#include "pathtracer.h"

#include <pugixml/pugixml.hpp>
#include <core/rendering/texture_renderer.h>
#include <util/files.h>

namespace glare::raytrace
{
	Pathtracer::Pathtracer()
		: Pathtracer(RayGeneratorType::eTrace)
	{

	}

	Pathtracer::Pathtracer(std::shared_ptr<core::SceneNode> graph_root)
		: Pathtracer(std::make_shared<SceneCollector>(graph_root))
	{

	}

	Pathtracer::Pathtracer(std::shared_ptr<core::SceneNode> graph_root, RayGeneratorType ray_generator)
		: Pathtracer(std::make_shared<SceneCollector>(graph_root), ray_generator)
	{

	}

	Pathtracer::Pathtracer(RayGeneratorType ray_generator)
		: Pathtracer(std::shared_ptr<SceneCollector>(nullptr), ray_generator)
	{
	}

	Pathtracer::Pathtracer(std::shared_ptr<SceneCollector> collector)
		: Pathtracer(collector, RayGeneratorType::eTrace)
	{
	}

	Pathtracer::Pathtracer(std::shared_ptr<SceneCollector> collector, RayGeneratorType ray_generator)
	{
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eDiffusion)] = 4;
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eReflection)] = 6;
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eTransmission)] = 12;
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eEmission)] = 1;

		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eDiffusion)] = 1;
		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eReflection)] = 3;
		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eTransmission)] = 3;
		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eEmission)] = 6;

		m_linespace_config.distance_threshold = 8.f;
		m_render_config.bounces = 16;
		Log_Hint << "Pathtracing Shader will now be compiled. This might take a couple of seconds.";
		m_render_shader = std::make_unique<core::Program>(files::shader("/pathtracer/pathtracer.comp"));
		m_generator_type = ray_generator;
		m_trace_buffer = std::make_unique<core::Buffer>();

		registerForMessage(tags::scene);

		if (collector)
			initialize(collector);
	}

	Pathtracer::~Pathtracer()
	{
		if (core::Context::hasCurrentContext() && !core::Context::current().window().isClosing())
			unregisterForMessage(tags::scene);
	}

	void Pathtracer::loadSettings(const fs::path &xml_file)
	{
		pugi::xml_document preferences_file;
		Log_Info << "Pathtracer settings file load status: " << preferences_file.load_file(xml_file.c_str()).description();

		//Pathtracer
		const auto pt_child = preferences_file.child("pathtracer");

		//bounces
		const auto bounces_child = pt_child.find_child_by_attribute("group", "name", "bounces");
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eDiffusion)] = static_cast<uint8_t>(bounces_child.find_child_by_attribute("item", "name", "diffusion").attribute("value").as_uint(2));
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eReflection)] = static_cast<uint8_t>(bounces_child.find_child_by_attribute("item", "name", "reflection").attribute("value").as_uint(4));
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eTransmission)] = static_cast<uint8_t>(bounces_child.find_child_by_attribute("item", "name", "transmission").attribute("value").as_uint(4));
		m_bounce_count_thresholds[static_cast<unsigned>(EffectType::eEmission)] = static_cast<uint8_t>(bounces_child.find_child_by_attribute("item", "name", "emission").attribute("value").as_uint(8));

		//ls thresholds
		const auto ls_thresholds_child = pt_child.find_child_by_attribute("group", "name", "ls-thresholds");
		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eDiffusion)] = static_cast<uint8_t>(ls_thresholds_child.find_child_by_attribute("item", "name", "diffusion").attribute("value").as_uint(2));
		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eReflection)] = static_cast<uint8_t>(ls_thresholds_child.find_child_by_attribute("item", "name", "reflection").attribute("value").as_uint(4));
		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eTransmission)] = static_cast<uint8_t>(ls_thresholds_child.find_child_by_attribute("item", "name", "transmission").attribute("value").as_uint(4));
		m_ls_bounce_count_thresholds[static_cast<unsigned>(EffectType::eEmission)] = static_cast<uint8_t>(ls_thresholds_child.find_child_by_attribute("item", "name", "emission").attribute("value").as_uint(8));

		m_linespace_config.accuracy_threshold = ls_thresholds_child.find_child_by_attribute("item", "name", "accuracy").attribute("value").as_float(0.5f);
		m_linespace_config.shadow_threshold = ls_thresholds_child.find_child_by_attribute("item", "name", "shadow").attribute("value").as_float(0.5f);
		m_linespace_config.distance_threshold = ls_thresholds_child.find_child_by_attribute("item", "name", "distance").attribute("value").as_float(10.f);

		m_render_config.clamp_direct = pt_child.find_child_by_attribute("item", "name", "clamp-direct").attribute("value").as_float(8);
		m_render_config.clamp_indirect = pt_child.find_child_by_attribute("item", "name", "clamp-indirect").attribute("value").as_float(8);
	}

	void Pathtracer::reset()
	{
		m_render_config.current_sample = 0;

		m_collector->apply(*m_render_shader);

