/*

 * Copyright 2008-2009 Katholieke Universiteit Leuven

 *

 * Use of this software is governed by the MIT license

 *

 * Written by Sven Verdoolaege, K.U.Leuven, Departement

 * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium

 */

#include <isl_ctx_private.h>

#include <isl_map_private.h>

#include "isl_basis_reduction.h"

#include "isl_scan.h"

#include <isl_seq.h>

#include "isl_tab.h"

#include <isl_val_private.h>

#include <isl_vec_private.h>

struct isl_counter {

  struct isl_scan_callback callback;

  isl_int count;

  isl_int max;

};

static isl_stat increment_counter(struct isl_scan_callback *cb,

  __isl_take isl_vec *sample)

{

  struct isl_counter *cnt = (struct isl_counter *)cb;

  isl_int_add_ui(cnt->count, cnt->count, 1);

  isl_vec_free(sample);

  if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))

    return isl_stat_ok;

  return isl_stat_error;

}

static int increment_range(struct isl_scan_callback *cb, isl_int min, isl_int max)

{

  struct isl_counter *cnt = (struct isl_counter *)cb;

  isl_int_add(cnt->count, cnt->count, max);

  isl_int_sub(cnt->count, cnt->count, min);

  isl_int_add_ui(cnt->count, cnt->count, 1);

  if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))

    return 0;

  isl_int_set(cnt->count, cnt->max);

  return -1;

}

/* Call callback->add with the current sample value of the tableau "tab".

 */

static int add_solution(struct isl_tab *tab, struct isl_scan_callback *callback)

{

  struct isl_vec *sample;

  if (!tab)

    return -1;

  sample = isl_tab_get_sample_value(tab);

  if (!sample)

    return -1;

  return callback->add(callback, sample);

}

static isl_stat scan_0D(__isl_take isl_basic_set *bset,

  struct isl_scan_callback *callback)

{

  struct isl_vec *sample;

  sample = isl_vec_alloc(bset->ctx, 1);

  isl_basic_set_free(bset);

  if (!sample)

    return isl_stat_error;

  isl_int_set_si(sample->el[0], 1);

  return callback->add(callback, sample);

}

/* Look for all integer points in "bset", which is assumed to be bounded,

 * and call callback->add on each of them.

 *

 * We first compute a reduced basis for the set and then scan

 * the set in the directions of this basis.

 * We basically perform a depth first search, where in each level i

 * we compute the range in the i-th basis vector direction, given

 * fixed values in the directions of the previous basis vector.

 * We then add an equality to the tableau fixing the value in the

 * direction of the current basis vector to each value in the range

 * in turn and then continue to the next level.

 *

 * The search is implemented iteratively.  "level" identifies the current

 * basis vector.  "init" is true if we want the first value at the current

 * level and false if we want the next value.

 * Solutions are added in the leaves of the search tree, i.e., after

 * we have fixed a value in each direction of the basis.

 */

isl_stat isl_basic_set_scan(__isl_take isl_basic_set *bset,

  struct isl_scan_callback *callback)

{

  unsigned dim;

  struct isl_mat *B = NULL;

  struct isl_tab *tab = NULL;

  struct isl_vec *min;

  struct isl_vec *max;

  struct isl_tab_undo **snap;

  int level;

  int init;

  enum isl_lp_result res;

  if (!bset)

    return isl_stat_error;

  dim = isl_basic_set_total_dim(bset);

  if (dim == 0)

    return scan_0D(bset, callback);

  min = isl_vec_alloc(bset->ctx, dim);

  max = isl_vec_alloc(bset->ctx, dim);

  snap = isl_alloc_array(bset->ctx, struct isl_tab_undo *, dim);

  if (!min || !max || !snap)

    goto error;

  tab = isl_tab_from_basic_set(bset, 0);

  if (!tab)

    goto error;

  if (isl_tab_extend_cons(tab, dim + 1) < 0)

    goto error;

  tab->basis = isl_mat_identity(bset->ctx, 1 + dim);

  if (1)

    tab = isl_tab_compute_reduced_basis(tab);

  if (!tab)

    goto error;

  B = isl_mat_copy(tab->basis);

  if (!B)

    goto error;

  level = 0;

  init = 1;

  while (level >= 0) {

    int empty = 0;

    if (init) {

      res = isl_tab_min(tab, B->row[1 + level],

            bset->ctx->one, &min->el[level], NULL, 0);

      if (res == isl_lp_empty)

        empty = 1;

      if (res == isl_lp_error || res == isl_lp_unbounded)

        goto error;

      isl_seq_neg(B->row[1 + level] + 1,

            B->row[1 + level] + 1, dim);

      res = isl_tab_min(tab, B->row[1 + level],

            bset->ctx->one, &max->el[level], NULL, 0);

      isl_seq_neg(B->row[1 + level] + 1,

            B->row[1 + level] + 1, dim);

      isl_int_neg(max->el[level], max->el[level]);

      if (res == isl_lp_empty)

        empty = 1;

      if (res == isl_lp_error || res == isl_lp_unbounded)

        goto error;

      snap[level] = isl_tab_snap(tab);

