/*
     This file is part of GNUnet
     Copyright (C) 2012 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */
/**
 * @file regex/test_regex_proofs.c
 * @brief test for regex.c
 * @author Maximilian Szengel
 */
#include "platform.h"
#include "regex_internal_lib.h"
#include "regex_test_lib.h"
#include "regex_internal.h"


/**
 * Test if the given regex's canonical regex is the same as this canonical
 * regex's canonical regex. Confused? Ok, then: 1. construct a dfa A from the
 * given 'regex' 2. get the canonical regex of dfa A 3. construct a dfa B from
 * this canonical regex 3. compare the canonical regex of dfa A with the
 * canonical regex of dfa B.
 *
 * @param regex regular expression used for this test (see above).
 *
 * @return 0 on success, 1 on failure
 */
static unsigned int
test_proof(const char *regex)
{
  unsigned int error;
  struct REGEX_INTERNAL_Automaton *dfa;
  char *c_rx1;
  const char *c_rx2;

  dfa = REGEX_INTERNAL_construct_dfa(regex, strlen(regex), 1);
  GNUNET_assert(NULL != dfa);
  c_rx1 = GNUNET_strdup(REGEX_INTERNAL_get_canonical_regex(dfa));
  REGEX_INTERNAL_automaton_destroy(dfa);
  dfa = REGEX_INTERNAL_construct_dfa(c_rx1, strlen(c_rx1), 1);
  GNUNET_assert(NULL != dfa);
  c_rx2 = REGEX_INTERNAL_get_canonical_regex(dfa);

  error = (0 == strcmp(c_rx1, c_rx2)) ? 0 : 1;

  if (error > 0)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
                 "Comparing canonical regex of\n%s\nfailed:\n%s\nvs.\n%s\n",
                 regex, c_rx1, c_rx2);
    }

  GNUNET_free(c_rx1);
  REGEX_INTERNAL_automaton_destroy(dfa);

  return error;
}


/**
 * Use 'test_proof' function to randomly test the canonical regexes of 'count'
 * random expressions of length 'rx_length'.
 *
 * @param count number of random regular expressions to test.
 * @param rx_length length of the random regular expressions.
 *
 * @return 0 on succes, number of failures otherwise.
 */
static unsigned int
test_proofs_random(unsigned int count, size_t rx_length)
{
  unsigned int i;
  char *rand_rx;
  unsigned int failures;

  failures = 0;

  for (i = 0; i < count; i++)
    {
      rand_rx = REGEX_TEST_generate_random_regex(rx_length, NULL);
      failures += test_proof(rand_rx);
      GNUNET_free(rand_rx);
    }

  return failures;
}


/**
 * Test a number of known examples of regexes for proper canonicalization.
 *
 * @return 0 on success, number of failures otherwise.
 */
static unsigned int
test_proofs_static()
{
  unsigned int i;
  unsigned int error;

  const char *regex[8] = {
    "a|aa*a",
    "a+",
    "a*",
    "a*a*",
    "(F*C|WfPf|y+F*C)",
    "y*F*C|WfPf",
    "((a|b)c|(a|b)(d|(a|b)e))",
    "((a|b)(c|d)|(a|b)(a|b)e)"
  };

  const char *canon_rx1;
  const char *canon_rx2;
  struct REGEX_INTERNAL_Automaton *dfa1;
  struct REGEX_INTERNAL_Automaton *dfa2;

  error = 0;

  for (i = 0; i < 8; i += 2)
    {
      dfa1 = REGEX_INTERNAL_construct_dfa(regex[i], strlen(regex[i]), 1);
      dfa2 = REGEX_INTERNAL_construct_dfa(regex[i + 1], strlen(regex[i + 1]), 1);
      GNUNET_assert(NULL != dfa1);
      GNUNET_assert(NULL != dfa2);

      canon_rx1 = REGEX_INTERNAL_get_canonical_regex(dfa1);
      canon_rx2 = REGEX_INTERNAL_get_canonical_regex(dfa2);

      error += (0 == strcmp(canon_rx1, canon_rx2)) ? 0 : 1;

      if (error > 0)
        {
          GNUNET_log(GNUNET_ERROR_TYPE_ERROR,
                     "Comparing canonical regex failed:\nrx1:\t%s\ncrx1:\t%s\nrx2:\t%s\ncrx2:\t%s\n",
                     regex[i], canon_rx1, regex[i + 1], canon_rx2);
        }

      REGEX_INTERNAL_automaton_destroy(dfa1);
      REGEX_INTERNAL_automaton_destroy(dfa2);
    }

  return error;
}


int
main(int argc, char *argv[])
{
  GNUNET_log_setup("test-regex", "WARNING", NULL);

  int error;

  error = 0;

  error += test_proofs_static();
  error += test_proofs_random(100, 30);

  return error;
}