/**
 * @file
 * Multi-byte String manipulation functions
 *
 * @authors
 * Copyright (C) 2017-2023 Richard Russon <rich@flatcap.org>
 * Copyright (C) 2019 Pietro Cerutti <gahr@gahr.ch>
 *
 * @copyright
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * @page mutt_mbyte Multi-byte String manipulation functions
 *
 * Some commonly-used multi-byte string manipulation routines.
 */

#include "config.h"
#include <limits.h>
#include <stdbool.h>
#include <string.h>
#include <wchar.h>
#include <wctype.h>
#include "mbyte.h"
#include "buffer.h"
#include "charset.h"
#include "ctype2.h"
#include "memory.h"
#include "pool.h"
#include "string2.h"

bool OptLocales; ///< (pseudo) set if user has valid locale definition

/**
 * mutt_mb_charlen - Count the bytes in a (multibyte) character
 * @param[in]  s     String to be examined
 * @param[out] width Number of screen columns the character would use
 * @retval num Bytes in the first (multibyte) character of input consumes
 * @retval <0  Conversion error
 * @retval =0  End of input
 * @retval >0  Length (bytes)
 */
int mutt_mb_charlen(const char *s, int *width)
{
  if (!s || (*s == '\0'))
    return 0;

  wchar_t wc = 0;
  mbstate_t mbstate = { 0 };

  size_t n = mutt_str_len(s);
  size_t k = mbrtowc(&wc, s, n, &mbstate);
  if (width)
    *width = wcwidth(wc);
  return ((k == ICONV_ILLEGAL_SEQ) || (k == ICONV_BUF_TOO_SMALL)) ? -1 : k;
}

/**
 * mutt_mb_get_initials - Turn a name into initials
 * @param name   String to be converted
 * @param buf    Buffer for the result
 * @param buflen Size of the buffer
 * @retval 1 Success
 * @retval 0 Failure
 *
 * Take a name, e.g. "John F. Kennedy" and reduce it to initials "JFK".
 * The function saves the first character from each word.  Words are delimited
 * by whitespace, or hyphens (so "Jean-Pierre" becomes "JP").
 */
bool mutt_mb_get_initials(const char *name, char *buf, size_t buflen)
{
  if (!name || !buf)
    return false;

  while (*name)
  {
    /* Char's length in bytes */
    int clen = mutt_mb_charlen(name, NULL);
    if (clen < 1)
      return false;

    /* Ignore punctuation at the beginning of a word */
    if ((clen == 1) && mutt_ispunct(*name))
    {
      name++;
      continue;
    }

    if (clen >= buflen)
      return false;

    /* Copy one multibyte character */
    buflen -= clen;
    while (clen--)
      *buf++ = *name++;

    /* Skip to end-of-word */
    for (; *name; name += clen)
    {
      clen = mutt_mb_charlen(name, NULL);
      if (clen < 1)
        return false;
      if ((clen == 1) && (mutt_isspace(*name) || (*name == '-')))
        break;
    }

    /* Skip any whitespace, or hyphens */
    while (*name && (mutt_isspace(*name) || (*name == '-')))
      name++;
  }

  *buf = '\0';
  return true;
}

/**
 * mutt_mb_width - Measure a string's display width (in screen columns)
 * @param str     String to measure
 * @param col     Display column (used for expanding tabs)
 * @param indent  If true, newline-space will be indented 8 chars
 * @retval num String's width in screen columns
 *
 * This is like wcwidth(), but gets const char* not wchar_t*.
 */
int mutt_mb_width(const char *str, int col, bool indent)
{
  if (!str || !*str)
    return 0;

  bool nl = false;
  int total_width = 0;
  mbstate_t mbstate = { 0 };

  size_t str_len = mutt_str_len(str);

  while (*str && (str_len > 0))
  {
    wchar_t wc = L'\0';
    size_t consumed = mbrtowc(&wc, str, str_len, &mbstate);
    if (consumed == 0)
      break;

    if (consumed == ICONV_ILLEGAL_SEQ)
    {
      memset(&mbstate, 0, sizeof(mbstate));
      wc = ReplacementChar;
      consumed = 1;
    }
    else if (consumed == ICONV_BUF_TOO_SMALL)
    {
      wc = ReplacementChar;
      consumed = str_len;
    }

    int wchar_width = wcwidth(wc);
    if (wchar_width < 0)
      wchar_width = 1;

