#include "/Lib/Settings.glsl"
#include "/Lib/Utilities.glsl"
// MinecraftPT — Shadow Tracing
// Direct sunlight shadow rays: march from surface toward the sun through the
// voxel grid. Soft penumbra via distance-weighted ray length.

#ifndef SHADOW_TRACING_GLSL
#define SHADOW_TRACING_GLSL

#include "/Lib/PathTracing/Tracer/TracingUtilities.glsl"

float ShadowTracing(vec3 viewPos, vec3 worldPos, vec3 vertexNormal, vec3 lightVector, float lightMap){
	float shadow = 1.0;

	vec3 voxelPos = WorldToVoxel(worldPos);
	voxelPos += vertexNormal * (-viewPos.z * 0.0003);

	if (clamp(voxelPos, vec3(0.0), vec3(voxelResolution)) == voxelPos){
		lightMap = saturate(1.0 - lightMap * 2.0);
		vec2 shadowWeight = vec2(
			4.0 - 2.0 * saturate(lightMap - viewPos.z * 0.01),
			0.2 + 0.5 * saturate(lightMap - viewPos.z * 0.01)
		);

		Ray ray = PackRay(voxelPos, lightVector);

		vec3 voxelCoord = floor(ray.ori);
		vec3 totalStep = (ray.sdir * (voxelCoord - ray.ori + 0.5) + 0.5) * abs(ray.rdir);
		float rayLength = 0.0;
		vec3 tracingNext;

		bool hit = false;

		for (int i = 0; i < 64; i++){
			if (clamp(voxelCoord, vec3(0.0), vec3(voxelResolution - 0.5)) != voxelCoord) break;

			vec4 voxelData = texelFetch(voxelData3D, ivec3(voxelCoord), 0);
			float voxelID = DecodeVoxelID(voxelData.z);

			// Full block or cutout shape
			if (voxelID >= 999.0){
				hit = rayLength > 0.0;
			}else if (voxelID < 1000.0 && voxelID > 1.0){
				float rawID = 1000.0 - voxelID;
				rayLength = minVec3(totalStep);
				hit = HitShape_Lite(ray, voxelCoord, rawID, rayLength);
			}

			if (hit){
				shadow = saturate((rayLength - shadowWeight.y) * shadowWeight.x);
				break;
			}

			// Sparse skip
			float marker = voxelData.z;
			if (marker > 0.60 && marker < 0.92){
				float skipSize = marker > 0.90 ? 8.0 : (marker > 0.70 ? 4.0 : 2.0);
				vec3 nextBoundary = floor((voxelCoord + 1.0) / skipSize) * skipSize;
				vec3 distToBoundary = (nextBoundary - voxelCoord) * abs(ray.rdir);
				float tSkip = minVec3(distToBoundary) + 1e-4;
				rayLength += tSkip;
				vec3 stepVec = ray.sdir * abs(ray.rdir) * tSkip;
				ray.ori += stepVec;
				voxelCoord = floor(ray.ori);
				totalStep = (ray.sdir * (voxelCoord - ray.ori + 0.5) + 0.5) * abs(ray.rdir);
				continue;
			}

			rayLength = minVec3(totalStep);
			tracingNext = step(totalStep, vec3(rayLength));
			voxelCoord += tracingNext * ray.sdir;
			totalStep += tracingNext * abs(ray.rdir);
		}
	}

	return shadow;
}

// Simplified version for IRC / light sampling (no soft penumbra)
float SimpleShadowTracing(vec3 voxelPos, vec3 lightVector){
	Ray ray = PackRay(voxelPos, lightVector);

	vec3 voxelCoord = floor(ray.ori);
	vec3 totalStep = (ray.sdir * (voxelCoord - ray.ori + 0.5) + 0.5) * abs(ray.rdir);
	float rayLength = 0.0;
	vec3 tracingNext;

	bool hit = false;

	for (int i = 0; i < 64; i++){
		if (clamp(voxelCoord, vec3(0.0), vec3(voxelResolution - 0.5)) != voxelCoord) break;

		vec4 voxelData = texelFetch(voxelData3D, ivec3(voxelCoord), 0);
		float voxelID = DecodeVoxelID(voxelData.z);

		if (voxelID >= 999.0){
			hit = rayLength > 0.0;
		}else if (voxelID < 1000.0 && voxelID > 1.0){
			float rawID = 1000.0 - voxelID;
			rayLength = minVec3(totalStep);
			hit = HitShape_Lite(ray, voxelCoord, rawID, rayLength);
		}

		if (hit) break;

		// Sparse skip
		float marker = voxelData.z;
		if (marker > 0.60 && marker < 0.92){
			float skipSize = marker > 0.90 ? 8.0 : (marker > 0.70 ? 4.0 : 2.0);
			vec3 nextBoundary = floor((voxelCoord + 1.0) / skipSize) * skipSize;
			vec3 distToBoundary = (nextBoundary - voxelCoord) * abs(ray.rdir);
			float tSkip = minVec3(distToBoundary) + 1e-4;
			rayLength += tSkip;
			vec3 stepVec = ray.sdir * abs(ray.rdir) * tSkip;
			ray.ori += stepVec;
			voxelCoord = floor(ray.ori);
			totalStep = (ray.sdir * (voxelCoord - ray.ori + 0.5) + 0.5) * abs(ray.rdir);
			continue;
		}

		rayLength = minVec3(totalStep);
		tracingNext = step(totalStep, vec3(rayLength));
		voxelCoord += tracingNext * ray.sdir;
		totalStep += tracingNext * abs(ray.rdir);
	}

	return float(!hit);
}

#endif