////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2005-2024 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave 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.
//
// Octave 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 Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <limits>
#include <string>

#include "Matrix.h"
#include "eigs-base.h"
#include "unwind-prot.h"

#include "defun.h"
#include "error.h"
#include "errwarn.h"
#include "interpreter-private.h"
#include "oct-map.h"
#include "ov.h"
#include "ovl.h"
#include "pager.h"
#include "parse.h"
#include "variables.h"

OCTAVE_BEGIN_NAMESPACE(octave)

#if defined (HAVE_ARPACK)

struct eigs_callback
{
public:

  eigs_callback (octave::interpreter& interp)
    : m_interpreter (interp)
  { }

  ColumnVector
  eigs_func (const ColumnVector& x, int& eigs_error);

  ComplexColumnVector
  eigs_complex_func (const ComplexColumnVector& x, int& eigs_error);

  //--------

  octave::interpreter& m_interpreter;

  // Pointer for user defined function.
  octave_value m_eigs_fcn;

  // Have we warned about imaginary values returned from user function?
  bool m_warned_imaginary = false;
};

// Is this a recursive call?
static int call_depth = 0;

ColumnVector
eigs_callback::eigs_func (const ColumnVector& x, int& eigs_error)
{
  ColumnVector retval;
  octave_value_list args;
  args(0) = x;

  if (m_eigs_fcn.is_defined ())
    {
      octave_value_list tmp;

      try
        {
          tmp = m_interpreter.feval (m_eigs_fcn, args, 1);
        }
      catch (octave::execution_exception& ee)
        {
          err_user_supplied_eval (ee, "eigs");
        }

      if (tmp.length () && tmp(0).is_defined ())
        {
          if (! m_warned_imaginary && tmp(0).iscomplex ())
            {
              warning ("eigs: ignoring imaginary part returned from user-supplied function");
              m_warned_imaginary = true;
            }

          retval = tmp(0).xvector_value ("eigs: evaluation of user-supplied function failed");
        }
      else
        {
          eigs_error = 1;
          err_user_supplied_eval ("eigs");
        }
    }

  return retval;
}

ComplexColumnVector
eigs_callback::eigs_complex_func (const ComplexColumnVector& x,
                                  int& eigs_error)
{
  ComplexColumnVector retval;
  octave_value_list args;
  args(0) = x;

  if (m_eigs_fcn.is_defined ())
    {
      octave_value_list tmp;

      try
        {
          tmp = m_interpreter.feval (m_eigs_fcn, args, 1);
        }
      catch (octave::execution_exception& ee)
        {
          err_user_supplied_eval (ee, "eigs");
        }

      if (tmp.length () && tmp(0).is_defined ())
        {
          retval = tmp(0).xcomplex_vector_value ("eigs: evaluation of user-supplied function failed");
        }
      else
        {
          eigs_error = 1;
          err_user_supplied_eval ("eigs");
        }
    }

  return retval;
}

#endif

DEFMETHOD (__eigs__, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{d} =} __eigs__ (@var{A})
@deftypefnx {} {@var{d} =} __eigs__ (@var{A}, @var{k})
@deftypefnx {} {@var{d} =} __eigs__ (@var{A}, @var{k}, @var{sigma})
@deftypefnx {} {@var{d} =} __eigs__ (@var{A}, @var{k}, @var{sigma}, @var{opts})
@deftypefnx {} {@var{d} =} __eigs__ (@var{A}, @var{B})
@deftypefnx {} {@var{d} =} __eigs__ (@var{A}, @var{B}, @var{k})
@deftypefnx {} {@var{d} =} __eigs__ (@var{A}, @var{B}, @var{k}, @var{sigma})
@deftypefnx {} {@var{d} =} __eigs__ (@var{A}, @var{B}, @var{k}, @var{sigma}, @var{opts})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n}, @var{B})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n}, @var{k})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n}, @var{B}, @var{k})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n}, @var{k}, @var{sigma})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n}, @var{B}, @var{k}, @var{sigma})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n}, @var{k}, @var{sigma}, @var{opts})
@deftypefnx {} {@var{d} =} __eigs__ (@var{af}, @var{n}, @var{B}, @var{k}, @var{sigma}, @var{opts})
@deftypefnx {} {[@var{V}, @var{d}] =} __eigs__ (@var{A}, @dots{})
@deftypefnx {} {[@var{V}, @var{d}] =} __eigs__ (@var{af}, @var{n}, @dots{})
@deftypefnx {} {[@var{V}, @var{d}, @var{flag}] =} __eigs__ (@var{A}, @dots{})
@deftypefnx {} {[@var{V}, @var{d}, @var{flag}] =} __eigs__ (@var{af}, @var{n}, @dots{})
Undocumented internal function.
@end deftypefn */)
{
#if defined (HAVE_ARPACK)

