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module autosaver;


import qt.core.QObject;
import qt.core.QBasicTimer;
import qt.core.QTime;
import qt.core.QDir;
import qt.core.QCoreApplication;
//import qt.core.QMetaObject;

//import QtDebug;


const uint AUTOSAVE_IN  = 1000 * 3;  // seconds
const uint MAXWAIT = 1000 * 15; // seconds


/*
This class will call the save() slot on the parent object when the parent changes.
It will wait several seconds after changed() to combining multiple changes and
prevent continuous writing to disk.
*/

class AutoSaver : public QObject {

public:

	this(QObject parent)
	{
		super(parent);
		assert(parent);
	}
	
	~this()
	{
		if (m_timer.isActive())
			qWarning("AutoSaver: still active when destroyed, changes not saved.");
	}
	
	void saveIfNeccessary()
	{
		if (!m_timer.isActive())
			return;
		m_timer.stop();
		m_firstChange = new QTime();
		
		//TODO!
		//if (!QMetaObject.invokeMethod(parent(), "save", Qt.DirectConnection)) {
		//	qWarning("AutoSaver: error invoking slot save() on parent");
		//}
	}

public:

	void changeOccurred()
	{
		if (m_firstChange.isNull())
			m_firstChange.start();

		if (m_firstChange.elapsed() > MAXWAIT) {
			saveIfNeccessary();
		} else {
			m_timer.start(AUTOSAVE_IN, this);
		}
	}

protected:

	void timerEvent(QTimerEvent event)
	{
		if (event.timerId() == m_timer.timerId()) {
			saveIfNeccessary();
		} else {
			super.timerEvent(event);
		}
	}

private:

	QBasicTimer m_timer;
	QTime m_firstChange;
}