#include "geostat.h"
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include "log.h"

/* GENERATION OF A GAUSSIAN WHITE NOISE VECTOR    */
/*input:                                          */
/* seed: seed                                     */
/* n: number of components in the vector          */
/*output:                                         */
/* realization: structure defining the realization*/

void generate(long* seed, int n, struct realization_mod* realization) {
    clock_t t = clock();

    log_info("RESULT = in progress, n = %d", n);

    int i;
    long idum2 = 123456789, iy = 0;
    long* iv;
    int iset = 0;

    iv = (long*)malloc(NTAB * sizeof(long));

    /*negative seed*/
    if (*seed > 0.0)
        *seed = -(*seed);

    /*realization definition*/
    (*realization).n = n;
    (*realization).code = 0;
    (*realization).vector = (double*)malloc(n * sizeof(double));
    if ((*realization).vector == NULL) {
        log_error("RESULT = failed - No memory available in generate");
        exit;
    }

    /*Gaussian white noise generation*/
    for (i = 0; i < n; i++)
        (*realization).vector[i] = gasdev(seed, &idum2, &iy, iv, &iset);

    t = clock() - t;
    double time_taken = ((double)t)/CLOCKS_PER_SEC; // calculate the elapsed time

    log_info("RESULT = success, ELAPSED = %f seconds", time_taken);
    free(iv);
}