Add deezer cover provider

src/covermanager/deezercoverprovider.h

@@ -0,0 +1,63 @@
+/*
+ * Strawberry Music Player
+ * Copyright 2018, 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 DEEZERCOVERPROVIDER_H
+#define DEEZERCOVERPROVIDER_H
+
+#include "config.h"
+
+#include <stdbool.h>
+
+#include <QObject>
+#include <QVariant>
+#include <QByteArray>
+#include <QString>
+#include <QNetworkAccessManager>
+#include <QNetworkReply>
+#include <QJsonValue>
+#include <QJsonObject>
+#include <QJsonArray>
+
+#include "coverprovider.h"
+
+class DeezerCoverProvider : public CoverProvider {
+  Q_OBJECT
+
+ public:
+  explicit DeezerCoverProvider(QObject *parent = nullptr);
+  bool StartSearch(const QString &artist, const QString &album, int id);
+  void CancelSearch(int id);
+
+ private slots:
+  void HandleSearchReply(QNetworkReply *reply, int id);
+
+ private:
+  static const char *kApiUrl;
+  static const int kLimit;
+
+  QByteArray GetReplyData(QNetworkReply *reply);
+  QJsonObject ExtractJsonObj(QByteArray &data);
+  QJsonValue ExtractData(QByteArray &data);
+  void Error(QString error, QVariant debug = QVariant());
+
+  QNetworkAccessManager *network_;
+
+};
+
+#endif  // DEEZERCOVERPROVIDER_H