/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Solutions component.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
**     of its contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

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

#if defined(Q_OS_WIN)
#include <qt_windows.h>
#include <QLibrary>

typedef BOOL (WINAPI * PProcessIdToSessionId)(DWORD, DWORD*);

static PProcessIdToSessionId pProcessIdToSessionId = 0;

#endif
#if defined(Q_OS_UNIX) || defined(Q_OS_OS2)
#include <sys/types.h>
#include <time.h>
#include <unistd.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("[^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);
}

QtLocalPeer::~QtLocalPeer() {
  if (server != nullptr) {
    server->close();
  }
}

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, nullptr);
#endif
  }

  if (!connOk) {
    return false;
  }

  QByteArray uMsg(message.toUtf8());
  QDataStream ds(&socket);

  ds.writeBytes(uMsg.constData(), uMsg.size());
  bool res = socket.waitForBytesWritten(timeout);

  if (res) {
    res &= socket.waitForReadyRead(timeout);   // wait for ack

    if (res) {
      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 %s", socket->errorString().toLatin1().constData());
    delete socket;
    return;
  }

  QString message(QString::fromUtf8(uMsg));

  socket->write(ack, qstrlen(ack));
  socket->waitForBytesWritten(1000);
  socket->waitForDisconnected(1000); // make sure client reads ack
  delete socket;
  emit messageReceived(message); //### (might take a long time to return)
}
