/*
===========================================================================
Copyright (C) 2023-2024 Gian 'myT' Schellenbaum

This file is part of Challenge Quake 3 (CNQ3).

Challenge Quake 3 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.

Challenge Quake 3 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 Challenge Quake 3. If not, see <https://www.gnu.org/licenses/>.
===========================================================================
*/
// Shared Rendering Pipeline - core functionality


#include "srp_local.h"
#include "../client/cl_imgui.h"
#include "shaders/crp/world.h.hlsli"


extern IRenderPipeline* grpp;
extern IRenderPipeline* crpp;

SRP srp;
IRenderPipeline* renderPipeline;


static ImPlotPoint FrameTimeGetter(int index, void*)
{
	const FrameStats& fs = srp.frameStats;
	const int realIndex = (fs.frameIndex + index) % fs.frameCount;
	const float value = fs.p2pMS[realIndex];

	ImPlotPoint p;
	p.x = index;
	p.y = value;

	return p;
}

static void UpdateAnimatedImage(image_t* image, int w, int h, const byte* data, qbool dirty)
{
	if(w != image->width || h != image->height)
	{
		// @TODO: ?
		/*image->width = w;
		image->height = h;
		CreateTexture(&d3d.textures[image->texnum], image, 1, w, h);
		GAL_UpdateTexture(image, 0, 0, 0, w, h, data);*/
	}
	else if(dirty)
	{
		// @TODO: ?
		//GAL_UpdateTexture(image, 0, 0, 0, w, h, data);
	}
}


const image_t* GetBundleImage(const textureBundle_t& bundle)
{
	return R_UpdateAndGetBundleImage(&bundle, &UpdateAnimatedImage);
}

uint32_t GetBaseSamplerIndex(textureWrap_t wrap, TextureFilter::Id filter, uint32_t minLOD)
{
	Q_assert((uint32_t)wrap < TW_COUNT);
	Q_assert((uint32_t)filter < TextureFilter::Count);

	const uint32_t baseIndex =
		(uint32_t)filter +
		(uint32_t)TextureFilter::Count * (uint32_t)wrap +
		(uint32_t)TextureFilter::Count * (uint32_t)TW_COUNT * minLOD;

	return baseIndex;
}

uint32_t GetSamplerIndex(textureWrap_t wrap, TextureFilter::Id filter, uint32_t minLOD)
{
	const uint32_t baseIndex = GetBaseSamplerIndex(wrap, filter, minLOD);
	const uint32_t descIndex = renderPipeline->GetSamplerDescriptorIndexFromBaseIndex(baseIndex);

	return descIndex;
}

uint32_t GetSamplerIndex(const image_t* image)
{
	TextureFilter::Id filter = TextureFilter::Anisotropic;
	if(r_lego->integer &&
		srp.renderMode == RenderMode::World &&
		(image->flags & (IMG_LMATLAS | IMG_EXTLMATLAS | IMG_NOPICMIP)) == 0)
	{
		filter = TextureFilter::Point;
	}
	else if((image->flags & IMG_NOAF) != 0 ||
		srp.renderMode != RenderMode::World)
	{
		filter = TextureFilter::Linear;
	}

	int minLOD = 0;
	if(srp.renderMode == RenderMode::World &&
		(image->flags & IMG_NOPICMIP) == 0)
	{
		minLOD = Com_ClampInt(0, MaxTextureMips - 1, r_picmip->integer);
	}

	return GetSamplerIndex(image->wrapClampMode, filter, (uint32_t)minLOD);
}

void ReadTextureImage(void* outPixels, HTexture hreadback, int w, int h, int alignment, colorSpace_t colorSpace)
{
	MappedTexture mapped;
	BeginTextureReadback(mapped, hreadback);

	byte* const out0 = (byte*)outPixels;
	const byte* const in0 = mapped.mappedData;

	if(colorSpace == CS_RGBA)
	{
		const int dstRowSizeNoPadding = w * 4;
		mapped.dstRowByteCount = AlignUp(dstRowSizeNoPadding, alignment);

		for(int y = 0; y < mapped.rowCount; ++y)
		{
			byte* out = out0 + (mapped.rowCount - 1 - y) * mapped.dstRowByteCount;
			const byte* in = in0 + y * mapped.srcRowByteCount;
			memcpy(out, in, dstRowSizeNoPadding);
		}
	}
	else if(colorSpace == CS_BGR)
	{
		mapped.dstRowByteCount = AlignUp(w * 3, alignment);

		for(int y = 0; y < mapped.rowCount; ++y)
		{
			byte* out = out0 + (mapped.rowCount - 1 - y) * mapped.dstRowByteCount;
			const byte* in = in0 + y * mapped.srcRowByteCount;
			for(int x = 0; x < mapped.columnCount; ++x)
			{
				out[2] = in[0];
				out[1] = in[1];
				out[0] = in[2];
				out += 3;
				in += 4;
			}
		}
	}
	else
	{
		Q_assert(!"Unsupported color space");
	}