  int nargin = args.length ();

  if (nargin == 0)
    print_usage ();

  octave_value_list retval;

  std::string fcn_name;
  octave_idx_type n = 0;
  octave_idx_type k = 6;
  Complex sigma = 0.0;
  double sigmar, sigmai;
  bool have_sigma = false;
  std::string typ = "LM";
  Matrix amm, bmm, bmt;
  ComplexMatrix acm, bcm, bct;
  SparseMatrix asmm, bsmm, bsmt;
  SparseComplexMatrix ascm, bscm, bsct;
  int b_arg = 0;
  bool have_b = false;
  bool have_a_fcn = false;
  bool a_is_complex = false;
  bool b_is_complex = false;
  bool symmetric = false;
  bool sym_tested = false;
  bool cholB = false;
  bool a_is_sparse = false;
  bool b_is_sparse = false;
  ColumnVector permB;
  int arg_offset = 0;
  double tol = std::numeric_limits<double>::epsilon ();
  int maxit = 300;
  int disp = 0;
  octave_idx_type p = -1;
  ColumnVector resid;
  ComplexColumnVector cresid;
  octave_idx_type info = 1;

  eigs_callback callback (interp);

  unwind_protect_var<int> restore_var (call_depth);
  call_depth++;

  if (call_depth > 1)
    error ("eigs: invalid recursive call");

  if (args(0).is_function_handle () || args(0).is_inline_function ()
      || args(0).is_string ())
    {
      callback.m_eigs_fcn = get_function_handle (interp, args(0), "x");

      if (callback.m_eigs_fcn.is_undefined ())
        error ("eigs: unknown function");

      if (nargin < 2)
        error ("eigs: incorrect number of arguments");

      n = args(1).nint_value ();
      arg_offset = 1;
      have_a_fcn = true;
    }
  else
    {
      if (args(0).iscomplex ())
        {
          if (args(0).issparse ())
            {
              ascm = (args(0).sparse_complex_matrix_value ());
              a_is_sparse = true;
            }
          else
            acm = (args(0).complex_matrix_value ());
          a_is_complex = true;
        }
      else
        {
          if (args(0).issparse ())
            {
              asmm = (args(0).sparse_matrix_value ());
              a_is_sparse = true;
            }
          else
            {
              amm = (args(0).matrix_value ());
            }
        }
    }

  // Note hold off reading B until later to avoid issues of double
  // copies of the matrix if B is full/real while A is complex.
  if (nargin > 1 + arg_offset
      && ! (args(1 + arg_offset).is_real_scalar ()))
    {
      if (args(1+arg_offset).iscomplex ())
        {
          b_arg = 1+arg_offset;
          if (args(b_arg).issparse ())
            {
              bscm = (args(b_arg).sparse_complex_matrix_value ());
              b_is_sparse = true;
            }
          else
            bcm = (args(b_arg).complex_matrix_value ());
          have_b = true;
          b_is_complex = true;
          arg_offset++;
        }
      else
        {
          b_arg = 1+arg_offset;
          if (args(b_arg).issparse ())
            {
              bsmm = (args(b_arg).sparse_matrix_value ());
              b_is_sparse = true;
            }
          else
            bmm = (args(b_arg).matrix_value ());
          have_b = true;
          arg_offset++;
        }
    }

  if (nargin > (1+arg_offset))
    k = args(1+arg_offset).nint_value ();

  if (nargin > (2+arg_offset))
    {
      if (args(2+arg_offset).is_string ())
        {
          typ = args(2+arg_offset).string_value ();

          // Use STL function to convert to upper case
          transform (typ.begin (), typ.end (), typ.begin (), toupper);

          sigma = 0.0;
        }
      else
        {
          sigma = args(2+arg_offset).xcomplex_value ("eigs: SIGMA must be a scalar or a string");

          have_sigma = true;
        }
    }

  sigmar = sigma.real ();
  sigmai = sigma.imag ();

  if (nargin > (3+arg_offset))
    {
      if (! args(3+arg_offset).isstruct ())
        error ("eigs: OPTS argument must be a structure");

      octave_scalar_map map = args(3
                                   +arg_offset).xscalar_map_value ("eigs: OPTS argument must be a scalar structure");

      octave_value tmp;

