/* Copyright (c) 2003, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/* Some useful string utility functions used by the MySQL server */

#include "strfunc.h"
#include "sql_class.h"
#include "typelib.h"                            // TYPELIB
#include "m_ctype.h"                            // my_charset_latin1
#include "mysqld.h"                             // system_charset_info

/*
  Return bitmap for strings used in a set

  SYNOPSIS
  find_set()
  lib			Strings in set
  str			Strings of set-strings separated by ','
  err_pos		If error, set to point to start of wrong set string
  err_len		If error, set to the length of wrong set string
  set_warning		Set to 1 if some string in set couldn't be used

  NOTE
    We delete all end space from str before comparison

  RETURN
    bitmap of all sets found in x.
    set_warning is set to 1 if there was any sets that couldn't be set
*/

static const char field_separator=',';

ulonglong find_set(TYPELIB *lib, const char *str, size_t length,
                   const CHARSET_INFO *cs,
                   char **err_pos, uint *err_len, bool *set_warning)
{
  const CHARSET_INFO *strip= cs ? cs : &my_charset_latin1;
  const char *end= str + strip->cset->lengthsp(strip, str, length);
  ulonglong found= 0;
  *err_pos= 0;                  // No error yet
  *err_len= 0;
  if (str != end)
  {
    const char *start= str;    
    for (;;)
    {
      const char *pos= start;
      uint var_len;
      int mblen= 1;

      if (cs && cs->mbminlen > 1)
      {
        for ( ; pos < end; pos+= mblen)
        {
          my_wc_t wc;
          if ((mblen= cs->cset->mb_wc(cs, &wc, (const uchar *) pos, 
                                               (const uchar *) end)) < 1)
            mblen= 1; // Not to hang on a wrong multibyte sequence
          if (wc == (my_wc_t) field_separator)
            break;
        }
      }
      else
        for (; pos != end && *pos != field_separator; pos++) ;
      var_len= (uint) (pos - start);
      uint find= cs ? find_type2(lib, start, var_len, cs) :
                      find_type(lib, start, var_len, (bool) 0);
      if (!find && *err_len == 0) // report the first error with length > 0
      {
        *err_pos= (char*) start;
        *err_len= var_len;
        *set_warning= 1;
      }
      else
        found|= 1ULL << (find - 1);
      if (pos >= end)
        break;
      start= pos + mblen;
    }
  }
  return found;
}

/*
  Function to find a string in a TYPELIB
  (similar to find_type() of mysys/typelib.c)

  SYNOPSIS
   find_type()
   lib			TYPELIB (struct of pointer to values + count)
   find			String to find
   length		Length of string to find
   part_match		Allow part matching of value

 RETURN
  0 error
  > 0 position in TYPELIB->type_names +1
*/

uint find_type(const TYPELIB *lib, const char *find, size_t length,
               bool part_match)
{
  uint found_count=0, found_pos=0;
  const char *end= find+length;
  const char *i;
  const char *j;
  for (uint pos=0 ; (j=lib->type_names[pos++]) ; )
  {
    for (i=find ; i != end && 
	   my_toupper(system_charset_info,*i) == 
	   my_toupper(system_charset_info,*j) ; i++, j++) ;
    if (i == end)
    {
      if (! *j)
	return(pos);
      found_count++;
      found_pos= pos;
    }
  }
  return(found_count == 1 && part_match ? found_pos : 0);
}


/*
  Find a string in a list of strings according to collation

  SYNOPSIS
   find_type2()
   lib			TYPELIB (struct of pointer to values + count)
   x			String to find
   length               String length
   cs			Character set + collation to use for comparison

  NOTES

  RETURN
    0	No matching value
    >0  Offset+1 in typelib for matched string
*/

uint find_type2(const TYPELIB *typelib, const char *x, size_t length,
                const CHARSET_INFO *cs)
{
  int pos;
  const char *j;
  DBUG_ENTER("find_type2");
  DBUG_PRINT("enter",("x: '%.*s'  lib: 0x%p",
                      static_cast<int>(length), x, typelib));

  if (!typelib->count)
  {
    DBUG_PRINT("exit",("no count"));
    DBUG_RETURN(0);
  }

  for (pos=0 ; (j=typelib->type_names[pos]) ; pos++)
  {
    if (!my_strnncoll(cs, (const uchar*) x, length,
                          (const uchar*) j, typelib->type_lengths[pos]))
      DBUG_RETURN(pos+1);
  }
  DBUG_PRINT("exit",("Couldn't find type"));
  DBUG_RETURN(0);
} /* find_type */


/*
  Un-hex all elements in a typelib

  SYNOPSIS
   unhex_type2()
   interval       TYPELIB (struct of pointer to values + lengths + count)

  NOTES

  RETURN
    N/A
*/

void unhex_type2(TYPELIB *interval)
{
  for (uint pos= 0; pos < interval->count; pos++)
  {
    char *from, *to;
    for (from= to= (char*) interval->type_names[pos]; *from; )
    {
      /*
        Note, hexchar_to_int(*from++) doesn't work
        one some compilers, e.g. IRIX. Looks like a compiler
        bug in inline functions in combination with arguments
        that have a side effect. So, let's use from[0] and from[1]
        and increment 'from' by two later.
      */

