#include <inttypes.h>
#include "Gwater.h"
#include <unistd.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/glocale.h>

double get_dist(double *dist_to_nbr, double *contour)
{
    int ct_dir, r_nbr, c_nbr;
    double dx, dy, ns_res, ew_res;

    if (G_projection() == PROJECTION_LL) {
        double ew_dist1, ew_dist2, ew_dist3;
        double ns_dist1, ns_dist2, ns_dist3;

        G_begin_distance_calculations();

        /* EW Dist at North edge */
        ew_dist1 =
            G_distance(window.east, window.north, window.west, window.north);
        /* EW Dist at Center */
        ew_dist2 = G_distance(window.east, (window.north + window.south) / 2.,
                              window.west, (window.north + window.south) / 2.);
        /* EW Dist at South Edge */
        ew_dist3 =
            G_distance(window.east, window.south, window.west, window.south);
        /* NS Dist at East edge */
        ns_dist1 =
            G_distance(window.east, window.north, window.east, window.south);
        /* NS Dist at Center */
        ns_dist2 = G_distance((window.west + window.east) / 2., window.north,
                              (window.west + window.east) / 2., window.south);
        /* NS Dist at West edge */
        ns_dist3 =
            G_distance(window.west, window.north, window.west, window.south);

        ew_res = (ew_dist1 + ew_dist2 + ew_dist3) / (3 * window.cols);
        ns_res = (ns_dist1 + ns_dist2 + ns_dist3) / (3 * window.rows);
    }
    else {
        ns_res = window.ns_res;
        ew_res = window.ew_res;
    }

    for (ct_dir = 0; ct_dir < sides; ct_dir++) {
        /* get r, c (r_nbr, c_nbr) for neighbours */
        r_nbr = nextdr[ct_dir];
        c_nbr = nextdc[ct_dir];
        /* account for rare cases when ns_res != ew_res */
        dy = ABS(r_nbr) * ns_res;
        dx = ABS(c_nbr) * ew_res;
        if (ct_dir < 4)
            dist_to_nbr[ct_dir] = (dx + dy) * ele_scale;
        else
            dist_to_nbr[ct_dir] = sqrt(dx * dx + dy * dy) * ele_scale;
    }
    /* Quinn et al. 1991:
     * ns contour: ew_res / 2
     * ew contour: ns_res / 2
     * diag contour: sqrt(ns_res * nsres / 4 + ew_res * ew_res / 4) / 2
     *             = sqrt(ns_res * nsres + ew_res * ew_res) / 4
     * if ns_res == ew_res:
     *             sqrt(2 * (res * res) / 4 = res * 0.354
     *
     * contour lengths "have been subjectively chosen",
     * no justification why the diagonal contour is shorter
     * BUT: if the diag contour is a bit shorter than the cardinal contour,
     * this is further enhancing the correction for diagonal flow bias
     * diagonal slope is already corrected for longer distance
     * smaller slope and shorter contour length have the same effect:
     * higher TCI
     */
    if (sides == 8) {
        /* contours are sides of an octagon, irregular if ns_res != ew_res
         * ideally: arc lengths of an ellipse */
        contour[0] = contour[1] = tan(atan(ew_res / ns_res) / 2.) * ns_res;
        contour[2] = contour[3] = tan(atan(ns_res / ew_res) / 2.) * ew_res;
        G_debug(1, "ns contour: %.4f", contour[0]);
        G_debug(1, "ew contour: %.4f", contour[2]);
        contour[4] = (ew_res - contour[0]);
        contour[5] = (ns_res - contour[2]);
        contour[7] =
            sqrt(contour[4] * contour[4] + contour[5] * contour[5]) / 2.;
        G_debug(1, "diag contour: %.4f", contour[7]);
        contour[4] = contour[5] = contour[6] = contour[7];
    }
    else {
        /* contours are sides of a rectangle */
        contour[0] = contour[1] = ew_res;
        contour[2] = contour[3] = ns_res;
    }
    return ew_res * ns_res;
}

double get_slope_tci(CELL ele, CELL down_ele, double dist)
{
    if (down_ele >= ele)
        return 0.5 / dist;
    else
        return (double)(ele - down_ele) / dist;
}

int do_cum(void)
{
    int r, c, dr, dc;
    int r_nbr, c_nbr, ct_dir, np_side;
    char is_swale;
    DCELL value, valued;
    POINT point;
    GW_LARGE_INT killer;
    int threshold;
    int asp_r[9] = {0, -1, -1, -1, 0, 1, 1, 1, 0};
    int asp_c[9] = {0, 1, 0, -1, -1, -1, 0, 1, 1};
    WAT_ALT wa, wadown;
    char rtn_value;
    ASP_FLAG af, afdown;
    A_TANB sca_tanb;
    double *dist_to_nbr, *contour;
    double cell_size;

