#include "Lighting/LightEvaluation.h"
#include "Algorithm/BSDF.h"
#include "Algorithm/RayIntersection.h"

vec3s evaluate_bsdf_directional(directional_light_t light, const light_shading_context_t* context, vec3s throughput, uint32_t sample_index)
{
    float angular_radius = glm_rad(light.angular_diameter / 2.0f);

    uint16_t d1 = sobol_get_dimension(context->bounce_depth, PRNG_LIGHT_U);
    uint16_t d2 = sobol_get_dimension(context->bounce_depth, PRNG_LIGHT_V);

    vec3s wi = random_uniform_cdf_direction_angular(light.direction, sample_index, angular_radius, d1, d2);

    float n_dot_l = glms_vec3_dot(context->normal, wi);
    if (n_dot_l <= 0.0f)
    {
        return glms_vec3_zero();
    }

    ray_t shadow_ray = {
        .origin = BIAS_RAY_ORIGION(context->hit_point, context->normal),
        .direction = wi,
    };

    float closest = FLT_MAX;
    hit_result_t shadow_hit = {1};
    ray_intersect_bvh(shadow_ray, context->bvh_tree->nodes, context->bvh_tree->primitive_indices, context->bvh_tree->triangles, 0,
                      &closest, &shadow_hit);
    if (shadow_hit.hit)
    {
        return glms_vec3_zero();
    }

    shading_context_t shading_context = {
        .normal = context->normal,
        .wi = wi,
        .wo = glms_vec3_negate(context->wo)
    };
    vec3s bsdf = evaluate_material_bsdf(context->material, &shading_context);

    vec3s light_radiance = glms_vec3_scale(light.color, light.intensity);
    vec3s light_contribute = glms_vec3_scale(glms_vec3_mul(throughput, bsdf), fmaxf(0.0f, n_dot_l));
    return glms_vec3_mul(light_radiance, light_contribute);
}