When duplicate torrent is added set metadata to existing one

PR #17454. 
Closes #907.

src/base/bittorrent/session.cpp

@@ -2502,7 +2502,15 @@ bool Session::addTorrent_impl(const std::variant<MagnetUri, TorrentInfo> &source
 
     TorrentImpl *const torrent = m_torrents.value(id);
     if (torrent)
+    {
+        if (hasMetadata)
+        {
+            // Trying to set metadata to existing torrent in case if it has none
+            torrent->setMetadata(std::get<TorrentInfo>(source));
+        }
+
         return false;
+    }
 
     LoadTorrentParams loadTorrentParams = initLoadTorrentParams(addTorrentParams);
     lt::add_torrent_params &p = loadTorrentParams.ltAddTorrentParams;

src/base/bittorrent/torrent.h

@@ -298,6 +298,7 @@ namespace BitTorrent
         virtual void removeUrlSeeds(const QVector<QUrl> &urlSeeds) = 0;
         virtual bool connectPeer(const PeerAddress &peerAddress) = 0;
         virtual void clearPeers() = 0;
+        virtual bool setMetadata(const TorrentInfo &torrentInfo) = 0;
 
         virtual QString createMagnetURI() const = 0;
         virtual nonstd::expected<QByteArray, QString> exportToBuffer() const = 0;

src/base/bittorrent/torrentimpl.cpp

@@ -2126,6 +2126,19 @@ lt::torrent_handle TorrentImpl::nativeHandle() const
     return m_nativeHandle;
 }
 
+bool TorrentImpl::setMetadata(const TorrentInfo &torrentInfo)
+{
+    if (hasMetadata())
+        return false;
+
+#ifdef QBT_USES_LIBTORRENT2
+    return m_nativeHandle.set_metadata(torrentInfo.nativeInfo()->info_section());
+#else
+    const std::shared_ptr<lt::torrent_info> nativeInfo = torrentInfo.nativeInfo();
+    return m_nativeHandle.set_metadata(lt::span<const char>(nativeInfo->metadata().get(), nativeInfo->metadata_size()));
+#endif
+}
+
 bool TorrentImpl::isMoveInProgress() const
 {
     return m_storageIsMoving;

src/base/bittorrent/torrentimpl.h

@@ -225,6 +225,7 @@ namespace BitTorrent
         void removeUrlSeeds(const QVector<QUrl> &urlSeeds) override;
         bool connectPeer(const PeerAddress &peerAddress) override;
         void clearPeers() override;
+        bool setMetadata(const TorrentInfo &torrentInfo) override;
 
         QString createMagnetURI() const override;
         nonstd::expected<QByteArray, QString> exportToBuffer() const override;

src/gui/addnewtorrentdialog.cpp

@@ -435,6 +435,9 @@ bool AddNewTorrentDialog::loadTorrentImpl()
         BitTorrent::Torrent *const torrent = BitTorrent::Session::instance()->findTorrent(torrentID);
         if (torrent)
         {
+            // Trying to set metadata to existing torrent in case if it has none
+            torrent->setMetadata(m_torrentInfo);
+
             if (torrent->isPrivate() || m_torrentInfo.isPrivate())
             {
                 RaisedMessageBox::warning(this, tr("Torrent is already present"), tr("Torrent '%1' is already in the transfer list. Trackers cannot be merged because it is a private torrent.").arg(torrent->name()), QMessageBox::Ok);