    G_message(_("SECTION 3: Accumulating Surface Flow with SFD."));

    /* distances to neighbours, contour lengths */
    dist_to_nbr = (double *)G_malloc(sides * sizeof(double));
    contour = (double *)G_malloc(sides * sizeof(double));

    cell_size = get_dist(dist_to_nbr, contour);

    if (bas_thres <= 0)
        threshold = 60;
    else
        threshold = bas_thres;
    for (killer = 0; killer < do_points; killer++) {
        G_percent(killer, do_points, 1);
        seg_get(&astar_pts, (char *)&point, 0, killer);
        r = point.r;
        c = point.c;
        seg_get(&aspflag, (char *)&af, r, c);
        if (af.asp) {
            dr = r + asp_r[ABS(af.asp)];
            dc = c + asp_c[ABS(af.asp)];
        }
        /* skip user-defined depressions */
        else
            dr = dc = -1;

        FLAG_UNSET(af.flag, WORKEDFLAG);

        if (dr >= 0 && dr < nrows && dc >= 0 && dc < ncols) {
            np_side = -1;
            r_nbr = dr;
            c_nbr = dc;

            for (ct_dir = 0; ct_dir < sides; ct_dir++) {
                /* get r, c (r_nbr, c_nbr) for neighbours */
                r_nbr = r + nextdr[ct_dir];
                c_nbr = c + nextdc[ct_dir];

                if (dr == r_nbr && dc == c_nbr)
                    np_side = ct_dir;
            }
            /* do not distribute flow along edges, this causes artifacts */
            if (FLAG_GET(af.flag, EDGEFLAG)) {
                if (FLAG_GET(af.flag, SWALEFLAG) && af.asp > 0) {
                    af.asp = -1 * drain[r - dr + 1][c - dc + 1];
                }
                seg_put(&aspflag, (char *)&af, r, c);
                seg_get(&watalt, (char *)&wadown, dr, dc);
                valued = wadown.wat;
                if (valued > 0) {
                    wadown.wat = -valued;
                    seg_put(&watalt, (char *)&wadown, dr, dc);
                }
                continue;
            }

            seg_get(&watalt, (char *)&wa, r, c);
            value = wa.wat;
            if (rtn_flag) {
                bseg_get(&rtn, (char *)&rtn_value, dr, dc);
                value *= rtn_value / 100.0;
            }
            is_swale = FLAG_GET(af.flag, SWALEFLAG);
            if (fabs(value) >= threshold && !is_swale) {
                is_swale = 1;
                FLAG_SET(af.flag, SWALEFLAG);
            }
            seg_get(&watalt, (char *)&wadown, dr, dc);
            valued = wadown.wat;
            if (value > 0) {
                if (valued > 0)
                    valued += value;
                else
                    valued -= value;
            }
            else {
                if (valued < 0)
                    valued += value;
                else
                    valued = value - valued;
            }
            wadown.wat = valued;
            seg_put(&watalt, (char *)&wadown, dr, dc);

            /* topographic wetness index ln(a / tan(beta)) and
             * stream power index a * tan(beta) */
            if (atanb_flag) {
                sca_tanb.sca = fabs(value) * (cell_size / contour[np_side]);

                sca_tanb.tanb =
                    get_slope_tci(wa.ele, wadown.ele, dist_to_nbr[np_side]);
                seg_put(&atanb, (char *)&sca_tanb, r, c);
            }

