#include "precompiled.h"
#pragma hdrstop

#include "tr_local.h"
#include <math.h>

static idVec3 RB_DXRMakeVec3(float x, float y, float z)
{
	idVec3 v;
	v.x = x;
	v.y = y;
	v.z = z;
	return v;
}

static idVec3 RB_DXRSubVec3(const idVec3& a, const idVec3& b)
{
	return RB_DXRMakeVec3(a.x - b.x, a.y - b.y, a.z - b.z);
}

static idVec3 RB_DXRScaleVec3(const idVec3& v, float s)
{
	return RB_DXRMakeVec3(v.x * s, v.y * s, v.z * s);
}

static float RB_DXRDotVec3(const idVec3& a, const idVec3& b)
{
	return a.x * b.x + a.y * b.y + a.z * b.z;
}

static idVec3 RB_DXRCrossVec3(const idVec3& a, const idVec3& b)
{
	return RB_DXRMakeVec3(
		a.y * b.z - a.z * b.y,
		a.z * b.x - a.x * b.z,
		a.x * b.y - a.y * b.x);
}

static float RB_DXRLengthVec3(const idVec3& v)
{
	return sqrtf(v.x * v.x + v.y * v.y + v.z * v.z);
}

static idVec3 RB_DXRNormalizeVec3Safe(const idVec3& v, const idVec3& fallback)
{
	const float len = RB_DXRLengthVec3(v);
	if (len > 1e-20f)
	{
		const float invLen = 1.0f / len;
		return RB_DXRMakeVec3(v.x * invLen, v.y * invLen, v.z * invLen);
	}
	return fallback;
}

static idVec3 RB_DXRTransformLightVector(const idMat3& axis, const idVec3& v)
{
	return RB_DXRMakeVec3(
		axis[0].x * v.x + axis[1].x * v.y + axis[2].x * v.z,
		axis[0].y * v.x + axis[1].y * v.y + axis[2].y * v.z,
		axis[0].z * v.x + axis[1].z * v.y + axis[2].z * v.z);
}

static void RB_DXRReportPathTraceProfile(void)
{
	const int showProfile = r_showPathTraceProfile.GetInteger();
	if (showProfile <= 0)
		return;

	static int lastPrintTime = 0;
	if (showProfile == 1)
	{
		const int now = Sys_Milliseconds();
		if (now - lastPrintTime < 1000)
			return;
		lastPrintTime = now;
	}

	glRaytracingProfileCounters_t profile;
	if (!glRaytracingLightingGetProfileCounters(&profile))
		return;

	const uint32_t pixels = profile.width * profile.height;
	common->Printf(
		"pathTrace: %.2fms %ux%u px=%u lights=%u p/s/r=%u/%u/%u shadow=%u vol=%u spp=%u bounces=%u meshes=%u inst=%u rays/px direct=%u shadow=%u gi=%u giLight=%u gather=%u refl=%u volume=%u denoise=%u\n",
		profile.gpuMsec,
		profile.width,
		profile.height,
		pixels,
		profile.lightCount,
		profile.pointLightCount,
		profile.spotLightCount,
		profile.rectLightCount,
		profile.shadowCastingLightCount,
		profile.volumetricLightCount,
		profile.samplesPerPixel,
		profile.maxBounces,
		profile.meshCount,
		profile.instanceCount,
		profile.directLightSamplesPerPixel,
		profile.directShadowRaysPerPixel,
		profile.indirectBounceRaysPerPixel,
		profile.indirectLightEvalsPerPixel,
		profile.finalGatherRaysPerPixel,
		profile.reflectionRaysPerPixel,
		profile.volumetricShadowRaysPerPixel,
		profile.enableDenoiser);
}