      *to++= (char) (hexchar_to_int(from[0]) << 4) +
                     hexchar_to_int(from[1]);
      from+= 2;
    }
    interval->type_lengths[pos] /= 2;
  }
}


/*
  Check if the first word in a string is one of the ones in TYPELIB

  SYNOPSIS
    check_word()
    lib		TYPELIB
    val		String to check
    end		End of input
    end_of_word	Store value of last used byte here if we found word

  RETURN
    0	 No matching value
    > 1  lib->type_names[#-1] matched
	 end_of_word will point to separator character/end in 'val'
*/

uint check_word(TYPELIB *lib, const char *val, const char *end,
		const char **end_of_word)
{
  int res;
  const char *ptr;

  /* Fiend end of word */
  for (ptr= val ; ptr < end && my_isalpha(&my_charset_latin1, *ptr) ; ptr++)
    ;
  if ((res=find_type(lib, val, (uint) (ptr - val), 1)) > 0)
    *end_of_word= ptr;
  return res;
}


/*
  Converts a string between character sets

  SYNOPSIS
    strconvert()
    from_cs       source character set
    from          source, a null terminated string
    to            destination buffer
    to_length     destination buffer length

  NOTES
    'to' is always terminated with a '\0' character.
    If there is no enough space to convert whole string,
    only prefix is converted, and terminated with '\0'.

  RETURN VALUES
    result string length
*/


size_t strconvert(CHARSET_INFO *from_cs, const char *from,
                  CHARSET_INFO *to_cs, char *to, size_t to_length, uint *errors)
{
  int cnvres;
  my_wc_t wc;
  char *to_start= to;
  uchar *to_end= (uchar*) to + to_length - 1;
  my_charset_conv_mb_wc mb_wc= from_cs->cset->mb_wc;
  my_charset_conv_wc_mb wc_mb= to_cs->cset->wc_mb;
  uint error_count= 0;

  while (1)
  {
    /*
      Using 'from + 10' is safe:
      - it is enough to scan a single character in any character set.
      - if remaining string is shorter than 10, then mb_wc will return
        with error because of unexpected '\0' character.
    */
    if ((cnvres= (*mb_wc)(from_cs, &wc,
                          (uchar*) from, (uchar*) from + 10)) > 0)
    {
      if (!wc)
        break;
      from+= cnvres;
    }
    else if (cnvres == MY_CS_ILSEQ)
    {
      error_count++;
      from++;
      wc= '?';
    }
    else
      break; // Impossible char.

outp:

    if ((cnvres= (*wc_mb)(to_cs, wc, (uchar*) to, to_end)) > 0)
      to+= cnvres;
    else if (cnvres == MY_CS_ILUNI && wc != '?')
    {
      error_count++;
      wc= '?';
      goto outp;
    }
    else
      break;
  }
  *to= '\0';
  *errors= error_count;
  return static_cast<size_t>(to - to_start);

}


/*
  Searches for a LEX_STRING in an LEX_STRING array.

  SYNOPSIS
    find_string_in_array()
      heap    The array
      needle  The string to search for

  NOTE
    The last LEX_STRING in the array should have str member set to NULL

  RETURN VALUES
    -1   Not found
    >=0  Ordinal position
*/

int find_string_in_array(LEX_STRING * const haystack, LEX_STRING * const needle,
                         CHARSET_INFO * const cs)
{
  const LEX_STRING *pos;
  for (pos= haystack; pos->str; pos++)
    if (!cs->coll->strnncollsp(cs, (uchar *) pos->str, pos->length,
                               (uchar *) needle->str, needle->length, 0))
    {
      return static_cast<int>(pos - haystack);
    }
  return -1;
}


char *set_to_string(THD *thd, LEX_STRING *result, ulonglong set,
                    const char *lib[])
{
  char buff[STRING_BUFFER_USUAL_SIZE*8];
  String tmp(buff, sizeof(buff), &my_charset_latin1);
  LEX_STRING unused;

  if (!result)
    result= &unused;

  tmp.length(0);

  for (uint i= 0; set; i++, set >>= 1)
    if (set & 1) {
      tmp.append(lib[i]);
      tmp.append(',');
    }

  if (tmp.length())
  {
    result->str=    thd->strmake(tmp.ptr(), tmp.length()-1);
    result->length= tmp.length()-1;
  }
  else
  {
    result->str= const_cast<char*>("");
    result->length= 0;
  }
  return result->str;
}

char *flagset_to_string(THD *thd, LEX_STRING *result, ulonglong set,
                        const char *lib[])
{
  char buff[STRING_BUFFER_USUAL_SIZE*8];
  String tmp(buff, sizeof(buff), &my_charset_latin1);
  LEX_STRING unused;

  if (!result) result= &unused;

  tmp.length(0);

  // note that the last element is always "default", and it's ignored below
  for (uint i= 0; lib[i+1]; i++, set >>= 1)
  {
    tmp.append(lib[i]);
    tmp.append(set & 1 ? "=on," : "=off,");
  }

  result->str=    thd->strmake(tmp.ptr(), tmp.length()-1);
  result->length= tmp.length()-1;

  return result->str;
}

