/*
Gwenview: an image viewer
Copyright 2007 Aurélien Gâteau <agateau@kde.org>

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

This program 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

*/
#include "document.moc"

// Qt
#include <QApplication>
#include <QImage>
#include <QQueue>
#include <QUndoStack>

// KDE
#include <KDebug>
#include <KFileItem>
#include <KJobUiDelegate>
#include <KLocale>
#include <KUrl>

// Local
#include "documentjob.h"
#include "emptydocumentimpl.h"
#include "imagemetainfomodel.h"
#include "loadingdocumentimpl.h"
#include "loadingjob.h"
#include "savejob.h"

namespace Gwenview
{

struct DocumentPrivate
{
    AbstractDocumentImpl* mImpl;
    KUrl mUrl;
    bool mKeepRawData;
    QQueue<DocumentJob*> mJobQueue;

    /**
     * @defgroup imagedata should be reset in reload()
     * @{
     */
    QSize mSize;
    QImage mImage;
    QMap<int, QImage> mDownSampledImageMap;
    Exiv2::Image::AutoPtr mExiv2Image;
    MimeTypeUtils::Kind mKind;
    QByteArray mFormat;
    ImageMetaInfoModel mImageMetaInfoModel;
    QUndoStack mUndoStack;
    QString mErrorString;
    /** @} */

    void scheduleImageLoading(int invertedZoom)
    {
        LoadingDocumentImpl* impl = qobject_cast<LoadingDocumentImpl*>(mImpl);
        Q_ASSERT(impl);
        impl->loadImage(invertedZoom);
    }
};

qreal Document::maxDownSampledZoom()
{
    return 0.5;
}

Document::Document(const KUrl& url)
: QObject()
, d(new DocumentPrivate)
{
    d->mImpl = 0;
    d->mUrl = url;
    d->mKeepRawData = false;
    connect(&d->mUndoStack, SIGNAL(indexChanged(int)), SLOT(slotUndoIndexChanged()));

    reload();
}

Document::~Document()
{
    // We do not want undo stack to emit signals, forcing us to emit signals
    // ourself while we are being destroyed.
    disconnect(&d->mUndoStack, 0, this, 0);

    delete d->mImpl;
    delete d;
}

void Document::reload()
{
    d->mSize = QSize();
    d->mImage = QImage();
    d->mDownSampledImageMap.clear();
    d->mExiv2Image.reset();
    d->mKind = MimeTypeUtils::KIND_UNKNOWN;
    d->mFormat = QByteArray();
    d->mImageMetaInfoModel.setUrl(d->mUrl);
    d->mUndoStack.clear();
    d->mErrorString.clear();

    switchToImpl(new LoadingDocumentImpl(this));
}

const QImage& Document::image() const
{
    return d->mImage;
}

/**
 * invertedZoom is the biggest power of 2 for which zoom < 1/invertedZoom.
 * Example:
 * zoom = 0.4 == 1/2.5 => invertedZoom = 2 (1/2.5 < 1/2)
 * zoom = 0.2 == 1/5   => invertedZoom = 4 (1/5   < 1/4)
 */
inline int invertedZoomForZoom(qreal zoom)
{
    int invertedZoom;
    for (invertedZoom = 1; zoom < 1. / (invertedZoom * 2); invertedZoom *= 2) {}
    return invertedZoom;
}

const QImage& Document::downSampledImageForZoom(qreal zoom) const
{
    static const QImage sNullImage;

    int invertedZoom = invertedZoomForZoom(zoom);
    if (invertedZoom == 1) {
        return d->mImage;
    }

    if (!d->mDownSampledImageMap.contains(invertedZoom)) {
        if (!d->mImage.isNull()) {
            // Special case: if we have the full image and the down sampled
            // image would be too small, return the original image.
            const QSize downSampledSize = d->mImage.size() / invertedZoom;
            if (downSampledSize.isEmpty()) {
                return d->mImage;
            }
        }
        return sNullImage;
    }

    return d->mDownSampledImageMap[invertedZoom];
}

Document::LoadingState Document::loadingState() const
{
    return d->mImpl->loadingState();
}

