Undo: make dive site merging undoable

This one was rather trivial, as there is no actual merging
done. Quite simply, a number of dive sites are removed and
their dive added to a different dive site.

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

7 files changed, 66 insertions, 36 deletions

diff --git a/core/divesite.c b/core/divesite.c
index 892a2dd78..8757aeed7 100644
--- a/core/divesite.c
+++ b/core/divesite.c
@@ -310,31 +310,6 @@ void merge_dive_site(struct dive_site *a, struct dive_site *b)
 	}
 }
 
-void merge_dive_sites(struct dive_site *ref, struct dive_site *dive_sites[], int count)
-{
-	int curr_dive, i;
-	struct dive *d;
-	for(i = 0; i < count; i++){
-		if (dive_sites[i] == ref)
-			continue;
-
-		for_each_dive(curr_dive, d) {
-			if (d->dive_site != dive_sites[i] )
-				continue;
-			unregister_dive_from_dive_site(d);
-			add_dive_to_dive_site(d, ref);
-			invalidate_dive_cache(d);
-		}
-	}
-
-	for(i = 0; i < count; i++) {
-		if (dive_sites[i] == ref)
-			continue;
-		delete_dive_site(dive_sites[i], &dive_site_table);
-	}
-	mark_divelist_changed(true);
-}
-
 struct dive_site *find_or_create_dive_site_with_name(const char *name, struct dive_site_table *ds_table)
 {
 	int i;
diff --git a/core/divesite.h b/core/divesite.h
index 50bd0b406..433ad056e 100644
--- a/core/divesite.h
+++ b/core/divesite.h
@@ -69,7 +69,6 @@ void copy_dive_site(struct dive_site *orig, struct dive_site *copy);
 void merge_dive_site(struct dive_site *a, struct dive_site *b);
 unsigned int get_distance(const location_t *loc1, const location_t *loc2);
 struct dive_site *find_or_create_dive_site_with_name(const char *name, struct dive_site_table *ds_table);
-void merge_dive_sites(struct dive_site *ref, struct dive_site *dive_sites[], int count);
 void purge_empty_dive_sites(struct dive_site_table *ds_table);
 void clear_dive_site_table(struct dive_site_table *ds_table);
 void add_dive_to_dive_site(struct dive *d, struct dive_site *ds);
diff --git a/desktop-widgets/command.cpp b/desktop-widgets/command.cpp
index 785443390..adfd32960 100644
--- a/desktop-widgets/command.cpp
+++ b/desktop-widgets/command.cpp
@@ -118,4 +118,9 @@ void addDiveSite(const QString &name)
 	execute(new AddDiveSite(name));
 }
 
+void mergeDiveSites(dive_site *ds, const QVector<dive_site *> &sites)
+{
+	execute(new MergeDiveSites(ds, sites));
+}
+
 } // namespace Command
diff --git a/desktop-widgets/command.h b/desktop-widgets/command.h
index d1a8326ea..1bcc69089 100644
--- a/desktop-widgets/command.h
+++ b/desktop-widgets/command.h
@@ -48,6 +48,7 @@ void editDiveSiteCountry(dive_site *ds, const QString &value);
 void editDiveSiteLocation(dive_site *ds, location_t value);
 void editDiveSiteTaxonomy(dive_site *ds, taxonomy_data &value); // value is consumed (i.e. will be erased after call)!
 void addDiveSite(const QString &name);
+void mergeDiveSites(dive_site *ds, const QVector<dive_site *> &sites);
 
 } // namespace Command
 
diff --git a/desktop-widgets/command_divesite.cpp b/desktop-widgets/command_divesite.cpp
index 04ee3b212..a5dce00d1 100644
--- a/desktop-widgets/command_divesite.cpp
+++ b/desktop-widgets/command_divesite.cpp
@@ -266,4 +266,45 @@ void EditDiveSiteTaxonomy::undo()
 	redo();
 }
 
