FileDownloader.h

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#ifndef OSMSCOUT_CLIENT_QT_FILEDOWNLOADER_H
#define OSMSCOUT_CLIENT_QT_FILEDOWNLOADER_H

/*
  OSMScout - a Qt backend for libosmscout and libosmscout-map
  Copyright (C) 2017 Rinigus

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
*/

#include <QObject>
#include <QString>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QFile>
#include <QUrl>
#include <QProcess>
#include <QByteArray>
#include <QTime>
#include <QFileInfo>
#include <QTimer>
#include <QDir>

#include <osmscout/ClientQtImportExport.h>

#include <chrono>

namespace osmscout {

namespace FileDownloaderConfig {

static constexpr uint64_t BufferNetwork{1024*1024*1}; 
static constexpr std::chrono::seconds DownloadReadTimeout{60}; 
static constexpr std::chrono::seconds BackOffInitial{1}; 
static constexpr std::chrono::seconds BackOffMax{300}; 
static constexpr int MaxDownloadRetries{-1}; 
}

class OSMSCOUT_CLIENT_QT_API FileDownloader : public QObject
{
  Q_OBJECT

#ifdef OSMSCOUT_CLIENT_QT_FILEDOWNLOADER_TEST
public: // make possible to modify internal state in test
#else
private:
#endif

  struct BackOff {
    int downloadRetries{0};

    std::chrono::seconds backOffTime{FileDownloaderConfig::BackOffInitial};
    QTimer restartTimer;

    bool scheduleRestart();
    void recover();
  };

  BackOff backOff;

  QNetworkAccessManager *manager;
  QUrl url;
  QString path;

  QNetworkReply *reply{nullptr};

  QFile file;

  bool isOk{true};
  bool finishedSuccessfully{false};

  uint64_t downloaded{0};

  QTimer timeoutTimer;

public:
  explicit FileDownloader(QNetworkAccessManager *manager,
                          QString url,
                          QString path,
                          QObject *parent = nullptr);
  ~FileDownloader() override;

  operator bool() const { return isOk; }
  QString getFileName() const { return QFileInfo(path).fileName(); }
  QString getFilePath() const { return path; }
  uint64_t getBytesDownloaded() const;

signals:
  void downloadedBytes(uint64_t sz);
  void writtenBytes(uint64_t sz);
  void finished(QString path);
  void error(QString error_text, bool recoverable);

public slots:
  void startDownload();

protected slots:
  void onNetworkReadyRead();
  void onDownloaded();
  void onNetworkError(QNetworkReply::NetworkError code);
  void onTimeout();

protected:
  void onFinished();
  void onError(const QString &err);

  bool restartDownload(); 
};


class OSMSCOUT_CLIENT_QT_API DownloadJob: public QObject
{
  Q_OBJECT

protected:
  QList<FileDownloader*>  jobs;
  QNetworkAccessManager   *webCtrl;

  QDir                    target;

  bool                    done{false};
  bool                    started{false};
  bool                    successful{false};
  bool                    canceledByUser{false};

  uint64_t                downloadedBytes{0};

  QString                 error;

  bool                    replaceExisting;

signals:
  void finished(); // successfully
  void failed(QString error);
  void canceled();
  void downloadProgress();

public slots:
  void onJobFailed(QString errorMessage, bool recoverable);
  void onJobFinished(QString path);
  void onDownloadProgress(uint64_t);
  void downloadNextFile();

public:
  DownloadJob(QNetworkAccessManager *webCtrl, QDir target, bool replaceExisting);
  ~DownloadJob() override;

  DownloadJob(const DownloadJob&) = delete;
  DownloadJob(DownloadJob&&) = delete;

  DownloadJob& operator=(const DownloadJob&) = delete;
  DownloadJob& operator==(const DownloadJob&&) = delete;

  void start(const QString &serverBasePath, const QStringList &files);

  void cancel();

  virtual uint64_t expectedSize() const = 0;

  inline bool isDone() const
  {
    return done;
  }

  inline bool isSuccessful() const
  {
    return successful;
  }

  inline bool isDownloading() const
  {
    return started && !done;
  }

  inline QString getError() const
  {
    return error;
  }

  inline bool isReplaceExisting() const
  {
    return replaceExisting;
  }

  inline QDir getDestinationDirectory() const
  {
    return target;
  }

  double getProgress();
  QString getDownloadingFile();

protected:
  void clearJobs();

};

}

#endif // OSMSCOUT_CLIENT_QT_FILEDOWNLOADER_H