void Document::switchToImpl(AbstractDocumentImpl* impl)
{
    Q_ASSERT(impl);
    if (d->mImpl) {
        d->mImpl->deleteLater();
    }
    d->mImpl = impl;

    connect(d->mImpl, SIGNAL(metaInfoLoaded()),
            this, SLOT(emitMetaInfoLoaded()));
    connect(d->mImpl, SIGNAL(loaded()),
            this, SLOT(emitLoaded()));
    connect(d->mImpl, SIGNAL(loadingFailed()),
            this, SLOT(emitLoadingFailed()));
    connect(d->mImpl, SIGNAL(imageRectUpdated(QRect)),
            this, SIGNAL(imageRectUpdated(QRect)));
    connect(d->mImpl, SIGNAL(isAnimatedUpdated()),
            this, SIGNAL(isAnimatedUpdated()));
    d->mImpl->init();
}

void Document::setImageInternal(const QImage& image)
{
    d->mImage = image;
    d->mDownSampledImageMap.clear();

    // If we didn't get the image size before decoding the full image, set it
    // now
    setSize(d->mImage.size());
}

KUrl Document::url() const
{
    return d->mUrl;
}

QByteArray Document::rawData() const
{
    return d->mImpl->rawData();
}

bool Document::keepRawData() const
{
    return d->mKeepRawData;
}

void Document::setKeepRawData(bool value)
{
    d->mKeepRawData = value;
}

void Document::waitUntilLoaded()
{
    startLoadingFullImage();
    while (true) {
        LoadingState state = loadingState();
        if (state == Loaded || state == LoadingFailed) {
            return;
        }
        qApp->processEvents(QEventLoop::ExcludeUserInputEvents);
    }
}

DocumentJob* Document::save(const KUrl& url, const QByteArray& format)
{
    waitUntilLoaded();
    DocumentJob* job = d->mImpl->save(url, format);
    if (!job) {
        kWarning() << "Implementation does not support saving!";
        setErrorString(i18nc("@info", "Gwenview cannot save this kind of documents."));
        return false;
    }
    job->setProperty("oldUrl", d->mUrl);
    job->setProperty("newUrl", url);
    connect(job, SIGNAL(result(KJob*)), SLOT(slotSaveResult(KJob*)));
    enqueueJob(job);
    return job;
}

void Document::slotSaveResult(KJob* job)
{
    if (job->error()) {
        setErrorString(job->errorString());
    } else {
        d->mUndoStack.setClean();
        SaveJob* saveJob = static_cast<SaveJob*>(job);
        d->mUrl = saveJob->newUrl();
        d->mImageMetaInfoModel.setUrl(d->mUrl);
        saved(saveJob->oldUrl(), d->mUrl);
    }
}

QByteArray Document::format() const
{
    return d->mFormat;
}

void Document::setFormat(const QByteArray& format)
{
    d->mFormat = format;
    emit metaInfoUpdated();
}

MimeTypeUtils::Kind Document::kind() const
{
    return d->mKind;
}

void Document::setKind(MimeTypeUtils::Kind kind)
{
    d->mKind = kind;
    emit kindDetermined(d->mUrl);
}

QSize Document::size() const
{
    return d->mSize;
}

bool Document::hasAlphaChannel() const
{
    if (d->mImage.isNull()) {
        return false;
    } else {
        return d->mImage.hasAlphaChannel();
    }
}

int Document::memoryUsage() const
{
    // FIXME: Take undo stack into account
    int usage = d->mImage.numBytes();
    usage += rawData().length();
    return usage;
}

void Document::setSize(const QSize& size)
{
    if (size == d->mSize) {
        return;
    }
    d->mSize = size;
    d->mImageMetaInfoModel.setImageSize(size);
    emit metaInfoUpdated();
}

bool Document::isModified() const
{
    return !d->mUndoStack.isClean();
}

AbstractDocumentEditor* Document::editor()
{
    return d->mImpl->editor();
}

void Document::setExiv2Image(Exiv2::Image::AutoPtr image)
{
    d->mExiv2Image = image;
    d->mImageMetaInfoModel.setExiv2Image(d->mExiv2Image.get());
    emit metaInfoUpdated();
}

void Document::setDownSampledImage(const QImage& image, int invertedZoom)
{
    Q_ASSERT(!d->mDownSampledImageMap.contains(invertedZoom));
    d->mDownSampledImageMap[invertedZoom] = image;
    emit downSampledImageReady();
}

