subsurface/commands/command_divelist.cpp

// SPDX-License-Identifier: GPL-2.0

#include "command_divelist.h"
#include "core/divelist.h"
#include "core/qthelper.h"
#include "core/selection.h"
#include "core/subsurface-qt/divelistnotifier.h"
#include "qt-models/filtermodels.h"
#include "../profile-widget/profilewidget2.h"
#include "core/divefilter.h"

#include <array>

namespace Command {

// Helper function that takes care to unselect trips that are removed from the backend
static void remove_trip_from_backend(dive_trip *trip)
{
	if (trip->selected)
		deselect_trip(trip);
	remove_trip(trip, &trip_table);	// Remove trip from backend
}

// This helper function removes a dive, takes ownership of the dive and adds it to a DiveToAdd structure.
// If the trip the dive belongs to becomes empty, it is removed and added to the tripsToAdd vector.
// It is crucial that dives are added in reverse order of deletion, so that the indices are correctly
// set and that the trips are added before they are used!
DiveToAdd DiveListBase::removeDive(struct dive *d, std::vector<OwningTripPtr> &tripsToAdd)
{
	// If the dive was the current dive, reset the current dive. The calling
	// command is responsible of finding a new dive.
	if (d == current_dive)
		current_dive = nullptr;

	// remove dive from trip and site - if this is the last dive in the trip
	// remove the whole trip.
	DiveToAdd res;
	res.trip = unregister_dive_from_trip(d);
	if (d->dive_site)
		diveSiteCountChanged(d->dive_site);
	res.site = unregister_dive_from_dive_site(d);
	if (res.trip && res.trip->dives.nr == 0) {
		remove_trip_from_backend(res.trip);	// Remove trip from backend
		tripsToAdd.emplace_back(res.trip);	// Take ownership of trip
	}

	int idx = get_divenr(d);
	if (idx < 0)
		qWarning("Deletion of unknown dive!");

	if (!d->hidden_by_filter)
		--shown_dives;

	res.dive.reset(unregister_dive(idx));		// Remove dive from backend

	return res;
}

void DiveListBase::diveSiteCountChanged(struct dive_site *ds)
{
	if (std::find(sitesCountChanged.begin(), sitesCountChanged.end(), ds) == sitesCountChanged.end())
		sitesCountChanged.push_back(ds);
}

// This helper function adds a dive and returns ownership to the backend. It may also add a dive trip.
// It is crucial that dives are added in reverse order of deletion (see comment above)!
// Returns pointer to added dive (which is owned by the backend!)
dive *DiveListBase::addDive(DiveToAdd &d)
{
	if (d.trip)
		add_dive_to_trip(d.dive.get(), d.trip);
	if (d.site) {
		add_dive_to_dive_site(d.dive.get(), d.site);
		diveSiteCountChanged(d.site);
	}
	dive *res = d.dive.release();		// Give up ownership of dive

	// When we add dives, we start in hidden-by-filter status. Once all
	// dives have been added, their status will be updated.
	res->hidden_by_filter = true;

	int idx = dive_table_get_insertion_index(&dive_table, res);
	fulltext_register(res);				// Register the dive's fulltext cache
	add_to_dive_table(&dive_table, idx, res);	// Return ownership to backend
	invalidate_dive_cache(res);		// Ensure that dive is written in git_save()

	return res;
}

// Some signals are sent in batches per trip. To avoid writing the same loop
// twice, this template takes a vector of trip / dive pairs, sorts it
// by trip and then calls a function-object with trip and a QVector of dives in that trip.
// The dives are sorted by the dive_less_than() function defined in the core.
// Input parameters:
//	- dives: a vector of trip,dive pairs, which will be sorted and processed in batches by trip.
//	- action: a function object, taking a trip-pointer and a QVector of dives, which will be called for each batch.
template<typename Function>
void processByTrip(std::vector<std::pair<dive_trip *, dive *>> &dives, Function action)
{
	// Sort lexicographically by trip then according to the dive_less_than() function.
	std::sort(dives.begin(), dives.end(),
		  [](const std::pair<dive_trip *, dive *> &e1, const std::pair<dive_trip *, dive *> &e2)
		  { return e1.first == e2.first ? dive_less_than(e1.second, e2.second) : e1.first < e2.first; });

	// Then, process the dives in batches by trip
	size_t i, j; // Begin and end of batch
	for (i = 0; i < dives.size(); i = j) {
		dive_trip *trip = dives[i].first;
		for (j = i + 1; j < dives.size() && dives[j].first == trip; ++j)
			; // pass
		// Copy dives into a QVector. Some sort of "range_view" would be ideal, but Qt doesn't work this way.
		QVector<dive *> divesInTrip(j - i);
		for (size_t k = i; k < j; ++k)
			divesInTrip[k - i] = dives[k].second;

		// Finally, emit the signal
		action(trip, divesInTrip);
	}
}

// This helper function calls removeDive() on a list of dives to be removed and
// returns a vector of corresponding DiveToAdd objects, which can later be readded.
// Moreover, a vector of deleted trips is returned, if trips became empty.
// The passed in vector is cleared.
DivesAndTripsToAdd DiveListBase::removeDives(DivesAndSitesToRemove &divesAndSitesToDelete)
{
	std::vector<DiveToAdd> divesToAdd;
	std::vector<OwningTripPtr> tripsToAdd;
	std::vector<OwningDiveSitePtr> sitesToAdd;
	divesToAdd.reserve(divesAndSitesToDelete.dives.size());
	sitesToAdd.reserve(divesAndSitesToDelete.sites.size());

