Mobile: add second filter proxy model for dive list

This one significantly reduces the number of dives that are handed to the
ListView in QML. For every trip that isn't expanded (only zero or one trips are
expanded at any time, so almost all the others are collapsed), send only first
dive to the View to allow creation of the section. Hide the rest so we don't
have all these invisible, zero height entries for the vertical dive list.

A big part of this commit is moving a few functions from the DiveListSortModel
to the CollapsedDiveListSortModel. Those are the ones that are needed for the
trip header.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

2 files changed, 209 insertions, 62 deletions

diff --git a/qt-models/divelistmodel.cpp b/qt-models/divelistmodel.cpp
index 99d8bc588..c9bcaa2e1 100644
--- a/qt-models/divelistmodel.cpp
+++ b/qt-models/divelistmodel.cpp
@@ -5,7 +5,172 @@
 #include "core/trip.h"
 #include "core/settings/qPrefGeneral.h"
 #include "core/ssrf.h" // for LOG_STP
+#include "core/errorhelper.h" // for verbose
 #include <QDateTime>
+#include <QDebug>
+
+// the DiveListSortModel creates the sorted, filtered list of dives that the user
+// can flip through horizontally
+// the CollapsedDiveListSortModel creates the vertical dive list which is a second
+// filter on top of the one applied to the DiveListSortModel
+
+CollapsedDiveListSortModel::CollapsedDiveListSortModel()
+{
+	setSourceModel(DiveListSortModel::instance());
+	setDynamicSortFilter(true);
+	updateFilterState();
+	// make sure that we after changes to the underlying model (and therefore the dive list
+	// we update the filter state
+	connect(DiveListModel::instance(), &DiveListModel::rowsInserted, this, &CollapsedDiveListSortModel::updateFilterState);
+	connect(DiveListModel::instance(), &DiveListModel::rowsMoved, this, &CollapsedDiveListSortModel::updateFilterState);
+	connect(DiveListModel::instance(), &DiveListModel::rowsRemoved, this, &CollapsedDiveListSortModel::updateFilterState);
+}
+
+CollapsedDiveListSortModel *CollapsedDiveListSortModel::instance()
+{
+	static CollapsedDiveListSortModel self;
+	return &self;
+}
+
+void CollapsedDiveListSortModel::setSourceModel(QAbstractItemModel *sourceModel)
+{
+	QSortFilterProxyModel::setSourceModel(sourceModel);
+	updateFilterState();
+}
+
+// In QtQuick ListView, section headings can only be strings. To identify dives
+// that belong to the same trip, a string containing the trip-id is passed in.
+// To format the trip heading, the string is then converted back with this function.
+static dive_trip *tripIdToObject(const QString &s)
+{
+	if (s.isEmpty())
+		return nullptr;
+	int id = s.toInt();
+	dive_trip **trip = std::find_if(&trip_table.trips[0], &trip_table.trips[trip_table.nr],
+					[id] (const dive_trip *t) { return t->id == id; });
+	if (trip == &trip_table.trips[trip_table.nr]) {
+		fprintf(stderr, "Warning: unknown trip id passed through QML: %d\n", id);
+		return nullptr;
+	}
+	return *trip;
+}
+
+// the trip title is designed to be location (# dives)
+// or, if there is no location name date range (# dives)
+// where the date range is given as "month year" or "month-month year" or "month year - month year"
+QString CollapsedDiveListSortModel::tripTitle(const QString &section)
+{
+	const dive_trip *dt = tripIdToObject(section);
+	if (!dt)
+		return QString();
+	QString numDives = tr("(%n dive(s))", "", dt->dives.nr);
+	int shown = trip_shown_dives(dt);
+	QString shownDives = shown != dt->dives.nr ? QStringLiteral(" ") + tr("(%L1 shown)").arg(shown) : QString();
+	QString title(dt->location);
+
+	if (title.isEmpty()) {
+		// so use the date range
+		QDateTime firstTime = QDateTime::fromMSecsSinceEpoch(1000*trip_date(dt), Qt::UTC);
+		QString firstMonth = firstTime.toString("MMM");