    } else

      isl_int_add_ui(min->el[level], min->el[level], 1);

    if (empty || isl_int_gt(min->el[level], max->el[level])) {

      level--;

      init = 0;

      if (level >= 0)

        if (isl_tab_rollback(tab, snap[level]) < 0)

          goto error;

      continue;

    }

    if (level == dim - 1 && callback->add == increment_counter) {

      if (increment_range(callback,

              min->el[level], max->el[level]))

        goto error;

      level--;

      init = 0;

      if (level >= 0)

        if (isl_tab_rollback(tab, snap[level]) < 0)

          goto error;

      continue;

    }

    isl_int_neg(B->row[1 + level][0], min->el[level]);

    if (isl_tab_add_valid_eq(tab, B->row[1 + level]) < 0)

      goto error;

    isl_int_set_si(B->row[1 + level][0], 0);

    if (level < dim - 1) {

      ++level;

      init = 1;

      continue;

    }

    if (add_solution(tab, callback) < 0)

      goto error;

    init = 0;

    if (isl_tab_rollback(tab, snap[level]) < 0)

      goto error;

  }

  isl_tab_free(tab);

  free(snap);

  isl_vec_free(min);

  isl_vec_free(max);

  isl_basic_set_free(bset);

  isl_mat_free(B);

  return isl_stat_ok;

error:

  isl_tab_free(tab);

  free(snap);

  isl_vec_free(min);

  isl_vec_free(max);

  isl_basic_set_free(bset);

  isl_mat_free(B);

  return isl_stat_error;

}

isl_stat isl_set_scan(__isl_take isl_set *set,

  struct isl_scan_callback *callback)

{

  int i;

  if (!set || !callback)

    goto error;

  set = isl_set_cow(set);

  set = isl_set_make_disjoint(set);

  set = isl_set_compute_divs(set);

  if (!set)

    goto error;

  for (i = 0; i < set->n; ++i)

    if (isl_basic_set_scan(isl_basic_set_copy(set->p[i]),

          callback) < 0)

      goto error;

  isl_set_free(set);

  return isl_stat_ok;

error:

  isl_set_free(set);

  return isl_stat_error;

}

int isl_basic_set_count_upto(__isl_keep isl_basic_set *bset,

  isl_int max, isl_int *count)

{

  struct isl_counter cnt = { { &increment_counter } };

  if (!bset)

    return -1;

  isl_int_init(cnt.count);

  isl_int_init(cnt.max);

  isl_int_set_si(cnt.count, 0);

  isl_int_set(cnt.max, max);

  if (isl_basic_set_scan(isl_basic_set_copy(bset), &cnt.callback) < 0 &&

      isl_int_lt(cnt.count, cnt.max))

    goto error;

  isl_int_set(*count, cnt.count);

  isl_int_clear(cnt.max);

  isl_int_clear(cnt.count);

  return 0;

error:

  isl_int_clear(cnt.count);

  return -1;

}

int isl_set_count_upto(__isl_keep isl_set *set, isl_int max, isl_int *count)

{

  struct isl_counter cnt = { { &increment_counter } };

  if (!set)

    return -1;

  isl_int_init(cnt.count);

  isl_int_init(cnt.max);

  isl_int_set_si(cnt.count, 0);

  isl_int_set(cnt.max, max);

  if (isl_set_scan(isl_set_copy(set), &cnt.callback) < 0 &&

      isl_int_lt(cnt.count, cnt.max))

    goto error;

  isl_int_set(*count, cnt.count);

  isl_int_clear(cnt.max);

  isl_int_clear(cnt.count);

  return 0;

error:

  isl_int_clear(cnt.count);

  return -1;

}

int isl_set_count(__isl_keep isl_set *set, isl_int *count)

{

  if (!set)

    return -1;

  return isl_set_count_upto(set, set->ctx->zero, count);

}

/* Count the total number of elements in "set" (in an inefficient way) and

 * return the result.

 */

__isl_give isl_val *isl_set_count_val(__isl_keep isl_set *set)

{

  isl_val *v;

  if (!set)

    return NULL;

  v = isl_val_zero(isl_set_get_ctx(set));

  v = isl_val_cow(v);

  if (!v)

    return NULL;

  if (isl_set_count(set, &v->n) < 0)

    v = isl_val_free(v);

  return v;

}