	EndTextureReadback();
}

void UpdateEntityData(bool& depthHack, int entityNum, double originalTime)
{
	depthHack = false;

	if(entityNum != ENTITYNUM_WORLD)
	{
		backEnd.currentEntity = &backEnd.refdef.entities[entityNum];
		if(backEnd.currentEntity->intShaderTime)
		{
			backEnd.refdef.floatTime = originalTime - (double)backEnd.currentEntity->e.shaderTime.iShaderTime / 1000.0;
		}
		else
		{
			backEnd.refdef.floatTime = originalTime - backEnd.currentEntity->e.shaderTime.fShaderTime;
		}
		// we have to reset the shaderTime as well otherwise image animations start
		// from the wrong frame
		tess.shaderTime = backEnd.refdef.floatTime - tess.shader->timeOffset;

		// set up the transformation matrix
		R_RotateForEntity(backEnd.currentEntity, &backEnd.viewParms, &backEnd.orient);

		if(backEnd.currentEntity->e.renderfx & RF_DEPTHHACK)
		{
			depthHack = true;
		}
	}
	else
	{
		backEnd.currentEntity = &tr.worldEntity;
		backEnd.refdef.floatTime = originalTime;
		backEnd.orient = backEnd.viewParms.world;
		// we have to reset the shaderTime as well otherwise image animations on
		// the world (like water) continue with the wrong frame
		tess.shaderTime = backEnd.refdef.floatTime - tess.shader->timeOffset;
	}
}

cullType_t GetMirrorredCullType(cullType_t cullType)
{
	switch(cullType)
	{
		case CT_BACK_SIDED: return CT_FRONT_SIDED;
		case CT_FRONT_SIDED: return CT_BACK_SIDED;
		default: return CT_TWO_SIDED;
	}
}

uint32_t AlphaTestShaderConstFromStateBits(unsigned int stateBits)
{
	stateBits &= GLS_ATEST_BITS;
	switch(stateBits)
	{
		case GLS_ATEST_GE_80: return ATEST_GE_HALF;
		case GLS_ATEST_GT_0: return ATEST_GT_0;
		case GLS_ATEST_LT_80: return ATEST_LT_HALF;
		default: return ATEST_NONE;
	}
}

void R_SelectRenderPipeline()
{
	if(r_pipeline->integer == 0)
	{
		renderPipeline = grpp;
	}
	else
	{
		renderPipeline = crpp;
	}
}


void FrameStats::EndFrame()
{
	frameCount = min(frameCount + 1, (int)MaxFrames);
	frameIndex = (frameIndex + 1) % MaxFrames;
	Com_StatsFromArray(p2pMS, frameCount, temp, &p2pStats);
}


void RenderPassStats::EndFrame(uint32_t cpu, uint32_t gpu)
{
	static uint32_t tempSamples[MaxStatsFrameCount];
	samplesCPU[index] = cpu;
	samplesGPU[index] = gpu;
	count = min(count + 1, (uint32_t)MaxStatsFrameCount);
	index = (index + 1) % MaxStatsFrameCount;
	Com_StatsFromArray((const int*)samplesCPU, count, (int*)tempSamples, &statsCPU);
	Com_StatsFromArray((const int*)samplesGPU, count, (int*)tempSamples, &statsGPU);
}


uint32_t SRP::BeginRenderPass(const char* name, float r, float g, float b)
{
	if(!enableRenderPassQueries)
	{
		CmdBeginDebugLabel(name, r, g, b);
		return 0xDEADBEEF;
	}

	RenderPassFrame& f = renderPasses[tr.frameCount % FrameCount];
	if(f.count >= ARRAY_LEN(f.passes))
	{
		Q_assert(0);
		return UINT32_MAX;
	}

	CmdBeginDebugLabel(name, r, g, b);

	const uint32_t index = f.count++;
	RenderPassQueries& q = f.passes[index];
	Q_strncpyz(q.name, name, sizeof(q.name));
	q.cpuStartUS = Sys_Microseconds();
	q.queryIndex = CmdBeginDurationQuery();

	return index;
}

void SRP::EndRenderPass(uint32_t index)
{
	if(!enableRenderPassQueries)
	{
		CmdEndDebugLabel();
		return;
	}

	Q_assert(index != 0xDEADBEEF); // enableRenderPassQueries should still be false!
	RenderPassFrame& f = renderPasses[tr.frameCount % FrameCount];
	if(index >= f.count)
	{
		Q_assert(0);
		return;
	}

