/* This file is part of the KDE project
 *
 * Copyright (C) 2000 Waldo Bastian <bastian@kde.org>
 * Copyright (C) 2007 Nick Shaforostoff <shafff@ukr.net>
 *
 * 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 "khtml_pagecache.h"

#include <kcompressiondevice.h>
#include <QTemporaryFile>

#include <QQueue>
#include <QHash>
#include <QList>
#include <QTimer>
#include <QFile>
#include <QDir>
#include <QDataStream>
#include <assert.h>

// We keep 12 pages in memory.
#ifndef KHTML_PAGE_CACHE_SIZE
#define KHTML_PAGE_CACHE_SIZE 12
#endif

template class QList<KHTMLPageCacheDelivery *>;
class KHTMLPageCacheEntry
{
    friend class KHTMLPageCache;
public:
    KHTMLPageCacheEntry(long id);

    ~KHTMLPageCacheEntry();

    void addData(const QByteArray &data);
    void endData();

    bool isComplete() const
    {
        return m_complete;
    }
    QString fileName() const
    {
        return m_fileName;
    }

    KHTMLPageCacheDelivery *fetchData(QObject *recvObj, const char *recvSlot);
private:
    long m_id;
    bool m_complete;
    QByteArray m_buffer;
    QIODevice *m_file;
    QString m_fileName;
};

class KHTMLPageCachePrivate
{
public:
    long newId;
    bool deliveryActive;
    QHash<int, KHTMLPageCacheEntry *> dict;
    QList<KHTMLPageCacheDelivery *> delivery;
    QQueue<long> expireQueue;
};

KHTMLPageCacheEntry::KHTMLPageCacheEntry(long id)
    : m_id(id)
    , m_complete(false)
{
    QTemporaryFile f(QDir::tempPath() + "/khtmlcacheXXXXXX.tmp");
    f.open();
    m_fileName = f.fileName();
    f.setAutoRemove(false);

    m_file = new KCompressionDevice(m_fileName, KCompressionDevice::GZip);
    m_file->open(QIODevice::WriteOnly);
}

KHTMLPageCacheEntry::~KHTMLPageCacheEntry()
{
    delete m_file;
    QFile::remove(m_fileName);
}

void
KHTMLPageCacheEntry::addData(const QByteArray &data)
{
    m_buffer += data;
}

void
KHTMLPageCacheEntry::endData()
{
    m_complete = true;
    m_file->write(m_buffer);
    m_buffer.clear();
    m_file->close();
}

KHTMLPageCacheDelivery *
KHTMLPageCacheEntry::fetchData(QObject *recvObj, const char *recvSlot)
{
    // Duplicate fd so that entry can be safely deleted while delivering the data.
    KCompressionDevice *dev = new KCompressionDevice(m_fileName, KCompressionDevice::GZip);
    dev->open(QIODevice::ReadOnly);
    KHTMLPageCacheDelivery *delivery = new KHTMLPageCacheDelivery(dev); // takes ownership of dev

    recvObj->connect(delivery, SIGNAL(emitData(QByteArray)), recvSlot);
    delivery->recvObj = recvObj;
    return delivery;
}

class KHTMLPageCacheSingleton
{
public:
    KHTMLPageCache instance;
};

Q_GLOBAL_STATIC(KHTMLPageCacheSingleton, _self)

KHTMLPageCache *
KHTMLPageCache::self()
{
    return &_self()->instance;
}

KHTMLPageCache::KHTMLPageCache()
    : d(new KHTMLPageCachePrivate)
{
    d->newId = 1;
    d->deliveryActive = false;
}

KHTMLPageCache::~KHTMLPageCache()
{
    qDeleteAll(d->dict);
    qDeleteAll(d->delivery);
    delete d;
}

long
KHTMLPageCache::createCacheEntry()
{

    KHTMLPageCacheEntry *entry = new KHTMLPageCacheEntry(d->newId);
    d->dict.insert(d->newId, entry);
    d->expireQueue.append(d->newId);
    if (d->expireQueue.count() > KHTML_PAGE_CACHE_SIZE) {
        delete d->dict.take(d->expireQueue.dequeue());
    }
    return (d->newId++);
}

void
KHTMLPageCache::addData(long id, const QByteArray &data)
{

    KHTMLPageCacheEntry *entry = d->dict.value(id);
    if (entry) {
        entry->addData(data);
    }
}

void
KHTMLPageCache::endData(long id)
{
    KHTMLPageCacheEntry *entry = d->dict.value(id);
    if (entry) {
        entry->endData();
    }
}

void
KHTMLPageCache::cancelEntry(long id)
{
    KHTMLPageCacheEntry *entry = d->dict.take(id);
    if (entry) {
        d->expireQueue.removeAll(entry->m_id);
        delete entry;
    }
}

bool
KHTMLPageCache::isValid(long id)
{
    return d->dict.contains(id);
}

bool
KHTMLPageCache::isComplete(long id)
{
    KHTMLPageCacheEntry *entry = d->dict.value(id);
    if (entry) {
        return entry->isComplete();
    }
    return false;
}

void
KHTMLPageCache::fetchData(long id, QObject *recvObj, const char *recvSlot)
{
    KHTMLPageCacheEntry *entry = d->dict.value(id);
    if (!entry || !entry->isComplete()) {
        return;
    }

    // Make this entry the most recent entry.
    d->expireQueue.removeAll(entry->m_id);
    d->expireQueue.enqueue(entry->m_id);

    d->delivery.append(entry->fetchData(recvObj, recvSlot));
    if (!d->deliveryActive) {
        d->deliveryActive = true;
        QTimer::singleShot(20, this, SLOT(sendData()));
    }
}

void
KHTMLPageCache::cancelFetch(QObject *recvObj)
{
    QMutableListIterator<KHTMLPageCacheDelivery *> it(d->delivery);
    while (it.hasNext()) {
        KHTMLPageCacheDelivery *delivery = it.next();
        if (delivery->recvObj == recvObj) {
            delete delivery;
            it.remove();
        }
    }
}

void
KHTMLPageCache::sendData()
{
    if (d->delivery.isEmpty()) {
        d->deliveryActive = false;
        return;
    }

    KHTMLPageCacheDelivery *delivery = d->delivery.takeFirst();
    assert(delivery);

    QByteArray byteArray(delivery->file->read(64 * 1024));
    delivery->emitData(byteArray);

    //put back in queue
    if (delivery->file->atEnd()) {
        // done.
        delivery->file->close();
        delivery->emitData(QByteArray()); // Empty array
        delete delivery;
    } else {
        d->delivery.append(delivery);
    }

    QTimer::singleShot(0, this, SLOT(sendData()));
}

void
KHTMLPageCache::saveData(long id, QDataStream *str)
{
    assert(d->dict.contains(id));
    KHTMLPageCacheEntry *entry = d->dict.value(id);

    if (!entry->isComplete()) {
        QTimer::singleShot(20, this, SLOT(saveData()));
        return;
    }

    KCompressionDevice file(entry->fileName(), KCompressionDevice::GZip);
    if (!file.open(QIODevice::ReadOnly)) {
        return;
    }

    const QByteArray byteArray(file.readAll());
    file.close();

    str->writeRawData(byteArray.constData(), byteArray.length());

}

KHTMLPageCacheDelivery::~KHTMLPageCacheDelivery()
{
    file->close();
    delete file;
}

