SubsonicScrobbler, add Scrobble method in SubsonicService

* new class SubsonicScrobbleRequest, use queue again, clean up

* add checkbox to enable server-side scrobbling to Subsonic settings page

* Check serversidescrobbling in SubsonicScrobbler::ReloadSettings instead of SubsonicService

TODO: SubsonicScrobbler::ReloadSettings needs to be called when
SubsonicSettings change.

src/subsonic/subsonicscrobblerequest.h

@@ -0,0 +1,90 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2019, Jonas Kvinge <jonas@jkvinge.net>
+ * Copyright 2020, Pascal Below <spezifisch@below.fr>
+ *
+ * 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 SUBSONICSCROBBLEREQUEST_H
+#define SUBSONICSCROBBLEREQUEST_H
+
+#include "config.h"
+
+#include <memory>
+
+#include <QtGlobal>
+#include <QObject>
+#include <QDateTime>
+#include <QPair>
+#include <QQueue>
+#include <QVariant>
+#include <QString>
+#include <QStringList>
+
+#include "subsonicbaserequest.h"
+
+class QNetworkReply;
+class Application;
+class SubsonicService;
+class SubsonicUrlHandler;
+
+class SubsonicScrobbleRequest : public SubsonicBaseRequest {
+  Q_OBJECT
+
+ public:
+  explicit SubsonicScrobbleRequest(SubsonicService *service, SubsonicUrlHandler *url_handler, Application *app, QObject *parent);
+  ~SubsonicScrobbleRequest() override;
+
+  void CreateScrobbleRequest(const QString song_id, const bool submission, const QDateTime start_time);
+
+ private slots:
+  void ScrobbleReplyReceived(QNetworkReply *reply);
+
+ private:
+  typedef QPair<QString, QString> Param;
+  typedef QList<Param> ParamList;
+
+  struct Request {
+    explicit Request() : submission(false) {}
+    // subsonic song id
+    QString song_id;
+    // submission: true=Submission, false=NowPlaying
+    bool submission;
+    // song start time
+    qint64 time_ms;
+  };
+
+  void FlushScrobbleRequests();
+  void FinishCheck();
+
+  void Error(const QString &error, const QVariant &debug = QVariant()) override;
+
+  static const int kMaxConcurrentScrobbleRequests;
+
+  SubsonicService *service_;
+  SubsonicUrlHandler *url_handler_;
+  Application *app_;
+
+  QQueue<Request> scrobble_requests_queue_;
+
+  int scrobble_requests_active_;
+
+  QStringList errors_;
+  QList<QNetworkReply*> replies_;
+
+};
+
+#endif  // SUBSONICSCROBBLEREQUEST_H