	// Remember old number of shown dives
	int oldShown = shown_dives;

	// Make sure that the dive list is sorted. The added dives will be sent in a signal
	// and the recipients assume that the dives are sorted the same way as they are
	// in the core list.
	std::sort(divesAndSitesToDelete.dives.begin(), divesAndSitesToDelete.dives.end(), dive_less_than);

	for (dive *d: divesAndSitesToDelete.dives)
		divesToAdd.push_back(removeDive(d, tripsToAdd));
	divesAndSitesToDelete.dives.clear();

	for (dive_site *ds: divesAndSitesToDelete.sites) {
		int idx = unregister_dive_site(ds);
		sitesToAdd.emplace_back(ds);
		emit diveListNotifier.diveSiteDeleted(ds, idx);
	}
	divesAndSitesToDelete.sites.clear();

	// We send one dives-deleted signal per trip (see comments in divelistnotifier.h).
	// Therefore, collect all dives in an array and sort by trip.
	std::vector<std::pair<dive_trip *, dive *>> dives;
	dives.reserve(divesToAdd.size());
	for (const DiveToAdd &entry: divesToAdd)
		dives.push_back({ entry.trip, entry.dive.get() });

	// Send signals.
	processByTrip(dives, [&](dive_trip *trip, const QVector<dive *> &divesInTrip) {
		// Check if this trip is supposed to be deleted, by checking if it was marked as "add it".
		bool deleteTrip = trip &&
				  std::find_if(tripsToAdd.begin(), tripsToAdd.end(), [trip](const OwningTripPtr &ptr)
					       { return ptr.get() == trip; }) != tripsToAdd.end();
		emit diveListNotifier.divesDeleted(trip, deleteTrip, divesInTrip);
	});

	if (oldShown != shown_dives)
		emit diveListNotifier.numShownChanged();

	return { std::move(divesToAdd), std::move(tripsToAdd), std::move(sitesToAdd) };
}

// This helper function is the counterpart fo removeDives(): it calls addDive() on a list
// of dives to be (re)added and returns a vector of the added dives. It does this in reverse
// order, so that trips are created appropriately and indexing is correct.
// The passed in vector is cleared.
DivesAndSitesToRemove DiveListBase::addDives(DivesAndTripsToAdd &toAdd)
{
	std::vector<dive *> res;
	std::vector<dive_site *> sites;
	std::vector<std::pair<dive_trip *, dive *>> dives;
	res.resize(toAdd.dives.size());
	sites.reserve(toAdd.sites.size());
	dives.reserve(toAdd.sites.size());

	// Make sure that the dive list is sorted. The added dives will be sent in a signal
	// and the recipients assume that the dives are sorted the same way as they are
	// in the core list.
	std::sort(toAdd.dives.begin(), toAdd.dives.end(),
		  [](const DiveToAdd &d, const DiveToAdd &d2)
		  { return dive_less_than(d.dive.get(), d2.dive.get()); });

	// Now, add the dives
	// Note: the idiomatic STL-way would be std::transform, but let's use a loop since
	// that is closer to classical C-style.
	auto it2 = res.rbegin();
	QVector<dive *> divesToFilter;
	divesToFilter.reserve(toAdd.dives.size());
	for (auto it = toAdd.dives.rbegin(); it != toAdd.dives.rend(); ++it, ++it2) {
		*it2 = addDive(*it);
		dives.push_back({ (*it2)->divetrip, *it2 });
		divesToFilter.push_back(*it2);
	}
	toAdd.dives.clear();

	ShownChange change = DiveFilter::instance()->update(divesToFilter);

	// If the dives belong to new trips, add these as well.
	// Remember the pointers so that we can later check if a trip was newly added
	std::vector<dive_trip *> addedTrips;
	addedTrips.reserve(toAdd.trips.size());
	for (OwningTripPtr &trip: toAdd.trips) {
		addedTrips.push_back(trip.get());
		insert_trip(trip.release(), &trip_table); // Return ownership to backend
	}
	toAdd.trips.clear();

	// Finally, add any necessary dive sites
	for (OwningDiveSitePtr &ds: toAdd.sites) {
		sites.push_back(ds.get());
		int idx = register_dive_site(ds.release()); // Return ownership to backend
		emit diveListNotifier.diveSiteAdded(sites.back(), idx);
	}
	toAdd.sites.clear();

	// Send signals by trip.
	processByTrip(dives, [&](dive_trip *trip, const QVector<dive *> &divesInTrip) {
		// Now, let's check if this trip is supposed to be created, by checking if it was marked as "add it".
		bool createTrip = trip && std::find(addedTrips.begin(), addedTrips.end(), trip) != addedTrips.end();
		// Finally, emit the signal
		emit diveListNotifier.divesAdded(trip, createTrip, divesInTrip);
	});

	if (!change.newShown.empty() || !change.newHidden.empty())
		emit diveListNotifier.numShownChanged();

	return { res, sites };
}

// This helper function renumbers dives according to an array of id/number pairs.
// The old numbers are stored in the array, thus calling this function twice has no effect.
static void renumberDives(QVector<QPair<dive *, int>> &divesToRenumber)
{
	QVector<dive *> dives;
	dives.reserve(divesToRenumber.size());
	for (auto &pair: divesToRenumber) {
		dive *d = pair.first;
		if (!d)
			continue;
		std::swap(d->number, pair.second);
		dives.push_back(d);
		invalidate_dive_cache(d);
	}