static glRaytracingLight_t RB_DXRMakeSpotLightFromRenderLight(
	const renderLight_t& srcLight,
	const idVec3& worldOrigin,
	float r, float g, float b,
	float intensity)
{
	const idVec3 targetW = RB_DXRTransformLightVector(srcLight.axis, srcLight.target);
	const idVec3 rightW = RB_DXRTransformLightVector(srcLight.axis, srcLight.right);
	const idVec3 upW = RB_DXRTransformLightVector(srcLight.axis, srcLight.up);
	const idVec3 startW = RB_DXRTransformLightVector(srcLight.axis, srcLight.start);
	const idVec3 endW = RB_DXRTransformLightVector(srcLight.axis, srcLight.end);

	idVec3 fallbackDir = RB_DXRCrossVec3(rightW, upW);
	fallbackDir = RB_DXRNormalizeVec3Safe(fallbackDir, RB_DXRMakeVec3(0.0f, 0.0f, -1.0f));

	const idVec3 dir = RB_DXRNormalizeVec3Safe(targetW, fallbackDir);

	float centerDepth = RB_DXRDotVec3(targetW, dir);
	if (centerDepth <= 1e-4f)
	{
		centerDepth = RB_DXRLengthVec3(targetW);
	}
	if (centerDepth <= 1e-4f)
	{
		centerDepth = RB_DXRDotVec3(endW, dir);
	}
	if (centerDepth <= 1e-4f)
	{
		centerDepth = 64.0f;
	}

	const idVec3 rightPerp = RB_DXRSubVec3(
		rightW,
		RB_DXRScaleVec3(dir, RB_DXRDotVec3(rightW, dir)));

	const idVec3 upPerp = RB_DXRSubVec3(
		upW,
		RB_DXRScaleVec3(dir, RB_DXRDotVec3(upW, dir)));

	idVec3 axisU = RB_DXRCrossVec3(RB_DXRMakeVec3(0.0f, 0.0f, 1.0f), dir);
	axisU = RB_DXRNormalizeVec3Safe(axisU, RB_DXRMakeVec3(1.0f, 0.0f, 0.0f));
	axisU = RB_DXRNormalizeVec3Safe(rightPerp, axisU);

	idVec3 axisV = RB_DXRCrossVec3(dir, axisU);
	axisV = RB_DXRNormalizeVec3Safe(axisV, RB_DXRMakeVec3(0.0f, 1.0f, 0.0f));
	if (RB_DXRDotVec3(axisV, upPerp) < 0.0f)
	{
		axisV = RB_DXRScaleVec3(axisV, -1.0f);
	}

	float tanHalfWidth = RB_DXRLengthVec3(rightPerp) / centerDepth;
	float tanHalfHeight = RB_DXRLengthVec3(upPerp) / centerDepth;

	float nearPlane = RB_DXRDotVec3(startW, dir);
	if (nearPlane < 0.0f)
	{
		nearPlane = 0.0f;
	}

	float farPlane = RB_DXRDotVec3(endW, dir);
	if (farPlane < centerDepth)
	{
		farPlane = centerDepth;
	}
	if (farPlane <= nearPlane)
	{
		farPlane = nearPlane + 64.0f;
	}

	glRaytracingLight_t light = glRaytracingLightingMakeSpotLight(
		worldOrigin.x, worldOrigin.y, worldOrigin.z,
		dir.x, dir.y, dir.z,
		axisU.x, axisU.y, axisU.z,
		axisV.x, axisV.y, axisV.z,
		nearPlane,
		farPlane,
		tanHalfWidth,
		tanHalfHeight,
		r, g, b,
		intensity,
		1u);

	light.samples = srcLight.noShadows ? 0u : 1u;
	light.pointRadiusPad = srcLight.noSpecular ? 1.0f : 0.0f;

	return light;
}

static void RB_DXRAddUniquePathTraceArea(idList<int>& areas, int areaNum)
{
	if (areaNum < 0)
		return;
	if (areas.FindIndex(areaNum) >= 0)
		return;
	areas.Append(areaNum);
}

static int RB_DXRSingleReferencedLightArea(const idRenderLightLocal* light)
{
	if (!light)
		return -1;

