desktop: remember previous state when switching to dive site mode

The dive-site editing can be reached from two states: from the
dive view and the dive list view. It always jumped back to
the dive view.

Therefore, remember the state. Use a stack-like structure, so
that the feature can be used for the dive-site view as well.

This is a bit inconsistent, because for example the statistics
view does not remember the previous state and allows a direct
jump to a different state. That should be fixed at some point.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

desktop-widgets/divesitelistview.cpp

@@ -48,7 +48,7 @@ DiveSiteListView::DiveSiteListView(QWidget *parent) : QWidget(parent)
 
 void DiveSiteListView::done()
 {
-	MainWindow::instance()->setApplicationState(MainWindow::ApplicationState::Default);
+	MainWindow::instance()->enterPreviousState();
 }
 
 void DiveSiteListView::diveSiteClicked(const QModelIndex &index)

desktop-widgets/locationinformation.cpp

@@ -220,7 +220,7 @@ void LocationInformationWidget::acceptChanges()
 
 	MainWindow::instance()->diveList->setEnabled(true);
 	MainWindow::instance()->setEnabledToolbar(true);
-	MainWindow::instance()->setApplicationState(MainWindow::ApplicationState::Default);
+	MainWindow::instance()->enterPreviousState();
 	DiveFilter::instance()->stopFilterDiveSites();
 
 	// Subtlety alert: diveSite must be cleared *after* exiting the dive-site mode.

desktop-widgets/mainwindow.cpp

@@ -282,6 +282,7 @@ void MainWindow::editDiveSite(dive_site *ds)
 	if (!ds)
 		return;
 	diveSiteEdit->initFields(ds);
+	state_stack.push_back(appState);
 	setApplicationState(ApplicationState::EditDiveSite);
 }
 
@@ -765,6 +766,7 @@ void MainWindow::on_actionViewDiveSites_triggered()
 {
 	if (!userMayChangeAppState())
 		return;
+	state_stack.push_back(appState);
 	setApplicationState(ApplicationState::DiveSites);
 }
 
@@ -1472,6 +1474,17 @@ bool MainWindow::userMayChangeAppState() const
 	return applicationState[(int)appState].allowUserChange;
 }
 
+// For the dive-site list view and the dive-site edit states,
+// we remember the previous state and then switch back to that.
+void MainWindow::enterPreviousState()
+{
+	if (state_stack.empty())
+		setApplicationState(ApplicationState::Default);
+	ApplicationState prev = state_stack.back();
+	state_stack.pop_back();
+	setApplicationState(prev);
+}
+
 void MainWindow::setApplicationState(ApplicationState state)
 {
 	if (appState == state)

desktop-widgets/mainwindow.h

@@ -72,6 +72,7 @@ public:
 	void importFiles(const QStringList importFiles);
 	void setToolButtonsEnabled(bool enabled);
 	void setApplicationState(ApplicationState state);
+	void enterPreviousState();
 	NotificationWidget *getNotificationWidget();
 	void enableDisableCloudActions();
 	void enableDisableOtherDCsActions();
@@ -162,6 +163,7 @@ slots:
 
 private:
 	ApplicationState appState;
+	std::vector<ApplicationState> state_stack;
 	Ui::MainWindow ui;
 	FilterWidget filterWidget;
 	std::unique_ptr<QSplitter> topSplitter;