/*

 * 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 int 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 0;

	return -1;

}

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 int scan_0D(struct 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 -1;

	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.

 */

int isl_basic_set_scan(struct 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 -1;

	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 0;

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 -1;

}

int 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 0;

error:

	isl_set_free(set);

	return -1;

}

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;

}