Add smart playlists, ratings and Qobuz

Fixes #259
Fixes #264

src/smartplaylists/playlistgenerator.h

@@ -0,0 +1,100 @@
+/*
+ * Strawberry Music Player
+ * This file was part of Clementine.
+ * Copyright 2010, David Sansome <me@davidsansome.com>
+ *
+ * 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 PLAYLISTGENERATOR_H
+#define PLAYLISTGENERATOR_H
+
+#include "config.h"
+
+#include <memory>
+
+#include <QObject>
+#include <QByteArray>
+#include <QString>
+
+#include "playlist/playlistitem.h"
+
+class CollectionBackend;
+
+class PlaylistGenerator : public QObject, public std::enable_shared_from_this<PlaylistGenerator> {
+  Q_OBJECT
+
+ public:
+  explicit PlaylistGenerator();
+
+  static const int kDefaultLimit;
+  static const int kDefaultDynamicHistory;
+  static const int kDefaultDynamicFuture;
+
+  enum Type {
+    Type_None = 0,
+    Type_Query = 1
+  };
+
+  // Creates a new PlaylistGenerator of the given type
+  static std::shared_ptr<PlaylistGenerator> Create(const Type type = Type_Query);
+
+  // Should be called before Load on a new PlaylistGenerator
+  void set_collection(CollectionBackend *backend) { backend_ = backend; }
+  void set_name(const QString &name) { name_ = name; }
+  CollectionBackend *collection() const { return backend_; }
+  QString name() const { return name_; }
+
+  // Name of the subclass
+  virtual Type type() const = 0;
+
+  // Serializes the PlaylistGenerator's settings
+  // Called on UI-thread.
+  virtual void Load(const QByteArray &data) = 0;
+  // Called on UI-thread.
+  virtual QByteArray Save() const = 0;
+
+  // Creates and returns a playlist
+  // Called from non-UI thread.
+  virtual PlaylistItemList Generate() = 0;
+
+  // If the generator can be used as a dynamic playlist then GenerateMore should return the next tracks in the sequence.
+  // The subclass should remember the last GetDynamicHistory() + GetDynamicFuture() tracks,
+  // and ensure that the tracks returned from this method are not in that set.
+  virtual bool is_dynamic() const { return false; }
+  virtual void set_dynamic(const bool dynamic) { Q_UNUSED(dynamic); }
+  // Called from non-UI thread.
+  virtual PlaylistItemList GenerateMore(int count) {
+    Q_UNUSED(count);
+    return PlaylistItemList();
+  }
+
+  virtual int GetDynamicHistory() { return kDefaultDynamicHistory; }
+  virtual int GetDynamicFuture() { return kDefaultDynamicFuture; }
+
+ signals:
+  void Error(const QString& message);
+
+ protected:
+  CollectionBackend *backend_;
+
+ private:
+  QString name_;
+
+};
+
+#include "playlistgenerator_fwd.h"
+
+#endif  // PLAYLISTGENERATOR_H