      // issym is ignored for complex matrix inputs
      tmp = map.getfield ("issym");
      if (tmp.is_defined ())
        {
          if (tmp.numel () != 1)
            error ("eigs: OPTS.issym must be a scalar value");

          symmetric = tmp.xbool_value ("eigs: OPTS.issym must be a logical value");
          sym_tested = true;
        }

      // isreal is ignored if A is not a function
      if (have_a_fcn)
        {
          tmp = map.getfield ("isreal");
          if (tmp.is_defined ())
            {
              if (tmp.numel () != 1)
                error ("eigs: OPTS.isreal must be a scalar value");

              a_is_complex = ! tmp.xbool_value ("eigs: OPTS.isreal must be a logical value");
            }
        }

      tmp = map.getfield ("tol");
      if (tmp.is_defined ())
        tol = tmp.double_value ();

      tmp = map.getfield ("maxit");
      if (tmp.is_defined ())
        maxit = tmp.nint_value ();

      tmp = map.getfield ("p");
      if (tmp.is_defined ())
        p = tmp.nint_value ();

      tmp = map.getfield ("v0");
      if (tmp.is_defined ())
        {
          if (a_is_complex || b_is_complex)
            cresid = ComplexColumnVector (tmp.complex_vector_value ());
          else
            resid = ColumnVector (tmp.vector_value ());
        }

      tmp = map.getfield ("disp");
      if (tmp.is_defined ())
        disp = tmp.nint_value ();

      tmp = map.getfield ("cholB");
      if (tmp.is_defined ())
        {
          if (tmp.numel () != 1)
            error ("eigs: OPTS.cholB must be a scalar value");

          cholB = tmp.xbool_value ("eigs: OPTS.cholB must be a logical value");
        }

      tmp = map.getfield ("permB");
      if (tmp.is_defined ())
        permB = ColumnVector (tmp.vector_value ()) - 1.0;
    }

  if (nargin > (4+arg_offset))
    error ("eigs: incorrect number of arguments");

  // Test undeclared (no issym) matrix inputs for symmetry
  if (! sym_tested && ! have_a_fcn)
    {
      if (a_is_complex)
        {
          if (a_is_sparse)
            symmetric = ascm.ishermitian ();
          else
            symmetric = acm.ishermitian ();
        }
      else
        {
          if (a_is_sparse)
            symmetric = asmm.issymmetric ();
          else
            symmetric = amm.issymmetric ();
        }
    }

  if (have_b)
    {
      if (a_is_complex || b_is_complex)
        {
          if (b_is_sparse)
            bscm = args(b_arg).sparse_complex_matrix_value ();
          else
            bcm = args(b_arg).complex_matrix_value ();
        }
      else
        {
          if (b_is_sparse)
            bsmm = args(b_arg).sparse_matrix_value ();
          else
            bmm = args(b_arg).matrix_value ();
        }
    }

  // Mode 1 for SM mode seems unstable for some reason.
  // Use Mode 3 instead, with sigma = 0.
  if (! have_sigma && typ == "SM")
    have_sigma = true;

  octave_idx_type nconv;
  if (a_is_complex || b_is_complex)
    {
      EigsComplexFunc
      eigs_complex_fcn = [&callback] (const ComplexColumnVector& x,
                                      int& eigs_error)
      {
        return callback.eigs_complex_func (x, eigs_error);
      };

      ComplexMatrix eig_vec;
      ComplexColumnVector eig_val;

