Dive list: move trip merging logic into divelist.c

This also fixes a couple of issues with the existing code:
- removes a memory leak
- treats null and "" the same

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

divelist.c

@@ -864,6 +864,25 @@ void select_dives_in_trip(struct dive_trip *trip)
 		select_dive(get_divenr(dive));
 }
 
+/* This only gets called with non-NULL trips.
+ * It does not combine notes or location, just picks the first one
+ * (or the second one if the first one is empty */
+void combine_trips(struct dive_trip *trip_a, struct dive_trip *trip_b)
+{
+	if (same_string(trip_a->location, "") && trip_b->location) {
+		free(trip_a->location);
+		trip_a->location = strdup(trip_b->location);
+	}
+	if (same_string(trip_a->notes, "") && trip_b->notes) {
+		free(trip_a->notes);
+		trip_a->notes = strdup(trip_b->notes);
+	}
+	/* this also removes the dives from trip_b and eventually
+	 * calls delete_trip(trip_b) when the last dive has been moved */
+	while (trip_b->dives)
+		add_dive_to_trip(trip_b->dives, trip_a);
+}
+
 void mark_divelist_changed(int changed)
 {
 	dive_list_changed = changed;

divelist.h

@@ -32,6 +32,7 @@ extern void select_dive(int idx);
 extern void deselect_dive(int idx);
 extern void select_dives_in_trip(struct dive_trip *trip);
 extern void deselect_dives_in_trip(struct dive_trip *trip);
+extern void combine_trips(struct dive_trip *trip_a, struct dive_trip *trip_b);
 extern void find_new_trip_start_time(dive_trip_t *trip);
 extern struct dive *first_selected_dive();
 extern struct dive *last_selected_dive();

qt-ui/divelistview.cpp

@@ -535,17 +535,9 @@ void DiveListView::merge_trip(const QModelIndex &a, int offset)
 
 	dive_trip_t *trip_a = (dive_trip_t *)a.data(DiveTripModel::TRIP_ROLE).value<void *>();
 	dive_trip_t *trip_b = (dive_trip_t *)b.data(DiveTripModel::TRIP_ROLE).value<void *>();
-	// TODO: merge_trip on the C code? some part of this needs to stay ( getting the trips from the model,
-	// but not the algorithm.
 	if (trip_a == trip_b || !trip_a || !trip_b)
 		return;
-
+	combine_trips(trip_a, trip_b);
-	if (!trip_a->location && trip_b->location)
-		trip_a->location = strdup(trip_b->location);
-	if (!trip_a->notes && trip_b->notes)
-		trip_a->notes = strdup(trip_b->notes);
-	while (trip_b->dives)
-		add_dive_to_trip(trip_b->dives, trip_a);
 	rememberSelection();
 	reload(currentLayout, false);
 	fixMessyQtModelBehaviour();