/****************************************************************************
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** This file is part of the Qt Solutions component.
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** modification, are permitted provided that the following conditions are
** met:
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**     notice, this list of conditions and the following disclaimer.
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**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
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#include "LocalPeer.h"
#include <QCoreApplication>
#include <QDataStream>
#include <QTime>
#include <QLocalServer>
#include <QLocalSocket>
#include <QDir>
#include "LockedFile.h"

#if defined(Q_OS_WIN)
#include <QLibrary>
#include <qt_windows.h>
typedef BOOL(WINAPI* PProcessIdToSessionId)(DWORD, DWORD*);
static PProcessIdToSessionId pProcessIdToSessionId = 0;
#endif
#if defined(Q_OS_UNIX)
#include <sys/types.h>
#include <unistd.h>
#endif

#include <chrono>
#include <thread>
#include <QCryptographicHash>
#include <QRegularExpression>

static const char* ack = "ack";

ApplicationId ApplicationId::fromTraditionalApp()
{
	QString protoId = QCoreApplication::applicationFilePath();
#if defined(Q_OS_WIN)
	protoId = protoId.toLower();
#endif
	auto prefix = protoId.section(QLatin1Char('/'), -1);
	prefix.remove(QRegularExpression("[^a-zA-Z]"));
	prefix.truncate(6);
	QByteArray idc = protoId.toUtf8();
	quint16 idNum = qChecksum(idc.constData(), idc.size());
	auto socketName = QLatin1String("qtsingleapp-") + prefix +
					  QLatin1Char('-') + QString::number(idNum, 16);
#if defined(Q_OS_WIN)
	if (!pProcessIdToSessionId) {
		QLibrary lib("kernel32");
		pProcessIdToSessionId =
			(PProcessIdToSessionId)lib.resolve("ProcessIdToSessionId");
	}
	if (pProcessIdToSessionId) {
		DWORD sessionId = 0;
		pProcessIdToSessionId(GetCurrentProcessId(), &sessionId);
		socketName += QLatin1Char('-') + QString::number(sessionId, 16);
	}
#else
	socketName += QLatin1Char('-') + QString::number(::getuid(), 16);
#endif
	return ApplicationId(socketName);
}

ApplicationId ApplicationId::fromPathAndVersion(const QString& dataPath,
												const QString& version)
{
	QCryptographicHash shasum(QCryptographicHash::Algorithm::Sha1);
	QString result = dataPath + QLatin1Char('-') + version;
	shasum.addData(result.toUtf8());
	return ApplicationId(QLatin1String("qtsingleapp-") +
						 QString::fromLatin1(shasum.result().toHex()));
}

ApplicationId ApplicationId::fromCustomId(const QString& id)
{
	return ApplicationId(QLatin1String("qtsingleapp-") + id);
}

ApplicationId ApplicationId::fromRawString(const QString& id)
{
	return ApplicationId(id);
}

LocalPeer::LocalPeer(QObject* parent, const ApplicationId& appId)
	: QObject(parent), id(appId)
{
	socketName = id.toString();
	server.reset(new QLocalServer());
	QString lockName = QDir(QDir::tempPath()).absolutePath() +
					   QLatin1Char('/') + socketName +
					   QLatin1String("-lockfile");
	lockFile.reset(new LockedFile(lockName));
	lockFile->open(QIODevice::ReadWrite);
}

LocalPeer::~LocalPeer() {}

ApplicationId LocalPeer::applicationId() const
{
	return id;
}

bool LocalPeer::isClient()
{
	if (lockFile->isLocked())
		return false;

	if (!lockFile->lock(LockedFile::WriteLock, false))
		return true;

	bool res = server->listen(socketName);
#if defined(Q_OS_UNIX)
	// ### Workaround
	if (!res && server->serverError() == QAbstractSocket::AddressInUseError) {
		QFile::remove(QDir::cleanPath(QDir::tempPath()) + QLatin1Char('/') +
					  socketName);
		res = server->listen(socketName);
	}
#endif
	if (!res)
		qWarning("QtSingleCoreApplication: listen on local socket failed, %s",
				 qPrintable(server->errorString()));
	QObject::connect(server.get(), &QLocalServer::newConnection, this,
					 &LocalPeer::receiveConnection);
	return false;
}

bool LocalPeer::sendMessage(const QByteArray& message, int timeout)
{
	if (!isClient())
		return false;

	QLocalSocket socket;
	bool connOk = false;
	for (int i = 0; i < 2; i++) {
		// Try twice, in case the other instance is just starting up
		socket.connectToServer(socketName);
		connOk = socket.waitForConnected(timeout / 2);
		if (connOk || i) {
			break;
		}
		std::this_thread::sleep_for(std::chrono::milliseconds(250));
	}
	if (!connOk) {
		return false;
	}

	QByteArray uMsg(message);
	QDataStream ds(&socket);

	ds.writeBytes(uMsg.constData(), uMsg.size());
	if (!socket.waitForBytesWritten(timeout)) {
		return false;
	}

	// wait for 'ack'
	if (!socket.waitForReadyRead(timeout)) {
		return false;
	}

	// make sure we got 'ack'
	if (!(socket.read(qstrlen(ack)) == ack)) {
		return false;
	}
	return true;
}

void LocalPeer::receiveConnection()
{
	QLocalSocket* socket = server->nextPendingConnection();
	if (!socket) {
		return;
	}

	while (socket->bytesAvailable() < (int)sizeof(quint32)) {
		socket->waitForReadyRead();
	}
	QDataStream ds(socket);
	QByteArray uMsg;
	quint32 remaining;
	ds >> remaining;
	uMsg.resize(remaining);
	int got = 0;
	char* uMsgBuf = uMsg.data();
	do {
		got = ds.readRawData(uMsgBuf, remaining);
		remaining -= got;
		uMsgBuf += got;
	} while (remaining && got >= 0 && socket->waitForReadyRead(2000));
	if (got < 0) {
		qWarning("QtLocalPeer: Message reception failed %s",
				 socket->errorString().toLatin1().constData());
		delete socket;
		return;
	}
	socket->write(ack, qstrlen(ack));
	socket->waitForBytesWritten(1000);
	socket->waitForDisconnected(1000); // make sure client reads ack
	delete socket;
	emit messageReceived(uMsg); // ### (might take a long time to return)
}
