/*  This file is part of the KDE libraries
 *  Copyright (C) 1999-2000 Waldo Bastian <bastian@kde.org>
 *  Copyright (C) 2005-2009 David Faure <faure@kde.org>
 *  Copyright (C) 2008 Hamish Rodda <rodda@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 version 2 as published by the Free Software Foundation;
 *
 *  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 "ksycoca.h"
#include "ksycoca_p.h"
#include "ksycocatype.h"
#include "ksycocafactory.h"
#include "kglobal.h"
#include "kde_file.h"
#include "kconfiggroup.h"
#include "ksharedconfig.h"
#include "kdebug.h"
#include "kstandarddirs.h"

#include <QtCore/QDataStream>
#include <QtCore/QCoreApplication>
#include <QtCore/QFile>
#include <QtCore/QBuffer>
#include <QProcess>
#include <QtDBus/QtDBus>
#include <QtCore/qthread.h>

#include <config.h>

#include <stdlib.h>
#include <fcntl.h>

#include "ksycocadevices_p.h"

static bool s_autoRebuild = true;

// The following limitations are in place:
// Maximum length of a single string: 8192 bytes
// Maximum length of a string list: 1024 strings
// Maximum number of entries: 8192
//
// The purpose of these limitations is to limit the impact
// of database corruption.

Q_DECLARE_OPERATORS_FOR_FLAGS(KSycocaPrivate::BehaviorsIfNotFound)

KSycocaPrivate::KSycocaPrivate()
    : databaseStatus(DatabaseNotOpen),
      readError(false),
      timeStamp(0),
      m_databasePath(),
      updateSig(0),
      m_device(0)
{
    m_sycocaStrategy = StrategyFile;
    KConfigGroup config(KGlobal::config(), "KSycoca");
    setStrategyFromString(config.readEntry("strategy"));
}

void KSycocaPrivate::setStrategyFromString(const QString& strategy) {
    if (strategy == QLatin1String("file")) {
        m_sycocaStrategy = StrategyFile;
    } else if (!strategy.isEmpty()) {
        kWarning(7011) << "Unknown sycoca strategy:" << strategy;
    }
}

int KSycoca::version()
{
    return KSYCOCA_VERSION;
}

class KSycocaSingleton
{
public:
    KSycocaSingleton() { }
    ~KSycocaSingleton()
    {
        if (m_threadSycocas) {
            delete m_threadSycocas;
            m_threadSycocas = 0;
        }
    }

    bool hasSycoca() const {
        return (m_threadSycocas != 0);
    }
    KSycoca* sycoca() {
        if (!m_threadSycocas) {
            m_threadSycocas = new KSycoca();
        }
        return m_threadSycocas;
    }
    void setSycoca(KSycoca* s) {
        m_threadSycocas = s;
    }

private:
    static thread_local KSycoca* m_threadSycocas;
};
thread_local KSycoca* KSycocaSingleton::m_threadSycocas = 0;

K_GLOBAL_STATIC(KSycocaSingleton, ksycocaInstance)

// Read-only constructor
KSycoca::KSycoca()
    : d(new KSycocaPrivate())
{
    QDBusConnection::sessionBus().connect(
        QString(), QString(),
        QString::fromLatin1("org.kde.KSycoca"),
        QString::fromLatin1("notifyDatabaseChanged"),
        this, SLOT(notifyDatabaseChanged(QStringList))
    );
}

bool KSycocaPrivate::openDatabase(bool openDummyIfNotFound)
{
    Q_ASSERT(databaseStatus == DatabaseNotOpen);

    delete m_device; m_device = 0;
    QString path = KSycoca::absoluteFilePath();

    bool canRead = KDE::access(path, R_OK) == 0;
    kDebug(7011) << "Trying to open ksycoca from" << path;
    if (!canRead) {
        path = KSycoca::absoluteFilePath(KSycoca::GlobalDatabase);
        if (!path.isEmpty()) {
            kDebug(7011) << "Trying to open global ksycoca from " << path;
            canRead = KDE::access(path, R_OK) == 0;
        }
    }

    bool result = true;
    if (canRead) {
        m_databasePath = path;
        checkVersion();
    } else { // No database file
        kDebug(7011) << "Could not open ksycoca";
        m_databasePath.clear();
        databaseStatus = NoDatabase;
        if (openDummyIfNotFound) {
            // We open a dummy database instead.
            //kDebug(7011) << "No database, opening a dummy one.";

            m_sycocaStrategy = StrategyDummyBuffer;
            (void)stream();
        } else {
            result = false;
        }
    }
    return result;
}

KSycocaAbstractDevice* KSycocaPrivate::device()
{
    if (m_device) {
        return m_device;
    }

    Q_ASSERT(!m_databasePath.isEmpty());

