Dive list: hand-code the DiveTripModel

The dive list is fed data by means of a sorted "DiveTripModel".
There are two modes: list and tree. This was implemented rather
elegantly with a general "TreeModel", which can represent trees
of arbitrary depths.

Nevertheless, we have at most two levels and on the second level
only dives can reside. Implementing proper model-semantics
(insert, delete, move) will be quite a challenge and implementing
it under the umbrella of a very general model will not make it
easier.

Therefore, for now, hardcode the model:
At the top-level there are items which may either be a trip
(can contain multiple dives) or a dive (contains exactly one dive).

Thus, we can completely de-virutalize the DiveItem and TripItem
classes, which are now trivial wrappers around dive * and dive_trip *.

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

2 files changed, 163 insertions, 51 deletions

diff --git a/qt-models/divetripmodel.cpp b/qt-models/divetripmodel.cpp
index 2dd6def83..58ccc0fd2 100644
--- a/qt-models/divetripmodel.cpp
+++ b/qt-models/divetripmodel.cpp
@@ -310,14 +310,6 @@ QVariant DiveItem::data(int column, int role) const
 	return retVal;
 }
 
-Qt::ItemFlags DiveItem::flags(const QModelIndex &index) const
-{
-	if (index.column() == NR) {
-		return TreeItem::flags(index) | Qt::ItemIsEditable;
-	}
-	return TreeItem::flags(index);
-}
-
 bool DiveItem::setData(const QModelIndex &index, const QVariant &value, int role)
 {
 	if (role != Qt::EditRole)
@@ -436,19 +428,70 @@ DiveTripModel *DiveTripModel::instance()
 }
 
 DiveTripModel::DiveTripModel(QObject *parent) :
-	TreeModel(parent),
+	QAbstractItemModel(parent),
 	currentLayout(TREE)
 {
-	columns = COLUMNS;
 }
 
-Qt::ItemFlags DiveTripModel::flags(const QModelIndex &index) const
+int DiveTripModel::columnCount(const QModelIndex&) const
 {
-	if (!index.isValid())
+	return COLUMNS;
+}
+
+int DiveTripModel::rowCount(const QModelIndex &parent) const
+{
+	// No parent means top level - return the number of top-level items
+	if (!parent.isValid())
+		return items.size();
+
+	// If the parent has a parent, this is a dive -> no entries
+	if (parent.parent().isValid())
 		return 0;
 
-	TripItem *item = static_cast<TripItem *>(index.internalPointer());
-	return item->flags(index);
+	// If this is outside of our top-level list -> no entries
+	int row = parent.row();
+	if (row < 0 || row >= (int)items.size())
+		return 0;
+
+	// Only trips have items
+	const Item &entry =  items[parent.row()];
+	return entry.trip ? entry.dives.size() : 0;
+}
+
+static const quintptr noParent = ~(quintptr)0; // This is the "internalId" marker for top-level item
+
+QModelIndex DiveTripModel::index(int row, int column, const QModelIndex &parent) const
+{
+	if (!hasIndex(row, column, parent))
+		return QModelIndex();
+
+	// In the "internalId", we store either ~0 no top-level items or the
+	// index of the parent item. A top-level item has an invalid parent.
+	return createIndex(row, column, parent.isValid() ? parent.row() : noParent);
+}
+
+QModelIndex DiveTripModel::parent(const QModelIndex &index) const
+{
+	if (!index.isValid())
+		return QModelIndex();
+
+	// In the "internalId", we store either ~0 for top-level items
+	// or the index of the parent item.
+	quintptr id = index.internalId();
+	if (id == noParent)
+		return QModelIndex();
+
+	// Parent must be top-level item
+	return createIndex(id, 0, noParent);
+}
+
+Qt::ItemFlags DiveTripModel::flags(const QModelIndex &index) const
+{
+	dive *d = diveOrNull(index);
+	Qt::ItemFlags base = Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+
+	// Only dives have editable fields and only the number is editable
+	return d && index.column() == NR ? base | Qt::ItemIsEditable : base;
 }
 