            /* update asp for depression */
            if (is_swale || fabs(valued) >= threshold) {
                seg_get(&aspflag, (char *)&afdown, dr, dc);
                FLAG_SET(afdown.flag, SWALEFLAG);
                seg_put(&aspflag, (char *)&afdown, dr, dc);
                is_swale = 1;
            }
            else {
                seg_get(&aspflag, (char *)&afdown, dr, dc);
                if (er_flag && !is_swale &&
                    !FLAG_GET(afdown.flag, RUSLEBLOCKFLAG))
                    slope_length(r, c, dr, dc);
            }
        }
        seg_put(&aspflag, (char *)&af, r, c);
    }
    G_percent(do_points, do_points, 1); /* finish it */

    seg_close(&astar_pts);

    return 0;
}

/***************************************
 *
 * MFD references
 *
 * original:
 * Quinn, P., Beven, K., Chevallier, P., and Planchon, 0. 1991.
 * The prediction of hillslope flow paths for distributed hydrological
 * modelling using digital terrain models, Hydrol. Process., 5, 59-79.
 *
 * modified by Holmgren (1994):
 * Holmgren, P. 1994. Multiple flow direction algorithms for runoff
 * modelling in grid based elevation models: an empirical evaluation
 * Hydrol. Process., 8, 327-334.
 *
 * implemented here:
 * Holmgren (1994) with modifications to honour A * path in order to get
 * out of depressions and across obstacles with graceful flow convergence
 * before depressions/obstacles and graceful flow divergence after
 * depressions/obstacles
 *
 * Topographic Convergence Index (TCI)
 * tendency of water to accumulate at a given point considering
 * the gravitational forces to move the water accumulated at that
 * point further downstream
 *
 * after Quinn et al. (1991), modified and adapted for the modified
 * Holmgren MFD algorithm
 * TCI: specific catchment area divided by tangens of slope
 * specific catchment area: total catchment area divided by contour line
 * TCI for D8:     A / (L * tanb)
 * TCI for MFD:    A / (SUM(L_i) * (SUM(tanb_i * weight_i) / SUM(weight_i))
 *
 * A: total catchment area
 * L_i: contour length towards i_th cell
 * tanb_i: slope = tan(b) towards i_th cell
 * weight_i: weight for flow distribution towards i_th cell
 * ************************************/

int do_cum_mfd(void)
{
    int r, c, dr, dc;
    DCELL value, valued, *wat_nbr;
    double sum_contour, cell_size;
    POINT point;
    WAT_ALT wa;
    char rtn_value;
    ASP_FLAG af, afdown;
    A_TANB sca_tanb;
    GW_LARGE_INT killer;
    int threshold;

    /* MFD */
    int mfd_cells, stream_cells, swale_cells, astar_not_set, is_null;
    double *dist_to_nbr, *contour, *weight, sum_weight, max_weight;
    int r_nbr, c_nbr, r_max, c_max, ct_dir, np_side /* , max_side */;
    CELL ele, *ele_nbr;
    double prop, max_val;
    int workedon, edge, is_swale, flat;
    char *flag_nbr;
    int asp_r[9] = {0, -1, -1, -1, 0, 1, 1, 1, 0};
    int asp_c[9] = {0, 1, 0, -1, -1, -1, 0, 1, 1};

    /* drainage directions bitmask encoded CW from North
     * drainage directions are set for each current cell
     *
     * bit positions, zero-based
     *
     *     X = current cell
     *
     *       6   7   0
     *       5   X   1
     *       4   3   2
     */
    /* int nextmfd[8] = { 3, 7, 5, 1, 0, 4, 2, 6 }; */
    /* int mfdir; */

    G_message(_("SECTION 3a: Accumulating Surface Flow with MFD."));
    G_debug(1, "MFD convergence factor set to %d.", c_fac);

    /* distances to neighbours */
    dist_to_nbr = (double *)G_malloc(sides * sizeof(double));
    weight = (double *)G_malloc(sides * sizeof(double));
    contour = (double *)G_malloc(sides * sizeof(double));

    cell_size = get_dist(dist_to_nbr, contour);

    flag_nbr = (char *)G_malloc(sides * sizeof(char));
    wat_nbr = (DCELL *)G_malloc(sides * sizeof(DCELL));
    ele_nbr = (CELL *)G_malloc(sides * sizeof(CELL));

    workedon = 0;

    if (bas_thres <= 0)
        threshold = 60;
    else
        threshold = bas_thres;

    for (killer = 0; killer < do_points; killer++) {
        G_percent(killer, do_points, 1);
        seg_get(&astar_pts, (char *)&point, 0, killer);
        r = point.r;
        c = point.c;
        seg_get(&aspflag, (char *)&af, r, c);
        if (af.asp) {
            dr = r + asp_r[ABS(af.asp)];
            dc = c + asp_c[ABS(af.asp)];
        }
        /* skip user-defined depressions */
        else
            dr = dc = -1;

