5 files changed, 127 insertions, 0 deletions
diff --git a/desktop-widgets/CMakeLists.txt b/desktop-widgets/CMakeLists.txt
index efccfcc26..c494f1a8b 100644
--- a/desktop-widgets/CMakeLists.txt
+++ b/desktop-widgets/CMakeLists.txt
@@ -62,6 +62,8 @@ set(SUBSURFACE_INTERFACE
 	command_base.h
 	command_divelist.cpp
 	command_divelist.h
+	command_divesite.cpp
+	command_divesite.h
 	configuredivecomputerdialog.cpp
 	configuredivecomputerdialog.h
 	divecomputermanagementdialog.cpp
diff --git a/desktop-widgets/command.cpp b/desktop-widgets/command.cpp
index 2e2982860..80a233404 100644
--- a/desktop-widgets/command.cpp
+++ b/desktop-widgets/command.cpp
@@ -2,6 +2,7 @@
 
 #include "command.h"
 #include "command_divelist.h"
+#include "command_divesite.h"
 
 namespace Command {
 
@@ -76,4 +77,10 @@ void mergeDives(const QVector <dive *> &dives)
 	execute(new MergeDives(dives));
 }
 
+// Dive site related commands
+void deleteDiveSites(const QVector <dive_site *> &sites)
+{
+	execute(new DeleteDiveSites(sites));
+}
+
 } // namespace Command
diff --git a/desktop-widgets/command.h b/desktop-widgets/command.h
index dfc79a9e6..77920a81c 100644
--- a/desktop-widgets/command.h
+++ b/desktop-widgets/command.h
@@ -38,6 +38,10 @@ void splitDives(dive *d, duration_t time);
 void splitDiveComputer(dive *d, int dc_num);
 void mergeDives(const QVector <dive *> &dives);
 
+// 3) Dive-site related commands
+
+void deleteDiveSites(const QVector <dive_site *> &sites);
+
 } // namespace Command
 
 #endif // COMMAND_H
diff --git a/desktop-widgets/command_divesite.cpp b/desktop-widgets/command_divesite.cpp
new file mode 100644
index 000000000..d4c5d87b8
--- /dev/null
+++ b/desktop-widgets/command_divesite.cpp
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "command_divesite.h"
+#include "core/divesite.h"
+#include "core/subsurface-qt/DiveListNotifier.h"
+
+namespace Command {
+
+// Helper functions to add / remove a set of dive sites
+
+// Add a set of dive sites to the core. The dives that were associated with
+// that dive site will be restored to that dive site.
+static std::vector<dive_site *> addDiveSites(std::vector<OwningDiveSitePtr> &sites)
+{
+	std::vector<dive_site *> res;
+	res.reserve(sites.size());
+
+	for (OwningDiveSitePtr &ds: sites) {
+		// Readd the dives that belonged to this site
+		for (int i = 0; i < ds->dives.nr; ++i) {
+			// TODO: send dive site changed signal
+			ds->dives.dives[i]->dive_site = ds.get();
+		}
+
+		// Add dive site to core, but remember a non-owning pointer first.
+		res.push_back(ds.get());
+		int idx = register_dive_site(ds.release()); // Return ownership to backend.
+		emit diveListNotifier.diveSiteAdded(res.back(), idx); // Inform frontend of new dive site.
+	}
+
+	// Clear vector of unused owning pointers
+	sites.clear();
+
+	return res;
+}
+
+// Remove a set of dive sites. Get owning pointers to them. The dives are set to
+// being at no dive site, but the dive site will retain a list of dives, so
+// that the dives can be readded to the site on undo.
+static std::vector<OwningDiveSitePtr> removeDiveSites(std::vector<dive_site *> &sites)
+{
+	std::vector<OwningDiveSitePtr> res;
+	res.reserve(sites.size());
+
+	for (dive_site *ds: sites) {
+		// Reset the dive_site field of the affected dives
+		for (int i = 0; i < ds->dives.nr; ++i) {
+			// TODO: send dive site changed signal
+			ds->dives.dives[i]->dive_site = nullptr;
+		}
+
+		// Remove dive site from core and take ownership.
+		int idx = unregister_dive_site(ds);
+		res.emplace_back(ds);
+		emit diveListNotifier.diveSiteDeleted(ds, idx); // Inform frontend of removed dive site.
+	}
+
+	sites.clear();
+
+	return res;
+}
+
+DeleteDiveSites::DeleteDiveSites(const QVector<dive_site *> &sites) : sitesToRemove(sites.toStdVector())
+{
+	setText(tr("delete %n dive site(s)", "", sites.size()));
+}
+
+bool DeleteDiveSites::workToBeDone()
+{
+	return !sitesToRemove.empty();
+}
+
+void DeleteDiveSites::redo()
+{
+	sitesToAdd = std::move(removeDiveSites(sitesToRemove));
+}
+
+void DeleteDiveSites::undo()
+{
+	sitesToRemove = std::move(addDiveSites(sitesToAdd));
+}
+
+} // namespace Command
diff --git a/desktop-widgets/command_divesite.h b/desktop-widgets/command_divesite.h
new file mode 100644
index 000000000..9c4f93058
--- /dev/null
+++ b/desktop-widgets/command_divesite.h
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+// Note: this header file is used by the undo-machinery and should not be included elsewhere.
+
+#ifndef COMMAND_DIVESITE_H
+#define COMMAND_DIVESITE_H
+
+#include "command_base.h"
+
+#include <QVector>
+
+// We put everything in a namespace, so that we can shorten names without polluting the global namespace
+namespace Command {
+
+class DeleteDiveSites : public Base {
+public:
+	DeleteDiveSites(const QVector<dive_site *> &sites);
+private:
+	bool workToBeDone() override;
+
+	// For redo
+	std::vector<dive_site *> sitesToRemove;
+
+	// For undo
+	std::vector<OwningDiveSitePtr> sitesToAdd;
+	void undo() override;
+	void redo() override;
+};
+
+} // namespace Command
+
+#endif // COMMAND_DIVESITE_H