#5993: Improve magnets handling in main window

Disable "Open Folder" and "Verify Local Data" actions for magnets in
Torrent menu. If more than one torrent is selected, "Verify Local Data"
is enabled but only non-magnets are verified if activated.
Add a few sanity checks when opening folder, just in case.

qt/MainWindow.cc

@@ -569,10 +569,20 @@ void openSelect (const QString& path)
 void
 MainWindow::openFolder ()
 {
-  const int torrentId (*getSelectedTorrents ().begin ());
+  const QSet<int> selectedTorrents = getSelectedTorrents ();
+  if (selectedTorrents.size () != 1)
+    return;
+
+  const int torrentId (*selectedTorrents.begin ());
   const Torrent * tor (myModel.getTorrentFromId (torrentId));
+  if (tor == nullptr)
+    return;
+
   QString path (tor->getPath ());
-  const FileList files = tor->files ();
+  const FileList& files = tor->files ();
+  if (files.isEmpty ())
+    return;
+
   const QString firstfile = files.at (0).filename;
   int slashIndex = firstfile.indexOf (QLatin1Char ('/'));
   if (slashIndex > -1)
@@ -586,6 +596,7 @@ MainWindow::openFolder ()
       return;
     }
 #endif
+
   QDesktopServices::openUrl (QUrl::fromLocalFile (path));
 }
 
@@ -734,6 +745,7 @@ MainWindow::refreshActionSensitivity ()
   int queued (0);
   int selectedAndPaused (0);
   int selectedAndQueued (0);
+  int selectedWithMetadata (0);
   int canAnnounce (0);
   const QAbstractItemModel * model (ui.listView->model ());
   const QItemSelectionModel * selectionModel (ui.listView->selectionModel ());
@@ -755,20 +767,23 @@ MainWindow::refreshActionSensitivity ()
           if (isPaused) ++ paused;
           if (isSelected && isPaused) ++selectedAndPaused;
           if (isSelected && isQueued) ++selectedAndQueued;
+          if (isSelected && tor->hasMetadata ()) ++selectedWithMetadata;
           if (tor->canManualAnnounce ()) ++canAnnounce;
         }
     }
 
   const bool haveSelection (selected > 0);
-  ui.action_Verify->setEnabled (haveSelection);
+  const bool haveSelectionWithMetadata = selectedWithMetadata > 0;
+  const bool oneSelection (selected == 1);
+
+  ui.action_Verify->setEnabled (haveSelectionWithMetadata);
   ui.action_Remove->setEnabled (haveSelection);
   ui.action_Delete->setEnabled (haveSelection);
   ui.action_Properties->setEnabled (haveSelection);
   ui.action_DeselectAll->setEnabled (haveSelection);
   ui.action_SetLocation->setEnabled (haveSelection);
 
-  const bool oneSelection (selected == 1);
+  ui.action_OpenFolder->setEnabled (oneSelection && haveSelectionWithMetadata && mySession.isLocal ());
-  ui.action_OpenFolder->setEnabled (oneSelection && mySession.isLocal ());
   ui.action_CopyMagnetToClipboard->setEnabled (oneSelection);
 
   ui.action_SelectAll->setEnabled (selected < rowCount);
@@ -799,14 +814,15 @@ MainWindow::clearSelection ()
 }
 
 QSet<int>
-MainWindow::getSelectedTorrents () const
+MainWindow::getSelectedTorrents (bool withMetadataOnly) const
 {
   QSet<int> ids;
 
   for (const QModelIndex& index: ui.listView->selectionModel ()->selectedRows ())
     {
       const Torrent * tor (index.data (TorrentModel::TorrentRole).value<const Torrent*> ());
-      ids.insert (tor->id ());
+      if (tor != nullptr && (!withMetadataOnly || tor->hasMetadata ()))
+        ids.insert (tor->id ());
     }
 
   return ids;
@@ -870,7 +886,7 @@ MainWindow::deleteSelected ()
 void
 MainWindow::verifySelected ()
 {
-  mySession.verifyTorrents (getSelectedTorrents ());
+  mySession.verifyTorrents (getSelectedTorrents (true));
 }
 void
 MainWindow::reannounceSelected ()

qt/MainWindow.h

@@ -88,7 +88,7 @@ class MainWindow: public QMainWindow
   private:
     QIcon getStockIcon (const QString&, int fallback = -1);
 
-    QSet<int> getSelectedTorrents () const;
+    QSet<int> getSelectedTorrents (bool withMetadataOnly = false) const;
     void updateNetworkIcon ();
 
     QMenu * createOptionsMenu ();