/* PSPP - a program for statistical analysis.
   Copyright (C) 2010, 2011, 2012 Free Software Foundation, Inc.

   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 <config.h>

#include <gsl/gsl_cdf.h>
#include <gsl/gsl_matrix.h>
#include <gsl/gsl_combination.h>
#include <math.h>

#include "data/case.h"
#include "data/casegrouper.h"
#include "data/casereader.h"
#include "data/dataset.h"
#include "data/dictionary.h"
#include "data/format.h"
#include "data/value.h"
#include "language/command.h"
#include "language/commands/split-file.h"
#include "language/lexer/lexer.h"
#include "language/lexer/value-parser.h"
#include "language/lexer/variable-parser.h"
#include "libpspp/assertion.h"
#include "libpspp/ll.h"
#include "libpspp/message.h"
#include "libpspp/misc.h"
#include "libpspp/taint.h"
#include "linreg/sweep.h"
#include "math/categoricals.h"
#include "math/covariance.h"
#include "math/interaction.h"
#include "math/moments.h"
#include "output/pivot-table.h"

#include <locale.h>
#include "gettext.h"
#define N_(msgid) msgid
#define _(msgid) gettext (msgid)
#define NC_(msgctxt,msgid) msgid
#define C_(msgctxt,msgid) pgettext (msgctxt, msgid)

struct glm_spec
  {
    const struct variable **dep_vars;
    size_t n_dep_vars;

    const struct variable **factor_vars;
    size_t n_factor_vars;

    struct interaction **interactions;
    size_t n_interactions;

    enum mv_class exclude;

    const struct variable *wv;    /* The weight variable */

    const struct dictionary *dict;

    int ss_type;
    bool intercept;

    double alpha;

    bool dump_coding;
  };

struct glm_workspace
  {
    double total_ssq;
    struct moments *totals;

    struct categoricals *cats;

    /*
      Sums of squares due to different variables. Element 0 is the SSE
      for the entire model. For i > 0, element i is the SS due to
      variable i.
    */
    gsl_vector *ssq;
  };

/* Default design: all possible interactions */
static void
design_full (struct glm_spec *glm)
{
  size_t n = (1 << glm->n_factor_vars) - 1;
  glm->interactions = xnmalloc (n, sizeof *glm->interactions);

  /* All subsets, with exception of the empty set, of [0, glm->n_factor_vars) */
  for (size_t sz = 1; sz <= glm->n_factor_vars; ++sz)
    {
      gsl_combination *c = gsl_combination_calloc (glm->n_factor_vars, sz);

      do
        {
          struct interaction *iact = interaction_create (NULL);
          for (int e = 0; e < gsl_combination_k (c); ++e)
            interaction_add_variable (
              iact, glm->factor_vars [gsl_combination_get (c, e)]);

          glm->interactions[glm->n_interactions++] = iact;
        }
      while (gsl_combination_next (c) == GSL_SUCCESS);

      gsl_combination_free (c);
    }
  assert (glm->n_interactions == n);
}

static void output_glm (const struct glm_spec *,
                        const struct glm_workspace *ws);
static void run_glm (struct glm_spec *cmd, struct casereader *input,
                     const struct dataset *ds);

static struct interaction *parse_design_term (struct lexer *,
                                              const struct dictionary *);

int
cmd_glm (struct lexer *lexer, struct dataset *ds)
{
  struct const_var_set *factors = NULL;
  bool design = false;
  struct dictionary *dict = dataset_dict (ds);
  struct glm_spec glm = {
    .dict = dict,
    .exclude = MV_ANY,
    .intercept = true,
    .wv = dict_get_weight (dict),
    .alpha = 0.05,
    .ss_type = 3,
  };

  int dep_vars_start = lex_ofs (lexer);
  if (!parse_variables_const (lexer, glm.dict,
                              &glm.dep_vars, &glm.n_dep_vars,
                              PV_NO_DUPLICATE | PV_NUMERIC))
    goto error;
  int dep_vars_end = lex_ofs (lexer) - 1;

  if (!lex_force_match (lexer, T_BY))
    goto error;

