// Copyright (c) 2017-2022, 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

/// @file
/// libCEED QFunctions for diffusion operator example using PETSc

#ifndef bp4_h
#define bp4_h

#include <math.h>

// -----------------------------------------------------------------------------
// This QFunction sets up the rhs and true solution for the problem
// -----------------------------------------------------------------------------
CEED_QFUNCTION(SetupDiffRhs3)(void *ctx, CeedInt Q,
                              const CeedScalar *const *in,
                              CeedScalar *const *out) {
#ifndef M_PI
#  define M_PI    3.14159265358979323846
#endif
  const CeedScalar *x = in[0], *w = in[1];
  CeedScalar *true_soln = out[0], *rhs = out[1];

  // Quadrature Point Loop
  CeedPragmaSIMD
  for (CeedInt i=0; i<Q; i++) {
    const CeedScalar c[3] = { 0, 1., 2. };
    const CeedScalar k[3] = { 1., 2., 3. };

    // Component 1
    true_soln[i+0*Q] = sin(M_PI*(c[0] + k[0]*x[i+Q*0])) *
                       sin(M_PI*(c[1] + k[1]*x[i+Q*1])) *
                       sin(M_PI*(c[2] + k[2]*x[i+Q*2]));
    // Component 2
    true_soln[i+1*Q] = 2 * true_soln[i+0*Q];
    // Component 3
    true_soln[i+2*Q] = 3 * true_soln[i+0*Q];

    // Component 1
    rhs[i+0*Q] = w[i+Q*6] * M_PI*M_PI * (k[0]*k[0] + k[1]*k[1] + k[2]*k[2]) *
                 true_soln[i+0*Q];
    // Component 2
    rhs[i+1*Q] = 2 * rhs[i+0*Q];
    // Component 3
    rhs[i+2*Q] = 3 * rhs[i+0*Q];
  } // End of Quadrature Point Loop

  return 0;
}

// -----------------------------------------------------------------------------
// This QFunction applies the diffusion operator for a vector field of 3 components.
//
// Inputs:
//   ug     - Input vector Jacobian at quadrature points
//   q_data  - Geometric factors
//
// Output:
//   vJ     - Output vector (test functions) Jacobian at quadrature points
//
// -----------------------------------------------------------------------------
CEED_QFUNCTION(Diff3)(void *ctx, CeedInt Q,
                     const CeedScalar *const *in, CeedScalar *const *out) {
  const CeedScalar *ug = in[0], *qd = in[1];
  CeedScalar *vg = out[0];

  // Quadrature Point Loop
  CeedPragmaSIMD
  for (CeedInt i=0; i<Q; i++) {
    // Read spatial derivatives of u components
    const CeedScalar uJ[3][3]         = {{ug[i+(0+0*3)*Q],
                                          ug[i+(0+1*3)*Q],
                                          ug[i+(0+2*3)*Q]},
                                         {ug[i+(1+0*3)*Q],
                                          ug[i+(1+1*3)*Q],
                                          ug[i+(1+2*3)*Q]},
                                         {ug[i+(2+0*3)*Q],
                                          ug[i+(2+1*3)*Q],
                                          ug[i+(2+2*3)*Q]}
                                        };
    // Read q_data (dXdxdXdx_T symmetric matrix)
    const CeedScalar dXdxdXdx_T[3][3] = {{qd[i+0*Q],
                                          qd[i+1*Q],
                                          qd[i+2*Q]},
                                         {qd[i+1*Q],
                                          qd[i+3*Q],
                                          qd[i+4*Q]},
                                         {qd[i+2*Q],
                                          qd[i+4*Q],
                                          qd[i+5*Q]}
                                        };

    for (int k=0; k<3; k++) // k = component
      for (int j=0; j<3; j++) // j = direction of vg
        vg[i+(k+j*3)*Q] = (uJ[k][0] * dXdxdXdx_T[0][j] +
                           uJ[k][1] * dXdxdXdx_T[1][j] +
                           uJ[k][2] * dXdxdXdx_T[2][j]);
  } // End of Quadrature Point Loop

  return 0;
}
// -----------------------------------------------------------------------------

#endif // bp4_h