#include "Triangle.h"

namespace raytry {
    Triangle::Triangle(QVector3D a, QVector3D b, QVector3D c) : a{a}, b{b}, c{c} {
        an = bn = cn = QVector3D::crossProduct(b - a, c - a).normalized();
    }

    Triangle::Triangle(const QVector3D &a, const QVector3D &b, const QVector3D &c, const QVector3D &an, const QVector3D &bn, const QVector3D &cn, const RenderMaterial &mat) : a(a), b(b), c(c), an(an), bn(bn), cn(cn), mat(mat) {}

    std::optional<float> Triangle::intersects(const Ray &ray) const {
        // Möller, Trumbore
        const QVector3D &v0v1 = b - a;
        const QVector3D &v0v2 = c - a;
        const auto pvec = QVector3D::crossProduct(ray.directionVec, v0v2);
        const float det = QVector3D::dotProduct(v0v1, pvec);
        if (qFuzzyIsNull(det)) {
            return std::nullopt;
        }
        const float invDet = 1 / det;
        const auto tvec = ray.originVec - a;
        const float u = QVector3D::dotProduct(tvec, pvec) * invDet;
        if (u < 0 || u > 1) {
            return std::nullopt;
        }
        const auto qvec = QVector3D::crossProduct(tvec, v0v1);
        const float v = QVector3D::dotProduct(ray.directionVec, qvec) * invDet;
        if (v < 0 || u + v > 1) {
            return std::nullopt;
        }
        const auto& t = QVector3D::dotProduct(v0v2, qvec) * invDet;
        if (t < nearCrop) {
            return std::nullopt;
        }
        return std::make_optional<float>(t);
    }

    const QVector3D &Triangle::aVec() const {
        return a;
    }

    const QVector3D &Triangle::bVec() const {
        return b;
    }

    const QVector3D &Triangle::cVec() const {
        return c;
    }

    RenderMaterial Triangle::material() const {
        return mat;
    }

    void Triangle::setMaterial(RenderMaterial material) {
        mat = material;
    }

    QVector3D Triangle::calculateNormal(QVector3D hitpoint) const {
        // FIXME
        return an;
    }

}// namespace raytry