/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source 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, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#include "image/gif.h"

#include "common/array.h"
#include "common/stream.h"
#include "common/textconsole.h"
#include "common/util.h"
#include "graphics/surface.h"
#include "graphics/pixelformat.h"

#ifdef USE_GIF
#include <gif_lib.h>
#endif

namespace Image {

GIFDecoder::GIFDecoder() : _outputSurface(0), _palette(0), _colorCount(0) {
}

GIFDecoder::~GIFDecoder() {
	destroy();
}

#ifdef USE_GIF
static int gifReadFromStream(GifFileType *gif, GifByteType *bytes, int size) {
	Common::SeekableReadStream *stream = (Common::SeekableReadStream *)gif->UserData;
	return stream->read(bytes, size);
}
#endif

bool GIFDecoder::loadStream(Common::SeekableReadStream &stream) {
	destroy();

#ifdef USE_GIF
	int error = 0;
	GifFileType *gif = DGifOpen(&stream, gifReadFromStream, &error);
	if (!gif) {
		warning("GIF open failed with error %s", GifErrorString(error));
		return false;
	}

	const int errcode = DGifSlurp(gif);
	if (errcode != GIF_OK) {
		warning("GIF failed to load");
		DGifCloseFile(gif, 0);
		return false;
	}

	if (gif->ImageCount <= 0) {
		warning("GIF doesn't contain valid image data");
		DGifCloseFile(gif, 0);
		return false;
	}

	if (gif->ImageCount > 1) {
		warning("GIF contains more than one frame - only loading the first one");
	}

	const SavedImage *gifImage = gif->SavedImages;

	const int width = gif->SWidth;
	const int height = gif->SHeight;

	const ColorMapObject *colorMap = gif->SColorMap;
	_transparentColor = NO_TRANSPARENT_COLOR;
	for (int i = 0; i < gif->ExtensionBlockCount; ++i) {
		const ExtensionBlock &eb = gif->ExtensionBlocks[i];
		GraphicsControlBlock gcb;
		DGifExtensionToGCB(eb.ByteCount, eb.Bytes, &gcb);
		if (gcb.TransparentColor != NO_TRANSPARENT_COLOR) {
			_transparentColor = gcb.TransparentColor;
			break;
		}
	}

	_colorCount = colorMap->ColorCount;
	_outputSurface = new Graphics::Surface();
	_palette = new uint8[_colorCount * 3];

	const Graphics::PixelFormat format = Graphics::PixelFormat::createFormatCLUT8();
	for (int i = 0; i < _colorCount; ++i) {
		_palette[(i * 3) + 0] = colorMap->Colors[i].Red;
		_palette[(i * 3) + 1] = colorMap->Colors[i].Green;
		_palette[(i * 3) + 2] = colorMap->Colors[i].Blue;
	}

	// TODO: support transparency

	_outputSurface->create(width, height, format);
	const uint8 *in = (const uint8 *)gifImage->RasterBits;
	uint8 *pixelPtr = (uint8 *)_outputSurface->getBasePtr(0, 0);
	if (gif->Image.Interlace) {
		const int interlacedOffset[] = {0, 4, 2, 1};
		const int interlacedJumps[] = {8, 8, 4, 2};
		for (int i = 0; i < 4; ++i) {
			for (int row = interlacedOffset[i]; row < height; row += interlacedJumps[i]) {
				memcpy(pixelPtr + width * row, in, width);
				in += width;
			}
		}
	} else {
		memcpy(pixelPtr, in, width * height);
	}

	DGifCloseFile(gif, 0);
	return true;
#else
	return false;
#endif
}

void GIFDecoder::destroy() {
	if (_outputSurface) {
		_outputSurface->free();
		delete _outputSurface;
		_outputSurface = 0;
	}
	if (_palette) {
		delete[] _palette;
		_palette = 0;
	}
}

} // End of namespace Image