    KSycocaAbstractDevice* device = m_device;
    if (m_sycocaStrategy == StrategyDummyBuffer) {
        device = new KSycocaBufferDevice();
    } else {
        if (!device) {
            device = new KSycocaFileDevice(m_databasePath);
            if (!device->device()->open(QIODevice::ReadOnly)) {
                kError(7011) << "Couldn't open" << m_databasePath << "even though it is readable? Impossible.";
                //delete device; device = 0; // this would crash in the return statement...
            }
        }
    }
    if (device) {
        m_device = device;
    }
    return m_device;
}

QDataStream*& KSycocaPrivate::stream()
{
    if (!m_device) {
        if (databaseStatus == DatabaseNotOpen) {
            checkDatabase(KSycocaPrivate::IfNotFoundRecreate | KSycocaPrivate::IfNotFoundOpenDummy);
        }

        device(); // create m_device
    }

    return m_device->stream();
}

// Read-write constructor - only for KBuildSycoca
KSycoca::KSycoca(bool /* dummy */)
    : d(new KSycocaPrivate)
{
    // This instance was not created by the singleton, but by a direct call to new!
    ksycocaInstance->setSycoca(this);
}

KSycoca* KSycoca::self()
{
    KSycoca* s = ksycocaInstance->sycoca();
    Q_ASSERT(s);
    return s;
}

KSycoca::~KSycoca()
{
    d->closeDatabase();
    delete d;
    //if (ksycocaInstance.exists()
    //    && ksycocaInstance->self == this)
    //    ksycocaInstance->self = 0;
}

bool KSycoca::isAvailable()
{
    return self()->d->checkDatabase(KSycocaPrivate::IfNotFoundDoNothing/* don't open dummy db if not found */);
}

void KSycocaPrivate::closeDatabase()
{
    delete m_device;
    m_device = 0;

    // It is very important to delete all factories here
    // since they cache information about the database file
    // But other threads might be using them, so this class is
    // refcounted, and deleted when the last thread is done with them
    qDeleteAll(m_factories);
    m_factories.clear();

    databaseStatus = DatabaseNotOpen;
    timeStamp = 0;
}

void KSycoca::addFactory(KSycocaFactory *factory)
{
    d->addFactory(factory);
}

void KSycoca::notifyDatabaseChanged(const QStringList &changeList)
{
    d->changeList = changeList;
    //kDebug(7011) << QThread::currentThread() << "got a notifyDatabaseChanged signal" << changeList;
    // kbuildsycoca tells us the database file changed
    // Close the database and forget all about what we knew
    // The next call to any public method will recreate
    // everything that's needed.
    d->closeDatabase();

    // Now notify applications
    emit databaseChanged(changeList);
}

QDataStream * KSycoca::findEntry(int offset, KSycocaType &type)
{
    QDataStream* str = stream();
    Q_ASSERT(str);
    //kDebug(7011) << QString("KSycoca::_findEntry(offset=%1)").arg(offset,8,16);
    str->device()->seek(offset);
    qint32 aType;
    *str >> aType;
    type = KSycocaType(aType);
    //kDebug(7011) << QString("KSycoca::found type %1").arg(aType);
    return str;
}

KSycocaFactoryList* KSycoca::factories()
{
    return d->factories();
}

// Warning, checkVersion rewinds to the beginning of stream().
bool KSycocaPrivate::checkVersion()
{
    QDataStream *m_str = device()->stream();
    Q_ASSERT(m_str);
    m_str->device()->seek(0);
    qint32 aVersion = 0;
    *m_str >> aVersion;
    if (aVersion < KSYCOCA_VERSION) {
        kWarning(7011) << "Found version" << aVersion << ", expecting version" << KSYCOCA_VERSION << "or higher.";
        databaseStatus = BadVersion;
        return false;
    }
    databaseStatus = DatabaseOK;
    return true;
}

// If it returns true, the database is valid and the stream has rewinded to the beginning
// and past the version number.
bool KSycocaPrivate::checkDatabase(BehaviorsIfNotFound ifNotFound)
{
    if (databaseStatus == DatabaseOK) {
        if (checkVersion()) {
            // the version is ok, but must rewind the stream anyway
            return true;
        }
    }

    closeDatabase(); // close the dummy one

    // Check if new database already available
    if (openDatabase(ifNotFound & IfNotFoundOpenDummy)) {
        if (checkVersion()) {
            // Database exists, and version is ok.
            return true;
        }
    }

    if (ifNotFound & IfNotFoundRecreate) {
        // We simply need to run kbuildsycoca to recreate the sycoca file.
        kDebug(7011) << QThread::currentThread() << "We have no database.... launching" << KBUILDSYCOCA_EXENAME;
        if (QProcess::execute(KStandardDirs::findExe(QString::fromLatin1(KBUILDSYCOCA_EXENAME))) != 0) {
            kWarning(7011) << "Running KSycoca failed.";
        }

        closeDatabase(); // close the dummy one

        // Ok, the new database should be here now, open it.
        if (!openDatabase(ifNotFound & IfNotFoundOpenDummy)) {
            kDebug(7011) << "Still no database...";
            return false; // Still no database - uh oh
        }
        if (!checkVersion()) {
            kDebug(7011) << "Still outdated...";
            return false; // Still outdated - uh oh
        }

