// # This file uses avx2
// # This is the first variant and should serve as a base for further avx2 optimizations

// Okay our first step is to use a SoA instead of an AoS
// We only do SoA for the pedestrian struct, there we wanna optimize such that we access for the ped-ped forces adjacent pedestrians (in the arrays)

#include "../headers/board.hpp"
#include "../headers/constants.hpp"
#include "../headers/pedestrian_reduced.hpp"

#include <algorithm>
#include <cmath>
#include <fstream>
#include <iostream>
#include <math.h>
#include <random>
#include <tuple>
#include <vector>

#define SEED 42
#define BOARD_WIDTH 10.0
#define BOARD_LENGTH 50.0
#define WALL_EPS 1e-3
#define BOARD_WIDTH_MINUS_WALL_EPS 9.999

#ifndef RANDOM_SEED
#define RANDOM_SEED 0
#endif

#ifndef BENCHMARK
#define BENCHMARK 0
#endif

using namespace std;

// we wanna use arrays so we can implement SOA, we create arrays for all the data we need and access
vector<double> pos_x, pos_y;
vector<double> sb_sq;
vector<double> sb_e_x, sb_e_y;
vector<double> e_x, e_y;
vector<double> curr_vel_x, curr_vel_y;
vector<double> w_x, w_y;
vector<double> desired_v0;
vector<double> v_max;
vector<double> destination_x, destination_y;
vector<int> color;

Pedestrian *init_pedestrians(int n_p) {

#if RANDOM_SEED
  random_device rd;
  mt19937 gen(rd());
#else
  mt19937 gen(SEED);
#endif

  normal_distribution<double> velocity_gen(v0_mean, v0_std_dev);
  uniform_real_distribution<double> y_gen(0.3, BOARD_WIDTH - 0.3);
  uniform_real_distribution<double> x_gen_left(2.0, BOARD_LENGTH / 2.0);
  uniform_real_distribution<double> x_gen_right(BOARD_LENGTH / 2.0, BOARD_LENGTH - 2.0);

  // resize all our arrays for this run
  pos_x.resize(n_p);
  pos_y.resize(n_p);
  sb_sq.resize(n_p);
  sb_e_x.resize(n_p);
  sb_e_y.resize(n_p);
  e_x.resize(n_p);
  e_y.resize(n_p);
  curr_vel_x.resize(n_p);
  curr_vel_y.resize(n_p);
  w_x.resize(n_p);
  w_y.resize(n_p);
  desired_v0.resize(n_p);
  v_max.resize(n_p);
  destination_x.resize(n_p);
  destination_y.resize(n_p);
  color.resize(n_p);

  int n_p_half = n_p / 2;

  for (int i = 0; i < n_p_half; i++) {
    double x = x_gen_left(gen);
    double y = y_gen(gen);

    double dest_x = BOARD_LENGTH + 30.0; // renamed to avoid shadowing destination_x[]
    double dest_y = y;                   // same idea for destination_y[]

    double init_e_x = dest_x - x;
    double init_e_y = dest_y - y;
    double init_e_norm = sqrt(init_e_x * init_e_x + init_e_y * init_e_y);
    double init_e_unit_x = init_e_x / init_e_norm;
    double init_e_unit_y = init_e_y / init_e_norm;

    double d_v0;
    do {
      d_v0 = velocity_gen(gen);
    } while (d_v0 <= 0.1);

    double v_m = 1.3 * d_v0;

    color[i] = 0;
    pos_x[i] = x;
    pos_y[i] = y;
    e_x[i] = init_e_unit_x;
    e_y[i] = init_e_unit_y;
    v_max[i] = v_m;
    desired_v0[i] = d_v0;
    destination_x[i] = dest_x;
    destination_y[i] = dest_y;

    // Fields the Pedestrian constructor would have zero-initialized:
    w_x[i] = 0.0;
    w_y[i] = 0.0;
    curr_vel_x[i] = 0.0;
    curr_vel_y[i] = 0.0;
    sb_sq[i] = 0.0;
    sb_e_x[i] = 0.0;
    sb_e_y[i] = 0.0;
  }

  for (int i = n_p_half; i < n_p; i++) {
    double x = x_gen_right(gen);
    double y = y_gen(gen);

    double dest_x = -30;
    double dest_y = y;

    double init_e_x = dest_x - x;
    double init_e_y = dest_y - y;
    double init_e_norm = sqrt(init_e_x * init_e_x + init_e_y * init_e_y);
    double init_e_unit_x = init_e_x / init_e_norm;
    double init_e_unit_y = init_e_y / init_e_norm;

    double d_v0;
    do {
      d_v0 = velocity_gen(gen);
    } while (d_v0 <= 0.1);

    double v_m = 1.3 * d_v0;

    color[i] = 1;
    pos_x[i] = x;
    pos_y[i] = y;
    e_x[i] = init_e_unit_x;
    e_y[i] = init_e_unit_y;
    v_max[i] = v_m;
    desired_v0[i] = d_v0;
    destination_x[i] = dest_x;
    destination_y[i] = dest_y;

