/*
    Copyright (C) 2017 Aseman Team
    http://aseman.co

    AsemanQtTools is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    AsemanQtTools is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/****************************************************************************
**
** This file is part of a Qt Solutions component.
** 
** Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
** 
** Contact:  Qt Software Information (qt-info@nokia.com)
** 
** Commercial Usage  
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Solutions Commercial License Agreement provided
** with the Software or, alternatively, in accordance with the terms
** contained in a written agreement between you and Nokia.
** 
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
** 
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
** 
** GNU General Public License Usage 
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
** 
** Please note Third Party Software included with Qt Solutions may impose
** additional restrictions and it is the user's responsibility to ensure
** that they have met the licensing requirements of the GPL, LGPL, or Qt
** Solutions Commercial license and the relevant license of the Third
** Party Software they are using.
** 
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.
** 
****************************************************************************/


#include "qtlocalpeer.h"
#include <QtCore/QCoreApplication>
#include <QtCore/QTime>
#include <QDataStream>
#include <QRegularExpression>

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

namespace QtLP_Private {
#include "qtlockedfile.cpp"
#if defined(Q_OS_WIN)
#include "qtlockedfile_win.cpp"
#else
#include "qtlockedfile_unix.cpp"
#endif
}

const char* QtLocalPeer::ack = "ack";

QtLocalPeer::QtLocalPeer(QObject* parent, const QString &appId)
    : QObject(parent), id(appId)
{
    QString prefix = id;
    if (id.isEmpty()) {
        id = QCoreApplication::applicationFilePath();
#if defined(Q_OS_WIN)
        id = id.toLower();
#endif
        prefix = id.section(QLatin1Char('/'), -1);
    }
    prefix.remove(QRegularExpression(QStringLiteral("[^a-zA-Z]")));
    prefix.truncate(6);

    QByteArray idc = id.toUtf8();
    quint16 idNum = qChecksum(idc.constData(), idc.size());
    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

    server = new QLocalServer(this);
    QString lockName = QDir(QDir::tempPath()).absolutePath()
                       + QLatin1Char('/') + socketName
                       + QLatin1String("-lockfile");
    lockFile.setFileName(lockName);
    lockFile.open(QIODevice::ReadWrite);
}



bool QtLocalPeer::isClient()
{
    if (lockFile.isLocked())
        return false;

    if (!lockFile.lock(QtLP_Private::QtLockedFile::WriteLock, false))
        return true;

    bool res = server->listen(socketName);
#if defined(Q_OS_UNIX) && (QT_VERSION >= QT_VERSION_CHECK(4,5,0))
    // ### 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, &QLocalServer::newConnection, this, &QtLocalPeer::receiveConnection);
    return false;
}


bool QtLocalPeer::sendMessage(const QString &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;
        int ms = 250;
#if defined(Q_OS_WIN)
        Sleep(DWORD(ms));
#else
        struct timespec ts = { ms / 1000, (ms % 1000) * 1000 * 1000 };
        nanosleep(&ts, NULL);
#endif
    }
    if (!connOk)
        return false;

    QByteArray uMsg(message.toUtf8());
    QDataStream ds(&socket);
    ds.writeBytes(uMsg.constData(), uMsg.size());
    bool res = socket.waitForBytesWritten(timeout);
    res &= socket.waitForReadyRead(timeout);   // wait for ack
    res &= (socket.read(qstrlen(ack)) == ack);
    return res;
}


void QtLocalPeer::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" << socket->errorString();
        delete socket;
        return;
    }
    QString message(QString::fromUtf8(uMsg));
    socket->write(ack, qstrlen(ack));
    socket->waitForBytesWritten(1000);
    delete socket;
    Q_EMIT messageReceived(message); //### (might take a long time to return)
}