	// Send signals.
	emit diveListNotifier.divesChanged(dives, DiveField::NR);
}

// This helper function moves a dive to a trip. The old trip is recorded in the
// passed-in structure. This means that calling the function twice on the same
// object is a no-op concerning the dive. If the old trip was deleted from the
// core, an owning pointer to the removed trip is returned, otherwise a null pointer.
static OwningTripPtr moveDiveToTrip(DiveToTrip &diveToTrip)
{
	// Firstly, check if we move to the same trip and bail if this is a no-op.
	if (diveToTrip.trip == diveToTrip.dive->divetrip)
		return {};

	// Remove from old trip
	OwningTripPtr res;

	// Remove dive from trip - if this is the last dive in the trip, remove the whole trip.
	dive_trip *trip = unregister_dive_from_trip(diveToTrip.dive);
	if (trip && trip->dives.nr == 0) {
		remove_trip_from_backend(trip);	// Remove trip from backend
		res.reset(trip);
	}

	// Store old trip and get new trip we should associate this dive with
	std::swap(trip, diveToTrip.trip);
	if (trip)
		add_dive_to_trip(diveToTrip.dive, trip);
	invalidate_dive_cache(diveToTrip.dive);		// Ensure that dive is written in git_save()
	return res;
}

// This helper function moves a set of dives between trips using the
// moveDiveToTrip function. Before doing so, it adds the necessary trips to
// the core. Trips that are removed from the core because they are empty
// are recorded in the passed in struct. The vectors of trips and dives
// are reversed. Thus, calling the function twice on the same object is
// a no-op.
static void moveDivesBetweenTrips(DivesToTrip &dives)
{
	// We collect an array of created trips so that we can instruct
	// the model to create a new entry
	std::vector<dive_trip *> createdTrips;
	createdTrips.reserve(dives.tripsToAdd.size());

	// First, bring back the trip(s)
	for (OwningTripPtr &trip: dives.tripsToAdd) {
		dive_trip *t = trip.release();	// Give up ownership
		createdTrips.push_back(t);
		insert_trip(t, &trip_table);	// Return ownership to backend
	}
	dives.tripsToAdd.clear();

	for (DiveToTrip &dive: dives.divesToMove) {
		OwningTripPtr tripToAdd = moveDiveToTrip(dive);
		// register trips that we'll have to readd
		if (tripToAdd)
			dives.tripsToAdd.push_back(std::move(tripToAdd));
	}

	// We send one signal per from-trip/to-trip pair.
	// First, collect all dives in a struct and sort by from-trip/to-trip.
	struct DiveMoved {
		dive_trip *from;
		dive_trip *to;
		dive *d;
	};
	std::vector<DiveMoved> divesMoved;
	divesMoved.reserve(dives.divesToMove.size());
	for (const DiveToTrip &entry: dives.divesToMove)
		divesMoved.push_back({ entry.trip, entry.dive->divetrip, entry.dive });

	// Sort lexicographically by from-trip, to-trip and by start-time.
	// Use std::tie() for lexicographical sorting.
	std::sort(divesMoved.begin(), divesMoved.end(), [] ( const DiveMoved &d1, const DiveMoved &d2)
		  { return std::tie(d1.from, d1.to, d1.d->when) < std::tie(d2.from, d2.to, d2.d->when); });

	// Now, process the dives in batches by trip
	// TODO: this is a bit different from the cases above, so we don't use the processByTrip template,
	// but repeat the loop here. We might think about generalizing the template, if more of such
	// "special cases" appear.
	size_t i, j; // Begin and end of batch
	for (i = 0; i < divesMoved.size(); i = j) {
		dive_trip *from = divesMoved[i].from;
		dive_trip *to = divesMoved[i].to;
		for (j = i + 1; j < divesMoved.size() && divesMoved[j].from == from && divesMoved[j].to == to; ++j)
			; // pass
		// Copy dives into a QVector. Some sort of "range_view" would be ideal, but Qt doesn't work this way.
		QVector<dive *> divesInTrip(j - i);
		for (size_t k = i; k < j; ++k)
			divesInTrip[k - i] = divesMoved[k].d;

		// Check if the from-trip was deleted: If yes, it was recorded in the tripsToAdd structure.
		// Only set the flag if this is that last time this trip is featured.
		bool deleteFrom = from &&
				  std::find_if(divesMoved.begin() + j, divesMoved.end(), // Is this the last occurence of "from"?
					       [from](const DiveMoved &entry) { return entry.from == from; }) == divesMoved.end() &&
				  std::find_if(dives.tripsToAdd.begin(), dives.tripsToAdd.end(), // Is "from" in tripsToAdd?
					       [from](const OwningTripPtr &trip) { return trip.get() == from; }) != dives.tripsToAdd.end();
		// Check if the to-trip has to be created. For this purpose, we saved an array of trips to be created.
		bool createTo = false;
		if (to) {
			// Check if the element is there...
			auto it = std::find(createdTrips.begin(), createdTrips.end(), to);

