/*
    Copyright (C) 2014-2021 Carl Hetherington <cth@carlh.net>

    This file is part of DCP-o-matic.

    DCP-o-matic 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.

    DCP-o-matic 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 DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.

*/


#ifndef DCPOMATIC_IMAGE_PROXY_H
#define DCPOMATIC_IMAGE_PROXY_H


/** @file  src/lib/image_proxy.h
 *  @brief ImageProxy and subclasses.
 */


#include "image.h"
extern "C" {
#include <libavutil/pixfmt.h>
}
#include <dcp/types.h>
#include <boost/optional.hpp>
#include <boost/utility.hpp>


class Image;
class Socket;

namespace xmlpp {
	class Element;
}

namespace cxml {
	class Node;
}


/** @class ImageProxy
 *  @brief A class which holds an Image, and can produce it on request.
 *
 *  This is so that decoding of source images can be postponed until
 *  the encoder thread, where multi-threading is happening, instead
 *  of happening in a single-threaded decoder.
 *
 *  For example, large TIFFs are slow to decode, so this class will keep
 *  the TIFF data compressed until the decompressed image is needed.
 *  At this point, the class decodes the TIFF to an Image.
 */
class ImageProxy
{
public:
	ImageProxy() {}
	virtual ~ImageProxy() {}

	ImageProxy(ImageProxy const&) = delete;
	ImageProxy& operator=(ImageProxy const&) = delete;

	struct Result {
		Result(std::shared_ptr<const Image> image_, int log2_scaling_, bool error_ = false)
			: image(image_)
			, log2_scaling(log2_scaling_)
			, error(error_)
		{}

		std::shared_ptr<const Image> image;
		/** log2 of any scaling down that has already been applied to the image;
		 *  e.g. if the image is already half the size of the original, this value
		 *  will be 1.
		 */
		int log2_scaling;
		/** true if there was an error during image decoding, otherwise false */
		bool error;
	};

	/** @param log Log to write to, or 0.
	 *  @param size Size that the returned image will be scaled to, in case this
	 *  can be used as an optimisation.
	 */
	virtual Result image(
		Image::Alignment alignment,
		boost::optional<dcp::Size> size = boost::optional<dcp::Size>()
		) const = 0;

	virtual void add_metadata(xmlpp::Element *) const = 0;
	virtual void write_to_socket(std::shared_ptr<Socket>) const = 0;
	/** @return true if our image is definitely the same as another, false if it is probably not */
	virtual bool same(std::shared_ptr<const ImageProxy>) const = 0;
	/** Do any useful work that would speed up a subsequent call to ::image().
	 *  This method may be called in a different thread to image().
	 *  @return log2 of any scaling down that will be applied to the image.
	 */
	virtual int prepare(Image::Alignment, boost::optional<dcp::Size> = boost::optional<dcp::Size>()) const { return 0; }
	virtual size_t memory_used() const = 0;
};


std::shared_ptr<ImageProxy> image_proxy_factory(std::shared_ptr<cxml::Node> xml, std::shared_ptr<Socket> socket);


#endif