/*
  Copyright (c) 2014 Anton Titov.

  Copyright (c) 2014 pCloud Ltd.  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.  Neither the name of pCloud Ltd nor the names of
  its contributors may be used to endorse or promote products derived
  from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "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 pCloud
  Ltd 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 <pthread.h>
#include <ctype.h>
#include <string.h>

#include "ppassword.h"
#include "pmem.h"
#include "pdbg.h"
#include "ppassworddict.h"
#include "putil.h"

static int find_in_dict(const unsigned char *pwd, size_t len) {
  size_t hi, lo, med, l;
  int c;
  if (len > 8)
    len = 8;
  else if (len <= 3)
    return 0;
  lo = 0;
  hi = ARRAY_SIZE(passworddict);
  while (lo < hi) {
    med = (lo + hi) / 2;
    l = len;
    while (l && passworddict[med][l - 1] == 0)
      l--;
    c = memcmp(pwd, passworddict[med], l);
    if (c < 0)
      hi = med;
    else if (c > 0)
      lo = med + 1;
    else {
      //      if (l==8 || passworddict[med][l]==0){
      while (l < 8 && l <= len && med < ARRAY_SIZE(passworddict) &&
             !memcmp(pwd, passworddict[med + 1], l + 1)) {
        hi = len;
        med++;
        while (hi > 0 && passworddict[med][hi - 1] == 0)
          hi--;
        if (memcmp(pwd, passworddict[med], hi))
          break;
        else
          l = hi;
      }
      //        pdbg_logf(D_NOTICE, "pwd=%s l=%lu", pwd, (unsigned long)l);
      return l;
      /*      }
            else
              hi--;*/
    }
  }
  return 0;
}

static int is_punct(int c) {
  return strchr("!@#$%^&*()_+[]{},.<>:;'\"`\\/~|", c) != NULL;
}

#define mul_score(num)                                                         \
  do {                                                                         \
    oscore = score;                                                            \
    score *= num;                                                              \
    if (unlikely(oscore > score)) {                                            \
      pdbg_logf(D_NOTICE, "got overflow");                                         \
      return ~((uint64_t)0);                                                   \
    }                                                                          \
  } while (0)

static uint64_t trailing_num_score(uint64_t num, size_t numlen,
                                   const unsigned char *nstr) {
  uint64_t score, oscore;
  size_t i, j;
  if (numlen == 1) {
    if (num <= 1)
      return 2;
    else
      return 5;
  } else if (numlen ==
             2) { // chances are too high that this might be a guessable year
    if (num == 11)
      return 2;
    else if (num == 69 || num % 10 == num / 10 || num % 10 + 1 == num / 10)
      return 4;
    else
      return 8;
  } else if (numlen == 4 && num >= 1900 && num <= 2030) // probably a year
    return 10;
  if (nstr[0] == '1')
    score = 1;
  else if (nstr[0] == '0')
    score = 2;
  else
    score = 8;
  i = 1;
  do {
    for (j = i; j > 0; j--)
      if (i + j <= numlen && !memcmp(nstr + i, nstr + i - j, j)) {
        mul_score(2);
        i += j;
        goto ex;
      }
    if (nstr[i] == nstr[i - 1] || nstr[i] == nstr[i - 1] + 1 ||
        nstr[i] == nstr[i - 1] - 1)
      mul_score(2);
    else
      mul_score(10);
    i++;
  ex:;
  } while (i < numlen);
  return score;
}

static int keyboard_buddies(int ch1, int ch2) {
  static const char *kb = "qwertyuiop[]asdfghjkl;'\\zxcvbnm,./"
                          "QWERTYUIOP{}ASDFGHJKL:\"|ZXCVBNM<>?~!@#$%^&*()_+";
  char *f;
  f = strchr(kb, ch1);
  return f && (f[1] == ch2 || (f > kb && *(f - 1) == ch2));
}