	CmdEndDebugLabel();

	RenderPassQueries& q = f.passes[index];
	q.cpuDurationUS = (uint32_t)(Sys_Microseconds() - q.cpuStartUS);
	CmdEndDurationQuery(q.queryIndex);
}

void SRP::DrawGUI()
{
	uint32_t durations[MaxDurationQueries];
	GetDurations(durations);

	wholeFrameStats.EndFrame(rhie.renderToPresentUS, durations[0]);

	const RenderPassFrame& currFrame = renderPasses[(tr.frameCount % FrameCount) ^ 1];
	RenderPassFrame& tempFrame = tempRenderPasses;

	// see if the render pass list is the same as the previous frame's
	bool sameRenderPass = true;
	if(currFrame.count == tempRenderPasses.count)
	{
		for(uint32_t p = 0; p < currFrame.count; ++p)
		{
			if(Q_stricmp(currFrame.passes[p].name, tempRenderPasses.passes[p].name) != 0)
			{
				sameRenderPass = false;
				break;
			}
		}
	}
	else
	{
		sameRenderPass = false;
	}

	// write out the displayed timings into the temp buffer
	tempFrame.count = currFrame.count;
	if(sameRenderPass)
	{
		for(uint32_t p = 0; p < currFrame.count; ++p)
		{
			const uint32_t index = currFrame.passes[p].queryIndex;
			if(index < MaxDurationQueries)
			{
				renderPassStats[p].EndFrame(currFrame.passes[p].cpuDurationUS, durations[index]);
				tempFrame.passes[p].gpuDurationUS = renderPassStats[p].statsGPU.median;
				tempFrame.passes[p].cpuDurationUS = renderPassStats[p].statsCPU.median;
			}
		}
	}
	else
	{
		for(uint32_t p = 0; p < currFrame.count; ++p)
		{
			const uint32_t index = currFrame.passes[p].queryIndex;
			if(index < MaxDurationQueries)
			{
				tempFrame.passes[p].gpuDurationUS = durations[index];
				tempFrame.passes[p].cpuDurationUS = currFrame.passes[p].cpuDurationUS;
			}
		}
	}

	static bool breakdownActive = false;
	ToggleBooleanWithShortcut(breakdownActive, ImGuiKey_F);
	GUI_AddMainMenuItem(GUI_MainMenu::Perf, "Frame breakdown", "Ctrl+F", &breakdownActive);
	if(breakdownActive)
	{
		if(ImGui::Begin("Frame breakdown", &breakdownActive, ImGuiWindowFlags_AlwaysAutoResize))
		{
			if(BeginTable("Frame breakdown", 3))
			{
				TableHeader(3, "Pass", "GPU [us]", "CPU [us]");

				TableRow(3, "Whole frame",
					va("%d", (int)wholeFrameStats.statsGPU.median),
					va("%d", (int)wholeFrameStats.statsCPU.median));

				for(uint32_t p = 0; p < currFrame.count; ++p)
				{
					const RenderPassQueries& rp = tempFrame.passes[p];
					if(rp.queryIndex < MaxDurationQueries)
					{
						TableRow(3, rp.name,
							va("%d", (int)rp.gpuDurationUS),
							va("%d", (int)rp.cpuDurationUS));
					}
				}

				ImGui::EndTable();
			}

			if(psoStatsValid)
			{
				ImGui::Text("PSO count: %d", (int)psoCount);
				ImGui::Text("PSO changes: %d", (int)psoChangeCount);
			}
		}
		ImGui::End();
	}

	// save the current render pass list in the temp buffer
	memcpy(&tempFrame, &currFrame, sizeof(tempFrame));

	static bool frameTimeActive = false;
	GUI_AddMainMenuItem(GUI_MainMenu::Perf, "Frame stats", NULL, &frameTimeActive);
	if(frameTimeActive)
	{
		if(ImGui::Begin("Frame stats", &frameTimeActive, ImGuiWindowFlags_AlwaysAutoResize))
		{
			if(BeginTable("Frame stats", 2))
			{
				const FrameStats& fs = frameStats;
				const stats_t& s = fs.p2pStats;
				TableRow2("Skipped frames", fs.skippedFrames);
				TableRow2("Frame time target", rhie.targetFrameDurationMS);
				TableRow2("Frame time average", s.average);
				TableRow2("Frame time std dev.", s.stdDev);
				TableRow2("Input to render", (float)rhie.inputToRenderUS / 1000.0f);
				TableRow2("Input to present", (float)rhie.inputToPresentUS / 1000.0f);