  if (!parse_variables_const (lexer, glm.dict,
                              &glm.factor_vars, &glm.n_factor_vars,
                              PV_NO_DUPLICATE | PV_NUMERIC))
    goto error;

  if (glm.n_dep_vars > 1)
    {
      lex_ofs_error (lexer, dep_vars_start, dep_vars_end,
                     _("Multivariate analysis is not yet implemented."));
      goto error;
    }

  factors = const_var_set_create_from_array (glm.factor_vars, glm.n_factor_vars);

  size_t allocated_interactions = 0;
  while (lex_token (lexer) != T_ENDCMD)
    {
      lex_match (lexer, T_SLASH);

      if (lex_match_id (lexer, "MISSING"))
        {
          lex_match (lexer, T_EQUALS);
          while (lex_token (lexer) != T_ENDCMD
                 && lex_token (lexer) != T_SLASH)
            {
              if (lex_match_id (lexer, "INCLUDE"))
                glm.exclude = MV_SYSTEM;
              else if (lex_match_id (lexer, "EXCLUDE"))
                glm.exclude = MV_ANY;
              else
                {
                  lex_error_expecting (lexer, "INCLUDE", "EXCLUDE");
                  goto error;
                }
            }
        }
      else if (lex_match_id (lexer, "INTERCEPT"))
        {
          lex_match (lexer, T_EQUALS);
          while (lex_token (lexer) != T_ENDCMD
                 && lex_token (lexer) != T_SLASH)
            {
              if (lex_match_id (lexer, "INCLUDE"))
                glm.intercept = true;
              else if (lex_match_id (lexer, "EXCLUDE"))
                glm.intercept = false;
              else
                {
                  lex_error_expecting (lexer, "INCLUDE", "EXCLUDE");
                  goto error;
                }
            }
        }
      else if (lex_match_id (lexer, "CRITERIA"))
        {
          lex_match (lexer, T_EQUALS);
          if (!lex_force_match_phrase (lexer, "ALPHA(")
              || !lex_force_num (lexer))
            goto error;
          glm.alpha = lex_number (lexer);
          lex_get (lexer);
          if (!lex_force_match (lexer, T_RPAREN))
            goto error;
        }
      else if (lex_match_id (lexer, "METHOD"))
        {
          lex_match (lexer, T_EQUALS);
          if (!lex_force_match_phrase (lexer, "SSTYPE(")
              || !lex_force_int_range (lexer, "SSTYPE", 1, 3))
            goto error;

          glm.ss_type = lex_integer (lexer);
          lex_get (lexer);

          if (!lex_force_match (lexer, T_RPAREN))
            goto error;
        }
      else if (lex_match_id (lexer, "DESIGN"))
        {
          lex_match (lexer, T_EQUALS);

          do
            {
              struct interaction *iact = parse_design_term (lexer, glm.dict);
              if (!iact)
                goto error;

              if (glm.n_interactions >= allocated_interactions)
                glm.interactions = x2nrealloc (glm.interactions,
                                               &allocated_interactions,
                                               sizeof *glm.interactions);
              glm.interactions[glm.n_interactions++] = iact;

              lex_match (lexer, T_COMMA);
            }
          while (lex_token (lexer) != T_ENDCMD && lex_token (lexer) != T_SLASH);

          if (glm.n_interactions > 0)
            design = true;
        }
      else if (lex_match_id (lexer, "SHOWCODES"))
        {
          /* Undocumented debug option */
          glm.dump_coding = true;
        }
      else
        {
          lex_error_expecting (lexer, "MISSING", "INTERCEPT", "CRITERIA",
                               "METHOD", "DESIGN");
          goto error;
        }
    }

  if (!design)
    design_full (&glm);

  struct casegrouper *grouper = casegrouper_create_splits (proc_open (ds), glm.dict);
  struct casereader *group;
  while (casegrouper_get_next_group (grouper, &group))
    run_glm (&glm, group, ds);
  bool ok = casegrouper_destroy (grouper);
  ok = proc_commit (ds) && ok;

  const_var_set_destroy (factors);
  free (glm.factor_vars);
  for (size_t i = 0; i < glm.n_interactions; ++i)
    interaction_destroy (glm.interactions[i]);

