#ifndef MATERIAL_H
#define MATERIAL_H

#include "Algorithm/Sobol.h"
#include "Common.h"

typedef struct
{
    vec3s normal;
    vec3s position;
    vec3s wi;
    vec3s wo;
}shading_context_t;

typedef vec3s (*sample_bsdf_f)(const void* data, vec3s normal, vec3s wo, uint32_t index, uint32_t bounce, float* pdf_out);
typedef float (*sample_bsdf_pdf_f)(const void* data, vec3s normal, vec3s wo, vec3s wi);
typedef vec3s (*evaluate_bsdf_f)(const shading_context_t* context, const void* data);

typedef struct
{
    // TODO: alpha, displacement, etc.
    vec3s emission; // We have to have emission outside of data because data is only for bsdf, and emission is not part of bsdf. Maybe another shading properties struct is needed if the number of properties increases.
    sample_bsdf_f sample_bsdf;
    sample_bsdf_pdf_f sample_bsdf_pdf;
    evaluate_bsdf_f evaluate_bsdf;
    void* data;
}material_t;

typedef struct
{
    uint8_t id;
} material_entity_t;

//TODO: Handle material remove, we can use something like sparse set.
typedef struct
{
    uint8_t count;
    uint8_t size;
    material_t* buffer;
} material_collection_t;

bool material_collection_init(size_t size, material_collection_t* materials);
void material_collection_resize(material_collection_t* materials, size_t size);
void material_collection_free(material_collection_t* materials);

material_entity_t material_create(sample_bsdf_f sample, sample_bsdf_pdf_f sample_pdf, evaluate_bsdf_f evaluate, void* data, material_collection_t* collection);

vec3s sample_material_bsdf(const material_t* material, vec3s normal, vec3s wo, uint32_t sample_index, uint32_t bounce, float* pdf_out);
float sample_material_bsdf_pdf(const material_t* material, vec3s normal, vec3s wo, vec3s wi);
vec3s evaluate_material_bsdf(const material_t* material, const shading_context_t* context);

#endif // MATERIAL_H