      if (have_a_fcn)
        {
          if (b_is_sparse)
            nconv = EigsComplexNonSymmetricFunc
                    (eigs_complex_fcn, n, typ, sigma, k, p, info, eig_vec,
                     eig_val, bscm, permB, cresid, octave_stdout, tol,
                     (nargout > 1), cholB, disp, maxit);
          else
            nconv = EigsComplexNonSymmetricFunc
                    (eigs_complex_fcn, n, typ, sigma, k, p, info, eig_vec,
                     eig_val, bcm, permB, cresid, octave_stdout, tol,
                     (nargout > 1), cholB, disp, maxit);
        }
      else if (have_sigma)
        {
          if (a_is_sparse)
            nconv = EigsComplexNonSymmetricMatrixShift
                    (ascm, sigma, k, p, info, eig_vec, eig_val, bscm, permB,
                     cresid, octave_stdout, tol, (nargout > 1), cholB, disp,
                     maxit);
          else
            nconv = EigsComplexNonSymmetricMatrixShift
                    (acm, sigma, k, p, info, eig_vec, eig_val, bcm, permB,
                     cresid, octave_stdout, tol, (nargout > 1), cholB, disp,
                     maxit);
        }
      else
        {
          if (a_is_sparse)
            nconv = EigsComplexNonSymmetricMatrix
                    (ascm, typ, k, p, info, eig_vec, eig_val, bscm, permB,
                     cresid, octave_stdout, tol, (nargout > 1), cholB, disp,
                     maxit);
          else
            nconv = EigsComplexNonSymmetricMatrix
                    (acm, typ, k, p, info, eig_vec, eig_val, bcm, permB,
                     cresid, octave_stdout, tol, (nargout > 1), cholB, disp,
                     maxit);
        }

      if (nargout < 2)
        {
          if (symmetric)
            retval(0) = real (eig_val);
          else
            retval(0) = eig_val;
        }
      else
        {
          if (symmetric)
            retval = ovl (eig_vec, DiagMatrix (real (eig_val)), double (info));
          else
            retval = ovl (eig_vec, ComplexDiagMatrix (eig_val), double (info));
        }
    }
  else if (sigmai != 0.0)
    {
      EigsComplexFunc
      eigs_complex_fcn = [&callback] (const ComplexColumnVector& x,
                                      int& eigs_error)
      {
        return callback.eigs_complex_func (x, eigs_error);
      };

      // Promote real problem to a complex one.
      ComplexMatrix eig_vec;
      ComplexColumnVector eig_val;

      if (have_a_fcn)
        {
          if (b_is_sparse)
            nconv = EigsComplexNonSymmetricFunc
                    (eigs_complex_fcn, n, typ, sigma, k, p, info, eig_vec,
                     eig_val, bscm, permB, cresid, octave_stdout, tol,
                     (nargout > 1), cholB, disp, maxit);
          else
            nconv = EigsComplexNonSymmetricFunc
                    (eigs_complex_fcn, n, typ, sigma, k, p, info, eig_vec,
                     eig_val, bcm, permB, cresid, octave_stdout, tol,
                     (nargout > 1), cholB, disp, maxit);
        }
      else
        {
          if (a_is_sparse)
            nconv = EigsComplexNonSymmetricMatrixShift
                    (SparseComplexMatrix (asmm), sigma, k, p, info, eig_vec,
                     eig_val, SparseComplexMatrix (bsmm), permB, cresid,
                     octave_stdout, tol, (nargout > 1), cholB, disp, maxit);
          else
            nconv = EigsComplexNonSymmetricMatrixShift
                    (ComplexMatrix (amm), sigma, k, p, info, eig_vec,
                     eig_val, ComplexMatrix (bmm), permB, cresid,
                     octave_stdout, tol, (nargout > 1), cholB, disp, maxit);
        }

      if (nargout < 2)
        {
          if (symmetric)
            retval(0) = real (eig_val);
          else
            retval(0) = eig_val;
        }
      else
        {
          if (symmetric)
            retval = ovl (eig_vec, DiagMatrix (real (eig_val)), double (info));
          else
            retval = ovl (eig_vec, ComplexDiagMatrix (eig_val), double (info));
        }
    }
  else
    {
      EigsFunc eigs_fcn = [&callback] (const ColumnVector& x, int& eigs_error)
      {
        return callback.eigs_func (x, eigs_error);
      };

      if (symmetric)
        {
          Matrix eig_vec;
          ColumnVector eig_val;