+		QString firstYear = firstTime.toString("yyyy");
+		QDateTime lastTime = QDateTime::fromMSecsSinceEpoch(1000*dt->dives.dives[0]->when, Qt::UTC);
+		QString lastMonth = lastTime.toString("MMM");
+		QString lastYear = lastTime.toString("yyyy");
+		if (lastMonth == firstMonth && lastYear == firstYear)
+			title = firstMonth + " " + firstYear;
+		else if (lastMonth != firstMonth && lastYear == firstYear)
+			title = firstMonth + "-" + lastMonth + " " + firstYear;
+		else
+			title = firstMonth + " " + firstYear + " - " + lastMonth + " " + lastYear;
+	}
+	return QStringLiteral("%1 %2%3").arg(title, numDives, shownDives);
+}
+
+QString CollapsedDiveListSortModel::tripShortDate(const QString &section)
+{
+	const dive_trip *dt = tripIdToObject(section);
+	if (!dt)
+		return QString();
+	QDateTime firstTime = QDateTime::fromMSecsSinceEpoch(1000*trip_date(dt), Qt::UTC);
+	QString firstMonth = firstTime.toString("MMM");
+	return QStringLiteral("%1\n'%2").arg(firstMonth,firstTime.toString("yy"));
+}
+
+void CollapsedDiveListSortModel::setActiveTrip(const QString &trip)
+{
+	m_activeTrip = trip;
+	updateFilterState();
+	invalidateFilter();
+}
+
+QString CollapsedDiveListSortModel::activeTrip() const
+{
+	return m_activeTrip;
+}
+
+// tell us if this dive is the first dive in a trip that has at least one
+// dive that isn't hidden (even if this dive is hidden)
+static bool isFirstInNotCompletelyHiddenTrip(struct dive *d)
+{
+	struct dive_trip *dt = d->divetrip;
+	if (dt->dives.nr > 0 && dt->dives.dives[0] == d) {
+		// ok, this is the first dive in its trip
+		int i = -1;
+		while (++i < dt->dives.nr)
+			if (!dt->dives.dives[i]->hidden_by_filter)
+				return true;
+	}
+	return false;
+}
+
+// the mobile app allows only one selected dive
+// that means there are either zero or exactly one expanded trip -
+bool CollapsedDiveListSortModel::isExpanded(struct dive_trip *dt) const
+{
+	return !m_activeTrip.isEmpty() && dt == tripIdToObject(m_activeTrip);
+}
+
+void CollapsedDiveListSortModel::updateFilterState()
+{
+	// now do something clever to show the right dives
+	// first make sure that the underlying filtering is taken care of
+	DiveListSortModel::instance()->updateFilterState();
+	int i;
+	struct dive *d;
+	for_each_dive(i, d) {
+		CollapsedState state = DontShow;
+		struct dive_trip *dt = d->divetrip;
+
+		// we show the dives that are outside of a trip or inside of the one expanded trip
+		if (!d->hidden_by_filter && (dt == nullptr || isExpanded(dt)))
+			state = ShowDive;
+		// we mark the first dive of a trip that contains any unfiltered dives as ShowTrip  or ShowDiveAndTrip (if this is the one expanded trip)
+		if (dt != nullptr && isFirstInNotCompletelyHiddenTrip(d))
+			state = (state == ShowDive) ? ShowDiveAndTrip : ShowTrip;
+		d->collapsed = state;
+	}
+	// everything up to here can be done even if we don't have a source model
+	if (sourceModel() != nullptr) {
+		QVector<int> changedRoles = { DiveListModel::CollapsedRole };
+		dataChanged(index(0,0), index(rowCount() - 1, 0), changedRoles);
+	}
+}
+
+void CollapsedDiveListSortModel::updateSelectionState()
+{
+	QVector<int> changedRoles = { DiveListModel::SelectedRole };
+	dataChanged(index(0,0), index(rowCount() - 1, 0), changedRoles);
+}
+
+bool CollapsedDiveListSortModel::filterAcceptsRow(int source_row, const QModelIndex &) const
+{
+	// get the corresponding dive from the DiveListModel and check if we should show it
+	const dive *d = DiveListModel::instance()->getDive(source_row);
+	if (verbose > 1)
+		qDebug() << "FAR source row" << source_row << "dive" << (d ? QString::number(d->number) : "NULL") << "is" << (d != nullptr && d->collapsed != DontShow) <<
+			    (d != nullptr ? QString::number(d->collapsed) : "");
+	return d != nullptr && d->collapsed != DontShow;
+}
 
