#include "forces.hpp"
#include <math.h>

double w(Vector2d e, Vector2d f) {
  if (e.dot(f) >= f.norm() * cos_phi)
    return 1.0;
  else
    return c;
}

double g(double v_max_alpha, double w_alpha_norm) {
  if (w_alpha_norm <= v_max_alpha) {
    return 1;
  }
  return v_max_alpha / w_alpha_norm;
}

void compute_acceleration_term(Pedestrian *p) {
  Vector2d desired_velocity = p->e * p->desired_v0;
  Vector2d actual_velocity = p->curr_vel;
  p->f_i += (desired_velocity - actual_velocity) / tau_alpha;
}

void compute_repulsive_effects_from_pedestrians(Pedestrian *pedestrians, Pedestrian *p, int N) {

  for (int i = 0; i < N; i++) {

    if (pedestrians + i == p)
      continue;

    // # Optional: Do not consider far away pedestrians from current pedestrian
    // # Might get better speed up, remove if not
    // if ((pedestrians[i].curr_pos - p->curr_pos).norm() > DISTANCE) {
    //   continue;
    // }

    Vector2d r_ab = p->curr_pos - pedestrians[i].curr_pos;

    double r_ab_norm = r_ab.norm();

    Vector2d e_b = pedestrians[i].e;

    double s_b = pedestrians[i].desired_v0 * delta_t;

    Vector2d r_ab2 = r_ab - (e_b * s_b);

    double r_ab2_norm = r_ab2.norm();

    double b = sqrt(pow(r_ab_norm + r_ab2_norm, 2) - pow(s_b, 2)) / 2;

    Vector2d b_grad = (r_ab / r_ab_norm + r_ab2 / r_ab2_norm) * (r_ab_norm + r_ab2_norm) / (4 * b);

    Vector2d f_ped = b_grad * ((V0_AB / SIGMA) * (exp(-b / SIGMA)));

    p->f_i += f_ped * w(p->e, f_ped * -1);
  }
}

void compute_repulsive_effects_from_borders(Board &board, Pedestrian *p) {

  Obstacle *obstacles = board.obstacles;
  int n_borders = board.n_obstacles;

  for (int i = 0; i < n_borders; i++) {

    Obstacle obstacle = obstacles[i];

    Vector2d r_aB = p->curr_pos - obstacle.find_nearest_obstacle_point(p->curr_pos);

    Vector2d f_obst = (r_aB / r_aB.norm()) * (U0_AB / R) * std::exp(-r_aB.norm() / R);

    p->f_i += f_obst;
  }
}