  free (glm.interactions);
  free (glm.dep_vars);

  return CMD_SUCCESS;

error:
  const_var_set_destroy (factors);
  free (glm.factor_vars);
  for (size_t i = 0; i < glm.n_interactions; ++i)
    interaction_destroy (glm.interactions[i]);

  free (glm.interactions);
  free (glm.dep_vars);

  return CMD_FAILURE;
}

static inline bool
not_dropped (size_t j, const bool *ff)
{
  return !ff[j];
}

static void
fill_submatrix (const gsl_matrix * cov, gsl_matrix * submatrix, bool *dropped_f)
{
  size_t i;
  size_t j;
  size_t n = 0;
  size_t m = 0;

  for (i = 0; i < cov->size1; i++)
    {
      if (not_dropped (i, dropped_f))
        {
          m = 0;
          for (j = 0; j < cov->size2; j++)
            {
              if (not_dropped (j, dropped_f))
                {
                  gsl_matrix_set (submatrix, n, m,
                                  gsl_matrix_get (cov, i, j));
                  m++;
                }
            }
          n++;
        }
    }
}


/*
   Type 1 sums of squares.
   Populate SSQ with the Type 1 sums of squares according to COV
 */
static void
ssq_type1 (struct covariance *cov, gsl_vector *ssq, const struct glm_spec *cmd)
{
  const gsl_matrix *cm = covariance_calculate_unnormalized (cov);
  size_t i;
  size_t k;
  bool *model_dropped = XCALLOC (covariance_dim (cov), bool);
  bool *submodel_dropped = XCALLOC (covariance_dim (cov), bool);
  const struct categoricals *cats = covariance_get_categoricals (cov);

  size_t n_dropped_model = 0;
  size_t n_dropped_submodel = 0;

  for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
    {
      n_dropped_model++;
      n_dropped_submodel++;
      model_dropped[i] = true;
      submodel_dropped[i] = true;
    }

  for (k = 0; k < cmd->n_interactions; k++)
    {
      gsl_matrix *model_cov = NULL;
      gsl_matrix *submodel_cov = NULL;

      n_dropped_submodel = n_dropped_model;
      for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
        submodel_dropped[i] = model_dropped[i];

      for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
        {
          const struct interaction * x =
            categoricals_get_interaction_by_subscript (cats, i - cmd->n_dep_vars);

          if (x == cmd->interactions [k])
            {
              model_dropped[i] = false;
              n_dropped_model--;
            }
        }

      model_cov = gsl_matrix_alloc (cm->size1 - n_dropped_model, cm->size2 - n_dropped_model);
      submodel_cov = gsl_matrix_alloc (cm->size1 - n_dropped_submodel, cm->size2 - n_dropped_submodel);

      fill_submatrix (cm, model_cov,    model_dropped);
      fill_submatrix (cm, submodel_cov, submodel_dropped);

      reg_sweep (model_cov, 0);
      reg_sweep (submodel_cov, 0);

      gsl_vector_set (ssq, k + 1,
                      gsl_matrix_get (submodel_cov, 0, 0) - gsl_matrix_get (model_cov, 0, 0)
                );

      gsl_matrix_free (model_cov);
      gsl_matrix_free (submodel_cov);
    }

  free (model_dropped);
  free (submodel_dropped);
}

/*
   Type 2 sums of squares.
   Populate SSQ with the Type 2 sums of squares according to COV
 */
static void
ssq_type2 (struct covariance *cov, gsl_vector *ssq, const struct glm_spec *cmd)
{
  const gsl_matrix *cm = covariance_calculate_unnormalized (cov);
  bool *model_dropped = XCALLOC (covariance_dim (cov), bool);
  bool *submodel_dropped = XCALLOC (covariance_dim (cov), bool);
  const struct categoricals *cats = covariance_get_categoricals (cov);

  for (size_t k = 0; k < cmd->n_interactions; k++)
    {
      gsl_matrix *model_cov = NULL;
      gsl_matrix *submodel_cov = NULL;
      size_t n_dropped_model = 0;
      size_t n_dropped_submodel = 0;
      for (size_t i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
        {
          const struct interaction * x =
            categoricals_get_interaction_by_subscript (cats, i - cmd->n_dep_vars);