			// ...if it is - remove it as we don't want the model to create the trip twice!
			if (it != createdTrips.end()) {
				createTo = true;
				// erase/remove would be more performant, but this is irrelevant in the big scheme of things.
				createdTrips.erase(it);
			}
		}

		// Finally, emit the signal
		emit diveListNotifier.divesMovedBetweenTrips(from, to, deleteFrom, createTo, divesInTrip);
	}

	// Reverse the tripsToAdd and the divesToAdd, so that on undo/redo the operations
	// will be performed in reverse order.
	std::reverse(dives.tripsToAdd.begin(), dives.tripsToAdd.end());
	std::reverse(dives.divesToMove.begin(), dives.divesToMove.end());
}

void DiveListBase::initWork()
{
}

void DiveListBase::finishWork()
{
	for (dive_site *ds: sitesCountChanged)
		emit diveListNotifier.diveSiteDiveCountChanged(ds);
}

void DiveListBase::undo()
{
	initWork();
	undoit();
	finishWork();
}

void DiveListBase::redo()
{
	initWork();
	redoit();
	finishWork();
}

AddDive::AddDive(dive *d, bool autogroup, bool newNumber)
{
	setText(Command::Base::tr("add dive"));
	// By convention, d is a pointer to "displayed dive" or a temporary variable and can be overwritten.
	d->maxdepth.mm = 0;
	d->dc.maxdepth.mm = 0;
	fixup_dive(d);

	// this only matters if undoit were called before redoit
	currentDive = nullptr;

	// Get an owning pointer to a moved dive.
	OwningDivePtr divePtr(move_dive(d));
	divePtr->selected = false; // If we clone a planned dive, it might have been selected.
				   // We have to clear the flag, as selections will be managed
				   // on dive-addition.

	// If we alloc a new-trip for autogrouping, get an owning pointer to it.
	OwningTripPtr allocTrip;
	dive_trip *trip = divePtr->divetrip;
	dive_site *site = divePtr->dive_site;
	// We have to delete the pointers to trip and site, because this would prevent the core from adding to the
	// trip or site and we would get the count-of-dives in the trip or site wrong. Yes, that's all horribly subtle!
	divePtr->divetrip = nullptr;
	divePtr->dive_site = nullptr;
	if (!trip && autogroup) {
		bool alloc;
		trip = get_trip_for_new_dive(divePtr.get(), &alloc);
		if (alloc)
			allocTrip.reset(trip);
	}

	int idx = dive_table_get_insertion_index(&dive_table, divePtr.get());
	if (newNumber)
		divePtr->number = get_dive_nr_at_idx(idx);

	divesToAdd.dives.push_back({ std::move(divePtr), trip, site });
	if (allocTrip)
		divesToAdd.trips.push_back(std::move(allocTrip));
}

bool AddDive::workToBeDone()
{
	return true;
}

void AddDive::redoit()
{
	// Remember selection so that we can undo it
	selection = getDiveSelection();
	currentDive = current_dive;

	divesAndSitesToRemove = addDives(divesToAdd);
	sort_trip_table(&trip_table); // Though unlikely, adding a dive may reorder trips

	// Select the newly added dive
	setSelection(divesAndSitesToRemove.dives, divesAndSitesToRemove.dives[0]);
}

void AddDive::undoit()
{
	// Simply remove the dive that was previously added...
	divesToAdd = removeDives(divesAndSitesToRemove);
	sort_trip_table(&trip_table); // Though unlikely, removing a dive may reorder trips

	// ...and restore the selection
	setSelection(selection, currentDive);
}

ImportDives::ImportDives(struct dive_table *dives, struct trip_table *trips, struct dive_site_table *sites,
			 struct device_table *devices, struct filter_preset_table *filter_presets, int flags,
			 const QString &source)
{
	setText(Command::Base::tr("import %n dive(s) from %1", "", dives->nr).arg(source));

	// this only matters if undoit were called before redoit
	currentDive = nullptr;

	struct dive_table dives_to_add = empty_dive_table;
	struct dive_table dives_to_remove = empty_dive_table;
	struct trip_table trips_to_add = empty_trip_table;
	struct dive_site_table sites_to_add = empty_dive_site_table;
	process_imported_dives(dives, trips, sites, devices, flags,
			       &dives_to_add, &dives_to_remove, &trips_to_add,
			       &sites_to_add, &devicesToAddAndRemove);

	// Add trips to the divesToAdd.trips structure
	divesToAdd.trips.reserve(trips_to_add.nr);
	for (int i = 0; i < trips_to_add.nr; ++i)
		divesToAdd.trips.emplace_back(trips_to_add.trips[i]);

	// Add sites to the divesToAdd.sites structure
	divesToAdd.sites.reserve(sites_to_add.nr);
	for (int i = 0; i < sites_to_add.nr; ++i)
		divesToAdd.sites.emplace_back(sites_to_add.dive_sites[i]);