        // If kded is not running we need to launch it as it monitors for changes
        static const QString kdedInterface = QString::fromLatin1("org.kde.kded");
        QDBusConnectionInterface* sessionInterface = QDBusConnection::sessionBus().interface();
        const bool kdedRunning = sessionInterface->isServiceRegistered(kdedInterface);
        if (!kdedRunning) {
            kDebug(7011) << "Launching kded";
            sessionInterface->startService(kdedInterface);
        }

        return true;
    }

    return false;
}

QDataStream * KSycoca::findFactory(KSycocaFactoryId id)
{
    // Ensure we have a valid database (right version, and rewinded to beginning)
    if (!d->checkDatabase(KSycocaPrivate::IfNotFoundRecreate)) {
        return 0;
    }

    QDataStream* str = stream();
    Q_ASSERT(str);

    qint32 aId;
    qint32 aOffset;
    while (true) {
        *str >> aId;
        if (aId == 0) {
            kError(7011) << "Error, KSycocaFactory (id =" << int(id) << ") not found!";
            break;
        }
        *str >> aOffset;
        if (aId == id) {
            //kDebug(7011) << "KSycoca::findFactory(" << id << ") offset " << aOffset;
            str->device()->seek(aOffset);
            return str;
        }
    }
    return 0;
}

QString KSycoca::kfsstnd_prefixes()
{
    // do not try to launch kbuildsycoca from here; this code is also called by kbuildsycoca.
    if (!d->checkDatabase(KSycocaPrivate::IfNotFoundDoNothing)) {
        return QString();
    }
    QDataStream* str = stream();
    Q_ASSERT(str);
    qint32 aId;
    qint32 aOffset;
    // skip factories offsets
    while(true)
    {
        *str >> aId;
        if (aId) {
            *str >> aOffset;
        } else {
            // just read 0
            break;
        }
    }
    // We now point to the header
    QString prefixes;
    KSycocaEntry::read(*str, prefixes);
    *str >> d->timeStamp;
    KSycocaEntry::read(*str, d->language);
    *str >> d->updateSig;
    KSycocaEntry::read(*str, d->allResourceDirs);
    return prefixes;
}

quint32 KSycoca::timeStamp()
{
    if (!d->timeStamp) {
        (void) kfsstnd_prefixes();
    }
    return d->timeStamp;
}

quint32 KSycoca::updateSignature()
{
    if (!d->timeStamp) {
        (void) kfsstnd_prefixes();
    }
    return d->updateSig;
}

QString KSycoca::absoluteFilePath(DatabaseType type)
{
    if (type == GlobalDatabase) {
        QString path = KGlobal::dirs()->findResource("services", QString::fromLatin1(KSYCOCA_FILENAME));
        if (path.isEmpty())
            return KGlobal::dirs()->saveLocation("services") + QString::fromLatin1(KSYCOCA_FILENAME);
        return path;
    }

    return KGlobal::dirs()->saveLocation("cache") + QString::fromLatin1(KSYCOCA_FILENAME);
}

QString KSycoca::language()
{
    if (d->language.isEmpty()) {
        (void) kfsstnd_prefixes();
    }
    return d->language;
}

QStringList KSycoca::allResourceDirs()
{
    if (!d->timeStamp) {
        (void) kfsstnd_prefixes();
    }
    return d->allResourceDirs;
}

void KSycoca::flagError()
{
    kWarning(7011) << "KSycoca database corruption!";
    KSycocaPrivate* d = ksycocaInstance->sycoca()->d;
    if (d->readError) {
        return;
    }
    d->readError = true;
    if (s_autoRebuild) {
        // Rebuild the damned thing.
        if (QProcess::execute(KStandardDirs::findExe(QString::fromLatin1(KBUILDSYCOCA_EXENAME))) != 0) {
            kWarning(7011) << "Running KSycoca failed.";
        }
        // Old comment, maybe not true anymore:
        // Do not wait until the DBUS signal from kbuildsycoca here.
        // It deletes m_str which is a problem when flagError is called during the KSycocaFactory ctor...
    }
}


bool KSycoca::isBuilding()
{
    return false;
}

void KSycoca::disableAutoRebuild()
{
    s_autoRebuild = false;
}

QDataStream*& KSycoca::stream()
{
    return d->stream();
}

void KSycoca::clearCaches()
{
    if (ksycocaInstance.exists() && ksycocaInstance->hasSycoca()) {
        ksycocaInstance->sycoca()->d->closeDatabase();
    }
}

#include "moc_ksycoca.cpp"