 QVariant DiveTripModel::headerData(int section, Qt::Orientation orientation, int role) const
@@ -584,43 +627,49 @@ QVariant DiveTripModel::headerData(int section, Qt::Orientation orientation, int
 	return ret;
 }
 
+DiveTripModel::Item::Item(dive_trip *t, dive *d) : trip(t),
+	dives({ d })
+{
+}
+
+DiveTripModel::Item::Item(dive *d) : trip(nullptr),
+	dives({ d })
+{
+}
+
 void DiveTripModel::setupModelData()
 {
 	int i = dive_table.nr;
 
 	beginResetModel();
 
-	clear();
 	if (autogroup)
 		autogroup_dives();
-	QMap<dive_trip_t *, TripItem *> trips;
+	items.clear();
 	while (--i >= 0) {
-		struct dive *dive = get_dive(i);
-		update_cylinder_related_info(dive);
-		dive_trip_t *trip = dive->divetrip;
-
-		DiveItem *diveItem = new DiveItem();
-		diveItem->d = dive;
+		dive *d = get_dive(i);
+		update_cylinder_related_info(d);
+		dive_trip_t *trip = d->divetrip;
 
+		// If this dive doesn't have a trip or we are in list-mode, add
+		// as top-level item.
 		if (!trip || currentLayout == LIST) {
-			diveItem->parent = rootItem.get();
-			rootItem->children.push_back(diveItem);
+			items.emplace_back(d);
 			continue;
 		}
-		if (currentLayout == LIST)
-			continue;
 
-		if (!trips.keys().contains(trip)) {
-			TripItem *tripItem = new TripItem();
-			tripItem->trip = trip;
-			tripItem->parent = rootItem.get();
-			tripItem->children.push_back(diveItem);
-			trips[trip] = tripItem;
-			rootItem->children.push_back(tripItem);
-			continue;
+		// Check if that trip is already known to us: search for the first item
+		// where item->trip is equal to trip.
+		auto it = std::find_if(items.begin(), items.end(), [trip](const Item &item)
+				       { return item.trip == trip; });
+		if (it == items.end()) {
+			// We didn't find an entry for this trip -> add one
+			items.emplace_back(trip, d);
+
+		} else {
+			// We found the trip -> simply add the dive
+			it->dives.push_back(d);
 		}
-		TripItem *tripItem = trips[trip];
-		tripItem->children.push_back(diveItem);
 	}
 
 	endResetModel();
@@ -637,11 +686,47 @@ void DiveTripModel::setLayout(DiveTripModel::Layout layout)
 	setupModelData();
 }
 
+QPair<dive_trip *, dive *> DiveTripModel::tripOrDive(const QModelIndex &index) const
+{
+	if (!index.isValid())
+		return { nullptr, nullptr };
+
+	QModelIndex parent = index.parent();
+	// An invalid parent means that we're at the top-level
+	if (!parent.isValid()) {
+		const Item &entry = items[index.row()];
+		if (entry.trip)
+			return { entry.trip, nullptr };		// A trip
+		else
+			return { nullptr, entry.dives[0] };	// A dive
+	}
+
+	// Otherwise, we're at a leaf -> thats a dive
+	return { nullptr, items[parent.row()].dives[index.row()] };
+}
+
+dive *DiveTripModel::diveOrNull(const QModelIndex &index) const
+{
+	return tripOrDive(index).second;
+}
+
+QVariant DiveTripModel::data(const QModelIndex &index, int role) const
+{
+	// Set the font for all items alike
+	if (role == Qt::FontRole)
+		return defaultModelFont();
+
+	auto entry = tripOrDive(index);
+	if (entry.first)
+		return TripItem(entry.first).data(index.column(), role);
+	else if (entry.second)
+		return DiveItem(entry.second).data(index.column(), role);
+	else
+		return QVariant();
+}
+
 bool DiveTripModel::setData(const QModelIndex &index, const QVariant &value, int role)
 {
-	TreeItem *item = static_cast<TreeItem *>(index.internalPointer());
-	DiveItem *diveItem = dynamic_cast<DiveItem *>(item);
-	if (!diveItem)
-		return false;
-	return diveItem->setData(index, value, role);
+	dive *d = diveOrNull(index);
+	return d ? DiveItem(d).setData(index, value, role) : false;
 }
diff --git a/qt-models/divetripmodel.h b/qt-models/divetripmodel.h
index d33df2143..f6125d196 100644
--- a/qt-models/divetripmodel.h
+++ b/qt-models/divetripmodel.h
@@ -2,12 +2,12 @@
 #ifndef DIVETRIPMODEL_H
 #define DIVETRIPMODEL_H
 
