// GetDP - Copyright (C) 1997-2021 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_Hexahedron.h"
#include "Message.h"
#include "MallocUtils.h"

/* Gauss integration over a hexahedron */

void Gauss_Hexahedron(int Nbr_Points, int Num,
		      double *u, double *v, double *w, double *wght)
{
  switch (Nbr_Points) {

  case  6 :
    *u = xhex6 [Num] ; *v = yhex6 [Num] ; *w = zhex6 [Num] ;
    *wght = phex6 [Num] ; break ;

  case  14 :
    *u = xhex14 [Num] ; *v = yhex14 [Num] ; *w = zhex14 [Num] ;
    *wght = phex14 [Num] ; break ;

  case 34 :
    *u = xhex34[Num] ; *v = yhex34[Num] ; *w = zhex34[Num] ;
    *wght = phex34[Num] ; break ;

  case 77 :
    *u = xhex77[Num] ; *v = yhex77[Num] ; *w = zhex77[Num] ;
    *wght = phex77[Num] ; break ;

  default :
    Message::Error("Wrong number of Gauss points for Hexahedron: "
                   "valid choices: 6, 14, 34, 77");
    break;

  }
}

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

static int glhex[MAX_LINE_POINTS] = {-1};
static double *glxhex[MAX_LINE_POINTS], *glyhex[MAX_LINE_POINTS];
static double *glzhex[MAX_LINE_POINTS], *glphex[MAX_LINE_POINTS];

void GaussLegendre_Hexahedron(int Nbr_Points, int Num,
			      double *u, double *v, double *w, double *wght)
{
  int i, j, k, index = 0, nb;
  double pt1, pt2, pt3, wt1, wt2, wt3, dum;

  nb = (int)cbrt((double)Nbr_Points);

  if(nb * nb * nb != Nbr_Points || nb > MAX_LINE_POINTS){
    Message::Error("Number of points should be n^3 with n in [1,%d]", MAX_LINE_POINTS) ;
    return;
  }

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

  if(!glhex[nb - 1]){
    Message::Info("Computing GaussLegendre %dx%dx%d for Hexahedron", nb, nb, nb);
    glxhex[nb - 1] = (double*)Malloc(Nbr_Points * sizeof(double));
    glyhex[nb - 1] = (double*)Malloc(Nbr_Points * sizeof(double));
    glzhex[nb - 1] = (double*)Malloc(Nbr_Points * sizeof(double));
    glphex[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);
	for(k = 0; k < nb; k++) {
	  Gauss_Line(nb, k, &pt3, &dum, &dum, &wt3);
	  glxhex[nb - 1][index] = pt1;
	  glyhex[nb - 1][index] = pt2;
	  glzhex[nb - 1][index] = pt3;
	  glphex[nb - 1][index++] = wt1 * wt2 * wt3;
	}
      }
    }
    glhex[nb - 1] = 1;
  }

  *u = glxhex[nb - 1][Num] ; *v = glyhex[nb - 1][Num] ; *w = glzhex[nb - 1][Num] ;
  *wght = glphex[nb - 1][Num] ;
}
