#include "geostat.h"
#include "chunk_array.h"
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

/*FAST FOURIER TRANSFORM MOVING AVERAGE METHOD */
/*Turns a Gaussian white noise vector into a   */
/*spatially correlated vector                  */
/*input:                                       */
/*variogram: structure defining the variogram  */
/*           model                             */
/*grid: structure defining the grid            */
/*n: vector with the number of cells along the */
/*   X, Y and Z axes for the underlying grid   */
/*   i = [0 1 2]                               */
/*   --> 0 0 0        : n will be computed and */
/*   updated as output                         */
/*   --> nx ny nz: these dimensions are used   */
/*realin: structure defining a realization -   */
/*        must be a Gaussian white noise       */
/*output:                                      */
/*realout: structure defining a realization -  */

void FFTMA2(struct vario_mod variogram, struct grid_mod grid, int n[3], struct realization_mod* realin, struct realization_mod* realout, long* seed) {
    int NTOT, i, j, k, NMAX, NDIM, ntot, nmax, NXYZ, nxyz;
    int solver;
    double temp;
    chunk_array_t *covar, *ireal, *realization;
    double *workr, *worki;

    /*covariance axis normalization*/
    axes(variogram.ap, variogram.scf, variogram.Nvario);

    /*pseudo-grid definition*/
    cgrid(variogram, grid, n);

    /*constant definition*/
    NTOT = n[0] * n[1] * n[2];
    ntot = NTOT + 1;
    NMAX = n[0];
    NDIM = 3;
    for (i = 1; i < 3; i++) {
        if (n[i] > NMAX)
            NMAX = n[i];
        if (n[i] == 1)
            NDIM--;
    }
    nmax = NMAX + 1;
    NXYZ = grid.NX * grid.NY * grid.NZ;
    nxyz = NXYZ + 1;

    /*array initialization*/
    covar = chunk_array_create("covar.txt", ntot);

    workr = (double*)malloc(nmax * sizeof(double));
    testmemory(workr);

    worki = (double*)malloc(nmax * sizeof(double));
    testmemory(worki);

    printf("empece covariance\n");

    /*covariance function creation*/
    covariance(covar, variogram, grid, n);

    printf("termine covariance\n");

    ireal = chunk_array_create("ireal.txt", ntot);

    /*power spectrum*/
    fourt(covar, ireal, n, NDIM, 1, 0, workr, worki);

    realization = chunk_array_create("realization.txt", ntot);

    /*organization of the input Gaussian white noise*/
    solver = 0;
    prebuild_gwn(grid, n, realin, realization, solver, seed);

    /*forward fourier transform of the GWN*/
    fourt(realization, ireal, n, NDIM, 1, 0, workr, worki);

    /* build realization in spectral domain   */
    build_real(n, NTOT, covar, realization, ireal);

    chunk_array_free(covar);

    /*backward fourier transform*/
    fourt(realization, ireal, n, NDIM, 0, 1, workr, worki);

    chunk_array_free(ireal);

    free(workr);
    free(worki);

    /*output realization*/
    clean_real(realin, n, grid, realization, realout);
}