/**
 * @file System.hpp
 * @author jun <jun@firmwarejun.net>
 * @brief System declarations
 * @version 0.1
 * @date 2023-07-25
 *
 * Copyright (c) 2023 jun <https://git.firmwarejun.net/jun/MolecularDynamics2>
 *
 */

#pragma once

#include <functional>
#include <vector>

#include "Atom.hpp"

typedef std::function<double(double)> PotentialFunction;
typedef std::function<double(double)> ForceFunction;

class System {
private:
  std::vector<Atom> atoms;    ///< Atoms in the system
  std::vector<Atom> atomsOld; ///< Atoms in the system in the previous step

  std::vector<double> forceTable;     ///< Force table
  std::vector<double> forceTableOld;  ///< Force table in the previous step
  std::vector<double> potentialTable; ///< Potential table

  ForceFunction     forceGenerator;     ///< Force generator
  PotentialFunction potentialGenerator; ///< Potential generator

  double rcut;  ///< Cutoff radius
  double rcut2; ///< Cutoff radius squared

  std::size_t tableResolution = 1000; ///< Resolution of the force table

  double timeDelta = 0; ///< Time delta between steps

  /**
   * @brief Initialize the force and potential tables
   *
   */
  void initTables();

  /**
   * @brief Evaluate interaction forces between atoms
   *
   */
  void evaulateForces();

public:
  explicit System(double            timeDelta,
                  double            rcut,
                  PotentialFunction potentialFunction,
                  ForceFunction     forceFunction,
                  std::size_t       tableResolution = 1000);

  void step();

  /**
   * @brief Step the system to the first step using euler method
   *
   */
  void stepFirst();

  /**
   * @brief Add an atom to the system
   *
   * @param atom
   */
  void addAtom(Atom atom);

  /**
   * @brief Add a vector of atoms to the system
   *
   * @param atoms
   */
  void addAtom(std::vector<Atom> atoms);

  /**
   * @brief Print atoms
   *
   */
  void printAtoms();
};