          model_dropped[i] = false;
          submodel_dropped[i] = false;
          if (interaction_is_subset (cmd->interactions [k], x))
            {
              assert (n_dropped_submodel < covariance_dim (cov));
              n_dropped_submodel++;
              submodel_dropped[i] = true;

              if (cmd->interactions [k]->n_vars < x->n_vars)
                {
                  assert (n_dropped_model < covariance_dim (cov));
                  n_dropped_model++;
                  model_dropped[i] = true;
                }
            }
        }

      model_cov = gsl_matrix_alloc (cm->size1 - n_dropped_model, cm->size2 - n_dropped_model);
      submodel_cov = gsl_matrix_alloc (cm->size1 - n_dropped_submodel, cm->size2 - n_dropped_submodel);

      fill_submatrix (cm, model_cov,    model_dropped);
      fill_submatrix (cm, submodel_cov, submodel_dropped);

      reg_sweep (model_cov, 0);
      reg_sweep (submodel_cov, 0);

      gsl_vector_set (ssq, k + 1,
                      gsl_matrix_get (submodel_cov, 0, 0) - gsl_matrix_get (model_cov, 0, 0)
                );

      gsl_matrix_free (model_cov);
      gsl_matrix_free (submodel_cov);
    }

  free (model_dropped);
  free (submodel_dropped);
}

/*
   Type 3 sums of squares.
   Populate SSQ with the Type 2 sums of squares according to COV
 */
static void
ssq_type3 (struct covariance *cov, gsl_vector *ssq, const struct glm_spec *cmd)
{
  const gsl_matrix *cm = covariance_calculate_unnormalized (cov);
  bool *model_dropped = XCALLOC (covariance_dim (cov), bool);
  bool *submodel_dropped = XCALLOC (covariance_dim (cov), bool);
  const struct categoricals *cats = covariance_get_categoricals (cov);

  gsl_matrix *submodel_cov = gsl_matrix_alloc (cm->size1, cm->size2);
  fill_submatrix (cm, submodel_cov, submodel_dropped);
  reg_sweep (submodel_cov, 0);
  double ss0 = gsl_matrix_get (submodel_cov, 0, 0);
  gsl_matrix_free (submodel_cov);
  free (submodel_dropped);

  for (size_t k = 0; k < cmd->n_interactions; k++)
    {
      size_t n_dropped_model = 0;
      for (size_t i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
        {
          const struct interaction * x =
            categoricals_get_interaction_by_subscript (cats, i - cmd->n_dep_vars);

          model_dropped[i] = false;

          if (cmd->interactions [k] == x)
            {
              assert (n_dropped_model < covariance_dim (cov));
              n_dropped_model++;
              model_dropped[i] = true;
            }
        }

      gsl_matrix *model_cov = gsl_matrix_alloc (cm->size1 - n_dropped_model,
                                                cm->size2 - n_dropped_model);

      fill_submatrix (cm, model_cov, model_dropped);

      reg_sweep (model_cov, 0);

      gsl_vector_set (ssq, k + 1, gsl_matrix_get (model_cov, 0, 0) - ss0);

      gsl_matrix_free (model_cov);
    }
  free (model_dropped);
}

static void
run_glm (struct glm_spec *cmd, struct casereader *input,
         const struct dataset *ds)
{
  bool warn_bad_weight = true;
  struct dictionary *dict = dataset_dict (ds);


  input = casereader_create_filter_missing (input,
                                            cmd->dep_vars, cmd->n_dep_vars,
                                            cmd->exclude,
                                            NULL,  NULL);

  input = casereader_create_filter_missing (input,
                                            cmd->factor_vars, cmd->n_factor_vars,
                                            cmd->exclude,
                                            NULL,  NULL);

  struct glm_workspace ws = {
    .cats = categoricals_create (cmd->interactions, cmd->n_interactions,
                                 cmd->wv, MV_ANY)
  };

  struct covariance *cov = covariance_2pass_create (
    cmd->n_dep_vars, cmd->dep_vars, ws.cats, cmd->wv, cmd->exclude, true);

  output_split_file_values_peek (ds, input);

