/*
 Copyright (C) 2013 Marco Vassallo <gedeone-octave@users.sourceforge.net>

 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3 of the License, or (at your option) any later
 version.

 This program is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 details.

 You should have received a copy of the GNU General Public License along with
 this program; if not, see <http://www.gnu.org/licenses/>.
*/

#include "form.h"
#include "boundarycondition.h"
#include "femfenics_factory.h"
#include "dolfin_compat.h"

DEFUN_DLD (assemble, args, nargout,
"-*- texinfo -*-\n\
@deftypefn {Function File} {[@var{A}], [@var{x}(Optional)]} = \
assemble (@var{form_a}, @var{DirichletBC}) \n\
Construct the discretization of a Form and apply essential BC.\n\
The input arguments are\n\
@itemize @bullet\n\
@item @var{form_a} which is the form to assemble.\n\
It can be a form of rank 2 (BilinearForm or JacobianForm), \
a form of rank 1 (LinearForm or ResidualForm) or a form \
of rank 0 (Functional).\n\
@item @var{DirichletBC} represents the optional BC applied to \
the system. \n\
@end itemize \n\
The output @var{A} is a discretized representation of the @var{form_a}:\n\
@itemize @bullet\n\
@item @var{A} is a sparse Matrix if @var{form_a} is a bilinear form\n\
@item @var{A} is a Vector if @var{form_a} is a linear form\n\
@item @var{A} is a Double if @var{form_a} is a functional\n\
@end itemize \n\
If boundary condition has to be applied to a vector for a nonlinear problem \
then it should be provide as 2nd argument and it will be given back \
as the second output argument. For an example of this situation, please refer \
to the HyperElasticity example. \n\
@seealso{BilinearForm, LinearForm, ResidualForm, JacobianForm, Functional}\n\
@end deftypefn")
{
  int nargin = args.length ();
  octave_value_list retval;

  if (! boundarycondition_type_loaded)
    {
      boundarycondition::register_type ();
      boundarycondition_type_loaded = true;
      mlock ();
    }

  if (! form_type_loaded)
    {
      form::register_type ();
      form_type_loaded = true;
      mlock ();
    }

  if (nargout == 1)
    {
      if (nargin < 1)
        { print_usage (); }
      else
        {
          if (args(0).type_id () == form::static_type_id ())
            {
              const form & frm = static_cast<const form &> (args(0).get_rep ());

              if (! error_state)
                {
                  const dolfin::Form & a = frm.get_form ();
                  a.check ();

                  if (a.rank () == 2)
                    {
                      femfenics_factory factory;

                      dolfin::Matrix A;
                      dolfin::assemble (A, a);

                      for (std::size_t i = 1; i < nargin; ++i)
                        {
                          if (args(i).type_id () ==
                              boundarycondition::static_type_id ())
                            {
                              const boundarycondition & bc
                                = static_cast<const boundarycondition &>
                                  (args(i).get_rep ());

                              const std::vector<SHARED_PTR
                                <const dolfin::DirichletBC> >
                                & pbc = bc.get_bc ();

                              for (std::size_t j = 0; j < pbc.size (); ++j)
                                { pbc[j]->apply (A); }
                            }
                          else
                            { error ("assemble: unknown argument type"); }
                        }

                      retval(0) = factory.matrix (A);
                    }

                  else if (a.rank () == 1)
                    {
                      femfenics_factory factory;

                      dolfin::Vector A;
                      dolfin::assemble (A, a);

                      for (std::size_t i = 1; i < nargin; ++i)
                        {
                          if (args(i).type_id () ==
                              boundarycondition::static_type_id ())
                            {
                              const boundarycondition & bc
                                = static_cast<const boundarycondition &>
                                  (args(i).get_rep ());

                              const std::vector<SHARED_PTR
                                <const dolfin::DirichletBC> >
                                & pbc = bc.get_bc ();

                              for (std::size_t j = 0; j < pbc.size (); ++j)
                                { pbc[j]->apply (A); }
                            }
                          else
                            { error ("assemble: unknown argument type"); }
                        }

                      retval(0) = factory.vector (A);
                    }

                  else if (a.rank () == 0)
                    {
                      double b = dolfin::assemble (a);
                      retval(0) = octave_value (b);
                    }

                  else
                    { error ("assemble: unknown form size"); }
                }
            }
        }
    }
  else if (nargout == 2)
    {
      if (nargin < 2)
        { print_usage (); }
      else
        {
          if (args(0).type_id () == form::static_type_id ())
            {
              const form & frm =
                static_cast<const form &> (args(0).get_rep ());
              const Array<double> myx = args(1).array_value ();

              if (! error_state)
                {
                  const dolfin::Form & a = frm.get_form ();
                  a.check ();

                  if (a.rank () == 1)
                    {
                      femfenics_factory factory;

                      dolfin::Vector A;
                      dolfin::assemble (A, a);

#ifdef LATEST_DOLFIN
                      dolfin::Vector x (MPI_COMM_WORLD, myx.length ());
#else
                      dolfin::Vector x (myx.length ());
#endif
                      for (std::size_t i = 0; i < myx.length (); ++i)
                        { x.setitem (i, myx.xelem (i)); }

                      for (std::size_t i = 2; i < nargin; ++i)
                        {
                          if (args(i).type_id () ==
                              boundarycondition::static_type_id ())
                            {
                              const boundarycondition & bc
                                = static_cast<const boundarycondition &>
                                  (args(i).get_rep ());

                              const std::vector<SHARED_PTR
                                <const dolfin::DirichletBC> >
                                & pbc = bc.get_bc ();

                              for (std::size_t j = 0;
                                   j < pbc.size (); ++j)
                                { pbc[j]->apply (A, x); }
                            }
                          else
                            { error ("assemble: unknown argument type"); }
                        }

                      retval(0) = factory.vector (A);
                      retval(1) = factory.vector (x);
                    }

                  else
                    { error ("assemble: unknown size"); }
                }
            }
        }
    }

  return retval;
}