// This simple but useful code is from
// http://www.qtcentre.org/wiki/index.php?title=SingleApplication

#include <QTimer>
#include <QByteArray>

#include "single_application.h"

SingleApplication::SingleApplication(int &argc, char *argv[], const QString uniqueKey) : QApplication(argc, argv)
{
	sharedMemory.setKey(uniqueKey);
	if (sharedMemory.attach())
		_isRunning = true;
	else
	{
		_isRunning = false;
		// attach data to shared memory.
		QByteArray byteArray("0"); // default value to note that no message is available.
		if (!sharedMemory.create(byteArray.size()))
		{
			qDebug("Unable to create single instance.");
			return;
		}
		sharedMemory.lock();
		char *to = (char*)sharedMemory.data();
		const char *from = byteArray.data();
		memcpy(to, from, qMin(sharedMemory.size(), byteArray.size()));
		sharedMemory.unlock();
		// start checking for messages of other instances.
		QTimer *timer = new QTimer(this);
		connect(timer, SIGNAL(timeout()), this, SLOT(checkForMessage()));
		timer->start(500);
	}
}

// public slots.

void SingleApplication::checkForMessage()
{
	sharedMemory.lock();
	QByteArray byteArray = QByteArray((char*)sharedMemory.constData(), sharedMemory.size());
	sharedMemory.unlock();
	if (byteArray.left(1) == "0")
		return;
	byteArray.remove(0, 1);
	QString message = QString::fromUtf8(byteArray.constData());
	emit messageAvailable(message);
	// remove message from shared memory.
	byteArray = "0";
	sharedMemory.lock();
	char *to = (char*)sharedMemory.data();
	const char *from = byteArray.data();
	memcpy(to, from, qMin(sharedMemory.size(), byteArray.size()));
	sharedMemory.unlock();
}

// public functions.

bool SingleApplication::isRunning()
{
	return _isRunning;
}

bool SingleApplication::sendMessage(const QString &message)
{
	if (!_isRunning)
		return false;
	QByteArray byteArray("1");
	byteArray.append(message.toUtf8());
	byteArray.append('\0'); // < should be as char here, not a string!
	sharedMemory.lock();
	char *to = (char*)sharedMemory.data();
	const char *from = byteArray.data();
	memcpy(to, from, qMin(sharedMemory.size(), byteArray.size()));
	sharedMemory.unlock();
	return true;
}