// GetDP - Copyright (C) 1997-2022 P. Dular and C. Geuzaine, University of Liege
//
// See the LICENSE.txt file for license information. Please report all
// issues on https://gitlab.onelab.info/getdp/getdp/issues.

#include <math.h>
#include "Gauss.h"
#include "Gauss_Quadrangle.h"
#include "Message.h"
#include "MallocUtils.h"

/* Classic Gauss Integration over a quadrangle */

void Gauss_Quadrangle(int Nbr_Points, int Num, double *u, double *v, double *w,
                      double *wght)
{
  switch(Nbr_Points) {
  case 1:
    *u = xq1[Num];
    *v = yq1[Num];
    *w = 0.;
    *wght = pq1[Num];
    break;
  case 3:
    *u = xq3[Num];
    *v = yq3[Num];
    *w = 0.;
    *wght = pq3[Num];
    break;
  case 4:
    *u = xq4[Num];
    *v = yq4[Num];
    *w = 0.;
    *wght = pq4[Num];
    break;
  case 7:
    *u = xq7[Num];
    *v = yq7[Num];
    *w = 0.;
    *wght = pq7[Num];
    break;
  default:
    Message::Error("Wrong number of Gauss points for Quadrangle: "
                   "valid choices: 1, 3, 4, 7");
    break;
  }
}

/* Gauss-Legendre scheme to integrate over a quadrangle */

static int glq[MAX_LINE_POINTS] = {-1};
static double *glxq[MAX_LINE_POINTS], *glyq[MAX_LINE_POINTS],
  *glpq[MAX_LINE_POINTS];

void GaussLegendre_Quadrangle(int Nbr_Points, int Num, double *u, double *v,
                              double *w, double *wght)
{
  int i, j, index = 0, nb;
  double pt1, pt2, wt1, wt2, dum;

  nb = (int)(sqrt((double)Nbr_Points) + 0.5);

  if(nb * nb != Nbr_Points || nb > MAX_LINE_POINTS) {
    Message::Error("Number of points should be n^2 with n in [1,%d]",
                   MAX_LINE_POINTS);
    return;
  }

  if(glq[0] < 0)
    for(i = 0; i < MAX_LINE_POINTS; i++) glq[i] = 0;

  if(!glq[nb - 1]) {
    Message::Info("Computing GaussLegendre %dX%d for Quadrangle", nb, nb);
    glxq[nb - 1] = (double *)Malloc(Nbr_Points * sizeof(double));
    glyq[nb - 1] = (double *)Malloc(Nbr_Points * sizeof(double));
    glpq[nb - 1] = (double *)Malloc(Nbr_Points * sizeof(double));
    for(i = 0; i < nb; i++) {
      Gauss_Line(nb, i, &pt1, &dum, &dum, &wt1);
      for(j = 0; j < nb; j++) {
        Gauss_Line(nb, j, &pt2, &dum, &dum, &wt2);
        glxq[nb - 1][index] = pt1;
        glyq[nb - 1][index] = pt2;
        glpq[nb - 1][index++] = wt1 * wt2;
      }
    }
    glq[nb - 1] = 1;
  }

  *u = glxq[nb - 1][Num];
  *v = glyq[nb - 1][Num];
  *w = 0.;
  *wght = glpq[nb - 1][Num];
}

/* Gauss Integration over a quadrangle with a 1/R singularity over node
 * (-1,-1,0) */

void GaussSingularR_Quadrangle(int Nbr_Points, int Num, double *u, double *v,
                               double *w, double *wght)
{
  switch(Nbr_Points) {
  case 1:
    *u = xqs1[Num];
    *v = yqs1[Num];
    *w = 0.;
    *wght = pqs1[Num];
    break;
  case 3:
    *u = xqs3[Num];
    *v = yqs3[Num];
    *w = 0.;
    *wght = pqs3[Num];
    break;
  case 4:
    *u = xqs4[Num];
    *v = yqs4[Num];
    *w = 0.;
    *wght = pqs4[Num];
    break;
  default:
    Message::Error("Wrong number of (modified) Gauss Points for Quadrangle: "
                   "valid choices: 1, 3, 4");
    break;
  }
}
