/*
   This file is part of the KDE libraries
   Copyright (c) 2009 Till Adam <adam@kde.org>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#include "ktimezoned_win.moc"
#include "ktimezonedbase.moc"

#include <climits>
#include <cstdlib>

#include <QStringList>
#include <QTextStream>
#include <QDBusConnection>
#include <QDBusMessage>
#include <QThread>
#include <QDebug>

#include <kglobal.h>
#include <klocale.h>
#include <kcodecs.h>
#include <kdebug.h>
#include <kconfiggroup.h>

#include <kpluginfactory.h>
#include <kpluginloader.h>

#ifdef Q_OS_WIN
#include <Windows.h>
#endif

K_PLUGIN_CLASS_WITH_JSON(KTimeZoned, "ktimezoned.json")

// Config file entry names
const char LOCAL_ZONE[]     = "LocalZone";     // name of local time zone
static const TCHAR currentTimeZoneKey[] = TEXT("System\\CurrentControlSet\\Control\\TimeZoneInformation");

class RegistryWatcherThread : public QThread
{
    public:
    RegistryWatcherThread(KTimeZoned* parent)
    :QThread(parent),q(parent)
    {
    }

    ~RegistryWatcherThread()
    {
        RegCloseKey(key);
    }

    void run()
    {
//FIXME: the timezonechange needs to be handled differently
#ifndef _WIN32
        if ( RegOpenKeyEx( HKEY_LOCAL_MACHINE, currentTimeZoneKey, 0, KEY_READ, &key ) == ERROR_SUCCESS )
        {
            while(true)
            {
                RegNotifyChangeKeyValue( key, true, REG_NOTIFY_CHANGE_LAST_SET,
                                         NULL, false /*async, we want it to block*/ );
                q->updateLocalZone();
            }
        }
#endif
    }
    private:
        KTimeZoned* q;
        HKEY key;
};

KTimeZoned::KTimeZoned(QObject* parent, const QList<QVariant>& l)
  : KTimeZonedBase(parent, l), mRegistryWatcherThread(0)
{
    init(false);
}

KTimeZoned::~KTimeZoned()
{
    if (mRegistryWatcherThread)
    {
        mRegistryWatcherThread->quit();
        mRegistryWatcherThread->wait(100);
    }
    delete mRegistryWatcherThread;
}

void KTimeZoned::init(bool restart)
{
    if (restart)
    {
        qDebug() << "KTimeZoned::init(restart)";
        delete mRegistryWatcherThread;
        mRegistryWatcherThread = 0;
    }

    KConfig config(QLatin1String("ktimezonedrc"));
    if (restart)
        config.reparseConfiguration();
    KConfigGroup group(&config, "TimeZones");
    mConfigLocalZone = group.readEntry(LOCAL_ZONE);

    updateLocalZone();
    if (!mRegistryWatcherThread)
    {
        mRegistryWatcherThread = new RegistryWatcherThread(this);
        mRegistryWatcherThread->start();
    }
}

// Check if the local zone has been updated, and if so, write the new
// zone to the config file and notify interested parties.
void KTimeZoned::updateLocalZone()
{
    // On Windows, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones
    // holds the time zone database. The TZI binary value is the TIME_ZONE_INFORMATION structure.

    TIME_ZONE_INFORMATION tzinfo;
    DWORD res =  GetTimeZoneInformation(&tzinfo);
    if (res == TIME_ZONE_ID_INVALID) return; // hm
    mLocalZone = QString::fromUtf16( reinterpret_cast<ushort*>( tzinfo.StandardName ) );

    if (mConfigLocalZone != mLocalZone)
    {
        qDebug() << "Local timezone is now: " << mLocalZone;
        KConfig config(QLatin1String("ktimezonedrc"));
        KConfigGroup group(&config, "TimeZones");
        mConfigLocalZone = mLocalZone;
        group.writeEntry(LOCAL_ZONE, mConfigLocalZone);
        group.sync();

        QDBusMessage message = QDBusMessage::createSignal("/Daemon", "org.kde.KTimeZoned", "timeZoneChanged");
        QDBusConnection::sessionBus().send(message);
    }
}