Add ability to undo shifting of dive time

Adds the ability to undo shifting of dive times. The change is captured
at simplewidgets.cpp and an undo command is created.

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

qt-ui/simplewidgets.cpp

@@ -15,6 +15,7 @@
 #include "divelistview.h"
 #include "display.h"
 #include "profile/profilewidget2.h"
+#include "undocommands.h"
 
 class MinMaxAvgWidgetPrivate {
 public:
@@ -201,7 +202,16 @@ void ShiftTimesDialog::buttonClicked(QAbstractButton *button)
 			amount *= -1;
 		if (amount != 0) {
 			// DANGER, DANGER - this could get our dive_table unsorted...
-			shift_times(amount);
+			int i;
+			struct dive *dive;
+			QList<int> affectedDives;
+			for_each_dive (i, dive) {
+				if (!dive->selected)
+					continue;
+
+				affectedDives.append(dive->id);
+			}
+			MainWindow::instance()->undoStack->push(new UndoShiftTime(affectedDives, amount));
 			sort_table(&dive_table);
 			mark_divelist_changed(true);
 			MainWindow::instance()->dive_list()->rememberSelection();

qt-ui/undocommands.cpp

@@ -34,3 +34,31 @@ void UndoDeleteDive::redo()
 	dives.clear();
 	dives = newList;
 }
+
+
+UndoShiftTime::UndoShiftTime(QList<int> diveList, int amount)
+{
+	setText("shift time");
+	dives = diveList;
+	timeChanged = amount;
+}
+
+void UndoShiftTime::undo()
+{
+	for (int i = 0; i < dives.count(); i++) {
+		struct dive* d = get_dive_by_uniq_id(dives.at(i));
+		d->when -= timeChanged;
+	}
+	mark_divelist_changed(true);
+	MainWindow::instance()->refreshDisplay();
+}
+
+void UndoShiftTime::redo()
+{
+	for (int i = 0; i < dives.count(); i++) {
+		struct dive* d = get_dive_by_uniq_id(dives.at(i));
+		d->when += timeChanged;
+	}
+	mark_divelist_changed(true);
+	MainWindow::instance()->refreshDisplay();
+}

qt-ui/undocommands.h

@@ -14,4 +14,15 @@ private:
 	QList<struct dive*> dives;
 };
 
+class UndoShiftTime : public QUndoCommand {
+public:
+	UndoShiftTime(QList<int> diveList, int amount);
+	virtual void undo();
+	virtual void redo();
+
+private:
+	QList<int> dives;
+	int timeChanged;
+};
+
 #endif // UNDOCOMMANDS_H