/*! @file

    @id $Id$
*/
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#include <QtNetwork/QNetworkReply>
#include <QtNetwork/QSslError>
#include <map>

#include <cassert>
#include <QtCore/QDebug>
#ifndef LOG
#define LOG qDebug()<<__PRETTY_FUNCTION__
#endif

class DownloadManager: public QObject {
    Q_OBJECT;
  public:

    DownloadManager& operator+=(QNetworkReply* reply) {
      LOG;
      add(reply);
      return *this;
    }
    
    static QString networkError(QNetworkReply::NetworkError err) {
      LOG<<err;
      switch (err) {
        case QNetworkReply::NoError:
          return tr("Network connection successful, remote host can be"
                    " reached.");
        case QNetworkReply::ConnectionRefusedError:
          return tr("The remote server refused the connection (the server is"
                    " not accepting requests).");
        case QNetworkReply::RemoteHostClosedError:
          return tr("The remote server closed the connection prematurely,"
                    " before the entire reply was received and processed.");
        case QNetworkReply::HostNotFoundError:
          return tr("The remote host name was not found (invalid hostname).");
        case QNetworkReply::TimeoutError:
          return tr("The connection to the remote server timed out.");
        case QNetworkReply::OperationCanceledError:
          return tr("The operation was canceled via calls to abort() or"
                    " close() before it was finished.");
        case QNetworkReply::SslHandshakeFailedError:
          return tr("The SSL/TLS handshake failed and the encrypted channel"
                    " could not be established. The sslErrors() signal should"
                    " have been emitted.");
        case QNetworkReply::ProxyConnectionRefusedError:
          return tr("The connection to the proxy server was refused (the"
                    " proxy server is not accepting requests).");
        case QNetworkReply::ProxyConnectionClosedError:
          return tr("The proxy server closed the connection prematurely,"
                    " before the entire reply was received and processed.");
        case QNetworkReply::ProxyNotFoundError:
          return tr("The proxy host name was not found (invalid proxy"
                    " hostname).");
        case QNetworkReply::ProxyTimeoutError:
          return tr("The connection to the proxy timed out or the proxy did"
                    " not reply in time to the request sent.");
        case QNetworkReply::ProxyAuthenticationRequiredError:
          return tr("The proxy requires authentication in order to honour the"
                    " request but did not accept any credentials offered"
                    " (if any).");
        case QNetworkReply::ContentAccessDenied:
          return tr("The access to the remote content was denied (similar to"
                    " HTTP error 401).");
        case QNetworkReply::ContentOperationNotPermittedError:
          return tr("The operation requested on the remote content is not"
                    " permitted.");
        case QNetworkReply::ContentNotFoundError:
          return tr("The remote content was not found at the server (similar"
                    " to HTTP error 404).");
        case QNetworkReply::AuthenticationRequiredError:
          return tr("The remote server requires authentication to serve the"
                    " content but the credentials provided were not accepted"
                    " (if any).");
        case QNetworkReply::ProtocolUnknownError:
          return tr("The Network Access API cannot honor the request because"
                    " the protocol is not known.");
        case QNetworkReply::ProtocolInvalidOperationError:
          return tr("The requested operation is invalid for this protocol.");
        case QNetworkReply::UnknownNetworkError:
          return tr("An unknown network-related error was detected.");
        case QNetworkReply::UnknownProxyError:
          return tr("An unknown proxy-related error was detected.");
        case QNetworkReply::UnknownContentError:
          return tr("An unknonwn error related to the remote content was"
                    " detected.");
        case QNetworkReply::ProtocolFailure:
          return tr("A breakdown in protocol was detected (parsing error,"
                    " invalid or unexpected responses, etc.).");
        default:
          return tr("<strong>Unknown network error (code: %1).</string>")
            .arg(err);
      }
    }
    
  Q_SIGNALS:
      
    void progress(qint64 done, qint64 total);
    void started();
    void finished();

  public Q_SLOTS:

    void add(QNetworkReply* reply) {
      LOG<<reply->url().toString();
      _downloads[reply] = Progress(0, 0);
      assert(connect(reply, SIGNAL(downloadProgress(qint64, qint64)),
                     SLOT(downloadProgress(qint64, qint64))));
      assert(connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
                     SLOT(error(QNetworkReply::NetworkError))));
      assert(connect(reply, SIGNAL(finished()),
                     SLOT(slotFinished())));
      assert(connect(reply, SIGNAL(metaDataChanged()),
                     SLOT(metaDataChanged())));
      assert(connect(reply, SIGNAL(sslErrors(const QList<QSslError>&)),
                     SLOT(sslErrors(const QList<QSslError>&))));
      assert(connect(reply, SIGNAL(uploadProgress(qint64, qint64)),
                     SLOT(uploadProgress(qint64, qint64))));
      if (_downloads.size()==1) started();
    }

    void abort() {
      while (_downloads.size()) _downloads.begin()->first->abort();
    }

  private:

    void calcProgress() {
      //LOG;
      qint64 done(0);
      qint64 total(0);
      for (Downloads::iterator it(_downloads.begin());
           it!=_downloads.end(); ++it) {
        done += it->second.first;
        total += it->second.second;
      }
      progress(done, total);
    }
    
  private Q_SLOTS:
      
    void downloadProgress(qint64 bytesReceived, qint64 bytesTotal) {
      //LOG<<bytesReceived<<bytesTotal;
      _downloads[qobject_cast<QNetworkReply*>(sender())].first = bytesReceived;
      _downloads[qobject_cast<QNetworkReply*>(sender())].second = bytesTotal;
      calcProgress();
    }
    void error(QNetworkReply::NetworkError code) {
      LOG<<"Status:"<<networkError(code);
    }
    void slotFinished() {
      LOG;
      _downloads.erase(qobject_cast<QNetworkReply*>(sender()));
      if (_downloads.size()==0) finished();
    }
    void metaDataChanged() {
      LOG;
    }
    void sslErrors(const QList<QSslError> & errors) {
      LOG;
      for (QList<QSslError>::const_iterator err(errors.begin());
           err!=errors.end(); ++err)
        LOG<<"SSL-Error: "<<err->errorString();
    }
    void uploadProgress(qint64 bytesSent, qint64 bytesTotal) {
      //LOG<<bytesSent<<bytesTotal;
      _downloads[qobject_cast<QNetworkReply*>(sender())].first = bytesSent;
      _downloads[qobject_cast<QNetworkReply*>(sender())].second = bytesTotal;
      calcProgress();
    }

  private:

    typedef std::pair<qint64, qint64> Progress;
    typedef std::map<QNetworkReply*, Progress> Downloads;
    
    Downloads _downloads;
};