    if ((wc == L'\t') || (nl && (wc == L' ')))
    {
      /* correctly calc tab stop, even for sending as the line should look
       * pretty on the receiving end */
      nl = false;
      wchar_width = 8 - (col % 8);
    }
    else if (indent && (wc == '\n'))
    {
      /* track newlines for display-case: if we have a space after a newline,
       * assume 8 spaces as for display we always tab-fold */
      nl = true;
    }

    total_width += wchar_width;
    str += consumed;
    str_len -= consumed;
  }

  return total_width;
}

/**
 * mutt_mb_wcwidth - Measure the screen width of a character
 * @param wc Character to examine
 * @retval num Width in screen columns
 */
int mutt_mb_wcwidth(wchar_t wc)
{
  int n = wcwidth(wc);
  if (IsWPrint(wc) && (n > 0))
    return n;
  if (!(wc & ~0x7f))
    return 2;
  if (!(wc & ~0xffff))
    return 6;
  return 10;
}

/**
 * mutt_mb_wcswidth - Measure the screen width of a string
 * @param s String to measure
 * @param n Length of string in characters
 * @retval num Width in screen columns
 */
int mutt_mb_wcswidth(const wchar_t *s, size_t n)
{
  if (!s)
    return 0;

  int w = 0;
  while (n--)
    w += mutt_mb_wcwidth(*s++);
  return w;
}

/**
 * mutt_mb_width_ceiling - Keep the end of the string on-screen
 * @param s String being displayed
 * @param n Length of string in characters
 * @param w1 Width limit
 * @retval num Chars to skip
 *
 * Given a string and a width, determine how many characters from the
 * beginning of the string should be skipped so that the string fits.
 */
size_t mutt_mb_width_ceiling(const wchar_t *s, size_t n, int w1)
{
  if (!s)
    return 0;

  const wchar_t *s0 = s;
  int w = 0;
  for (; n; s++, n--)
    if ((w += mutt_mb_wcwidth(*s)) > w1)
      break;
  return s - s0;
}

/**
 * buf_mb_wcstombs - Convert a string from wide to multibyte characters
 * @param dest Buffer for the result
 * @param wstr Source wide string to convert
 * @param wlen Length of the wide string
 */
void buf_mb_wcstombs(struct Buffer *dest, const wchar_t *wstr, size_t wlen)
{
  if (!dest || !wstr)
    return;

  // Give ourselves 4 utf-8 bytes per wide character
  buf_alloc(dest, 4 * wlen);

  mbstate_t mbstate = { 0 };
  size_t k = 0;

  char *buf = dest->data;
  size_t buflen = dest->dsize;

  for (; (wlen > 0) && (buflen >= MB_LEN_MAX); buf += k, buflen -= k, wstr++, wlen--)
  {
    k = wcrtomb(buf, *wstr, &mbstate);
    if (k == ICONV_ILLEGAL_SEQ)
      break;
    if (*wstr == L'\0')
      break;
  }

  *buf = '\0';
  buf_fix_dptr(dest);
}

/**
 * mutt_mb_mbstowcs - Convert a string from multibyte to wide characters
 * @param[out] pwbuf    Buffer for the result
 * @param[out] pwbuflen Length of the result buffer
 * @param[in]  i        Starting index into the result buffer
 * @param[in]  buf      String to convert
 * @retval num First character after the result
 */
size_t mutt_mb_mbstowcs(wchar_t **pwbuf, size_t *pwbuflen, size_t i, const char *buf)
{
  if (!pwbuf || !pwbuflen || !buf)
    return 0;

  wchar_t wc = 0;
  mbstate_t mbstate = { 0 };
  size_t k;
  wchar_t *wbuf = *pwbuf;
  size_t wbuflen = *pwbuflen;

  while (*buf != '\0')
  {
    memset(&mbstate, 0, sizeof(mbstate));
    for (; (k = mbrtowc(&wc, buf, MB_LEN_MAX, &mbstate)) &&
           (k != ICONV_ILLEGAL_SEQ) && (k != ICONV_BUF_TOO_SMALL);
         buf += k)
    {
      if (i >= wbuflen)
      {
        wbuflen = i + 20;
        MUTT_MEM_REALLOC(&wbuf, wbuflen, wchar_t);
      }
      wbuf[i++] = wc;
    }
    if ((*buf != '\0') && ((k == ICONV_ILLEGAL_SEQ) || (k == ICONV_BUF_TOO_SMALL)))
    {
      if (i >= wbuflen)
      {
        wbuflen = i + 20;
        MUTT_MEM_REALLOC(&wbuf, wbuflen, wchar_t);
      }
      wbuf[i++] = ReplacementChar;
      buf++;
    }
  }
  *pwbuf = wbuf;
  *pwbuflen = wbuflen;
  return i;
}

