// ***************************************************************** -*- C++ -*-

/*

 * Copyright (C) 2004-2018 Exiv2 authors

 * This program is part of the Exiv2 distribution.

 *

 * 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, 5th Floor, Boston, MA 02110-1301 USA.

 */

/*

  File:      gifimage.cpp

  Author(s): Marco Piovanelli, Ovolab (marco)

  History:   26-Feb-2007, marco: created

 */

// *****************************************************************************

// included header files

#include "config.h"

#include "gifimage.hpp"

#include "image.hpp"

#include "basicio.hpp"

#include "error.hpp"

#include "futils.hpp"

// + standard includes

#include <string>

#include <cstring>

#include <iostream>

// *****************************************************************************

// class member definitions

namespace Exiv2 {

    GifImage::GifImage(BasicIo::AutoPtr io)

        : Image(ImageType::gif, mdNone, io)

    {

    } // GifImage::GifImage

    std::string GifImage::mimeType() const

    {

        return "image/gif";

    }

    void GifImage::setExifData(const ExifData& /*exifData*/)

    {

        // Todo: implement me!

        throw(Error(kerInvalidSettingForImage, "Exif metadata", "GIF"));

    }

    void GifImage::setIptcData(const IptcData& /*iptcData*/)

    {

        // Todo: implement me!

        throw(Error(kerInvalidSettingForImage, "IPTC metadata", "GIF"));

    }

    void GifImage::setComment(const std::string& /*comment*/)

    {

        // not supported

        throw(Error(kerInvalidSettingForImage, "Image comment", "GIF"));

    }

    void GifImage::readMetadata()

    {

#ifdef EXIV2_DEBUG_MESSAGES

        std::cerr << "Exiv2::GifImage::readMetadata: Reading GIF file " << io_->path() << "\n";

#endif

        if (io_->open() != 0)

        {

            throw Error(kerDataSourceOpenFailed, io_->path(), strError());

        }

        IoCloser closer(*io_);

        // Ensure that this is the correct image type

        if (!isGifType(*io_, true))

        {

            if (io_->error() || io_->eof()) throw Error(kerFailedToReadImageData);

            throw Error(kerNotAnImage, "GIF");

        }

        clearMetadata();

        byte buf[4];

        if (io_->read(buf, sizeof(buf)) == sizeof(buf))

        {

            pixelWidth_ = getShort(buf, littleEndian);

            pixelHeight_ = getShort(buf + 2, littleEndian);

        }

    } // GifImage::readMetadata

    void GifImage::writeMetadata()

    {

        // Todo: implement me!

        throw(Error(kerWritingImageFormatUnsupported, "GIF"));

    } // GifImage::writeMetadata

    // *************************************************************************

    // free functions

    Image::AutoPtr newGifInstance(BasicIo::AutoPtr io, bool /*create*/)

    {

        Image::AutoPtr image(new GifImage(io));

        if (!image->good())

        {

            image.reset();

        }

        return image;

    }

    bool isGifType(BasicIo& iIo, bool advance)

    {

        const int32_t len = 6;

        const unsigned char Gif87aId[8] = { 'G', 'I', 'F', '8', '7', 'a' };

        const unsigned char Gif89aId[8] = { 'G', 'I', 'F', '8', '9', 'a' };

        byte buf[len];

        iIo.read(buf, len);

        if (iIo.error() || iIo.eof())

        {

            return false;

        }

        bool matched =    (memcmp(buf, Gif87aId, len) == 0)

                       || (memcmp(buf, Gif89aId, len) == 0);

        if (!advance || !matched)

        {

            iIo.seek(-len, BasicIo::cur);

        }

        return matched;

    }

}                                       // namespace Exiv2