#pragma once
#include "constants_float.hpp"
#include "vector2d_float.hpp"

// Needed for visual simulation, in order to distinguish two groups of pedestrians:
//    - White pedestrians move from left to right
//    - Black pedestrians move from right to left
enum Color { WHITE, BLACK};

struct Pedestrian {

  Color color;

  // $\vec{v}_{\alpha}(t)$
  Vector2d curr_vel; // v_alpha  (actual, ≤ v_max)

  // $\vec{w}_{\alpha}$
  Vector2d w; // w_alpha  (preferred, integrates force)

  // $\vec{r}_\alpha(t)$
  Vector2d curr_pos;

  // $\vec{e}_{\alpha}(t)$
  Vector2d e; // desired direction vector

  // $v_{\alpha}^{max} = 1.3 v^{0}_{\alpha}$
  float v_max;

  // $v_\alpha^0$
  float desired_v0;

  // $\vec{r}^0_\alpha$
  Vector2d destination;
  // $s_\beta^2 = (v_\beta \Delta t)^2$
  float s_b_sq;
  // $s_\beta \vec{e}_\beta$
  Vector2d s_b_e;

  // Default constructor: initializes a pedestrian with color WHITE and all vector/scalar fields set to zero.
  Pedestrian() : color(WHITE), curr_vel(0.0, 0.0), w(0.0, 0.0), curr_pos(0.0, 0.0), e(0.0, 0.0), v_max(0.0), desired_v0(0.0), destination(0.0, 0.0), s_b_sq(0.0), s_b_e(0.0, 0.0) {}

  // Constructs a pedestrian with the given initial state and precomputes the
  // quantities used in the pedestrian-pedestrian repulsion term.
  //
  // The preferred velocity w is initialized to the current velocity c_v. The
  // cached quantities s_b_sq and s_b_e correspond to the predicted step of this
  // pedestrian over $\Delta t$:
  //
  //   s_b     = ||c_v|| * dt
  //   s_b_sq  = s_b^2
  //   s_b_e   = e * s_b
  //
  // These values are used when another pedestrian computes the elliptical
  // interaction term involving this pedestrian.
  //
  // @param clr The display/color category of the pedestrian.
  // @param c_v The initial current velocity.
  // @param c_p The initial current position.
  // @param e The initial desired direction of motion.
  // @param v_max The maximum speed that the pedestrian can reach.
  // @param desired_v0 The desired walking speed.
  // @param d The pedestrian's target destination point.
  //
  Pedestrian(Color clr, Vector2d c_v, Vector2d c_p, Vector2d e, float v_max, float desired_v0, Vector2d d) : color(clr), curr_vel(c_v), w(c_v), curr_pos(c_p), e(e), v_max(v_max), desired_v0(desired_v0), destination(d), s_b_sq(c_v.dot(c_v) * delta_t_sq), s_b_e(e * c_v.norm() * delta_t) {}
};