		m_render_shader->uniform("u_render_config.num_bounces", m_render_config.bounces);
		m_render_shader->uniform("u_render_config.clamp_direct", m_render_config.clamp_direct);
		m_render_shader->uniform("u_render_config.clamp_indirect", m_render_config.clamp_indirect);

		m_render_shader->uniform("u_linespace_properties.accuracy_quality", m_linespace_config.accuracy_threshold);
		m_render_shader->uniform("u_linespace_properties.shadow_quality", m_linespace_config.shadow_threshold);
		m_render_shader->uniform("u_linespace_properties.distance_threshold", m_linespace_config.distance_threshold);

		unsigned bounce_thresholds = 0;
		for (int i = 0; i < 4; ++i)
		{
			bounce_thresholds |= (m_bounce_count_thresholds[i] & 0xff) << (8 * i);
		}
		m_render_shader->uniform("u_render_config.bounce_thresholds", bounce_thresholds);

		m_linespace_config.bounce_thresholds = 0;
		for (int i = 0; i < 4; ++i)
		{
			m_linespace_config.bounce_thresholds |= (m_ls_bounce_count_thresholds[i] & 0xff) << (8 * i);
		}
		m_render_shader->uniform("u_linespace_properties.bounce_thresholds", m_linespace_config.bounce_thresholds);

		m_render_shader->bindSubroutine(gl::ShaderType::eCompute, "u_light_sample[0]", "samplePoint");
		m_render_shader->bindSubroutine(gl::ShaderType::eCompute, "u_light_sample[1]", "sampleSpot");
		m_render_shader->bindSubroutine(gl::ShaderType::eCompute, "u_light_sample[2]", "sampleDirectional");
		m_render_shader->bindSubroutine(gl::ShaderType::eCompute, "u_light_sample[3]", "sampleAmbient");
	}

	const core::TextureRGBA_32F &Pathtracer::render(uint32_t width, uint32_t height)
	{
		static auto color_storage = std::make_unique<core::TextureRGBA_32F>(width, height);
		if (width != m_last_width || height != m_last_height) {
			m_last_width = width;
			m_last_height = height;

			m_trace_buffer->reserve<Trace>(width * height, gl::BufferUsage::eDynamicCopy);
			m_render_target = std::make_unique<core::TextureRGBA_32F>(width, height);
			color_storage = std::make_unique<core::TextureRGBA_32F>(width, height);

			m_render_shader->uniform("u_render_target", m_render_target->makeImageResident(gl::Access::eReadWrite));
			m_render_shader->uniform("u_color_store", color_storage->makeImageResident(gl::Access::eReadWrite));
			m_render_shader->storageBuffer("trace_buffer", *m_trace_buffer);
			m_render_config.current_sample = 0;
		}

		if (m_render_config.current_sample == 0)
		{
			gl::clearTextureImage(color_storage->id(), 0, gl::TextureFormat::eRGBA, gl::Type::eFloat, glm::value_ptr(glm::vec4(0)));
		}

		if (m_skybox && m_skybox->isInitialized())
		{
			m_render_shader->uniform("u_environment.cubemap", m_skybox->makeResident());
			m_render_shader->uniform("u_environment.has_cubemap", 1);
		}
		else
		{
			m_render_shader->uniform("u_environment.color", glm::vec4(0.7f, 0.9f, 0.97f, 1));
			m_render_shader->uniform("u_environment.has_cubemap", 0);
		}

		for (unsigned sample = 0; sample < m_render_config.samples_per_frame; sample++) {

			if (m_render_config.current_sample >= m_render_config.max_samples)
				return *m_render_target;

			if (debug.print_render_times) core::ClockGL::instance().start();
			const static std::unique_ptr<RayGenerator> ray_generator = std::make_unique<RayGenerator>();
			ray_generator->generate(*this);
			if (debug.print_render_times) Log_Hint << "RENDER TIME [Generate Primary Rays]: " << core::ClockGL::instance().end() << " ns";

			if (debug.print_render_times) core::ClockGL::instance().start();
			m_render_shader->use();
			m_render_shader->uniform("u_render_config.current_sample", m_render_config.current_sample);
			m_render_shader->uniform("random_seed", ray_generator->randomSeed());
			m_render_shader->dispatch2d(width, 16, height, 16);
			if (debug.print_render_times) Log_Hint << "RENDER TIME [Trace and Bounce]: " << core::ClockGL::instance().end() << " ns";

			++m_render_config.current_sample;
		}

		return *m_render_target;
	}

	void Pathtracer::draw(std::shared_ptr<core::SceneNode> node)
	{
		// If it's not manually initialized via the GUI button, initialize the Pathtracer here.
		if (!m_collector)
			reload(node);

		static const std::shared_ptr<core::TextureRenderer> texture_renderer = core::DefaultTextureRenderers::makeSimpleRenderer();
		texture_renderer->draw(render(core::Context::current().window().getWidth(), core::Context::current().window().getHeight()));
	}

	void Pathtracer::saveRender(fs::path target) const
	{
		core::textures::saveTexture(target, *m_render_target);
	}

	void Pathtracer::setGenerator(RayGeneratorType generator)
	{
		m_generator_type = generator;
		reset();
	}