    // Fields the Pedestrian constructor would have zero-initialized:
    w_x[i] = 0.0;
    w_y[i] = 0.0;
    curr_vel_x[i] = 0.0;
    curr_vel_y[i] = 0.0;
    sb_sq[i] = 0.0;
    sb_e_x[i] = 0.0;
    sb_e_y[i] = 0.0;
  }

  return nullptr;
}

Board init_board_without_obstacles() { return Board(BOARD_LENGTH, BOARD_WIDTH, 0, nullptr); }

int run_simulation(Pedestrian *pedestrians, Board &board, int n_p, int n_iter, const char *dump_path) {

#if BENCHMARK
  (void)dump_path;
#endif

#if !BENCHMARK
  const int dump_interval = 1;

  vector<tuple<int, int, double, double, double, double, int>> samples;

  if (dump_path) {
    samples.reserve(static_cast<size_t>(n_iter / dump_interval + 1) * n_p);

    for (int i = 0; i < n_p; i++) {
      // Pedestrian &p = pedestrians[i];
      samples.emplace_back(0, i, pos_x[i], pos_y[i], e_x[i], e_y[i], color[i]);
    }
  }
#endif

  // # ADDs: n_iter * n_p * 11 +
  // #        n_iter * n_p * (n_p - 1) * 14 +
  // #        n_iter * n_p * board.n_obstacles * 12

  // # MULTs: n_iter * n_p * 21 +
  // #        n_iter * n_p * (n_p - 1) * 24 +
  // #        n_iter * n_p * board.n_obstacles * 19

  // # DIVs: n_iter * n_p * 2 +
  // #        n_iter * n_p * (n_p - 1) +
  // #        n_iter * n_p * board.n_obstacles

  // # SQRTs: n_iter * n_p * 3 +
  // #        n_iter * n_p * (n_p - 1) * 3 +
  // #        n_iter * n_p * board.n_obstacles

  // # EXPs: n_iter * n_p * (n_p - 1) +
  // #       n_iter * n_p * board.n_obstacles

  for (int t = 0; t < n_iter; t++) {

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

      double desired_velocity_x = e_x[i] * desired_v0[i];
      double desired_velocity_y = e_y[i] * desired_v0[i];

      double f_alpha_dt_x = (desired_velocity_x - curr_vel_x[i]) * dt_times_tau_alpha_inv;
      double f_alpha_dt_y = (desired_velocity_y - curr_vel_y[i]) * dt_times_tau_alpha_inv;

      for (int j = 0; j < n_p; j++) {

        if (i == j)
          continue;

        double r_ab_x = pos_x[i] - pos_x[j];
        double r_ab_y = pos_y[i] - pos_y[j];

        double r_ab_norm = sqrt(r_ab_x * r_ab_x + r_ab_y * r_ab_y);

        double r_ab2_x = r_ab_x - sb_e_x[j];
        double r_ab2_y = r_ab_y - sb_e_y[j];

        double r_ab2_norm = sqrt(r_ab2_x * r_ab2_x + r_ab2_y * r_ab2_y);
        double r_ab_norm_sum = r_ab_norm + r_ab2_norm;
        double two_b_sq = r_ab_norm_sum * r_ab_norm_sum - sb_sq[j];
        double two_b = sqrt(two_b_sq);
        double scalar_mult_common = (r_ab_norm_sum / (two_b * r_ab_norm * r_ab2_norm)) * (NEG_V0_AB_div_TWO_SIGMA * exp(two_b * NEG_TWO_SIGMA_INV));
        double scalar_mult_r_ab = scalar_mult_common * r_ab2_norm;
        double scalar_mult_r_ab2 = scalar_mult_common * r_ab_norm;

        double f_alpha_beta_neg_x = r_ab_x * scalar_mult_r_ab + r_ab2_x * scalar_mult_r_ab2;
        double f_alpha_beta_neg_y = r_ab_y * scalar_mult_r_ab + r_ab2_y * scalar_mult_r_ab2;

        double w_val;
        double a = (e_x[i] * f_alpha_beta_neg_x + e_y[i] * f_alpha_beta_neg_y) * cos_phi_inv;
        double b_sq = f_alpha_beta_neg_x * f_alpha_beta_neg_x + f_alpha_beta_neg_y * f_alpha_beta_neg_y;

        w_val = dt_neg;
        if (a >= 0 && (a * a > b_sq)) {
          w_val = c_neg_times_dt;
        }

        f_alpha_dt_x = f_alpha_dt_x + f_alpha_beta_neg_x * w_val;
        f_alpha_dt_y = f_alpha_dt_y + f_alpha_beta_neg_y * w_val;
      }

