#ifndef BTCSDIFFUSION_H_
#define BTCSDIFFUSION_H_

#include <Eigen/Sparse>
#include <tuple>
#include <vector>

/*!
 * Datatype to fill the sparse matrix which is used to solve the equation
 * system.
 */
typedef Eigen::Triplet<double> T;

typedef std::vector<std::tuple<int,double>> boundary_condition;

/*!
 * Class implementing a solution for a 1/2/3D diffusion equation using backward
 * euler.
 */
class BTCSDiffusion {

public:

    static const int BC_NEUMANN;
    static const int BC_DIRICHLET;

  /*!
   * Create 1D-diffusion module.
   *
   * @param x Count of cells in x direction.
   */
  BTCSDiffusion(int x);

  /*!
   * Currently not implemented: Create 2D-diffusion module.
   *
   * @param x Count of cells in x direction.
   * @param y Count of cells in y direction.
   */
  BTCSDiffusion(int x, int y);

  /*!
   * Currently not implemented: Create 3D-diffusion module.
   *
   * @param x Count of cells in x direction.
   * @param y Count of cells in y direction.
   * @param z Count of cells in z direction.
   */
  BTCSDiffusion(int x, int y, int z);

  /*!
   * With given ghost zones simulate diffusion. Only 1D allowed at this moment.
   *
   * @param c Vector describing the concentration of one solution of the grid as
   * continious memory (Row-wise).
   * @param alpha Vector of diffusioncoefficients for each grid element.
   * @param timestep Time (in seconds ?) to simulate.
   */
  void simulate(std::vector<double> &c, std::vector<double> &alpha,
                double timestep);

private:

  boundary_condition bc;

  int grid_dim;
  int dim_x;
  int dim_y;
  int dim_z;
};

#endif // BTCSDIFFUSION_H_