        /* WORKEDFLAG has been set during A* Search
         * reversed meaning here: 0 = done, 1 = not yet done */
        FLAG_UNSET(af.flag, WORKEDFLAG);

        if (dr >= 0 && dr < nrows && dc >= 0 && dc < ncols) {
            r_max = dr;
            c_max = dc;

            seg_get(&watalt, (char *)&wa, r, c);
            value = wa.wat;
            if (rtn_flag) {
                bseg_get(&rtn, (char *)&rtn_value, dr, dc);
                value *= rtn_value / 100.0;
            }

            /* get weights */
            max_weight = 0;
            sum_weight = 0;
            np_side = -1;
            mfd_cells = 0;
            astar_not_set = 1;
            ele = wa.ele;
            is_null = 0;
            edge = 0;
            /* this loop is needed to get the sum of weights */
            for (ct_dir = 0; ct_dir < sides; ct_dir++) {
                /* get r, c (r_nbr, c_nbr) for neighbours */
                r_nbr = r + nextdr[ct_dir];
                c_nbr = c + nextdc[ct_dir];
                weight[ct_dir] = -1;

                wat_nbr[ct_dir] = 0;
                ele_nbr[ct_dir] = 0;
                flag_nbr[ct_dir] = 0;

                /* check if neighbour is within region */
                if (r_nbr >= 0 && r_nbr < nrows && c_nbr >= 0 &&
                    c_nbr < ncols) {

                    if (dr == r_nbr && dc == c_nbr)
                        np_side = ct_dir;

                    seg_get(&aspflag, (char *)&afdown, r_nbr, c_nbr);
                    flag_nbr[ct_dir] = afdown.flag;
                    seg_get(&watalt, (char *)&wa, r_nbr, c_nbr);
                    wat_nbr[ct_dir] = wa.wat;
                    ele_nbr[ct_dir] = wa.ele;

                    if (FLAG_GET(flag_nbr[ct_dir], WORKEDFLAG)) {

                        edge = is_null = FLAG_GET(flag_nbr[ct_dir], NULLFLAG);
                        if (!is_null && ele_nbr[ct_dir] <= ele) {
                            if (ele_nbr[ct_dir] < ele) {
                                weight[ct_dir] =
                                    mfd_pow(((ele - ele_nbr[ct_dir]) /
                                             dist_to_nbr[ct_dir]),
                                            c_fac);
                            }
                            if (ele_nbr[ct_dir] == ele) {
                                weight[ct_dir] =
                                    mfd_pow((0.5 / dist_to_nbr[ct_dir]), c_fac);
                            }
                            sum_weight += weight[ct_dir];
                            mfd_cells++;

                            if (weight[ct_dir] > max_weight) {
                                max_weight = weight[ct_dir];
                            }

                            if (dr == r_nbr && dc == c_nbr) {
                                astar_not_set = 0;
                            }
                            if (value < 0 && wat_nbr[ct_dir] > 0) {
                                wa.wat = -wat_nbr[ct_dir];
                                seg_put(&watalt, (char *)&wa, r_nbr, c_nbr);
                            }
                        }
                    }
                }
                else
                    edge = 1;
                if (edge)
                    break;
            }
            /* do not continue streams along edges, this causes artifacts */
            if (edge) {
                seg_put(&aspflag, (char *)&af, r, c);
                continue;
            }

            /* honour A * path
             * mfd_cells == 0: fine, SFD along A * path
             * mfd_cells == 1 && astar_not_set == 0: fine, SFD along A * path
             * mfd_cells > 0 && astar_not_set == 1: A * path not included, add
             * to mfd_cells
             */

            /* MFD, A * path not included, add to mfd_cells */
            if (mfd_cells > 0 && astar_not_set == 1) {
                mfd_cells++;
                sum_weight += max_weight;
                weight[np_side] = max_weight;
            }

            /* set flow accumulation for neighbours */
            max_val = -1;
            sca_tanb.tanb = sum_contour = 0.;

            if (mfd_cells > 1) {
                prop = 0.0;
                for (ct_dir = 0; ct_dir < sides; ct_dir++) {
                    r_nbr = r + nextdr[ct_dir];
                    c_nbr = c + nextdc[ct_dir];

