/* Copyright (c) 2014, Vsevolod Stakhov
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *       * Redistributions of source code must retain the above copyright
 *         notice, this list of conditions and the following disclaimer.
 *       * Redistributions in binary form must reproduce the above copyright
 *         notice, this list of conditions and the following disclaimer in the
 *         documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "main.h"
#include "shingles.h"
#include "fstring.h"
#include "ottery.h"

static void
generate_random_string (char *begin, size_t len)
{
	gsize i;

	for (i = 0; i < len; i ++) {
		begin[i] = ottery_rand_range ('z' - 'a') + 'a';
	}
}

static GArray *
generate_fuzzy_words (gsize cnt, gsize max_len)
{
	GArray *res;
	gsize i, wlen;
	rspamd_fstring_t w;

	res = g_array_sized_new (FALSE, FALSE, sizeof (rspamd_fstring_t), cnt);

	for (i = 0; i < cnt; i ++) {
		wlen = ottery_rand_range (max_len) + 1;

		w.len = w.size = wlen;
		w.begin = g_malloc (wlen);
		generate_random_string (w.begin, wlen);
		g_array_append_val (res, w);
	}

	return res;
}

static void
permute_vector (GArray *in, gdouble prob)
{
	gsize i, total = 0;
	rspamd_fstring_t *w;

	for (i = 0; i < in->len; i ++) {
		if (ottery_rand_unsigned () <= G_MAXUINT * prob) {
			w = &g_array_index (in, rspamd_fstring_t, i);
			generate_random_string (w->begin, w->len);
			total ++;
		}
	}
	msg_debug ("generated %z permutations of %ud words", total, in->len);
}

static void
free_fuzzy_words (GArray *ar)
{
	gsize i;
	rspamd_fstring_t *w;

	for (i = 0; i < ar->len; i ++) {
		w = &g_array_index (ar, rspamd_fstring_t, i);
		g_free (w->begin);
	}
}

static void
test_case (gsize cnt, gsize max_len, gdouble perm_factor)
{
	GArray *input;
	struct rspamd_shingle *sgl, *sgl_permuted;
	gdouble res;
	guchar key[16];
	struct timespec ts1, ts2;

	ottery_rand_bytes (key, sizeof (key));
	input = generate_fuzzy_words (cnt, max_len);
	clock_gettime (CLOCK_MONOTONIC, &ts1);
	sgl = rspamd_shingles_generate (input, key, NULL,
			rspamd_shingles_default_filter, NULL);
	clock_gettime (CLOCK_MONOTONIC, &ts2);
	permute_vector (input, perm_factor);
	sgl_permuted = rspamd_shingles_generate (input, key, NULL,
			rspamd_shingles_default_filter, NULL);

	res = rspamd_shingles_compare (sgl, sgl_permuted);

	msg_debug ("percentage of common shingles: %.3f, generate time: %hd usec",
			res, ts_to_usec (&ts2) - ts_to_usec (&ts1));
	g_assert_cmpfloat (fabs ((1.0 - res) - sqrt (perm_factor)), <=, 0.20);

	free_fuzzy_words (input);
	g_free (sgl);
	g_free (sgl_permuted);
}

void
rspamd_shingles_test_func (void)
{
	//test_case (5, 100, 0.5);
	test_case (200, 10, 0.1);
	test_case (500, 20, 0.01);
	test_case (5000, 20, 0.01);
	test_case (5000, 15, 0);
	test_case (5000, 30, 1.0);
}