      for (int k = 0; k < board.n_obstacles; k++) {

        double v1_x = pos_x[i] - board.obstacles[k].start.x;
        double v1_y = pos_y[i] - board.obstacles[k].start.y;

        double projection = (v1_x * board.obstacles[k].obstacle_v.x + v1_y * board.obstacles[k].obstacle_v.y) * board.obstacles[k].length_sq_inv;

        if (projection < 0.0)
          projection = 0.0;
        else if (projection > 1.0)
          projection = 1.0;

        double r_aB_x = pos_x[i] - (board.obstacles[k].start.x + board.obstacles[k].obstacle_v.x * projection);
        double r_aB_y = pos_y[i] - (board.obstacles[k].start.y + board.obstacles[k].obstacle_v.y * projection);

        double r_aB_norm = sqrt(r_aB_x * r_aB_x + r_aB_y * r_aB_y);
        double scalar_mult = (NEG_U0_AB_div_R * exp(r_aB_norm * NEG_R_INV)) / r_aB_norm;
        double f_alpha_B_neg_x = r_aB_x * scalar_mult;
        double f_alpha_B_neg_y = r_aB_y * scalar_mult;

        double w_val;
        double a = (e_x[i] * f_alpha_B_neg_x + e_y[i] * f_alpha_B_neg_y) * cos_phi_inv;
        double b_sq = f_alpha_B_neg_x * f_alpha_B_neg_x + f_alpha_B_neg_y * f_alpha_B_neg_y;

        w_val = dt_neg;
        if (a >= 0 && (a * a > b_sq)) {
          w_val = c_neg_times_dt;
        }

        double f_alpha_B_dt_x = f_alpha_B_neg_x * w_val;
        double f_alpha_B_dt_y = f_alpha_B_neg_y * w_val;

        f_alpha_dt_x += f_alpha_B_dt_x;
        f_alpha_dt_y += f_alpha_B_dt_y;
      }

      w_x[i] += f_alpha_dt_x;
      w_y[i] += f_alpha_dt_y;
    }

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

      double w_norm = sqrt(w_x[i] * w_x[i] + w_y[i] * w_y[i]);

      double correction_factor = min(1.0, v_max[i] / w_norm);

      curr_vel_x[i] = w_x[i] * correction_factor;
      curr_vel_y[i] = w_y[i] * correction_factor;

      pos_x[i] = pos_x[i] + curr_vel_x[i] * dt;
      pos_y[i] = pos_y[i] + curr_vel_y[i] * dt;

      if (color[i] == 0 && pos_x[i] > (BOARD_LENGTH - 1.5)) {
        pos_x[i] = 1.0;
        destination_y[i] = pos_y[i];
        w_x[i] = desired_v0[i];
        w_y[i] = 0.0;
        curr_vel_x[i] = w_x[i];
        curr_vel_y[i] = w_y[i];
      }
      if (color[i] == 1 && pos_x[i] < 1.5) {
        pos_x[i] = BOARD_LENGTH - 1.0;
        destination_y[i] = pos_y[i];
        w_x[i] = -desired_v0[i];
        w_y[i] = 0.0;
        curr_vel_x[i] = w_x[i];
        curr_vel_y[i] = w_y[i];
      }

      pos_y[i] = clamp(pos_y[i], WALL_EPS, BOARD_WIDTH_MINUS_WALL_EPS);

      double ex = destination_x[i] - pos_x[i];
      double ey = destination_y[i] - pos_y[i];

      double e_norm_inv = 1.0 / sqrt(ex * ex + ey * ey);

      e_x[i] = ex * e_norm_inv;
      e_y[i] = ey * e_norm_inv;

      double velocity_norm_sq = curr_vel_x[i] * curr_vel_x[i] + curr_vel_y[i] * curr_vel_y[i];

      double velocity_norm = sqrt(velocity_norm_sq);

      sb_sq[i] = velocity_norm_sq * delta_t_sq;

      sb_e_x[i] = e_x[i] * (velocity_norm * delta_t);
      sb_e_y[i] = e_y[i] * (velocity_norm * delta_t);

#if !BENCHMARK
      if (dump_path && (t % dump_interval == 0)) {
        samples.emplace_back(t + 1, i, pos_x[i], pos_y[i], e_x[i], e_y[i], color[i]);
      }
#endif
    }
  }

#if !BENCHMARK
  if (dump_path) {
    ofstream out(dump_path);
    out << "time,id,x,y,p.e.x,p.e.y,color\n";

    for (auto &[t, id, x, y, e_x, e_y, c] : samples) {
      out << t << ',' << id << ',' << x << ',' << y << ',' << e_x << ',' << e_y << ',' << c << '\n';
    }
  }
#endif

  return 0;
}