/*
 * One-Clause BSD License ("1BSD")
 *
 * Copyright 2022  Kaz Kylheku <kaz@kylheku.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following condition is
 * met:
 *
 * 1. The source code distribution retains the above copyright notice,
 *    this condition, and the following disclaimer.
 *
 * 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 THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS 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.
 */

#ifndef JP_HASH_H
#define JP_HASH_H

#ifdef __cplusplus
extern "C" {
#endif

void jp_hash(char *out, const char *in);

#ifdef __cplusplus
}
#endif

#if JP_HASH_IMPL

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <openssl/sha.h>

#define elof(array) ((int)(sizeof(array)/sizeof(array[0])))

static const char *mora[] = {
 "a", "i", "u", "e", "o", "ya", "yu", "yo", "wa",
 "ka", "ki", "ku", "ke", "ko", "ga", "gi", "gu", "ge", "go",
 "sa", "shi", "su", "se", "so", "za", "ji", "zu", "ze", "zo",
 "ta", "chi", "tsu", "te", "to", "da", "de", "do",
 "na", "ni", "nu", "ne", "no", "ha", "hi", "fu", "he", "ho",
 "pa", "pi", "pu", "pe", "po", "ba", "bi", "bu", "be", "bo",
 "ma", "mi", "mu", "me", "mo", "ra", "ri", "ru", "re", "ro",
 "kya", "kyu", "kyo", "gya", "gyu", "gyo", "sha", "shu", "sho",
 "ja", "ju", "jo", "cha", "chu", "cho", "nya", "nyu", "nyo",
 "hya", "hyu", "hyo", "pya", "pyu", "pyo", "bya", "byu", "byo",
 "mya", "myu", "myo", "rya", "ryu", "ryo"
};

static const char *digit[] = {
  "0", "1", "2", "3", "4",
  "5", "6", "7", "8", "9"
};

static const char *symbol[] = {
  "!", "#", "@", "$", "%",
  "^", "&", "*", "?", "/"
};

void jp_hash(char *out, const char *in)
{
  unsigned char hash[32];
  uint16_t word[9];
  const char *ms[6];
  const char *sym;
  const char *dig;
  char *ms0;
  int i;

  SHA256((const unsigned char *) in, strlen(in), hash);

  for (i = 0; i < elof(word); i++)
    word[i] = hash[2*i] | (((uint16_t) hash[2*i + 1]) << 8);

  for (i = 0; i < elof(ms); i++)
    ms[i] = mora[word[i] % elof(mora)];

  dig = digit[word[6] % elof(digit)];
  sym = symbol[word[7] % elof(symbol)];

  ms0 = strdup(ms[0]);
  ms0[0] = toupper((unsigned char) ms0[0]);
  ms[0] = ms0;

  switch (word[8] & 7) {
  case 0:
    snprintf(out, 32, "%s%s%s%s%s%s%s%s",
             ms[0], ms[1], ms[2], sym,
             ms[3], ms[4], ms[5], dig);
    break;
  case 1:
    snprintf(out, 32, "%s%s%s%s%s%s%s%s",
             sym, ms[0], ms[1], ms[2],
             dig, ms[3], ms[4], ms[5]);
    break;
  case 2:
    snprintf(out, 32, "%s%s%s%s%s%s%s%s",
             ms[0], ms[1], sym, ms[2],
             ms[3], dig, ms[4], ms[5]);
    break;
  case 3:
    snprintf(out, 32, "%s%s%s%s%s%s%s%s",
             ms[0], ms[1], dig, ms[2],
             ms[3], sym, ms[4], ms[5]);
    break;
  case 4:
    snprintf(out, 32, "%s%s%sn%s%s%s%s%s",
             ms[0], ms[1], ms[2], sym,
             ms[3], ms[4], ms[5], dig);
    break;
  case 5:
    snprintf(out, 32, "%s%s%s%s%s%s%s%sn",
             sym, ms[0], ms[1], ms[2],
             dig, ms[3], ms[4], ms[5]);
    break;
  case 6:
    snprintf(out, 32, "%s%sn%s%s%s%s%s%s",
             ms[0], ms[1], sym, ms[2],
             ms[3], dig, ms[4], ms[5]);
    break;
  case 7:
    snprintf(out, 32, "%s%s%s%s%s%s%s%sn",
             ms[0], ms[1], dig, ms[2],
             ms[3], sym, ms[4], ms[5]);
    break;
  }

  free(ms0);
}

#if JP_HASH_MAIN

int main(int argc, char **argv)
{
  char jph[32];

  if (argc != 2) {
    if (argc)
      fprintf(stderr, "%s: one argument required\n", argv[0]);
    return EXIT_FAILURE;
  }

  jp_hash(jph, argv[1]);
  puts(jph);
  return 0;
}

#endif // JP_HASH_MAIN
#endif // JP_HASH_IMPL
#endif // JP_HASH_H