 DiveListSortModel::DiveListSortModel()
 {
@@ -23,6 +188,11 @@ DiveListSortModel *DiveListSortModel::instance()
 	return &self;
 }
 
+QString DiveListSortModel::getFilterString() const
+{
+	return filterString;
+}
+
 void DiveListSortModel::updateFilterState()
 {
 	if (filterString.isEmpty()) {
@@ -89,64 +259,6 @@ void DiveListSortModel::reload()
 	mySourceModel->resetInternalData();
 }
 
-// In QtQuick ListView, section headings can only be strings. To identify dives
-// that belong to the same trip, a string containing the trip-id is passed in.
-// To format the trip heading, the string is then converted back with this function.
-static dive_trip *tripIdToObject(const QString &s)
-{
-	if (s.isEmpty())
-		return nullptr;
-	int id = s.toInt();
-	dive_trip **trip = std::find_if(&trip_table.trips[0], &trip_table.trips[trip_table.nr],
-					[id] (const dive_trip *t) { return t->id == id; });
-	if (trip == &trip_table.trips[trip_table.nr]) {
-		fprintf(stderr, "Warning: unknown trip id passed through QML: %d\n", id);
-		return nullptr;
-	}
-	return *trip;
-}
-
-// the trip title is designed to be location (# dives)
-// or, if there is no location name date range (# dives)
-// where the date range is given as "month year" or "month-month year" or "month year - month year"
-QString DiveListSortModel::tripTitle(const QString &section)
-{
-	const dive_trip *dt = tripIdToObject(section);
-	if (!dt)
-		return QString();
-	QString numDives = tr("(%n dive(s))", "", dt->dives.nr);
-	int shown = trip_shown_dives(dt);
-	QString shownDives = shown != dt->dives.nr ? QStringLiteral(" ") + tr("(%L1 shown)").arg(shown) : QString();
-	QString title(dt->location);
-
-	if (title.isEmpty()) {
-		// so use the date range
-		QDateTime firstTime = QDateTime::fromMSecsSinceEpoch(1000*trip_date(dt), Qt::UTC);
-		QString firstMonth = firstTime.toString("MMM");
-		QString firstYear = firstTime.toString("yyyy");
-		QDateTime lastTime = QDateTime::fromMSecsSinceEpoch(1000*dt->dives.dives[0]->when, Qt::UTC);
-		QString lastMonth = lastTime.toString("MMM");
-		QString lastYear = lastTime.toString("yyyy");
-		if (lastMonth == firstMonth && lastYear == firstYear)
-			title = firstMonth + " " + firstYear;
-		else if (lastMonth != firstMonth && lastYear == firstYear)
-			title = firstMonth + "-" + lastMonth + " " + firstYear;
-		else
-			title = firstMonth + " " + firstYear + " - " + lastMonth + " " + lastYear;
-	}
-	return QStringLiteral("%1 %2%3").arg(title, numDives, shownDives);
-}
-
-QString DiveListSortModel::tripShortDate(const QString &section)
-{
-	const dive_trip *dt = tripIdToObject(section);
-	if (!dt)
-		return QString();
-	QDateTime firstTime = QDateTime::fromMSecsSinceEpoch(1000*trip_date(dt), Qt::UTC);
-	QString firstMonth = firstTime.toString("MMM");
-	return QStringLiteral("%1\n'%2").arg(firstMonth,firstTime.toString("yy"));
-}
-
 DiveListModel::DiveListModel()
 {
 	LOG_STP("run_ui diveListModel started");
@@ -281,6 +393,8 @@ QVariant DiveListModel::data(const QModelIndex &index, int role) const
 	case StartPressureRole: return getStartPressure(d);
 	case EndPressureRole: return getEndPressure(d);
 	case FirstGasRole: return getFirstGas(d);
+	case CollapsedRole: return d->collapsed;
+	case SelectedRole: return d->selected;
 	}
 	return QVariant();
 }
@@ -319,6 +433,8 @@ QHash<int, QByteArray> DiveListModel::roleNames() const
 	roles[StartPressureRole] = "startPressure";
 	roles[EndPressureRole] = "endPressure";
 	roles[FirstGasRole] = "firstGas";
+	roles[CollapsedRole] = "collapsed";
+	roles[SelectedRole] = "selected";
 	return roles;
 }
 
diff --git a/qt-models/divelistmodel.h b/qt-models/divelistmodel.h
index d9e0928dc..92e7a9291 100644
--- a/qt-models/divelistmodel.h
+++ b/qt-models/divelistmodel.h
@@ -7,15 +7,46 @@
 
 #include "core/subsurface-qt/DiveObjectHelper.h"
 
+class CollapsedDiveListSortModel : public QSortFilterProxyModel
+{
+	Q_OBJECT
+public:
+	static CollapsedDiveListSortModel *instance();
+	void setSourceModel(QAbstractItemModel *sourceModel);
+	Q_INVOKABLE QString tripTitle(const QString &trip);
+	Q_INVOKABLE QString tripShortDate(const QString &trip);
+	Q_INVOKABLE void setActiveTrip(const QString &trip);
+	Q_INVOKABLE QString activeTrip() const;
+	// super subtle optimization alert - in order to reduce the number of model accesses from QML,
+	// the two states where we show the dive in question have odd numbers
+	enum CollapsedState {
+		DontShow = 0,
+		ShowDive = 1,
+		ShowTrip = 2,
+		ShowDiveAndTrip = 3
+	};
+	void updateFilterState();
+	void updateSelectionState();
+
+protected:
+	bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const;
+
+private:
+	CollapsedDiveListSortModel();
+	bool isExpanded(struct dive_trip *dt) const;
+	QString m_activeTrip;
+};
+
 class DiveListSortModel : public QSortFilterProxyModel
 {
 	Q_OBJECT
 public:
 	static DiveListSortModel *instance();
 	void setSourceModel(QAbstractItemModel *sourceModel);
+	QString getFilterString() const;
 	Q_INVOKABLE void reload();
-	Q_INVOKABLE QString tripTitle(const QString &trip);
-	Q_INVOKABLE QString tripShortDate(const QString &trip);
+	QString filterString;
+	void updateFilterState();
 public slots:
 	int getIdxForId(int id);
 	void setFilter(QString f);
@@ -25,8 +56,6 @@ protected:
 	bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const;
 private:
 	DiveListSortModel();
-	QString filterString;
-	void updateFilterState();
 };
 
 QString formatSac(const dive *d);
@@ -74,6 +103,8 @@ public:
 		StartPressureRole,
 		EndPressureRole,
 		FirstGasRole,
+		CollapsedRole,
+		SelectedRole,
 	};
 
 	static DiveListModel *instance();