	// Add dives to the divesToAdd.dives structure
	divesToAdd.dives.reserve(dives_to_add.nr);
	for (int i = 0; i < dives_to_add.nr; ++i) {
		OwningDivePtr divePtr(dives_to_add.dives[i]);
		divePtr->selected = false; // See above in AddDive::AddDive()
		dive_trip *trip = divePtr->divetrip;
		divePtr->divetrip = nullptr; // See above in AddDive::AddDive()
		dive_site *site = divePtr->dive_site;
		divePtr->dive_site = nullptr; // See above in AddDive::AddDive()

		divesToAdd.dives.push_back({ std::move(divePtr), trip, site });
	}

	// Add dive to be deleted to the divesToRemove structure
	divesAndSitesToRemove.dives.reserve(dives_to_remove.nr);
	for (int i = 0; i < dives_to_remove.nr; ++i)
		divesAndSitesToRemove.dives.push_back(dives_to_remove.dives[i]);

	// When encountering filter presets with equal names, check whether they are
	// the same. If they are, ignore them.
	if (filter_presets) {
		for (const filter_preset &preset: *filter_presets) {
			QString name = preset.name;
			auto it = std::find_if(filter_preset_table.begin(), filter_preset_table.end(),
					       [&name](const filter_preset &preset) { return preset.name == name; });
			if (it != filter_preset_table.end() && it->data == preset.data)
				continue;
			filterPresetsToAdd.emplace_back(preset.name, preset.data);
		}

		// Consume the table for analogy with the other tables.
		filter_presets->clear();
	}
}

bool ImportDives::workToBeDone()
{
	return !divesToAdd.dives.empty();
}

void ImportDives::redoit()
{
	// Remember selection so that we can undo it
	currentDive = current_dive;

	// Add new dives and sites
	DivesAndSitesToRemove divesAndSitesToRemoveNew = addDives(divesToAdd);

	// Remove old dives and sites
	divesToAdd = removeDives(divesAndSitesToRemove);

	// Select the newly added dives
	setSelection(divesAndSitesToRemoveNew.dives, divesAndSitesToRemoveNew.dives.back());

	// Remember dives and sites to remove
	divesAndSitesToRemove = std::move(divesAndSitesToRemoveNew);

	// Add devices
	for (const device &dev: devicesToAddAndRemove.devices) {
		int idx = add_to_device_table(&device_table, &dev);
		emit diveListNotifier.deviceAdded(idx);
	}

	// Add new filter presets
	for (auto &it: filterPresetsToAdd) {
		filterPresetsToRemove.push_back(filter_preset_add(it.first, it.second));
		emit diveListNotifier.filterPresetAdded(filterPresetsToRemove.back());
	}
	filterPresetsToAdd.clear();

	emit diveListNotifier.divesImported();
}

void ImportDives::undoit()
{
	// Add new dives and sites
	DivesAndSitesToRemove divesAndSitesToRemoveNew = addDives(divesToAdd);

	// Remove old dives and sites
	divesToAdd = removeDives(divesAndSitesToRemove);

	// Remember dives and sites to remove
	divesAndSitesToRemove = std::move(divesAndSitesToRemoveNew);

	// ...and restore the selection
	setSelection(selection, currentDive);

	// Remove devices
	for (const device &dev: devicesToAddAndRemove.devices) {
		int idx = remove_device(&device_table, &dev);
		if (idx >= 0)
			emit diveListNotifier.deviceDeleted(idx);
	}

	// Remove filter presets. Do this in reverse order.
	for (auto it = filterPresetsToRemove.rbegin(); it != filterPresetsToRemove.rend(); ++it) {
		int index = *it;
		QString oldName = filter_preset_name_qstring(index);
		FilterData oldData = filter_preset_get(index);
		filter_preset_delete(index);
		emit diveListNotifier.filterPresetRemoved(index);
		filterPresetsToAdd.emplace_back(oldName, oldData);
	}
	filterPresetsToRemove.clear();
	std::reverse(filterPresetsToAdd.begin(), filterPresetsToAdd.end());
}

DeleteDive::DeleteDive(const QVector<struct dive*> &divesToDeleteIn)
{
	divesToDelete.dives = std::vector<dive *>(divesToDeleteIn.begin(), divesToDeleteIn.end());
	setText(QStringLiteral("%1 [%2]").arg(Command::Base::tr("delete %n dive(s)", "", divesToDelete.dives.size())).arg(getListOfDives(divesToDelete.dives)));
}

bool DeleteDive::workToBeDone()
{
	return !divesToDelete.dives.empty();
}

void DeleteDive::undoit()
{
	divesToDelete = addDives(divesToAdd);
	sort_trip_table(&trip_table); // Though unlikely, removing a dive may reorder trips

	// Select all re-added dives and make the first one current
	dive *currentDive = !divesToDelete.dives.empty() ? divesToDelete.dives[0] : nullptr;
	setSelection(divesToDelete.dives, currentDive);
}

void DeleteDive::redoit()
{
	divesToAdd = removeDives(divesToDelete);
	sort_trip_table(&trip_table); // Though unlikely, adding a dive may reorder trips

	// Deselect all dives and select dive that was close to the first deleted dive
	dive *newCurrent = nullptr;
	if (!divesToAdd.dives.empty()) {
		timestamp_t when = divesToAdd.dives[0].dive->when;
		newCurrent = find_next_visible_dive(when);
	}
	select_single_dive(newCurrent);
}


