undo: implement gas switch

This is a bit hairy as - in theory - one gas switch can remove
other gas switch(es) at the same timestamp. However, I did not
find a way to test it. Moreover, it is not clear whether the
dive-tabs are properly updated on undo/redo.

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

4 files changed, 81 insertions, 0 deletions

diff --git a/commands/command.cpp b/commands/command.cpp
index 54f9b22f9..c173494c0 100644
--- a/commands/command.cpp
+++ b/commands/command.cpp
@@ -354,4 +354,9 @@ void removeEvent(struct dive *d, int dcNr, struct event *ev)
 	execute(new RemoveEvent(d, dcNr, ev));
 }
 
+void addGasSwitch(struct dive *d, int dcNr, int seconds, int tank)
+{
+	execute(new AddGasSwitch(d, dcNr, seconds, tank));
+}
+
 } // namespace Command
diff --git a/commands/command.h b/commands/command.h
index 82931747c..66122ac99 100644
--- a/commands/command.h
+++ b/commands/command.h
@@ -111,6 +111,7 @@ void addEventDivemodeSwitch(struct dive *d, int dcNr, int seconds, int divemode)
 void addEventSetpointChange(struct dive *d, int dcNr, int seconds, pressure_t pO2);
 void renameEvent(struct dive *d, int dcNr, struct event *ev, const char *name);
 void removeEvent(struct dive *d, int dcNr, struct event *ev);
+void addGasSwitch(struct dive *d, int dcNr, int seconds, int tank);
 
 } // namespace Command
 
diff --git a/commands/command_event.cpp b/commands/command_event.cpp
index e32edfc41..6d217da65 100644
--- a/commands/command_event.cpp
+++ b/commands/command_event.cpp
@@ -5,6 +5,7 @@
 #include "core/subsurface-qt/divelistnotifier.h"
 #include "core/libdivecomputer.h"
 #include "core/gettextfromc.h"
+#include <QVector>
 
 namespace Command {
 
@@ -123,4 +124,65 @@ void RemoveEvent::undoit()
 	add_event_to_dc(dc, eventToAdd.release()); // return ownership to backend
 }
 
+AddGasSwitch::AddGasSwitch(struct dive *d, int dcNr, int seconds, int tank) : EventBase(d, dcNr)
+{
+	// If there is a gas change at this time stamp, remove it before adding the new one.
+	// There shouldn't be more than one gas change per time stamp. Just in case we'll
+	// support that anyway.
+	struct divecomputer *dc = get_dive_dc(d, dcNr);
+	struct event *gasChangeEvent = dc->events;
+	while ((gasChangeEvent = get_next_event_mutable(gasChangeEvent, "gaschange")) != NULL) {
+		if (gasChangeEvent->time.seconds == seconds) {
+			eventsToRemove.push_back(gasChangeEvent);
+			int idx = gasChangeEvent->gas.index;
+			if (std::find(cylinders.begin(), cylinders.end(), idx) == cylinders.end())
+				cylinders.push_back(idx); // cylinders might have changed their status
+		}
+		gasChangeEvent = gasChangeEvent->next;
+	}
+
+	eventsToAdd.emplace_back(create_gas_switch_event(d, dc, seconds, tank));
+}
+
+bool AddGasSwitch::workToBeDone()
+{
+	return true;
+}
+
+void AddGasSwitch::redoit()
+{
+	std::vector<OwningEventPtr> newEventsToAdd;
+	std::vector<event *> newEventsToRemove;
+	newEventsToAdd.reserve(eventsToRemove.size());
+	newEventsToRemove.reserve(eventsToAdd.size());
+	struct divecomputer *dc = get_dive_dc(d, dcNr);
+
+	for (event *ev: eventsToRemove) {
+		remove_event_from_dc(dc, ev);
+		newEventsToAdd.emplace_back(ev); // take ownership of event
+	}
+	for (OwningEventPtr &ev: eventsToAdd) {
+		newEventsToRemove.push_back(ev.get());
+		add_event_to_dc(dc, ev.release()); // return ownership to backend
+	}
+	eventsToAdd = std::move(newEventsToAdd);
+	eventsToRemove = std::move(newEventsToRemove);
+
+	// this means we potentially have a new tank that is being used and needs to be shown
+	fixup_dive(d);
+
+	for (int idx: cylinders)
+		emit diveListNotifier.cylinderEdited(d, idx);
+
+	// TODO: This is silly we send a DURATION change event so that the statistics are recalculated.
+	// We should instead define a proper DiveField that expresses the change caused by a gas switch.
+	emit diveListNotifier.divesChanged(QVector<dive *>{ d }, DiveField::DURATION | DiveField::DEPTH);
+}
+
+void AddGasSwitch::undoit()
+{
+	// Undo and redo do the same thing, as the dives-to-be-added and dives-to-be-removed are exchanged.
+	redoit();
+}
+
 } // namespace Command
diff --git a/commands/command_event.h b/commands/command_event.h
index eec5cb262..8e75dee6c 100644
--- a/commands/command_event.h
+++ b/commands/command_event.h
@@ -82,6 +82,19 @@ private:
 	event *eventToRemove;		// for redo
 };
 
+class AddGasSwitch : public EventBase {
+public:
+	AddGasSwitch(struct dive *d, int dcNr, int seconds, int tank);
+private:
+	bool workToBeDone() override;
+	void undoit() override;
+	void redoit() override;
+
+	std::vector<int> cylinders; // cylinders that are modified
+	std::vector<OwningEventPtr> eventsToAdd;
+	std::vector<event *> eventsToRemove;
+};
+
 } // namespace Command
 
 #endif // COMMAND_EVENT_H