  struct taint *taint = taint_clone (casereader_get_taint (input));

  ws.totals = moments_create (MOMENT_VARIANCE);

  struct casereader *reader = casereader_clone (input);
  struct ccase *c;
  for (; (c = casereader_read (reader)) != NULL; case_unref (c))
    {
      double weight = dict_get_case_weight (dict, c, &warn_bad_weight);

      for (int v = 0; v < cmd->n_dep_vars; ++v)
        moments_pass_one (ws.totals, case_num (c, cmd->dep_vars[v]), weight);

      covariance_accumulate_pass1 (cov, c);
    }
  casereader_destroy (reader);

  if (cmd->dump_coding)
    reader = casereader_clone (input);
  else
    reader = input;

  for (; (c = casereader_read (reader)) != NULL; case_unref (c))
    {
      double weight = dict_get_case_weight (dict, c, &warn_bad_weight);

      for (size_t v = 0; v < cmd->n_dep_vars; ++v)
        moments_pass_two (ws.totals, case_num (c, cmd->dep_vars[v]), weight);

      covariance_accumulate_pass2 (cov, c);
    }
  casereader_destroy (reader);


  if (cmd->dump_coding)
    {
      struct pivot_table *t = covariance_dump_enc_header (cov);
      for (reader = input;
           (c = casereader_read (reader)) != NULL; case_unref (c))
        {
          covariance_dump_enc (cov, c, t);
        }

      pivot_table_submit (t);
    }

  {
    const gsl_matrix *ucm = covariance_calculate_unnormalized (cov);
    gsl_matrix *cm = gsl_matrix_alloc (ucm->size1, ucm->size2);
    gsl_matrix_memcpy (cm, ucm);

    //    dump_matrix (cm);

    ws.total_ssq = gsl_matrix_get (cm, 0, 0);

    reg_sweep (cm, 0);

    /*
      Store the overall SSE.
    */
    ws.ssq = gsl_vector_alloc (cm->size1);
    gsl_vector_set (ws.ssq, 0, gsl_matrix_get (cm, 0, 0));
    switch (cmd->ss_type)
      {
      case 1:
        ssq_type1 (cov, ws.ssq, cmd);
        break;
      case 2:
        ssq_type2 (cov, ws.ssq, cmd);
        break;
      case 3:
        ssq_type3 (cov, ws.ssq, cmd);
        break;
      default:
        NOT_REACHED ();
        break;
      }
    //    dump_matrix (cm);
    gsl_matrix_free (cm);
  }

  if (!taint_has_tainted_successor (taint))
    output_glm (cmd, &ws);

  gsl_vector_free (ws.ssq);

  covariance_destroy (cov);
  moments_destroy (ws.totals);

  taint_destroy (taint);
}

static void
put_glm_row (struct pivot_table *table, int row,
             double a, double b, double c, double d, double e)
{
  double entries[] = { a, b, c, d, e };

  for (size_t col = 0; col < sizeof entries / sizeof *entries; col++)
    if (entries[col] != SYSMIS)
      pivot_table_put2 (table, col, row,
                        pivot_value_new_number (entries[col]));
}

static void
output_glm (const struct glm_spec *cmd, const struct glm_workspace *ws)
{
  struct pivot_table *table = pivot_table_create (
    N_("Tests of Between-Subjects Effects"));

  pivot_dimension_create (table, PIVOT_AXIS_COLUMN, N_("Statistics"),
                          (cmd->ss_type == 1 ? N_("Type I Sum Of Squares")
                           : cmd->ss_type == 2 ? N_("Type II Sum Of Squares")
                           : N_("Type III Sum Of Squares")), PIVOT_RC_OTHER,
                          N_("df"), PIVOT_RC_COUNT,
                          N_("Mean Square"), PIVOT_RC_OTHER,
                          N_("F"), PIVOT_RC_OTHER,
                          N_("Sig."), PIVOT_RC_SIGNIFICANCE);

  struct pivot_dimension *source = pivot_dimension_create (
    table, PIVOT_AXIS_ROW, N_("Source"),
    cmd->intercept ? N_("Corrected Model") : N_("Model"));

  double n_total, mean;
  moments_calculate (ws->totals, &n_total, &mean, NULL, NULL, NULL);

  double df_corr = 1.0 + categoricals_df_total (ws->cats);

  double mse = gsl_vector_get (ws->ssq, 0) / (n_total - df_corr);
  double intercept_ssq = pow2 (mean * n_total) / n_total;
  if (cmd->intercept)
    {
      int row = pivot_category_create_leaf (
        source->root, pivot_value_new_text (N_("Intercept")));

