#include "Lighting/SkyLight.h"
#include "Algorithm/BSDF.h"
#include "Algorithm/RayIntersection.h"
#include "Material/Material.h"

vec3s evaluate_bsdf_const_sky(const void* data, const light_shading_context_t* context, sobol_state_t* sobol_state)
{
    const constant_sky_data_t sky_data = *(const constant_sky_data_t*)data;

    if (context == NULL)
    {
        return sky_data.color; // No context, return the sky color directly.
    }

    vec3s wi = random_cosine_direction(context->normal, sobol_state);
    float pdf = pdf_cosine_weighted_hemisphere(context->normal, wi);

    ray_t shadow_ray = {
        .origin = glms_vec3_add(context->hit_point, glms_vec3_scale(context->normal, 0.001f)),
        .direction = wi,
    };

    hit_result_t shadow_hit = ray_intersect_any(context->triangles, shadow_ray);
    if (shadow_hit.hit)
    {
        return glms_vec3_zero(); // Skip if the ray hits something
    }

    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);
    bsdf = glms_vec3_mul(bsdf, sky_data.color);
    float cos_theta = fmaxf(glms_vec3_dot(wi, context->normal), 0.0f);

    float pdf_bsdf = sample_material_bsdf_pdf(context->material, shading_context.normal, shading_context.wo, shading_context.wi);
    float weight = power_heuristic(pdf, pdf_bsdf);

    vec3s env_contrib = glms_vec3_scale(glms_vec3_mul(context->throughput, bsdf), cos_theta / pdf);
    return glms_vec3_scale(env_contrib, weight);
}