#pragma once

#include <cassert>
#include <cmath>
#include <cstring>
#include <eigen3/Eigen/Dense>

class Utility {
 public:
  template <typename Derived>
  static Eigen::Quaternion<typename Derived::Scalar> deltaQ(const Eigen::MatrixBase<Derived> &theta) {
    typedef typename Derived::Scalar Scalar_t;

    Eigen::Quaternion<Scalar_t> dq;
    Eigen::Matrix<Scalar_t, 3, 1> half_theta = theta;
    half_theta /= static_cast<Scalar_t>(2.0);
    dq.w() = static_cast<Scalar_t>(1.0);
    dq.x() = half_theta.x();
    dq.y() = half_theta.y();
    dq.z() = half_theta.z();
    return dq;
  }

  template <typename Derived>
  static Eigen::Matrix<typename Derived::Scalar, 3, 3> skewSymmetric(const Eigen::MatrixBase<Derived> &q) {
    Eigen::Matrix<typename Derived::Scalar, 3, 3> ans;
    ans << typename Derived::Scalar(0), -q(2), q(1), q(2), typename Derived::Scalar(0), -q(0), -q(1), q(0),
        typename Derived::Scalar(0);
    return ans;
  }

  template <typename Derived>
  static Eigen::Quaternion<typename Derived::Scalar> positify(const Eigen::QuaternionBase<Derived> &q) {
    // printf("a: %f %f %f %f", q.w(), q.x(), q.y(), q.z());
    // Eigen::Quaternion<typename Derived::Scalar> p(-q.w(), -q.x(), -q.y(), -q.z());
    // printf("b: %f %f %f %f", p.w(), p.x(), p.y(), p.z());
    // return q.template w() >= (typename Derived::Scalar)(0.0) ? q : Eigen::Quaternion<typename
    // Derived::Scalar>(-q.w(), -q.x(), -q.y(), -q.z());
    return q;
  }

  template <typename Derived>
  static Eigen::Matrix<typename Derived::Scalar, 4, 4> Qleft(const Eigen::QuaternionBase<Derived> &q) {
    Eigen::Quaternion<typename Derived::Scalar> qq = positify(q);
    Eigen::Matrix<typename Derived::Scalar, 4, 4> ans;
    ans(0, 0) = qq.w(), ans.template block<1, 3>(0, 1) = -qq.vec().transpose();
    ans.template block<3, 1>(1, 0) = qq.vec(), ans.template block<3, 3>(1, 1) =
                                                   qq.w() * Eigen::Matrix<typename Derived::Scalar, 3, 3>::Identity() +
                                                   skewSymmetric(qq.vec());
    return ans;
  }

  template <typename Derived>
  static Eigen::Matrix<typename Derived::Scalar, 4, 4> Qright(const Eigen::QuaternionBase<Derived> &p) {
    Eigen::Quaternion<typename Derived::Scalar> pp = positify(p);
    Eigen::Matrix<typename Derived::Scalar, 4, 4> ans;
    ans(0, 0) = pp.w(), ans.template block<1, 3>(0, 1) = -pp.vec().transpose();
    ans.template block<3, 1>(1, 0) = pp.vec(), ans.template block<3, 3>(1, 1) =
                                                   pp.w() * Eigen::Matrix<typename Derived::Scalar, 3, 3>::Identity() -
                                                   skewSymmetric(pp.vec());
    return ans;
  }

  static Eigen::Vector3d R2ypr(const Eigen::Matrix3d &R) {
    Eigen::Vector3d n = R.col(0);
    Eigen::Vector3d o = R.col(1);
    Eigen::Vector3d a = R.col(2);

    Eigen::Vector3d ypr(3);
    double y = atan2(n(1), n(0));
    double p = atan2(-n(2), n(0) * cos(y) + n(1) * sin(y));
    double r = atan2(a(0) * sin(y) - a(1) * cos(y), -o(0) * sin(y) + o(1) * cos(y));
    ypr(0) = y;
    ypr(1) = p;
    ypr(2) = r;

    return ypr / M_PI * 180.0;
  }

  template <typename Derived>
  static Eigen::Matrix<typename Derived::Scalar, 3, 3> ypr2R(const Eigen::MatrixBase<Derived> &ypr) {
    typedef typename Derived::Scalar Scalar_t;

    Scalar_t y = ypr(0) / 180.0 * M_PI;
    Scalar_t p = ypr(1) / 180.0 * M_PI;
    Scalar_t r = ypr(2) / 180.0 * M_PI;

    Eigen::Matrix<Scalar_t, 3, 3> Rz;
    Rz << cos(y), -sin(y), 0, sin(y), cos(y), 0, 0, 0, 1;

    Eigen::Matrix<Scalar_t, 3, 3> Ry;
    Ry << cos(p), 0., sin(p), 0., 1., 0., -sin(p), 0., cos(p);

    Eigen::Matrix<Scalar_t, 3, 3> Rx;
    Rx << 1., 0., 0., 0., cos(r), -sin(r), 0., sin(r), cos(r);

    return Rz * Ry * Rx;
  }

  static Eigen::Matrix3d g2R(const Eigen::Vector3d &g);

  template <size_t N>
  struct uint_ {};

  template <size_t N, typename Lambda, typename IterT>
  void unroller(const Lambda &f, const IterT &iter, uint_<N>) {
    unroller(f, iter, uint_<N - 1>());
    f(iter + N);
  }

  template <typename Lambda, typename IterT>
  void unroller(const Lambda &f, const IterT &iter, uint_<0>) {
    f(iter);
  }

  template <typename T>
  static T normalizeAngle(const T &angle_degrees) {
    T two_pi(2.0 * 180);
    if (angle_degrees > 0)
      return angle_degrees - two_pi * std::floor((angle_degrees + T(180)) / two_pi);
    else
      return angle_degrees + two_pi * std::floor((-angle_degrees + T(180)) / two_pi);
  };
};