          if (have_a_fcn)
            {
              if (b_is_sparse)
                nconv = EigsRealSymmetricFunc
                        (eigs_fcn, n, typ, sigmar, k, p, info, eig_vec,
                         eig_val, bsmm, permB, resid, octave_stdout, tol,
                         (nargout > 1), cholB, disp, maxit);
              else
                nconv = EigsRealSymmetricFunc
                        (eigs_fcn, n, typ, sigmar, k, p, info, eig_vec,
                         eig_val, bmm, permB, resid, octave_stdout, tol,
                         (nargout > 1), cholB, disp, maxit);
            }
          else if (have_sigma)
            {
              if (a_is_sparse)
                nconv = EigsRealSymmetricMatrixShift
                        (asmm, sigmar, k, p, info, eig_vec, eig_val, bsmm,
                         permB, resid, octave_stdout, tol, (nargout > 1),
                         cholB, disp, maxit);
              else
                nconv = EigsRealSymmetricMatrixShift
                        (amm, sigmar, k, p, info, eig_vec, eig_val, bmm,
                         permB, resid, octave_stdout, tol, (nargout > 1),
                         cholB, disp, maxit);
            }
          else
            {
              if (a_is_sparse)
                nconv = EigsRealSymmetricMatrix
                        (asmm, typ, k, p, info, eig_vec, eig_val, bsmm,
                         permB, resid, octave_stdout, tol, (nargout > 1),
                         cholB, disp, maxit);
              else
                nconv = EigsRealSymmetricMatrix
                        (amm, typ, k, p, info, eig_vec, eig_val, bmm, permB,
                         resid, octave_stdout, tol, (nargout > 1), cholB,
                         disp, maxit);
            }

          if (nargout < 2)
            retval(0) = eig_val;
          else
            retval = ovl (eig_vec, DiagMatrix (eig_val), double (info));
        }
      else
        {
          ComplexMatrix eig_vec;
          ComplexColumnVector eig_val;

          if (have_a_fcn)
            {
              if (b_is_sparse)
                nconv = EigsRealNonSymmetricFunc
                        (eigs_fcn, n, typ, sigmar, k, p, info, eig_vec,
                         eig_val, bsmm, permB, resid, octave_stdout, tol,
                         (nargout > 1), cholB, disp, maxit);
              else
                nconv = EigsRealNonSymmetricFunc
                        (eigs_fcn, n, typ, sigmar, k, p, info, eig_vec,
                         eig_val, bmm, permB, resid, octave_stdout, tol,
                         (nargout > 1), cholB, disp, maxit);
            }
          else if (have_sigma)
            {
              if (a_is_sparse)
                nconv = EigsRealNonSymmetricMatrixShift
                        (asmm, sigmar, k, p, info, eig_vec, eig_val, bsmm,
                         permB, resid, octave_stdout, tol, (nargout > 1),
                         cholB, disp, maxit);
              else
                nconv = EigsRealNonSymmetricMatrixShift
                        (amm, sigmar, k, p, info, eig_vec, eig_val, bmm,
                         permB, resid, octave_stdout, tol, (nargout > 1),
                         cholB, disp, maxit);
            }
          else
            {
              if (a_is_sparse)
                nconv = EigsRealNonSymmetricMatrix
                        (asmm, typ, k, p, info, eig_vec, eig_val, bsmm,
                         permB, resid, octave_stdout, tol, (nargout > 1),
                         cholB, disp, maxit);
              else
                nconv = EigsRealNonSymmetricMatrix
                        (amm, typ, k, p, info, eig_vec, eig_val, bmm, permB,
                         resid, octave_stdout, tol, (nargout > 1), cholB,
                         disp, maxit);
            }

          if (nargout < 2)
            retval(0) = eig_val;
          else
            retval = ovl (eig_vec, ComplexDiagMatrix (eig_val), double (info));
        }
    }

  if (nconv <= 0)
    warning_with_id ("Octave:eigs:UnconvergedEigenvalues",
                     "eigs: None of the %" OCTAVE_IDX_TYPE_FORMAT
                     " requested eigenvalues converged", k);
  else if (nconv < k)
    warning_with_id ("Octave:eigs:UnconvergedEigenvalues",
                     "eigs: Only %" OCTAVE_IDX_TYPE_FORMAT
                     " of the %" OCTAVE_IDX_TYPE_FORMAT
                     " requested eigenvalues converged",
                     nconv, k);

  if (! fcn_name.empty ())
    {
      symbol_table& symtab = interp.get_symbol_table ();

      symtab.clear_function (fcn_name);
    }

  return retval;

#else

  octave_unused_parameter (interp);
  octave_unused_parameter (args);
  octave_unused_parameter (nargout);

  err_disabled_feature ("eigs", "ARPACK");

#endif
}

/*
## No test needed for internal helper function.
%!assert (1)
*/

OCTAVE_END_NAMESPACE(octave)