/**
 * mutt_mb_is_shell_char - Is character not typically part of a pathname
 * @param ch Character to examine
 * @retval true  Character is not typically part of a pathname
 * @retval false Character is typically part of a pathname
 *
 * @note The name is very confusing.
 */
bool mutt_mb_is_shell_char(wchar_t ch)
{
  static const wchar_t shell_chars[] = L"<>&()$?*;{}| "; /* ! not included because it can be part of a pathname in NeoMutt */
  return wcschr(shell_chars, ch);
}

/**
 * mutt_mb_is_lower - Does a multi-byte string contain only lowercase characters?
 * @param s String to check
 * @retval true  String contains no uppercase characters
 * @retval false Error, or contains some uppercase characters
 *
 * Non-alphabetic characters are considered lowercase.
 */
bool mutt_mb_is_lower(const char *s)
{
  if (!s)
    return false;

  wchar_t wc = 0;
  mbstate_t mbstate = { 0 };
  size_t l;

  memset(&mbstate, 0, sizeof(mbstate));
  size_t n = mutt_str_len(s);

  for (; (n > 0) && (*s != '\0') && (l = mbrtowc(&wc, s, n, &mbstate)) != 0; s += l, n -= l)
  {
    if ((l == ICONV_BUF_TOO_SMALL) || (l == ICONV_ILLEGAL_SEQ))
      return false; // error; assume upper-case
    if (iswalpha((wint_t) wc) && iswupper((wint_t) wc))
      return false; // upper-case
  }

  return true; // lower-case
}

/**
 * mutt_mb_is_display_corrupting_utf8 - Will this character corrupt the display?
 * @param wc Character to examine
 * @retval true  Character would corrupt the display
 * @retval false Character is safe to display
 *
 * @note This list isn't complete.
 */
bool mutt_mb_is_display_corrupting_utf8(wchar_t wc)
{
  if ((wc == (wchar_t) 0x00ad) || /* soft hyphen */
      (wc == (wchar_t) 0x200e) || /* left-to-right mark */
      (wc == (wchar_t) 0x200f) || /* right-to-left mark */
      (wc == (wchar_t) 0xfeff))   /* zero width no-break space */
  {
    return true;
  }

  /* left-to-right isolate, right-to-left isolate, first strong isolate,
   * pop directional isolate */
  if ((wc >= (wchar_t) 0x2066) && (wc <= (wchar_t) 0x2069))
    return true;

  /* left-to-right embedding, right-to-left embedding, pop directional formatting,
   * left-to-right override, right-to-left override */
  if ((wc >= (wchar_t) 0x202a) && (wc <= (wchar_t) 0x202e))
    return true;

  /* arabic letter mark */
  if (wc == (wchar_t) 0x061c)
    return true;

  return false;
}

/**
 * mutt_mb_filter_unprintable - Replace unprintable characters
 * @param[in,out] s String to modify
 * @retval  0 Success
 * @retval -1 Error
 *
 * Unprintable characters will be replaced with #ReplacementChar.
 *
 * @note The source string will be freed and a newly allocated string will be
 * returned in its place.  The caller should free the returned string.
 */
int mutt_mb_filter_unprintable(char **s)
{
  if (!s || !*s)
    return -1;

  wchar_t wc = 0;
  size_t k, k2;
  char scratch[MB_LEN_MAX + 1];
  char *p = *s;
  mbstate_t mbstate1 = { 0 };
  mbstate_t mbstate2 = { 0 };

  struct Buffer *buf = buf_pool_get();
  for (; (k = mbrtowc(&wc, p, MB_LEN_MAX, &mbstate1)); p += k)
  {
    if ((k == ICONV_ILLEGAL_SEQ) || (k == ICONV_BUF_TOO_SMALL))
    {
      k = 1;
      memset(&mbstate1, 0, sizeof(mbstate1));
      wc = ReplacementChar;
    }
    if (CharsetIsUtf8 && IsBOM(wc))
    {
      continue;
    }
    if (!IsWPrint(wc))
      wc = '?';
    else if (CharsetIsUtf8 && mutt_mb_is_display_corrupting_utf8(wc))
      continue;
    k2 = wcrtomb(scratch, wc, &mbstate2);
    scratch[k2] = '\0';
    buf_addstr(buf, scratch);
  }
  FREE(s);

  if (buf_is_empty(buf))
    *s = MUTT_MEM_CALLOC(1, char); // Fake empty string
  else
    *s = buf_strdup(buf);

  buf_pool_release(&buf);
  return 0;
}
