/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2021-2022, Ideas On Board
 *
 * AGC/AEC mean-based control algorithm
 */

#include "agc.h"

#include <algorithm>
#include <chrono>
#include <cmath>

#include <libcamera/base/log.h>
#include <libcamera/base/utils.h>

#include <libcamera/control_ids.h>
#include <libcamera/ipa/core_ipa_interface.h>

#include "libcamera/internal/yaml_parser.h"

#include "libipa/histogram.h"

/**
 * \file agc.h
 */

namespace libcamera {

using namespace std::literals::chrono_literals;

namespace ipa::rkisp1::algorithms {

/**
 * \class Agc
 * \brief A mean-based auto-exposure algorithm
 */

LOG_DEFINE_CATEGORY(RkISP1Agc)

int Agc::parseMeteringModes(IPAContext &context, const YamlObject &tuningData)
{
	if (!tuningData.isDictionary()) {
		LOG(RkISP1Agc, Error)
			<< "'AeMeteringMode' parameter not found in tuning file";
		return -EINVAL;
	}

	for (const auto &[key, value] : tuningData.asDict()) {
		if (controls::AeMeteringModeNameValueMap.find(key) ==
		    controls::AeMeteringModeNameValueMap.end()) {
			LOG(RkISP1Agc, Warning)
				<< "Skipping unknown metering mode '" << key << "'";
			continue;
		}

		std::vector<uint8_t> weights =
			value.getList<uint8_t>().value_or(std::vector<uint8_t>{});
		if (weights.size() != context.hw->numHistogramWeights) {
			LOG(RkISP1Agc, Warning)
				<< "Failed to read metering mode'" << key << "'";
			continue;
		}

		meteringModes_[controls::AeMeteringModeNameValueMap.at(key)] = weights;
	}

	if (meteringModes_.empty()) {
		LOG(RkISP1Agc, Warning)
			<< "No metering modes read from tuning file; defaulting to matrix";
		int32_t meteringModeId = controls::AeMeteringModeNameValueMap.at("MeteringMatrix");
		std::vector<uint8_t> weights(context.hw->numHistogramWeights, 1);

		meteringModes_[meteringModeId] = weights;
	}

	return 0;
}

uint8_t Agc::computeHistogramPredivider(Size &size, enum rkisp1_cif_isp_histogram_mode mode)
{
	/*
	 * The maximum number of pixels that could potentially be in one bin is
	 * if all the pixels of the image are in it, multiplied by 3 for the
	 * three color channels. The counter for each bin is 16 bits wide, so
	 * `factor` thus contains the number of times we'd wrap around. This is
	 * obviously the number of pixels that we need to skip to make sure
	 * that we don't wrap around, but we compute the square root of it
	 * instead, as the skip that we need to program is for both the x and y
	 * directions.
	 *
	 * Even though it looks like dividing into a counter of 65536 would
	 * overflow by 1, this is apparently fine according to the hardware
	 * documentation, and this successfully gets the expected documented
	 * predivider size for cases where:
	 * (width / predivider) * (height / predivider) * 3 == 65536.
	 *
	 * There's a bit of extra rounding math to make sure the rounding goes
	 * the correct direction so that the square of the step is big enough
	 * to encompass the `factor` number of pixels that we need to skip.
	 *
	 * \todo Take into account weights. That is, if the weights are low
	 * enough we can potentially reduce the predivider to increase
	 * precision. This needs some investigation however, as this hardware
	 * behavior is undocumented and is only an educated guess.
	 */
	int count = mode == RKISP1_CIF_ISP_HISTOGRAM_MODE_RGB_COMBINED ? 3 : 1;
	double factor = size.width * size.height * count / 65536.0;
	double root = std::sqrt(factor);
	uint8_t predivider;

	if (std::pow(std::floor(root), 2) < factor)
		predivider = static_cast<uint8_t>(std::ceil(root));
	else
		predivider = static_cast<uint8_t>(std::floor(root));

