// Copyright (c) 2017-2026, Lawrence Livermore National Security, LLC and other CEED contributors.
// All Rights Reserved. See the top-level LICENSE and NOTICE files for details.
//
// SPDX-License-Identifier: BSD-2-Clause
//
// This file is part of CEED:  http://github.com/ceed

#include <ceed.h>

static void Build2DSimplex(CeedScalar *q_ref, CeedScalar *q_weight, CeedScalar *interp, CeedScalar *grad) {
  CeedInt P = 6, Q = 4;

  q_ref[0]    = 0.2;
  q_ref[1]    = 0.6;
  q_ref[2]    = 1. / 3.;
  q_ref[3]    = 0.2;
  q_ref[4]    = 0.2;
  q_ref[5]    = 0.2;
  q_ref[6]    = 1. / 3.;
  q_ref[7]    = 0.6;
  q_weight[0] = 25. / 96.;
  q_weight[1] = 25. / 96.;
  q_weight[2] = -27. / 96.;
  q_weight[3] = 25. / 96.;

  // Loop over quadrature points
  for (int i = 0; i < Q; i++) {
    CeedScalar x1 = q_ref[0 * Q + i], x2 = q_ref[1 * Q + i];
    // Interp
    interp[i * P + 0] = 2. * (x1 + x2 - 1.) * (x1 + x2 - 1. / 2.);
    interp[i * P + 1] = -4. * x1 * (x1 + x2 - 1.);
    interp[i * P + 2] = 2. * x1 * (x1 - 1. / 2.);
    interp[i * P + 3] = -4. * x2 * (x1 + x2 - 1.);
    interp[i * P + 4] = 4. * x1 * x2;
    interp[i * P + 5] = 2. * x2 * (x2 - 1. / 2.);
    // Grad
    grad[(i + 0) * P + 0] = 2. * (1. * (x1 + x2 - 1. / 2.) + (x1 + x2 - 1.) * 1.);
    grad[(i + Q) * P + 0] = 2. * (1. * (x1 + x2 - 1. / 2.) + (x1 + x2 - 1.) * 1.);
    grad[(i + 0) * P + 1] = -4. * (1. * (x1 + x2 - 1.) + x1 * 1.);
    grad[(i + Q) * P + 1] = -4. * (x1 * 1.);
    grad[(i + 0) * P + 2] = 2. * (1. * (x1 - 1. / 2.) + x1 * 1.);
    grad[(i + Q) * P + 2] = 2. * 0.;
    grad[(i + 0) * P + 3] = -4. * (x2 * 1.);
    grad[(i + Q) * P + 3] = -4. * (1. * (x1 + x2 - 1.) + x2 * 1.);
    grad[(i + 0) * P + 4] = 4. * (1. * x2);
    grad[(i + Q) * P + 4] = 4. * (x1 * 1.);
    grad[(i + 0) * P + 5] = 2. * 0.;
    grad[(i + Q) * P + 5] = 2. * (1. * (x2 - 1. / 2.) + x2 * 1.);
  }
}