	RayGeneratorType Pathtracer::getGenerator() const
	{
		return m_generator_type;
	}

	void Pathtracer::initialize(std::shared_ptr<SceneCollector> collector)
	{
		m_collector = collector;
		m_collector->collect();

		m_skybox = core::Context::current().skybox();
		reset();
	}

	void Pathtracer::reload(std::shared_ptr<core::SceneNode> graph_root)
	{
		if (!m_collector)
		{
			m_collector = std::make_shared<SceneCollector>(graph_root);
		}
		else
		{
			m_collector->setDirty(DirtyFlags::eAll);
			m_collector->collect(graph_root);
		}

		m_skybox = core::Context::current().skybox();
		reset();
	}

	void Pathtracer::handle(messaging::message_t& message)
	{
		switch (message.name)
		{
		case tags::scene:
			reset();
			break;
		default: break;
		}
	}

	const core::Program& Pathtracer::shader() const
	{
		return *m_render_shader;
	}

	uint32_t Pathtracer::width() const
	{
		return m_last_width;
	}

	uint32_t Pathtracer::height() const
	{
		return m_last_height;
	}

	core::Buffer& Pathtracer::traceBuffer() const
	{
		return *m_trace_buffer;
	}

	const core::TextureRGBA_32F& Pathtracer::renderTarget() const
	{
		return *m_render_target;
	}

	std::shared_ptr<SceneCollector> Pathtracer::collector() const
	{
		return m_collector;
	}

	unsigned Pathtracer::currentSample() const
	{
		return m_render_config.current_sample;
	}

	void Pathtracer::setEffectBounces(EffectType type, uint8_t bounces)
	{
		uint8_t clamped = bounces & 0xff;

		if (clamped != bounces)
		{
			Log_Warn << bounces << " - value larger than 15 (0xf). Result of " << clamped << " may be unintended.";
		}

		m_bounce_count_thresholds[static_cast<unsigned>(type)] = clamped;
		reset();
	}

	uint8_t Pathtracer::getEffectBounces(EffectType type)
	{
		return m_bounce_count_thresholds[static_cast<unsigned>(type)];
	}

	void Pathtracer::setLinespaceBounceThresholds(EffectType type, uint8_t bounces)
	{
		uint8_t clamped = bounces & 0xff;

		if (clamped != bounces)
		{
			Log_Warn << bounces << " - value larger than 15 (0xf). Result of " << clamped << " may be unintended.";
		}

		m_ls_bounce_count_thresholds[unsigned(type)] = clamped;
		reset();
	}

	uint8_t Pathtracer::getLinespaceBounceThreshold(EffectType type)
	{
		return m_ls_bounce_count_thresholds[static_cast<unsigned>(type)];
	}

	void Pathtracer::setSkybox(std::shared_ptr<core::Skybox> skybox)
	{
		m_skybox = skybox;
		reset();
	}

	std::shared_ptr<core::Skybox> Pathtracer::getSkybox() const
	{
		return m_skybox;
	}

	void Pathtracer::setBounces(unsigned count)
	{
		reset();
		m_render_config.bounces = count;
	}

	unsigned Pathtracer::getBounces() const
	{
		return m_render_config.bounces;
	}

	void Pathtracer::setMaxSamples(unsigned count)
	{
		m_render_config.max_samples = count;
	}

	unsigned Pathtracer::getMaxSamples() const
	{
		return m_render_config.max_samples;
	}

	void Pathtracer::setSamplesPerFrame(unsigned count)
	{
		m_render_config.samples_per_frame = count;
	}

	unsigned Pathtracer::getSamplesPerFrame() const
	{
		return m_render_config.samples_per_frame;
	}

	void Pathtracer::setClampDirect(float clamp_direct)
	{
		m_render_config.clamp_direct = clamp_direct; reset();
	}

	float Pathtracer::getClampDirect() const
	{
		return m_render_config.clamp_direct;
	}

	void Pathtracer::setClampIndirect(float clamp_indirect)
	{
		m_render_config.clamp_indirect = clamp_indirect; reset();
	}

	float Pathtracer::getClampIndirect() const
	{
		return m_render_config.clamp_indirect;
	}

	void Pathtracer::setAccuracyThreshold(float accuracy_threshold)
	{
		m_linespace_config.accuracy_threshold = accuracy_threshold; reset();
	}

	float Pathtracer::getAccuracyThreshold() const
	{
		return m_linespace_config.accuracy_threshold;
	}

	void Pathtracer::setShadowThreshold(float shadow_threshold)
	{
		m_linespace_config.shadow_threshold = shadow_threshold; reset();
	}

	float Pathtracer::getShadowThreshold() const
	{
		return m_linespace_config.shadow_threshold;
	}

	void Pathtracer::setDistanceThreshold(float distance_threshold)
	{
		m_linespace_config.distance_threshold = distance_threshold; reset();
	}

	float Pathtracer::getDistanceThreshold() const
	{
		return m_linespace_config.distance_threshold;
	}
}