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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * stream.cpp - Video stream for a Camera
 */

#include <libcamera/stream.h>

#include <algorithm>
#include <array>
#include <iomanip>
#include <limits.h>
#include <sstream>

#include <libcamera/request.h>

#include "libcamera/internal/log.h"
#include "libcamera/internal/utils.h"

/**
 * \file stream.h
 * \brief Video stream for a Camera
 *
 * A camera device can provide frames in different resolutions and formats
 * concurrently from a single image source. The Stream class represents
 * one of the multiple concurrent streams.
 *
 * All streams exposed by a camera device share the same image source and are
 * thus not fully independent. Parameters related to the image source, such as
 * the exposure time or flash control, are common to all streams. Other
 * parameters, such as format or resolution, may be specified per-stream,
 * depending on the capabilities of the camera device.
 *
 * Camera devices expose at least one stream, and may expose additional streams
 * based on the device capabilities. This can be used, for instance, to
 * implement concurrent viewfinder and video capture, or concurrent viewfinder,
 * video capture and still image capture.
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(Stream)

/**
 * \class StreamFormats
 * \brief Hold information about supported stream formats
 *
 * The StreamFormats class holds information about the pixel formats and frame
 * sizes a stream supports. The class groups size information by the pixel
 * format which can produce it.
 *
 * There are two ways to examine the size information, as a range or as a list
 * of discrete sizes. When sizes are viewed as a range it describes the minimum
 * and maximum width and height values. The range description can include
 * horizontal and vertical steps.
 *
 * When sizes are viewed as a list of discrete sizes they describe the exact
 * dimensions which can be selected and used.
 *
 * Pipeline handlers can create StreamFormats describing each pixel format using
 * either a range or a list of discrete sizes. The StreamFormats class attempts
 * to translate between the two different ways to view them. The translations
 * are performed as:
 *
 *  - If the StreamFormat is constructed using a list of discrete image sizes
 *    and a range is requested, it gets created by taking the minimum and
 *    maximum width/height in the list. The step information is not recreated
 *    and is set to 0 to indicate the range is generated.
 *
 *  - If the image sizes used to construct a StreamFormat are expressed as a
 *    range and a list of discrete sizes is requested, one which fits inside
 *    that range are selected from a list of common sizes. The step information
 *    is taken into consideration when generating the sizes.
 *
 * Applications examining sizes as a range with step values of 0 shall be
 * aware that the range are generated from a list of discrete sizes and there
 * could be a large number of possible Size combinations that may not be
 * supported by the Stream.
 *
 * All sizes retrieved from StreamFormats shall be treated as advisory and no
 * size shall be considered to be supported until it has been verified using
 * CameraConfiguration::validate().
 *
 * \todo Review the usage patterns of this class, and cache the computed
 * pixelformats(), sizes() and range() if this would improve performances.
 */

StreamFormats::StreamFormats()
{
}

/**
 * \brief Construct a StreamFormats object with a map of image formats
 * \param[in] formats A map of pixel formats to a sizes description
 */
StreamFormats::StreamFormats(const std::map<PixelFormat, std::vector<SizeRange>> &formats)
	: formats_(formats)
{
}

/**
 * \brief Retrieve the list of supported pixel formats
 * \return The list of supported pixel formats
 */
std::vector<PixelFormat> StreamFormats::pixelformats() const
{
	std::vector<PixelFormat> formats;

	for (auto const &it : formats_)
		formats.push_back(it.first);

	return formats;
}

/**
 * \brief Retrieve the list of frame sizes supported for \a pixelformat
 * \param[in] pixelformat PixelFormat to retrieve sizes for
 *
 * If the sizes described for \a pixelformat are discrete they are returned
 * directly.
 *
 * If the sizes are described as a range, a list of discrete sizes are computed
 * from a list of common resolutions that fit inside the described range. When
 * computing the discrete list step values are considered but there are no
 * guarantees that all sizes computed are supported.
 *
 * \return A list of frame sizes or an empty list on error
 */
std::vector<Size> StreamFormats::sizes(const PixelFormat &pixelformat) const
{
	/*
	 * Sizes to try and extract from ranges.
	 * \todo Verify list of resolutions are good, current list compiled
	 * from v4l2 documentation and source code as well as lists of
	 * common frame sizes.
	 */
	static const std::array<Size, 53> rangeDiscreteSizes = {
		Size(160, 120),
		Size(240, 160),
		Size(320, 240),
		Size(400, 240),
		Size(480, 320),
		Size(640, 360),
		Size(640, 480),
		Size(720, 480),
		Size(720, 576),
		Size(768, 480),
		Size(800, 600),
		Size(854, 480),
		Size(960, 540),
		Size(960, 640),
		Size(1024, 576),
		Size(1024, 600),
		Size(1024, 768),
		Size(1152, 864),
		Size(1280, 1024),