/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the examples of the Qt Mobility Components.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
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** 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.
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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****************************************************************************/

#include "thumbnailcache.h"

#include "thumbnailmodel.h"

#include <QtCore/qcryptographichash.h>
#include <QtCore/qcoreapplication.h>
#include <QtCore/qcoreevent.h>
#include <QtCore/qdir.h>
#include <QtCore/qurl.h>
#include <QtGui/qimagereader.h>
#include <QtGui/qpixmap.h>

#if (QT_VERSION < QT_VERSION_CHECK(4, 7, 0))
uint qHash(const QUrl &url) { return qHash(url.toString()); }
#endif

class Thumbnail
{
public:
    Thumbnail(const QUrl &url)
        : url(url)
    {
    }

    const QUrl url;
    QPixmap pixmap;

private:
    ThumbnailCache *cache;
};

class ThumbnailEvent : public QEvent
{
public:
    ThumbnailEvent(const QUrl &url, const QImage &image)
        : QEvent(QEvent::User)
        , url(url)
        , image(image)
    {
    }

    const QUrl url;
    const QImage image;
};

ThumbnailCache::ThumbnailCache(QObject *parent)
    : QThread(parent)
#if defined(Q_OS_SYMBIAN) || defined(Q_WS_MAEMO_5) || defined(Q_WS_MAEMO_6)
    , cache(25)
#else
    , cache(150)
#endif
    , cancelled(false)
{
    start(QThread::LowestPriority);
}

ThumbnailCache::~ThumbnailCache()
{
    {
        QMutexLocker locker(&mutex);

        cancelled = true;

        waitCondition.wakeOne();
    }
    wait();
}

QPixmap ThumbnailCache::thumbnail(const QUrl &url)
{
    QMutexLocker locker(&mutex);

    if (Thumbnail *thumbnail = cache.object(url)) {
        return thumbnail->pixmap;
    } else {
        pendingUrls.enqueue(url);

        cache.insert(url, new Thumbnail(url));

        waitCondition.wakeOne();

        return QPixmap();
    }
}

bool ThumbnailCache::event(QEvent *event)
{
    if (event->type() == QEvent::User) {
        ThumbnailEvent *thumbnailEvent = static_cast<ThumbnailEvent *>(event);

        QMutexLocker locker(&mutex);

        if (Thumbnail *thumbnail = cache.object(thumbnailEvent->url)) {
            thumbnail->pixmap = QPixmap::fromImage(thumbnailEvent->image);

            locker.unlock();

            emit thumbnailReady();
        }
        return true;
    } else {
        return QThread::event(event);
    }
}

void ThumbnailCache::run()
{
    QMutexLocker locker(&mutex);

    while(!cancelled) {
        if (!pendingUrls.isEmpty()) {
            const QUrl url = pendingUrls.dequeue();

            if (cache.contains(url)) {
                locker.unlock();
                QImage image = loadImage(url);
                locker.relock();

                if (!image.isNull())
                    QCoreApplication::postEvent(this, new ThumbnailEvent(url, image));
            }
        } else {
            waitCondition.wait(&mutex);
        }
    }
}

QImage ThumbnailCache::loadImage(const QUrl &url) const
{
    const QString fileName = thumbnailPath(url);

    QImageReader reader(fileName);
    reader.setQuality(25);

    if (reader.supportsOption(QImageIOHandler::Size)) {
        QSize size = reader.size();

        if (!reader.supportsOption(QImageIOHandler::ScaledSize)
                && (size.width() > 1280 || size.height() > 1280)) {
            return QImage();
        }

        if (size.width() > ThumbnailModel::thumbnailSize.width()
                || size.height() > ThumbnailModel::thumbnailSize.height()) {
            size.scale(ThumbnailModel::thumbnailSize, Qt::KeepAspectRatio);
        }

        reader.setScaledSize(size);
    } else {
        reader.setScaledSize(ThumbnailModel::thumbnailSize);
    }

    return reader.read();
}

QString ThumbnailCache::thumbnailPath(const QUrl &url) const
{
#if defined(Q_OS_UNIX) && !(defined(Q_OS_SYMBIAN) || defined(Q_OS_MAC))
#if defined(Q_WS_MAEMO_5)
    QString thumbnailPath = QDir::homePath()
            + QLatin1String("/.thumbnails/cropped/")
            + QCryptographicHash::hash(url.toString().toUtf8(), QCryptographicHash::Md5).toHex()
            + QLatin1String(".jpeg");
#elif defined(Q_WS_MAEMO_6)
    QString thumbnailPath = QDir::homePath()
            + QLatin1String("/.thumbnails/grid/")
            + QCryptographicHash::hash(url.toString().toUtf8(), QCryptographicHash::Md5).toHex()
            + QLatin1String(".jpeg");
#else
    QString thumbnailPath = QDir::homePath()
            + QLatin1String("/.thumbnails/normal/")
            + QCryptographicHash::hash(url.toEncoded(), QCryptographicHash::Md5).toHex()
            + QLatin1String(".png");
#endif
    if (QFile::exists(thumbnailPath))
        return thumbnailPath;
#endif

    return url.toLocalFile();
}