ShiftTime::ShiftTime(std::vector<dive *> changedDives, int amount)
	: diveList(changedDives), timeChanged(amount)
{
	setText(QStringLiteral("%1 [%2]").arg(Command::Base::tr("shift time of %n dives", "", changedDives.size())).arg(getListOfDives(changedDives)));
}

void ShiftTime::redoit()
{
	std::vector<dive_trip *> trips;
	for (dive *d: diveList) {
		d->when += timeChanged;
		if (d->divetrip && std::find(trips.begin(), trips.end(), d->divetrip) == trips.end())
			trips.push_back(d->divetrip);
	}

	// Changing times may have unsorted the dive and trip tables
	sort_dive_table(&dive_table);
	sort_trip_table(&trip_table);
	for (dive_trip *trip: trips)
		sort_dive_table(&trip->dives); // Keep the trip-table in order

	// Send signals
	QVector<dive *> dives = stdToQt<dive *>(diveList);
	emit diveListNotifier.divesTimeChanged(timeChanged, dives);
	emit diveListNotifier.divesChanged(dives, DiveField::DATETIME);

	// Select the changed dives
	setSelection(diveList, diveList[0]);

	// Negate the time-shift so that the next call does the reverse
	timeChanged = -timeChanged;
}

bool ShiftTime::workToBeDone()
{
	return !diveList.empty();
}

void ShiftTime::undoit()
{
	// Same as redoit(), since after redoit() we reversed the timeOffset
	redoit();
}


RenumberDives::RenumberDives(const QVector<QPair<dive *, int>> &divesToRenumberIn) : divesToRenumber(divesToRenumberIn)
{
	std::vector<struct dive *> dives;
	dives.reserve(divesToRenumber.length());
	for (QPair<dive *, int>divePlusNumber: divesToRenumber)
		dives.push_back(divePlusNumber.first);
	setText(QStringLiteral("%1 [%2]").arg(Command::Base::tr("renumber %n dive(s)", "", divesToRenumber.count())).arg(getListOfDives(dives)));
}

void RenumberDives::undoit()
{
	renumberDives(divesToRenumber);

	// Select the changed dives
	std::vector<dive *> dives;
	dives.reserve(divesToRenumber.size());
	for (const QPair<dive *, int> &item: divesToRenumber)
		dives.push_back(item.first);
	setSelection(dives, dives[0]);
}

bool RenumberDives::workToBeDone()
{
	return !divesToRenumber.isEmpty();
}

void RenumberDives::redoit()
{
	// Redo and undo do the same thing!
	undoit();
}

bool TripBase::workToBeDone()
{
	return !divesToMove.divesToMove.empty();
}

void TripBase::redoit()
{
	moveDivesBetweenTrips(divesToMove);
	sort_trip_table(&trip_table); // Though unlikely, moving dives may reorder trips

	// Select the moved dives
	std::vector<dive *> dives;
	dives.reserve(divesToMove.divesToMove.size());
	for (const DiveToTrip &item: divesToMove.divesToMove)
		dives.push_back(item.dive);
	setSelection(dives, dives[0]);
}

void TripBase::undoit()
{
	// Redo and undo do the same thing!
	redoit();
}

RemoveDivesFromTrip::RemoveDivesFromTrip(const QVector<dive *> &divesToRemoveIn)
{
	// Filter out dives outside of trip. Note: This is in a separate loop to get the command-description right.
	QVector<dive *> divesToRemove;
	for (dive *d: divesToRemoveIn) {
		if (d->divetrip)
			divesToRemove.push_back(d);
	}
	setText(QStringLiteral("%1 [%2]").arg(Command::Base::tr("remove %n dive(s) from trip", "", divesToRemove.size())).arg(getListOfDives(divesToRemove)));
	divesToMove.divesToMove.reserve(divesToRemove.size());
	for (dive *d: divesToRemove) {
		// If a user manually removes a dive from a trip, don't autogroup this dive.
		// The flag will not be reset on undo, but that should be acceptable.
		d->notrip = true;
		divesToMove.divesToMove.push_back( {d, nullptr} );
	}
}

RemoveAutogenTrips::RemoveAutogenTrips()
{
	setText(Command::Base::tr("remove autogenerated trips"));
	// TODO: don't touch core-innards directly
	int i;
	struct dive *dive;
	for_each_dive(i, dive) {
		if (dive->divetrip && dive->divetrip->autogen)
			divesToMove.divesToMove.push_back( {dive, nullptr} );
	}
}

AddDivesToTrip::AddDivesToTrip(const QVector<dive *> &divesToAddIn, dive_trip *trip)
{
	setText(QStringLiteral("%1 [%2]").arg(Command::Base::tr("add %n dives to trip", "", divesToAddIn.size())).arg(getListOfDives(divesToAddIn)));
	for (dive *d: divesToAddIn)
		divesToMove.divesToMove.push_back( {d, trip} );
}

CreateTrip::CreateTrip(const QVector<dive *> &divesToAddIn)
{
	setText(Command::Base::tr("create trip"));

	if (divesToAddIn.isEmpty())
		return;

	dive_trip *trip = create_trip_from_dive(divesToAddIn[0]);
	divesToMove.tripsToAdd.emplace_back(trip);
	for (dive *d: divesToAddIn)
		divesToMove.divesToMove.push_back( {d, trip} );
}

