Mobile: don't format trip heading for all dives

QML's ListView uses the "section" property to test if items belong to the
same section. Apparently, this must be a string and therefore we can't
pass e.g. a dive-trip object. Therefore a specially formatted string
was passed in, which was guaranteed to be unique (contained the dive-trip
pointer value) and the fully formatted trip-title and short-date.

The disadvantage of that approach is that the formatting is performed for
every dive and not every trip. Perhaps not a problem now, but it makes
it for example necessary to cache the number of filtered dives.

To be more flexible, pass in only the pointer value formatted as
hexadecimal string and provide a function to convert that string
back to a trip-pointer (in the form of a QVariant, so that it can
be passed to QML). Moreover provide two functions for formatting the
title and the short-date.

The three new functions are members of DiveListSortModel. This might not
be the perfect place, but it is easy to reach from the DiveListView.

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

2 files changed, 53 insertions, 0 deletions

diff --git a/qt-models/divelistmodel.cpp b/qt-models/divelistmodel.cpp
index b12786fa9..bfed1d0cb 100644
--- a/qt-models/divelistmodel.cpp
+++ b/qt-models/divelistmodel.cpp
@@ -112,6 +112,56 @@ void DiveListSortModel::updateDivesShownInTrips()
 	}
 }
 
+// In QML, section headings can only be strings. To identify dives that
+// belong to the same trip, a string containing the trip-pointer in hexadecimal
+// encoding is passed in. To format the trip heading, the string is then
+// converted back with this function.
+QVariant DiveListSortModel::tripIdToObject(const QString &s)
+{
+	if (s.isEmpty())
+		return QVariant();
+	return QVariant::fromValue((dive_trip *)s.toULongLong(nullptr, 16));
+}
+
+// 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 QVariant &tripIn)
+{
+	dive_trip *dt = tripIn.value<dive_trip *>();
+	if (!dt)
+		return QString();
+	QString numDives = tr("(%n dive(s))", "", dt->showndives);
+	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").arg(title, numDives);
+}
+
+QString DiveListSortModel::tripShortDate(const QVariant &tripIn)
+{
+	dive_trip *dt = tripIn.value<dive_trip *>();
+	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::m_instance = NULL;
 
 DiveListModel::DiveListModel(QObject *parent) : QAbstractListModel(parent)
diff --git a/qt-models/divelistmodel.h b/qt-models/divelistmodel.h
index 05c3b76ff..0c393bc2d 100644
--- a/qt-models/divelistmodel.h
+++ b/qt-models/divelistmodel.h
@@ -15,6 +15,9 @@ public:
 	void setSourceModel(QAbstractItemModel *sourceModel);
 	Q_INVOKABLE void addAllDives();
 	Q_INVOKABLE void clear();
+	Q_INVOKABLE QVariant tripIdToObject(const QString &s);
+	Q_INVOKABLE QString tripTitle(const QVariant &trip);
+	Q_INVOKABLE QString tripShortDate(const QVariant &trip);
 public slots:
 	int getDiveId(int idx);
 	int getIdxForId(int id);