-#include "treemodel.h"
 #include "core/dive.h"
-#include <string>
+#include <QAbstractItemModel>
+#include <QCoreApplication>		// For Q_DECLARE_TR_FUNCTIONS
 
-struct DiveItem : public TreeItem {
-	Q_DECLARE_TR_FUNCTIONS(TripItem)
+struct DiveItem {
+	Q_DECLARE_TR_FUNCTIONS(TripItem)		// Is that TripItem on purpose?
 public:
 	enum Column {
 		NR,
@@ -31,10 +31,10 @@ public:
 		COLUMNS
 	};
 
-	QVariant data(int column, int role) const override;
+	QVariant data(int column, int role) const;
 	dive *d;
-	bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override;
-	Qt::ItemFlags flags(const QModelIndex &index) const override;
+	DiveItem(dive *dIn) : d(dIn) {}			// Trivial constructor
+	bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole);
 	QString displayDate() const;
 	QString displayDuration() const;
 	QString displayDepth() const;
@@ -50,14 +50,15 @@ public:
 	int weight() const;
 };
 
-struct TripItem : public TreeItem {
+struct TripItem {
 	Q_DECLARE_TR_FUNCTIONS(TripItem)
 public:
-	QVariant data(int column, int role) const override;
+	QVariant data(int column, int role) const;
 	dive_trip_t *trip;
+	TripItem(dive_trip_t *tIn) : trip(tIn) {}	// Trivial constructor
 };
 
-class DiveTripModel : public TreeModel {
+class DiveTripModel : public QAbstractItemModel {
 	Q_OBJECT
 public:
 	enum Column {
@@ -102,9 +103,35 @@ public:
 	DiveTripModel(QObject *parent = 0);
 	Layout layout() const;
 	void setLayout(Layout layout);
+	QVariant data(const QModelIndex &index, int role) const;
+	int columnCount(const QModelIndex&) const;
+	int rowCount(const QModelIndex &parent) const;
+	QModelIndex index(int row, int column, const QModelIndex &parent) const;
+	QModelIndex parent(const QModelIndex &index) const;
 
 private:
+	// The model has up to two levels. At the top level, we have either trips or dives
+	// that do not belong to trips. Such a top-level item is represented by the "Item"
+	// struct. Two cases two consider:
+	// 1) If "trip" is non-null, then this is a dive-trip and the dives are collected
+	// in the dives vector.  Note that in principle we could also get the dives in a
+	// trip from the backend, but there they are collected in a linked-list, which is
+	// quite inconvenient to access.
+	// 2) If "trip" is null, this is a dive and dives is supposed to contain exactly
+	// one element, which is the corresponding dive.
+	struct Item {
+		dive_trip		*trip;
+		QVector<dive *>		 dives;
+		Item(dive_trip *t, dive *d);	// Initialize a trip with one dive
+		Item(dive *d);			// Initialize a top-level dive
+	};
+
+	dive *diveOrNull(const QModelIndex &index) const;	// Returns a dive if this index represents a dive, null otherwise
+	QPair<dive_trip *, dive *> tripOrDive(const QModelIndex &index) const;
+								// Returns either a pointer to a trip or a dive, or twice null of index is invalid
+								// null, something is really wrong
 	void setupModelData();
+	std::vector<Item> items;				// Use std::vector for convenience of emplace_back()
 	Layout currentLayout;
 };