static uint64_t score_variants(const unsigned char *password,
                               const unsigned char *lpassword,
                               const unsigned char *npassword, size_t plen) {
  uint64_t score, oscore;
  size_t off, r, numchars, n, j;
  int d, haslow, hasup, hasnum, haspunct, hasspace, hasother;
  char ch, pch;
  off = 0;
  score = 1;
  haslow = hasup = hasnum = haspunct = hasspace = hasother = 0;
  numchars = 0;
  while (off < plen) {
    r = plen - off;
    d = find_in_dict(password + off, r);
    if (d) {
      mul_score(ARRAY_SIZE(passworddict) / 32 * d);
      off += d;
      continue;
    }
    d = find_in_dict(lpassword + off, r);
    if (d) {
      mul_score(ARRAY_SIZE(passworddict) / 16 * d);
      off += d;
      continue;
    }
    d = find_in_dict(npassword + off, r);
    if (d) {
      mul_score(ARRAY_SIZE(passworddict) / 8 * d);
      off += d;
      continue;
    }
    if (islower(password[off]))
      haslow = 1;
    else if (isupper(password[off]))
      hasup = 1;
    else if (isdigit(password[off]))
      hasnum = 1;
    else if (is_punct(password[off]))
      haspunct = 1;
    else if (isspace(password[off]))
      hasspace = 1;
    else
      hasother = 1;
    ch = password[off];
    if (!off) {
      if (ch == 'a')
        mul_score(2);
      else if (ch == 'q')
        mul_score(2);
      else if (ch == 'z')
        mul_score(4);
      else if (ch == '1')
        mul_score(2);
      else
        numchars++;
    } else {
      for (j = off; j > 0; j--)
        if (j <= r) {
          if (!memcmp(password + off, password + off - j, j)) {
            mul_score(1 + j);
            off += j;
            goto ex;
          } else if (!memcmp(lpassword + off, lpassword + off - j, j)) {
            mul_score(2 + j);
            off += j;
            goto ex;
          }
        }
      pch = password[off - 1];
      if (pch + 1 == ch || pch - 1 == ch)
        mul_score(2);
      else if (keyboard_buddies(pch, ch))
        mul_score(2);
      else if (keyboard_buddies(lpassword[off - 1], lpassword[off]))
        mul_score(4);
      else
        numchars++;
    }
    off++;
  ex:;
  }
  n = 0;
  if (haslow)
    n += 26;
  if (hasup)
    n += 26;
  if (hasnum)
    n += 10;
  if (haspunct)
    n += 20;
  if (hasspace)
    n += 2;
  if (hasother)
    n += 10;
  while (numchars--)
    mul_score(n);
  return score;
}

static uint64_t uint_sqrt(uint64_t n) {
  uint64_t h, l, m, m2;
  h = n / 2;
  l = 1;
  m = 1;
  if (n == 1)
    return 1;
  while (h > l + 1) {
    m = (h + l) / 2;
    m2 = m * m;
    if (m2 > n)
      h = m;
    else if (m2 < n)
      l = m;
    else
      break;
  }
  return m;
}

uint64_t ppassword_score(const char *cpassword) {
  uint64_t score, oscore, num;
  char unsigned *lpwd, *ldpwd, *password;
  size_t plen, nlen;
  char ch;
  plen = strlen(cpassword);
  password = (unsigned char *)cpassword;
  score = 1;
  // trailing ! is too common
  while (plen && password[plen - 1] == '!') {
    mul_score(2);
    plen--;
  }
  // trailing 1 is too common
  if (plen && password[plen - 1] == '1') {
    nlen = 0;
    do {
      mul_score(2);
      plen--;
      nlen++;
    } while (plen && password[plen - 1] == '1');
    while (nlen >= 2) {
      nlen /= 2;
      score = uint_sqrt(score);
    }
  }
  ch = 0;
  // if punctuation is in the end, we give it a low score
  while (plen && is_punct(password[plen - 1])) {
    plen--;
    if (password[plen] == ch)
      mul_score(2);
    else
      mul_score(10);
  }
  if (plen && isdigit(password[plen - 1])) {
    // number in the end, low score
    num = 0;
    nlen = 0;
    do {
      plen--;
      num = num * 10 + password[plen] - '0';
      nlen++;
    } while (plen && isdigit(password[plen - 1]));
    mul_score(trailing_num_score(num, nlen, password + plen));
    // check for punctuation again
    while (plen && is_punct(password[plen - 1])) {
      plen--;
      if (password[plen] == ch)
        mul_score(2);
      else
        mul_score(10);
    }
  }
  if (!plen)
    return score;
  lpwd = pmem_malloc(PMEM_SUBSYS_OTHER, sizeof(unsigned char) * plen);
  ldpwd = pmem_malloc(PMEM_SUBSYS_OTHER, sizeof(unsigned char) * plen);
  for (nlen = 0; nlen < plen; nlen++) {
    lpwd[nlen] = tolower(password[nlen]);
    if (lpwd[nlen] == '0')
      ldpwd[nlen] = 'o';
    else if (lpwd[nlen] == '1')
      ldpwd[nlen] = 'i';
    else if (lpwd[nlen] == '3')
      ldpwd[nlen] = 'e';
    else if (lpwd[nlen] == '4')
      ldpwd[nlen] = 'a';
    else if (lpwd[nlen] == '5')
      ldpwd[nlen] = 's';
    else if (lpwd[nlen] == '7')
      ldpwd[nlen] = 't';
    else if (lpwd[nlen] == '$')
      ldpwd[nlen] = 's';
    else if (lpwd[nlen] == '@')
      ldpwd[nlen] = 'a';
    else if (lpwd[nlen] == '!')
      ldpwd[nlen] = 'l';
    else
      ldpwd[nlen] = lpwd[nlen];
  }
  num = score_variants(password, lpwd, ldpwd, plen);
  putil_wipe(lpwd, plen);
  putil_wipe(ldpwd, plen);
  pmem_free(PMEM_SUBSYS_OTHER, lpwd);
  pmem_free(PMEM_SUBSYS_OTHER, ldpwd);
  mul_score(num);
  return score;
}