/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include "Scene/Ui/PerformanceOverlayUiElement.hpp"
#include "Base/FrameMetadata.hpp"
#include "Base/Utils.hpp"
#include "Host/SystemInfo.hpp"
#include "Math/ByteSize.hpp"

#include <imgui.h>

namespace OpenVulkano::Scene::UI
{
	namespace
	{
		float FloatValuesGetter(void *data, int index)
		{
			auto queue = reinterpret_cast<std::deque<float> *>(data);
			return (*queue)[index];
		}

		float FPSValuesGetter(void *data, int index)
		{
			auto queue = reinterpret_cast<std::deque<float> *>(data);
			float value = (*queue)[index];
			if(value != 0)
				return 1 / value;
			else
				return 0;
		}

		float RamValuesGetter(void *data, int index)
		{
			auto queue = reinterpret_cast<std::deque<float> *>(data);
			float used = (*queue)[index];
			float max = SystemInfo::GetAppRamMax();
			float percentage = used / max * 100;
			return percentage;
		}
	}

	void PerformanceOverlayUiElement::UpdateQueues()
	{
		m_frameTimes.push_back(static_cast<float>(CURRENT_FRAME.frameTime));
		while(m_frameTimes.size() > m_frameCount)
			m_frameTimes.pop_front();

		m_ramUsed.push_back(static_cast<float>(SystemInfo::GetAppRamUsed()));
		while(m_ramUsed.size() > m_ramUsageCount)
			m_ramUsed.pop_front();
	}

	void PerformanceOverlayUiElement::Init()
	{
	}

	void PerformanceOverlayUiElement::BeginDraw()
	{
		bool alwaysShow = true;
		ImGui::Begin("Debug Info", &alwaysShow);
	}

	void PerformanceOverlayUiElement::Draw()
	{
		UpdateQueues();

		ImVec2 availableSize = ImGui::GetContentRegionAvail();
		availableSize.y *= 1/3.;
		if(ImGui::CollapsingHeader("Frame Times/FPS"))
		{
			ImGui::Text("Last Frame Time: %f s", m_frameTimes.back());
			ImGui::SliderInt("Window Size", &m_frameCount, 10, 1000);
			ImGui::PlotLines("", &FloatValuesGetter, &m_frameTimes, (int)m_frameTimes.size(), 0, nullptr, FLT_MAX, FLT_MAX, availableSize);

			ImGui::Text("Last FPS: %f", 1 / m_frameTimes.back());
			ImGui::PlotLines("", &FPSValuesGetter, &m_frameTimes, (int)m_frameTimes.size(), 0, nullptr, FLT_MAX, FLT_MAX, availableSize);
		}

		if(ImGui::CollapsingHeader("RAM Usage"))
		{
			// NOTE(vb) used and max return unexpected values - used is bigger than max... Is it intended to do so?
			std::string used = Utils::PrettyBytes(SystemInfo::GetAppRamUsed());
			std::string max = Utils::PrettyBytes(SystemInfo::GetAppRamMax());
			std::string avail = Utils::PrettyBytes(SystemInfo::GetAppRamAvailable());
			ImGui::Text("RAM: %s / %s, Free: %s", used.c_str(), max.c_str(), avail.c_str());

			ImGui::SliderInt("Window Size", &m_ramUsageCount, 10, 1000);
			float scaleMin = 0.01;
			float scaleMax = 100;
			ImGui::PlotLines("", &RamValuesGetter, &m_ramUsed, (int)m_ramUsed.size(), 0, nullptr, scaleMin, scaleMax, availableSize);
		}
	}

	void PerformanceOverlayUiElement::EndDraw()
	{
		ImGui::End();
	}
}