QString Document::errorString() const
{
    return d->mErrorString;
}

void Document::setErrorString(const QString& string)
{
    d->mErrorString = string;
}

ImageMetaInfoModel* Document::metaInfo() const
{
    return &d->mImageMetaInfoModel;
}

void Document::startLoadingFullImage()
{
    LoadingState state = loadingState();
    if (state <= MetaInfoLoaded) {
        // Schedule full image loading
        LoadingJob* job = new LoadingJob;
        job->uiDelegate()->setAutoWarningHandlingEnabled(false);
        job->uiDelegate()->setAutoErrorHandlingEnabled(false);
        enqueueJob(job);
        d->scheduleImageLoading(1);
    } else if (state == Loaded) {
        return;
    } else if (state == LoadingFailed) {
        kWarning() << "Can't load full image: loading has already failed";
    }
}

bool Document::prepareDownSampledImageForZoom(qreal zoom)
{
    if (zoom >= maxDownSampledZoom()) {
        kWarning() << "No need to call prepareDownSampledImageForZoom if zoom >= " << maxDownSampledZoom();
        return true;
    }

    int invertedZoom = invertedZoomForZoom(zoom);
    if (d->mDownSampledImageMap.contains(invertedZoom)) {
        return true;
    }

    if (loadingState() == Loaded) {
        // Resample image from the full one
        d->mDownSampledImageMap[invertedZoom] = d->mImage.scaled(d->mImage.size() / invertedZoom, Qt::KeepAspectRatio, Qt::FastTransformation);
        if (d->mDownSampledImageMap[invertedZoom].size().isEmpty()) {
            d->mDownSampledImageMap[invertedZoom] = d->mImage;
            return true;
        }

        return true;
    }

    // Schedule down sampled image loading
    d->scheduleImageLoading(invertedZoom);

    return false;
}

void Document::emitMetaInfoLoaded()
{
    emit metaInfoLoaded(d->mUrl);
}

void Document::emitLoaded()
{
    emit loaded(d->mUrl);
}

void Document::emitLoadingFailed()
{
    emit loadingFailed(d->mUrl);
}

QUndoStack* Document::undoStack() const
{
    return &d->mUndoStack;
}

void Document::slotUndoIndexChanged()
{
    if (d->mUndoStack.isClean()) {
        // If user just undid all his changes this does not really correspond
        // to a save, but it's similar enough as far as Document users are
        // concerned
        saved(d->mUrl, d->mUrl);
    } else {
        modified(d->mUrl);
    }
}

bool Document::isEditable() const
{
    return d->mImpl->isEditable();
}

bool Document::isAnimated() const
{
    return d->mImpl->isAnimated();
}

void Document::startAnimation()
{
    return d->mImpl->startAnimation();
}

void Document::stopAnimation()
{
    return d->mImpl->stopAnimation();
}

void Document::enqueueJob(DocumentJob* job)
{
    d->mJobQueue.enqueue(job);
    job->setDocument(Ptr(this));
    connect(job, SIGNAL(destroyed(QObject*)),
            SLOT(slotJobDestroyed(QObject*)));
    if (d->mJobQueue.size() == 1) {
        job->start();
        busyChanged(d->mUrl, true);
    }
}

void Document::slotJobDestroyed(QObject* job)
{
    Q_ASSERT(!d->mJobQueue.isEmpty());
    if (d->mJobQueue.head() != job) {
        // Job was killed before it even got started, just remove it from the
        // queue and move along
        d->mJobQueue.removeAll(static_cast<DocumentJob*>(job));
        return;
    }
    d->mJobQueue.dequeue();
    if (d->mJobQueue.isEmpty()) {
        busyChanged(d->mUrl, false);
        allTasksDone();
    } else {
        d->mJobQueue.head()->start();
    }
}

bool Document::isBusy() const
{
    return !d->mJobQueue.isEmpty();
}

QSvgRenderer* Document::svgRenderer() const
{
    return d->mImpl->svgRenderer();
}

} // namespace
