#ifndef HERMITE_VALUE_H
#define HERMITE_VALUE_H

#include "../utility.h"
#include "../voxel_buffer.h"
#include <core/math/vector3.h>

namespace dmc {

struct HermiteValue {
	// TODO Rename isolevel
	float value; // Signed "distance" to surface
	Vector3 gradient; // "Normal" of the volume

	HermiteValue() :
			value(1.0) {
	}
};

inline HermiteValue get_hermite_value(const VoxelBuffer &voxels, unsigned int x, unsigned int y, unsigned int z) {

	x = x >= voxels.get_size().x ? voxels.get_size().x - 1 : x;
	x = x >= voxels.get_size().y ? voxels.get_size().y - 1 : x;
	x = x >= voxels.get_size().z ? voxels.get_size().z - 1 : x;

	HermiteValue v;

	v.value = voxels.get_voxel_iso(x, y, z, VoxelBuffer::CHANNEL_ISOLEVEL);
	// TODO It looks like this gradient should not be a normalized vector!
	v.gradient.x = voxels.get_voxel_iso(x, y, z, VoxelBuffer::CHANNEL_GRADIENT_X);
	v.gradient.y = voxels.get_voxel_iso(x, y, z, VoxelBuffer::CHANNEL_GRADIENT_Y);
	v.gradient.z = voxels.get_voxel_iso(x, y, z, VoxelBuffer::CHANNEL_GRADIENT_Z);

	return v;
}

inline HermiteValue get_interpolated_hermite_value(const VoxelBuffer &voxels, Vector3 pos) {

	int x0 = static_cast<int>(pos.x);
	int y0 = static_cast<int>(pos.y);
	int z0 = static_cast<int>(pos.z);

	int x1 = static_cast<int>(Math::ceil(pos.x));
	int y1 = static_cast<int>(Math::ceil(pos.y));
	int z1 = static_cast<int>(Math::ceil(pos.z));

	HermiteValue v0 = get_hermite_value(voxels, x0, y0, z0);
	HermiteValue v1 = get_hermite_value(voxels, x1, y0, z0);
	HermiteValue v2 = get_hermite_value(voxels, x1, y0, z1);
	HermiteValue v3 = get_hermite_value(voxels, x0, y0, z1);

	HermiteValue v4 = get_hermite_value(voxels, x0, y1, z0);
	HermiteValue v5 = get_hermite_value(voxels, x1, y1, z0);
	HermiteValue v6 = get_hermite_value(voxels, x1, y1, z1);
	HermiteValue v7 = get_hermite_value(voxels, x0, y1, z1);

	Vector3 rpos = pos - Vector3(x0, y0, z0);

	HermiteValue v;
	v.value = ::interpolate(v0.value, v1.value, v2.value, v3.value, v4.value, v5.value, v6.value, v7.value, rpos);
	v.gradient = ::interpolate(v0.gradient, v1.gradient, v2.gradient, v3.gradient, v4.gradient, v5.gradient, v6.gradient, v7.gradient, rpos);

	return v;
}

} // namespace dmc

#endif // HERMITE_VALUE_H