//
// Created by dominik on 8/12/24.
//

#include <cmath>
#include <random>

#include "base.h"

Motion::Motion(const double delta, const double eta, std::mt19937_64& rng) : m_delta(delta), m_eta(eta), m_rng(rng) {
    m_uni_dist = std::uniform_real_distribution(0., 1.);
}

Motion::Motion(std::mt19937_64& rng) : m_rng(rng) {
    m_uni_dist = std::uniform_real_distribution(0., 1.);
}

double Motion::omega_q(const double cos_theta, const double phi) const {
    const double cos_theta_square = cos_theta * cos_theta;
    const double sin_theta_square = 1. - cos_theta_square;

    return M_PI * m_delta * (3 * cos_theta_square - 1 - m_eta * sin_theta_square * cos(2.*phi));
}

double Motion::draw_position() {
    const double cos_theta = 1 - 2 * m_uni_dist(m_rng);
    const double phi = 2.0 * M_PI * m_uni_dist(m_rng);

    return omega_q(cos_theta, phi);
}