      /* The intercept for unbalanced models is of limited use and
         nobody knows how to calculate it properly */
      if (categoricals_isbalanced (ws->cats))
        {
          const double df = 1.0;
          const double F = intercept_ssq / df / mse;
          put_glm_row (table, row, intercept_ssq, 1.0, intercept_ssq / df,
                       F, gsl_cdf_fdist_Q (F, df, n_total - df_corr));
        }
    }

  double ssq_effects = 0.0;
  for (int f = 0; f < cmd->n_interactions; ++f)
    {
      double df = categoricals_df (ws->cats, f);
      double ssq = gsl_vector_get (ws->ssq, f + 1);
      ssq_effects += ssq;
      if (!cmd->intercept)
        {
          df++;
          ssq += intercept_ssq;
        }
      double F = ssq / df / mse;

      struct string str = DS_EMPTY_INITIALIZER;
      interaction_to_string (cmd->interactions[f], &str);
      int row = pivot_category_create_leaf (
        source->root, pivot_value_new_user_text_nocopy (ds_steal_cstr (&str)));

      put_glm_row (table, row, ssq, df, ssq / df, F,
                   gsl_cdf_fdist_Q (F, df, n_total - df_corr));
    }

  {
    /* Model / Corrected Model */
    double df = df_corr;
    double ssq = ws->total_ssq - gsl_vector_get (ws->ssq, 0);
    if (cmd->intercept)
      df--;
    else
      ssq += intercept_ssq;
    double F = ssq / df / mse;
    put_glm_row (table, 0, ssq, df, ssq / df, F,
                 gsl_cdf_fdist_Q (F, df, n_total - df_corr));
  }

  {
    int row = pivot_category_create_leaf (
      source->root,
      pivot_value_new_text_translate ("Error", C_("statistics", "Error")));
    const double df = n_total - df_corr;
    const double ssq = gsl_vector_get (ws->ssq, 0);
    const double mse = ssq / df;
    put_glm_row (table, row, ssq, df, mse, SYSMIS, SYSMIS);
  }

  {
    int row = pivot_category_create_leaf (source->root,
                                          pivot_value_new_text (N_("Total")));
    put_glm_row (table, row, ws->total_ssq + intercept_ssq, n_total,
                 SYSMIS, SYSMIS, SYSMIS);
  }

  if (cmd->intercept)
    {
      int row = pivot_category_create_leaf (
        source->root, pivot_value_new_text (N_("Corrected Total")));
      put_glm_row (table, row, ws->total_ssq, n_total - 1.0, SYSMIS,
                   SYSMIS, SYSMIS);
    }

  pivot_table_submit (table);
}

#if 0
static void
dump_matrix (const gsl_matrix * m)
{
  size_t i, j;
  for (i = 0; i < m->size1; ++i)
    {
      for (j = 0; j < m->size2; ++j)
        {
          double x = gsl_matrix_get (m, i, j);
          printf ("%.3f ", x);
        }
      printf ("\n");
    }
  printf ("\n");
}
#endif



static struct interaction *
parse_design_term (struct lexer *lexer, const struct dictionary *dict)
{
  struct interaction *iact = interaction_create (NULL);
  do
    {
      struct variable *var = parse_variable (lexer, dict);
      if (!var)
        goto error;
      interaction_add_variable (iact, var);

      if (lex_match (lexer, T_LPAREN) || lex_match_id (lexer, "WITHIN"))
        {
          lex_next_error (lexer, -1, -1,
                          "Nested variables are not yet implemented.");
          goto error;
        }
    }
  while (lex_match (lexer, T_ASTERISK));

  return iact;

error:
  interaction_destroy (iact);
  return NULL;
}
