#include "RenderMaterial.h"

namespace raytry {
    RenderMaterial::RenderMaterial(QColor materialColor) : diffuseColor{materialColor}, ambientIntensity{0.1f}, diffuseIntensity{0.75f}, specularIntensity{0.15f}, specularFalloff{10.0f}, reflectivity{0}, transparency{0}, refractionIndex{0} {
        ambientColor = mixColor(materialColor, 0.25f);
        specularColor = addColors({204, 204, 204}, mixColor(materialColor, 0.2f));
    }

    RenderMaterial::RenderMaterial(float ambientIntensity, const QColor &ambientColor, float diffuseIntensity, const QColor &diffuseColor, float specularIntensity, float specularFalloff, const QColor &specularColor) : ambientIntensity(ambientIntensity), ambientColor(ambientColor), diffuseIntensity(diffuseIntensity), diffuseColor(diffuseColor), specularIntensity(specularIntensity), specularFalloff(specularFalloff), specularColor(specularColor), reflectivity{0}, transparency{0}, refractionIndex{0} {
        assert(ambientIntensity >= 0 && ambientIntensity <= 1);
        assert(diffuseIntensity >= 0 && diffuseIntensity <= 1);
        assert(specularIntensity >= 0 && specularIntensity <= 1);
        assert(qFuzzyCompare(1.0f, ambientIntensity + diffuseIntensity + specularIntensity));
    }

    RenderMaterial::RenderMaterial(float ambientIntensity, const QColor &ambientColor, float diffuseIntensity, const QColor &diffuseColor, float specularIntensity, float specularFalloff, const QColor &specularColor, float reflectivity, float transparency, float refractionIndex) : ambientIntensity(ambientIntensity), ambientColor(ambientColor), diffuseIntensity(diffuseIntensity), diffuseColor(diffuseColor), specularIntensity(specularIntensity), specularFalloff(specularFalloff), specularColor(specularColor), reflectivity(reflectivity), transparency(transparency), refractionIndex(refractionIndex) {
        assert(ambientIntensity >= 0 && ambientIntensity <= 1);
        assert(diffuseIntensity >= 0 && diffuseIntensity <= 1);
        assert(specularIntensity >= 0 && specularIntensity <= 1);
        assert(qFuzzyCompare(1.0f, ambientIntensity + diffuseIntensity + specularIntensity));
    }

    std::optional<Ray> RenderMaterial::refractionRay(const Ray &incoming, const QVector3D &hitpoint, const QVector3D &normal) const {
        // source: https://www.scratchapixel.com/code.php?id=32&origin=/lessons/3d-basic-rendering/phong-shader-BRDF
        float cosi = std::clamp(QVector3D::dotProduct(incoming.directionVec, normal), -1.0f, 1.0f);
        float etai = 1, etat = refractionIndex;
        QVector3D n = normal;
        if (cosi < 0) { cosi = -cosi; } else { std::swap(etai, etat); n= -normal; }
        float eta = etai / etat;
        float k = 1 - eta * eta * (1 - cosi * cosi);
        if (k < 0) {
            return std::nullopt;
        } else {
            return std::make_optional<Ray>(hitpoint, eta * incoming.directionVec + (eta * cosi - sqrtf(k)) * n);
        }
    }

    Ray RenderMaterial::reflectionRay(const Ray &incoming, const QVector3D &hitpoint, const QVector3D &normal) const {
        // source: https://www.scratchapixel.com/code.php?id=32&origin=/lessons/3d-basic-rendering/phong-shader-BRDF
        return {hitpoint, incoming.directionVec - (2 * QVector3D::dotProduct(incoming.directionVec, normal) * normal)};
    }

    QColor mixColor(QColor input, float intensity) {
        input.setRedF(input.redF() * intensity);
        input.setGreenF(input.greenF() * intensity);
        input.setBlueF(input.blueF() * intensity);
        return input;
    }

    QColor addColors(QColor color1, const QColor& color2) {
        color1.setRedF(color1.redF() + color2.redF());
        color1.setGreenF(color1.greenF() + color2.greenF());
        color1.setBlueF(color1.blueF() + color2.blueF());
        return color1;
    }
}