AutogroupDives::AutogroupDives()
{
	setText(Command::Base::tr("autogroup dives"));

	dive_trip *trip;
	bool alloc;
	int from, to;
	for(int i = 0; (trip = get_dives_to_autogroup(&dive_table, i, &from, &to, &alloc)) != NULL; i = to) {
		// If this is an allocated trip, take ownership
		if (alloc)
			divesToMove.tripsToAdd.emplace_back(trip);
		for (int j = from; j < to; ++j)
			divesToMove.divesToMove.push_back( { get_dive(j), trip } );
	}
}

MergeTrips::MergeTrips(dive_trip *trip1, dive_trip *trip2)
{
	if (trip1 == trip2)
		return;
	dive_trip *newTrip = combine_trips(trip1, trip2);
	divesToMove.tripsToAdd.emplace_back(newTrip);
	for (int i = 0; i < trip1->dives.nr; ++i)
		divesToMove.divesToMove.push_back( { trip1->dives.dives[i], newTrip } );
	for (int i = 0; i < trip2->dives.nr; ++i)
		divesToMove.divesToMove.push_back( { trip2->dives.dives[i], newTrip } );
}

// std::array<dive *, 2> is the same as struct *dive[2], with the fundamental
// difference that it can be returned from functions. Thus, this constructor
// can be chained with the result of a function.
SplitDivesBase::SplitDivesBase(dive *d, std::array<dive *, 2> newDives)
{
	// If either of the new dives is null, simply return. Empty arrays indicate that nothing is to be done.
	if (!newDives[0] || !newDives[1])
		return;

	// Currently, the core code selects the dive -> this is not what we want, as
	// we manually manage the selection post-command.
	// TODO: Reset selection in core.
	newDives[0]->selected = false;
	newDives[1]->selected = false;

	// The new dives will be registered to the dive site using the site member
	// of the DiveToAdd structure. For this to work, we must set the dive's
	// dive_site member to null. Yes, that's subtle!
	newDives[0]->dive_site = nullptr;
	newDives[1]->dive_site = nullptr;

	diveToSplit.dives.push_back(d);
	splitDives.dives.resize(2);
	splitDives.dives[0].dive.reset(newDives[0]);
	splitDives.dives[0].trip = d->divetrip;
	splitDives.dives[0].site = d->dive_site;
	splitDives.dives[1].dive.reset(newDives[1]);
	splitDives.dives[1].trip = d->divetrip;
	splitDives.dives[1].site = d->dive_site;
}

bool SplitDivesBase::workToBeDone()
{
	return !diveToSplit.dives.empty();
}

void SplitDivesBase::redoit()
{
	divesToUnsplit = addDives(splitDives);
	unsplitDive = removeDives(diveToSplit);

	// Select split dives and make first dive current
	setSelection(divesToUnsplit.dives, divesToUnsplit.dives[0]);
}

void SplitDivesBase::undoit()
{
	// Note: reverse order with respect to redoit()
	diveToSplit = addDives(unsplitDive);
	splitDives = removeDives(divesToUnsplit);

	// Select unsplit dive and make it current
	setSelection(diveToSplit.dives, diveToSplit.dives[0] );
}

static std::array<dive *, 2> doSplitDives(const dive *d, duration_t time)
{
	// Split the dive
	dive *new1, *new2;
	if (time.seconds < 0)
		split_dive(d, &new1, &new2);
	else
		split_dive_at_time(d, time, &new1, &new2);

	return { new1, new2 };
}

SplitDives::SplitDives(dive *d, duration_t time) : SplitDivesBase(d, doSplitDives(d, time))
{
	setText(Command::Base::tr("split dive"));
}

static std::array<dive *, 2> splitDiveComputer(const dive *d, int dc_num)
{
	// Refuse to do anything if the dive has only one dive computer.
	// Yes, this should have been checked by the UI, but let's just make sure.
	if (!d->dc.next)
		return { nullptr, nullptr};

	dive *new1, *new2;
	split_divecomputer(d, dc_num, &new1, &new2);

	return { new1, new2 };
}

SplitDiveComputer::SplitDiveComputer(dive *d, int dc_num) : SplitDivesBase(d, splitDiveComputer(d, dc_num))
{
	setText(Command::Base::tr("split dive computer"));
}

DiveComputerBase::DiveComputerBase(dive *old_dive, dive *new_dive, int dc_nr_after_in) : dc_nr_before(dc_number),
	dc_nr_after(dc_nr_after_in)
{
	if (!new_dive)
		return;

	diveToRemove.dives.push_back(old_dive);

	// Currently, the core code selects the dive -> this is not what we want, as
	// we manually manage the selection post-command.
	// TODO: Reset selection in core.
	new_dive->selected = false;

	// Reset references to trip and site in the new dive, as the undo command
	// will add the dive to the trip and site.
	new_dive->divetrip = nullptr;
	new_dive->dive_site = nullptr;

	diveToAdd.dives.resize(1);
	diveToAdd.dives[0].dive.reset(new_dive);
	diveToAdd.dives[0].trip = old_dive->divetrip;
	diveToAdd.dives[0].site = old_dive->dive_site;
}

bool DiveComputerBase::workToBeDone()
{
	return !diveToRemove.dives.empty() || !diveToAdd.dives.empty();
}

void DiveComputerBase::redoit()
{
	DivesAndSitesToRemove addedDive = addDives(diveToAdd);
	diveToAdd = removeDives(diveToRemove);
	diveToRemove = std::move(addedDive);

	dc_number = dc_nr_after;