	return std::clamp<uint8_t>(predivider, 3, 127);
}

Agc::Agc()
{
	supportsRaw_ = true;
}

/**
 * \brief Initialise the AGC algorithm from tuning files
 * \param[in] context The shared IPA context
 * \param[in] tuningData The YamlObject containing Agc tuning data
 *
 * This function calls the base class' tuningData parsers to discover which
 * control values are supported.
 *
 * \return 0 on success or errors from the base class
 */
int Agc::init(IPAContext &context, const YamlObject &tuningData)
{
	int ret;

	ret = parseTuningData(tuningData);
	if (ret)
		return ret;

	const YamlObject &yamlMeteringModes = tuningData["AeMeteringMode"];
	ret = parseMeteringModes(context, yamlMeteringModes);
	if (ret)
		return ret;

	context.ctrlMap.merge(controls());

	return 0;
}

/**
 * \brief Configure the AGC given a configInfo
 * \param[in] context The shared IPA context
 * \param[in] configInfo The IPA configuration data
 *
 * \return 0
 */
int Agc::configure(IPAContext &context, const IPACameraSensorInfo &configInfo)
{
	/* Configure the default exposure and gain. */
	context.activeState.agc.automatic.gain = context.configuration.sensor.minAnalogueGain;
	context.activeState.agc.automatic.exposure =
		10ms / context.configuration.sensor.lineDuration;
	context.activeState.agc.manual.gain = context.activeState.agc.automatic.gain;
	context.activeState.agc.manual.exposure = context.activeState.agc.automatic.exposure;
	context.activeState.agc.autoEnabled = !context.configuration.raw;

	context.activeState.agc.constraintMode = constraintModes().begin()->first;
	context.activeState.agc.exposureMode = exposureModeHelpers().begin()->first;

	/*
	 * Define the measurement window for AGC as a centered rectangle
	 * covering 3/4 of the image width and height.
	 */
	context.configuration.agc.measureWindow.h_offs = configInfo.outputSize.width / 8;
	context.configuration.agc.measureWindow.v_offs = configInfo.outputSize.height / 8;
	context.configuration.agc.measureWindow.h_size = 3 * configInfo.outputSize.width / 4;
	context.configuration.agc.measureWindow.v_size = 3 * configInfo.outputSize.height / 4;

	/* \todo Run this again when FrameDurationLimits is passed in */
	setLimits(context.configuration.sensor.minShutterSpeed,
		  context.configuration.sensor.maxShutterSpeed,
		  context.configuration.sensor.minAnalogueGain,
		  context.configuration.sensor.maxAnalogueGain);

	resetFrameCount();

	return 0;
}

/**
 * \copydoc libcamera::ipa::Algorithm::queueRequest
 */
void Agc::queueRequest(IPAContext &context,
		       [[maybe_unused]] const uint32_t frame,
		       IPAFrameContext &frameContext,
		       const ControlList &controls)
{
	auto &agc = context.activeState.agc;

	if (!context.configuration.raw) {
		const auto &agcEnable = controls.get(controls::AeEnable);
		if (agcEnable && *agcEnable != agc.autoEnabled) {
			agc.autoEnabled = *agcEnable;

			LOG(RkISP1Agc, Debug)
				<< (agc.autoEnabled ? "Enabling" : "Disabling")
				<< " AGC";
		}
	}

	const auto &exposure = controls.get(controls::ExposureTime);
	if (exposure && !agc.autoEnabled) {
		agc.manual.exposure = *exposure * 1.0us
				    / context.configuration.sensor.lineDuration;

		LOG(RkISP1Agc, Debug)
			<< "Set exposure to " << agc.manual.exposure;
	}

	const auto &gain = controls.get(controls::AnalogueGain);
	if (gain && !agc.autoEnabled) {
		agc.manual.gain = *gain;

		LOG(RkISP1Agc, Debug) << "Set gain to " << agc.manual.gain;
	}

	frameContext.agc.autoEnabled = agc.autoEnabled;

	if (!frameContext.agc.autoEnabled) {
		frameContext.agc.exposure = agc.manual.exposure;
		frameContext.agc.gain = agc.manual.gain;
	}
}

/**