				ImGui::EndTable();
			}
		}
		ImGui::End();
	}

	static bool graphsActive = false;
	ToggleBooleanWithShortcut(graphsActive, ImGuiKey_G);
	GUI_AddMainMenuItem(GUI_MainMenu::Perf, "Frame time graphs", "Ctrl+G", &graphsActive);
	if(graphsActive)
	{
		const int windowFlags =
			ImGuiWindowFlags_NoDecoration |
			ImGuiWindowFlags_NoBackground |
			ImGuiWindowFlags_NoMove;
		ImGui::SetNextWindowSize(ImVec2(glConfig.vidWidth, glConfig.vidHeight / 2), ImGuiCond_Always);
		ImGui::SetNextWindowPos(ImVec2(0, glConfig.vidHeight / 2), ImGuiCond_Always);
		if(ImGui::Begin("Frame time graphs", &graphsActive, windowFlags))
		{
			const FrameStats& fs = frameStats;
			const double target = (double)rhie.targetFrameDurationMS;

			static bool autoFit = false;
			ImGui::Checkbox("Auto-fit", &autoFit);

			if(ImPlot::BeginPlot("Frame Times", ImVec2(-1, -1), ImPlotFlags_NoInputs))
			{
				const int axisFlags = 0; // ImPlotAxisFlags_NoTickLabels
				const int axisFlagsY = axisFlags | (autoFit ? ImPlotAxisFlags_AutoFit : 0);
				ImPlot::SetupAxes(NULL, NULL, axisFlags, axisFlagsY);
				ImPlot::SetupAxisLimits(ImAxis_X1, 0, FrameStats::MaxFrames, ImGuiCond_Always);
				if(!autoFit)
				{
					ImPlot::SetupAxisLimits(ImAxis_Y1, max(target - 2.0, 0.0), target + 2.0, ImGuiCond_Always);
				}

				ImPlot::SetNextFillStyle(IMPLOT_AUTO_COL, 1.0f);
				ImPlot::SetNextLineStyle(IMPLOT_AUTO_COL, 1.0f);
				ImPlot::PlotInfLines("Target", &target, 1, ImPlotInfLinesFlags_Horizontal);

				ImPlot::SetNextFillStyle(IMPLOT_AUTO_COL, 1.0f);
				ImPlot::SetNextLineStyle(IMPLOT_AUTO_COL, 1.0f);
				ImPlot::PlotLineG("Frame Time", &FrameTimeGetter, NULL, fs.frameCount, ImPlotLineFlags_None);

				ImPlot::EndPlot();
			}
		}
		ImGui::End();
	}

	GUI_DrawMainMenu();
	R_DrawGUI();
}

void SRP::BeginFrame()
{
	srp.renderPasses[tr.frameCount % FrameCount].count = 0;
	R_SetColorMappings();

	// nothing is bound to the command list yet!
	srp.renderMode = RenderMode::None;
}

void SRP::EndFrame()
{
	tr.tracedWorldShaderIndex = -1;
	if(tr.traceWorldShader && tr.world != NULL)
	{
		// schedule a GPU -> CPU transfer
		{
			BufferBarrier barrier(traceRenderBuffer, ResourceStates::CopySourceBit);
			CmdBarrier(0, NULL, 1, &barrier);
		}
		CmdCopyBuffer(traceReadbackBuffer, traceRenderBuffer);
		{
			BufferBarrier barrier(traceRenderBuffer, ResourceStates::UnorderedAccessBit);
			CmdBarrier(0, NULL, 1, &barrier);
		}

		// grab last frame's result
		uint32_t* shaderIndices = (uint32_t*)MapBuffer(traceReadbackBuffer);
		const uint32_t shaderIndex = shaderIndices[RHI::GetFrameIndex() ^ 1];
		UnmapBuffer(traceReadbackBuffer);
		if(shaderIndex < (uint32_t)tr.numShaders)
		{
			tr.tracedWorldShaderIndex = (int)shaderIndex;
		}
	}

	RHI::EndFrame();

	if(rhie.presentToPresentUS > 0)
	{
		frameStats.p2pMS[frameStats.frameIndex] = (float)rhie.presentToPresentUS / 1000.0f;
		frameStats.EndFrame();
	}
	else
	{
		frameStats.skippedFrames++;
	}

	if(backEnd.renderFrame)
	{
		Sys_V_EndFrame();
	}
}

void SRP::CreateShaderTraceBuffers()
{
	{
		BufferDesc desc("shader trace opaque", 2 * sizeof(uint32_t), ResourceStates::UnorderedAccessBit);
		traceRenderBuffer = CreateBuffer(desc);
	}

	{
		BufferDesc desc("shader trace opaque readback", 2 * sizeof(uint32_t), ResourceStates::Common);
		desc.memoryUsage = MemoryUsage::Readback;
		traceReadbackBuffer = CreateBuffer(desc);
	}
}