                    /* check if neighbour is within region */
                    if (r_nbr >= 0 && r_nbr < nrows && c_nbr >= 0 &&
                        c_nbr < ncols && weight[ct_dir] > -0.5) {

                        if (FLAG_GET(flag_nbr[ct_dir], WORKEDFLAG)) {
                            weight[ct_dir] = weight[ct_dir] / sum_weight;
                            /* check everything adds up to 1.0 */
                            prop += weight[ct_dir];

                            if (atanb_flag) {
                                sum_contour += contour[ct_dir];
                                sca_tanb.tanb +=
                                    get_slope_tci(ele, ele_nbr[ct_dir],
                                                  dist_to_nbr[ct_dir]) *
                                    weight[ct_dir];
                            }

                            if (value > 0) {
                                if (wat_nbr[ct_dir] > 0)
                                    wat_nbr[ct_dir] += value * weight[ct_dir];
                                else
                                    wat_nbr[ct_dir] -= value * weight[ct_dir];
                            }
                            else {
                                if (wat_nbr[ct_dir] < 0)
                                    wat_nbr[ct_dir] += value * weight[ct_dir];
                                else
                                    wat_nbr[ct_dir] = value * weight[ct_dir] -
                                                      wat_nbr[ct_dir];
                            }
                            valued = wat_nbr[ct_dir];
                            wa.wat = valued;
                            wa.ele = ele_nbr[ct_dir];
                            seg_put(&watalt, (char *)&wa, r_nbr, c_nbr);
                        }
                        else if (ct_dir == np_side) {
                            /* check for consistency with A * path */
                            workedon++;
                        }
                    }
                }

                /* adjust main drainage direction to A* path if possible */
                /*if (fabs(wat_nbr[np_side]) >= max_acc) {
                   max_acc = fabs(wat_nbr[np_side]);
                   r_max = dr;
                   c_max = dc;
                   } */

                if (fabs(prop - 1.0) > 5E-6f) {
                    G_warning(_("MFD: cumulative proportion of flow "
                                "distribution not 1.0 but %f"),
                              prop);
                }
            }
            /* SFD-like accumulation */
            else {
                valued = wat_nbr[np_side];
                if (value > 0) {
                    if (valued > 0)
                        valued += value;
                    else
                        valued -= value;
                }
                else {
                    if (valued < 0)
                        valued += value;
                    else
                        valued = value - valued;
                }
                wa.wat = valued;
                wa.ele = ele_nbr[np_side];
                seg_put(&watalt, (char *)&wa, dr, dc);

                if (atanb_flag) {
                    sum_contour = contour[np_side];
                    sca_tanb.tanb = get_slope_tci(ele, ele_nbr[np_side],
                                                  dist_to_nbr[np_side]);
                }
            }

            /* topographic wetness index ln(a / tan(beta)) and
             * stream power index a * tan(beta) */
            if (atanb_flag) {
                sca_tanb.sca = fabs(value) * (cell_size / sum_contour);
                seg_put(&atanb, (char *)&sca_tanb, r, c);
            }
        }
        seg_put(&aspflag, (char *)&af, r, c);
    }
    G_percent(do_points, do_points, 1); /* finish it */

    if (workedon)
        G_warning(_("MFD: A * path already processed when distributing flow: "
                    "%d of %" PRId64 " cells"),
                  workedon, do_points);

    G_message(_("SECTION 3b: Adjusting drainage directions."));

    for (killer = 0; killer < do_points; killer++) {
        G_percent(killer, do_points, 1);
        seg_get(&astar_pts, (char *)&point, 0, killer);
        r = point.r;
        c = point.c;
        seg_get(&aspflag, (char *)&af, r, c);
        if (af.asp) {
            dr = r + asp_r[ABS(af.asp)];
            dc = c + asp_c[ABS(af.asp)];
        }
        /* skip user-defined depressions */
        else
            dr = dc = -1;

        FLAG_SET(af.flag, WORKEDFLAG);

        if (dr >= 0 && dr < nrows && dc >= 0 && dc < ncols) {
            r_max = dr;
            c_max = dc;

            seg_get(&watalt, (char *)&wa, r, c);
            value = wa.wat;