	// Select added dive and make it current.
	// This automatically replots the profile.
	setSelection(diveToRemove.dives, diveToRemove.dives[0]);

	std::swap(dc_nr_before, dc_nr_after);
}

void DiveComputerBase::undoit()
{
	// Undo and redo do the same
	redoit();
}

MoveDiveComputerToFront::MoveDiveComputerToFront(dive *d, int dc_num)
	: DiveComputerBase(d, make_first_dc(d, dc_num), 0)
{
	setText(Command::Base::tr("move dive computer to front"));
}

DeleteDiveComputer::DeleteDiveComputer(dive *d, int dc_num)
	: DiveComputerBase(d, clone_delete_divecomputer(d, dc_num), std::min((int)number_of_computers(d) - 1, dc_num))
{
	setText(Command::Base::tr("delete dive computer"));
}

MergeDives::MergeDives(const QVector <dive *> &dives)
{
	setText(Command::Base::tr("merge dive"));

	// Just a safety check - if there's not two or more dives - do nothing
	// The caller should have made sure that this doesn't happen.
	if (dives.count() < 2) {
		qWarning("Merging less than two dives");
		return;
	}

	dive_trip *preferred_trip;
	dive_site *preferred_site;
	OwningDivePtr d(merge_dives(dives[0], dives[1], dives[1]->when - dives[0]->when, false, &preferred_trip, &preferred_site));

	// Currently, the core code selects the dive -> this is not what we want, as
	// we manually manage the selection post-command.
	// TODO: Remove selection code from core.
	d->selected = false;

	// Set the preferred dive trip, so that for subsequent merges the better trip can be selected
	d->divetrip = preferred_trip;
	for (int i = 2; i < dives.count(); ++i) {
		d.reset(merge_dives(d.get(), dives[i], dives[i]->when - d->when, false, &preferred_trip, &preferred_site));
		// Set the preferred dive trip and site, so that for subsequent merges the better trip and site can be selected
		d->divetrip = preferred_trip;
		d->dive_site = preferred_site;
	}

	// We got our preferred trip and site, so now the references can be deleted from the newly generated dive
	d->divetrip = nullptr;
	d->dive_site = nullptr;

	// The merged dive gets the number of the first dive with a non-zero number
	for (const dive *dive: dives) {
		if (dive->number) {
			d->number = dive->number;
			break;
		}
	}

	// We will only renumber the remaining dives if the joined dives are consecutive.
	// Otherwise all bets are off concerning what the user wanted and doing nothing seems
	// like the best option.
	int idx = get_divenr(dives[0]);
	int num = dives.count();
	if (idx < 0 || idx + num > dive_table.nr) {
		// It was the callers responsibility to pass only known dives.
		// Something is seriously wrong - give up.
		qWarning("Merging unknown dives");
		return;
	}
	// std::equal compares two ranges. The parameters are (begin_range1, end_range1, begin_range2).
	// Here, we can compare C-arrays, because QVector guarantees contiguous storage.
	if (std::equal(&dives[0], &dives[0] + num, &dive_table.dives[idx]) &&
	    dives[0]->number && dives.last()->number && dives[0]->number < dives.last()->number) {
		// We have a consecutive set of dives. Rename all following dives according to the
		// number of erased dives. This considers that there might be missing numbers.
		// Comment copied from core/divelist.c:
		// So if you had a dive list  1 3 6 7 8, and you
		// merge 1 and 3, the resulting numbered list will
		// be 1 4 5 6, because we assume that there were
		// some missing dives (originally dives 4 and 5),
		// that now will still be missing (dives 2 and 3
		// in the renumbered world).
		//
		// Obviously the normal case is that everything is
		// consecutive, and the difference will be 1, so the
		// above example is not supposed to be normal.
		int diff = dives.last()->number - dives[0]->number;
		divesToRenumber.reserve(dive_table.nr - idx - num);
		int previousnr = dives[0]->number;
		for (int i = idx + num; i < dive_table.nr; ++i) {
			int newnr = dive_table.dives[i]->number - diff;

			// Stop renumbering if stuff isn't in order (see also core/divelist.c)
			if (newnr <= previousnr)
				break;
			divesToRenumber.append(QPair<dive *,int>(dive_table.dives[i], newnr));
			previousnr = newnr;
		}
	}

	mergedDive.dives.resize(1);
	mergedDive.dives[0].dive = std::move(d);
	mergedDive.dives[0].trip = preferred_trip;
	mergedDive.dives[0].site = preferred_site;
	divesToMerge.dives = std::vector<dive *>(dives.begin(), dives.end());
}

bool MergeDives::workToBeDone()
{
	return !mergedDive.dives.empty();
}

void MergeDives::redoit()
{
	renumberDives(divesToRenumber);
	diveToUnmerge = addDives(mergedDive);
	unmergedDives = removeDives(divesToMerge);

	// Select merged dive and make it current
	setSelection(diveToUnmerge.dives, diveToUnmerge.dives[0]);
}

void MergeDives::undoit()
{
	divesToMerge = addDives(unmergedDives);
	mergedDive = removeDives(diveToUnmerge);
	renumberDives(divesToRenumber);

	// Select unmerged dives and make first one current
	setSelection(divesToMerge.dives, divesToMerge.dives[0]);
}

} // namespace Command