	int singleArea = -1;
	for (const areaReference_t* ref = light->references; ref; ref = ref->ownerNext)
	{
		if (!ref->area)
			continue;

		const int areaNum = ref->area->areaNum;
		if (singleArea < 0)
		{
			singleArea = areaNum;
			continue;
		}
		if (singleArea != areaNum)
		{
			return -1;
		}
	}

	return singleArea;
}

static bool RB_DXRBuildPathTraceLightAreaSet(idRenderWorldLocal* world, idList<int>& areas)
{
	areas.Clear();

	if (!r_pathTraceAreaLightCulling.GetBool())
		return false;
	if (!world || !backEnd.viewDef)
		return false;
	if (backEnd.viewDef->areaNum < 0)
		return false;
	if (world->pathTraceAreas.Num() != world->numPortalAreas)
		return false;

	const int depth = r_pathTraceAreaLightDepth.GetInteger();
	RB_DXRAddUniquePathTraceArea(areas, backEnd.viewDef->areaNum);

	int scanStart = 0;
	for (int step = 0; step < depth; step++)
	{
		const int scanEnd = areas.Num();
		for (int i = scanStart; i < scanEnd; i++)
		{
			const int areaNum = areas[i];
			if (areaNum < 0 || areaNum >= world->pathTraceAreas.Num())
				continue;

			const idRenderWorldLocal::pathTraceArea_t& area = world->pathTraceAreas[areaNum];
			if (!area.valid)
				continue;

			for (int neighborIndex = 0; neighborIndex < area.neighbors.Num(); neighborIndex++)
			{
				RB_DXRAddUniquePathTraceArea(areas, area.neighbors[neighborIndex]);
			}
		}

		if (areas.Num() == scanEnd)
			break;
		scanStart = scanEnd;
	}

	return areas.Num() > 0;
}

static bool RB_DXRPathTraceLightTouchesAreaSet(const idRenderLightLocal* light, const idList<int>& areas)
{
	if (!light)
		return true;

	if (light->areaNum >= 0 && areas.FindIndex(light->areaNum) >= 0)
		return true;

	for (const areaReference_t* ref = light->references; ref; ref = ref->ownerNext)
	{
		if (ref->area && areas.FindIndex(ref->area->areaNum) >= 0)
			return true;
	}

	return false;
}

/*
====================
RB_DXDrawInteractions
====================
*/
void RB_DXDrawInteractions(void)
{
	viewLight_t* vLight;

	QD3D12_SetToneMapBrightness(r_brightness.GetFloat());
	QD3D12_SetFrameGenerationMultiplier(r_frameGen.GetInteger());
	QD3D12_SetDepthOfField(
		r_depthOfField.GetBool() ? 1 : 0,
		r_dofFocusDistance.GetFloat(),
		r_dofFocusRange.GetFloat(),
		r_dofMaxBlur.GetFloat(),
		r_dofAmount.GetFloat(),
		r_dofDebug.GetBool() ? 1 : 0);

	idList<glRaytracingLight_t> screenParticleLights;
	idList<int> pathTraceLightAreas;
	const bool usePathTraceLightAreas = RB_DXRBuildPathTraceLightAreaSet(backEnd.viewDef ? backEnd.viewDef->renderWorld : NULL, pathTraceLightAreas);

	for (vLight = backEnd.viewDef->viewLights; vLight; vLight = vLight->next)
	{
		backEnd.vLight = vLight;

		// do fogging later
		if (vLight->lightShader->IsFogLight())
		{
			continue;
		}
		if (vLight->lightShader->IsBlendLight())
		{
			continue;
		}
		if (!R_MaskedOcclusionCulling_LightIsVisible(backEnd.viewDef, vLight->lightDef))
		{
			continue;
		}
		if (usePathTraceLightAreas && !RB_DXRPathTraceLightTouchesAreaSet(vLight->lightDef, pathTraceLightAreas))
		{
			continue;
		}