            /* get max flow accumulation */
            max_val = -1;
            /* max_side = 0; */
            mfd_cells = 0;
            /* mfdir = 0; */
            stream_cells = 0;
            swale_cells = 0;
            ele = wa.ele;
            is_null = 0;
            edge = 0;
            flat = 1;

            for (ct_dir = 0; ct_dir < sides; ct_dir++) {
                /* get r, c (r_nbr, c_nbr) for neighbours */
                r_nbr = r + nextdr[ct_dir];
                c_nbr = c + nextdc[ct_dir];
                weight[ct_dir] = -1;

                wat_nbr[ct_dir] = 0;
                ele_nbr[ct_dir] = 0;
                flag_nbr[ct_dir] = 0;

                /* check if neighbour is within region */
                if (r_nbr >= 0 && r_nbr < nrows && c_nbr >= 0 &&
                    c_nbr < ncols) {

                    seg_get(&aspflag, (char *)&afdown, r_nbr, c_nbr);
                    flag_nbr[ct_dir] = afdown.flag;
                    seg_get(&watalt, (char *)&wa, r_nbr, c_nbr);
                    wat_nbr[ct_dir] = wa.wat;
                    ele_nbr[ct_dir] = wa.ele;

                    /* check for swale or stream cells */
                    is_swale = FLAG_GET(flag_nbr[ct_dir], SWALEFLAG);
                    edge = FLAG_GET(flag_nbr[ct_dir], NULLFLAG);
                    if (is_swale)
                        swale_cells++;
                    if ((ABS(wat_nbr[ct_dir]) + 0.5) >= threshold &&
                        ele_nbr[ct_dir] > ele)
                        stream_cells++;

                    if (!(FLAG_GET(flag_nbr[ct_dir], WORKEDFLAG))) {

                        if (ele_nbr[ct_dir] != ele)
                            flat = 0;

                        edge = is_null = FLAG_GET(flag_nbr[ct_dir], NULLFLAG);
                        if (!is_null && ABS(wa.wat) > max_val) {
                            max_val = ABS(wa.wat);
                            r_max = r_nbr;
                            c_max = c_nbr;
                            /* max_side = ct_dir; */
                        }
                        if (!is_null && ele_nbr[ct_dir] <= ele) {
                            /* mfdir |= (1 << nextmfd[ct_dir]); */
                            mfd_cells++;
                        }
                    }
                }
                else
                    edge = 1;
                if (edge)
                    break;
            }
            /* do not continue streams along edges, this causes artifacts */
            if (edge) {
                is_swale = FLAG_GET(af.flag, SWALEFLAG);
                if (is_swale && af.asp > 0) {
                    af.asp = -1 * drain[r - r_nbr + 1][c - c_nbr + 1];
                }
                seg_put(&aspflag, (char *)&af, r, c);
                continue;
            }
            /* update asp */
            if (dr != r_max || dc != c_max) {
                if (af.asp < 0) {
                    af.asp = -1 * drain[r - r_max + 1][c - c_max + 1];
                }
                else
                    af.asp = drain[r - r_max + 1][c - c_max + 1];
            }
            /*
            if (mfd_cells == 1)
                mfdir = (1 << nextmfd[max_side]);
            */

            is_swale = FLAG_GET(af.flag, SWALEFLAG);
            /* start new stream */
            if (!is_swale && fabs(value) >= threshold && stream_cells < 1 &&
                swale_cells < 1 && !flat) {
                FLAG_SET(af.flag, SWALEFLAG);
                is_swale = 1;
            }
            /* continue stream */
            if (is_swale) {
                seg_get(&aspflag, (char *)&afdown, r_max, c_max);
                FLAG_SET(afdown.flag, SWALEFLAG);
                seg_put(&aspflag, (char *)&afdown, r_max, c_max);
            }
            else {
                if (er_flag && !is_swale && !FLAG_GET(af.flag, RUSLEBLOCKFLAG))
                    slope_length(r, c, r_max, c_max);
            }
        }
        seg_put(&aspflag, (char *)&af, r, c);
    }

    seg_close(&astar_pts);

    G_free(dist_to_nbr);
    G_free(weight);
    G_free(wat_nbr);
    G_free(ele_nbr);
    G_free(flag_nbr);

    return 0;
}

double mfd_pow(double base, int exp)
{
    int x;
    double result;

    result = base;
    if (exp == 1)
        return result;

    for (x = 2; x <= exp; x++) {
        result *= base;
    }
    return result;
}