+MergeDiveSites::MergeDiveSites(dive_site *dsIn, const QVector<dive_site *> &sites) : ds(dsIn)
+{
+	setText(tr("merge dive sites"));
+	sitesToRemove.reserve(sites.size());
+	for (dive_site *site: sites) {
+		if (site != ds)
+			sitesToRemove.push_back(site);
+	}
+}
+
+bool MergeDiveSites::workToBeDone()
+{
+	return !sitesToRemove.empty();
+}
+
+void MergeDiveSites::redo()
+{
+	// First, remove all dive sites
+	sitesToAdd = std::move(removeDiveSites(sitesToRemove));
+
+	// The dives of the above dive sites were reset to no dive sites.
+	// Add them to the merged-into dive site. Thankfully, we remember
+	// the dives in the sitesToAdd vector.
+	for (const OwningDiveSitePtr &site: sitesToAdd) {
+		for (int i = 0; i < site->dives.nr; ++i)
+			add_dive_to_dive_site(site->dives.dives[i], ds); // TODO: send dive changed signal
+	}
+}
+
+void MergeDiveSites::undo()
+{
+	// Before readding the dive sites, unregister the corresponding dives so that they can be
+	// readded to their old dive sites.
+	for (const OwningDiveSitePtr &site: sitesToAdd) {
+		for (int i = 0; i < site->dives.nr; ++i)
+			unregister_dive_from_dive_site(site->dives.dives[i]);
+	}
+
+	sitesToRemove = std::move(addDiveSites(sitesToAdd));
+}
+
 } // namespace Command
diff --git a/desktop-widgets/command_divesite.h b/desktop-widgets/command_divesite.h
index b73cc1b5a..58b3aabf5 100644
--- a/desktop-widgets/command_divesite.h
+++ b/desktop-widgets/command_divesite.h
@@ -117,6 +117,23 @@ private:
 	taxonomy_data value; // Value to be set
 };
 
+class MergeDiveSites : public Base {
+public:
+	MergeDiveSites(dive_site *ds, const QVector<dive_site *> &sites);
+private:
+	bool workToBeDone() override;
+	void undo() override;
+	void redo() override;
+
+	dive_site *ds;
+
+	// For redo
+	std::vector<dive_site *> sitesToRemove;
+
+	// For undo
+	std::vector<OwningDiveSitePtr> sitesToAdd;
+};
+
 } // namespace Command
 
 #endif // COMMAND_DIVESITE_H
diff --git a/desktop-widgets/locationinformation.cpp b/desktop-widgets/locationinformation.cpp
index 244e85f8d..330ccd6f5 100644
--- a/desktop-widgets/locationinformation.cpp
+++ b/desktop-widgets/locationinformation.cpp
@@ -62,24 +62,16 @@ void LocationInformationWidget::mergeSelectedDiveSites()
 {
 	if (!diveSite)
 		return;
-	if (QMessageBox::warning(MainWindow::instance(), tr("Merging dive sites"),
-				 tr("You are about to merge dive sites, you can't undo that action \n Are you sure you want to continue?"),
-				 QMessageBox::Ok, QMessageBox::Cancel) != QMessageBox::Ok)
-		return;
 
 	const QModelIndexList selection = ui.diveSiteListView->selectionModel()->selectedIndexes();
-	// std::vector guarantees contiguous storage and can therefore be passed to C-code
-	std::vector<struct dive_site *> selected_dive_sites;
+	QVector<dive_site *> selected_dive_sites;
 	selected_dive_sites.reserve(selection.count());
 	for (const QModelIndex &idx: selection) {
 		dive_site *ds = idx.data(LocationInformationModel::DIVESITE_ROLE).value<dive_site *>();
 		if (ds)
 			selected_dive_sites.push_back(ds);
 	}
-	merge_dive_sites(diveSite, selected_dive_sites.data(), (int)selected_dive_sites.size());
-	LocationInformationModel::instance()->update();
-	QSortFilterProxyModel *m = (QSortFilterProxyModel *)ui.diveSiteListView->model();
-	m->invalidate();
+	Command::mergeDiveSites(diveSite, selected_dive_sites);
 }
 
 void LocationInformationWidget::updateLabels()