		const renderLight_t& srcLight = vLight->lightDef->parms;
		const float r = srcLight.shaderParms[SHADERPARM_RED];
		const float g = srcLight.shaderParms[SHADERPARM_GREEN];
		const float b = srcLight.shaderParms[SHADERPARM_BLUE];
		const float intensity = 6.0f;

		glRaytracingLight_t light = {};
		bool supported = true;

		if (srcLight.pointLight)
		{
			light = glRaytracingLightingMakePointLight(
				vLight->globalLightOrigin.x,
				vLight->globalLightOrigin.y,
				vLight->globalLightOrigin.z,
				srcLight.lightRadius[0] * 1.15f,
				srcLight.lightRadius[1] * 1.15f,
				srcLight.lightRadius[2] * 1.5f,
				r, g, b,
				intensity);

			light.samples = srcLight.noShadows ? 0u : 1u;
			light.pointRadiusPad = srcLight.noSpecular ? 1.0f : 0.0f;
			light.areaNum = RB_DXRSingleReferencedLightArea(vLight->lightDef);

			const idVec3 axisU = RB_DXRNormalizeVec3Safe(RB_DXRTransformLightVector(srcLight.axis, RB_DXRMakeVec3(1.0f, 0.0f, 0.0f)), RB_DXRMakeVec3(1.0f, 0.0f, 0.0f));
			const idVec3 axisV = RB_DXRNormalizeVec3Safe(RB_DXRTransformLightVector(srcLight.axis, RB_DXRMakeVec3(0.0f, 1.0f, 0.0f)), RB_DXRMakeVec3(0.0f, 1.0f, 0.0f));
			const idVec3 axisW = RB_DXRNormalizeVec3Safe(RB_DXRTransformLightVector(srcLight.axis, RB_DXRMakeVec3(0.0f, 0.0f, 1.0f)), RB_DXRMakeVec3(0.0f, 0.0f, 1.0f));
			light.axisU.x = axisU.x;
			light.axisU.y = axisU.y;
			light.axisU.z = axisU.z;
			light.axisV.x = axisV.x;
			light.axisV.y = axisV.y;
			light.axisV.z = axisV.z;
			light.normal.x = axisW.x;
			light.normal.y = axisW.y;
			light.normal.z = axisW.z;
		}
		else if (!srcLight.parallel)
		{
			light = RB_DXRMakeSpotLightFromRenderLight(
				srcLight,
				vLight->globalLightOrigin,
				r, g, b,
				intensity);
			light.areaNum = RB_DXRSingleReferencedLightArea(vLight->lightDef);
		}
		else
		{
			// Parallel projected lights are not spot lights.
			// Handle them in a separate directional/orthographic path.
			supported = false;
			common->Warning("Parallel lights are not needed with raytracing! Just place a skybox.");
		}

		if (supported) {
			if (vLight->iesImage) {
				vLight->iesImage->Bind();
				if (vLight->iesImage->texnum != idImage::TEXTURE_NOT_LOADED) {
					light.iesTextureId = vLight->iesImage->texnum;
					light.iesStrength = 1.0f;
				}
			}
			glRaytracingLightingAddLight(&light);
			screenParticleLights.Append(light);
		}
	}

	if (backEnd.viewDef->renderWorld)
	{
		backEnd.viewDef->renderWorld->SubmitWorldDecalsToScreenSpace();
		glSetScreenSpaceParticleLightsQD3D12(screenParticleLights.Ptr(), screenParticleLights.Num());
		glRaytracingLightingSetGIAmount(r_pathTraceGIAmount.GetFloat());
		glRaytracingLightingSetWorldGrime(r_pathTraceWorldGrime.GetFloat());
		glRaytracingLightingSetSecondaryLightBudget(
			r_pathTraceSecondaryLightBudget.GetInteger(),
			r_pathTraceSecondaryLightCompensation.GetFloat());
		glLightScene(backEnd.viewDef->renderWorld->dxrWorldId);
		RB_DXRReportPathTraceProfile();
		glRaytracingLightingClearLights(false);
	}
}