/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   
   This library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA */

#include "my_handler.h"

int mi_compare_text(CHARSET_INFO *charset_info, uchar *a, uint a_length,
		    uchar *b, uint b_length, my_bool part_key,
		    my_bool skip_end_space)
{
  if (!part_key)
    return charset_info->coll->strnncollsp(charset_info, a, a_length,
                                           b, b_length, (my_bool)!skip_end_space);
  return charset_info->coll->strnncoll(charset_info, a, a_length,
                                       b, b_length, part_key);
}


static int compare_bin(uchar *a, uint a_length, uchar *b, uint b_length,
                       my_bool part_key, my_bool skip_end_space)
{
  uint length= min(a_length,b_length);
  uchar *end= a+ length;
  int flag;

  while (a < end)
    if ((flag= (int) *a++ - (int) *b++))
      return flag;
  if (part_key && b_length < a_length)
    return 0;
  if (skip_end_space && a_length != b_length)
  {
    int swap= 1;
    /*
      We are using space compression. We have to check if longer key
      has next character < ' ', in which case it's less than the shorter
      key that has an implicite space afterwards.

      This code is identical to the one in
      strings/ctype-simple.c:my_strnncollsp_simple
    */
    if (a_length < b_length)
    {
      /* put shorter key in a */
      a_length= b_length;
      a= b;
      swap= -1;					/* swap sign of result */
    }
    for (end= a + a_length-length; a < end ; a++)
    {
      if (*a != ' ')
	return (*a < ' ') ? -swap : swap;
    }
    return 0;
  }
  return (int) (a_length-b_length);
}


/*
  Compare two keys

  SYNOPSIS
    ha_key_cmp()
    keyseg	Array of key segments of key to compare
    a		First key to compare, in format from _mi_pack_key()
		This is normally key specified by user
    b		Second key to compare.  This is always from a row
    key_length	Length of key to compare.  This can be shorter than
		a to just compare sub keys
    next_flag	How keys should be compared
		If bit SEARCH_FIND is not set the keys includes the row
		position and this should also be compared
    diff_pos    OUT Number of first keypart where values differ, counting 
                from one.
    diff_pos[1] OUT  (b + diff_pos[1]) points to first value in tuple b
                      that is different from corresponding value in tuple a.
  
  EXAMPLES 
   Example1: if the function is called for tuples
     ('aaa','bbb') and ('eee','fff'), then
     diff_pos[0] = 1 (as 'aaa' != 'eee')
     diff_pos[1] = 0 (offset from beggining of tuple b to 'eee' keypart).

   Example2: if the index function is called for tuples
     ('aaa','bbb') and ('aaa','fff'),
     diff_pos[0] = 2 (as 'aaa' != 'eee')
     diff_pos[1] = 3 (offset from beggining of tuple b to 'fff' keypart,
                      here we assume that first key part is CHAR(3) NOT NULL)

  NOTES
    Number-keys can't be splited

  RETURN VALUES
    <0	If a < b
    0	If a == b
    >0	If a > b
*/

#define FCMP(A,B) ((int) (A) - (int) (B))

int ha_key_cmp(register HA_KEYSEG *keyseg, register uchar *a,
	       register uchar *b, uint key_length, uint nextflag,
	       uint *diff_pos)
{
  int flag;
  int16 s_1,s_2;
  int32 l_1,l_2;
  uint32 u_1,u_2;
  float f_1,f_2;
  double d_1,d_2;
  uint next_key_length;
  uchar *orig_b= b;

  *diff_pos=0;
  for ( ; (int) key_length >0 ; key_length=next_key_length, keyseg++)
  {
    uchar *end;
    uint piks=! (keyseg->flag & HA_NO_SORT);
    (*diff_pos)++;
    diff_pos[1]= (uint)(b - orig_b);

    /* Handle NULL part */
    if (keyseg->null_bit)
    {
      key_length--;
      if (*a != *b && piks)
      {
        flag = (int) *a - (int) *b;
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      }
      b++;
      if (!*a++)                                /* If key was NULL */
      {
        if (nextflag == (SEARCH_FIND | SEARCH_UPDATE))
          nextflag=SEARCH_SAME;                 /* Allow duplicate keys */
  	else if (nextflag & SEARCH_NULL_ARE_NOT_EQUAL)
	{
	  /*
	    This is only used from mi_check() to calculate cardinality.
	    It can't be used when searching for a key as this would cause
	    compare of (a,b) and (b,a) to return the same value.
	  */
	  return -1;
	}
        next_key_length=key_length;
        continue;                               /* To next key part */
      }
    }
    end= a+ min(keyseg->length,key_length);
    next_key_length=key_length-keyseg->length;

    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_TEXT:                       /* Ascii; Key is converted */
      if (keyseg->flag & HA_SPACE_PACK)
      {
        int a_length,b_length,pack_length;
        get_key_length(a_length,a);
        get_key_pack_length(b_length,pack_length,b);
        next_key_length=key_length-b_length-pack_length;

        if (piks &&
            (flag=mi_compare_text(keyseg->charset,a,a_length,b,b_length,
				  (my_bool) ((nextflag & SEARCH_PREFIX) &&
					     next_key_length <= 0),
				  (my_bool)!(nextflag & SEARCH_PREFIX))))
          return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
        a+=a_length;
        b+=b_length;
        break;
      }
      else
      {
	uint length=(uint) (end-a), a_length=length, b_length=length;
        if (piks &&
            (flag= mi_compare_text(keyseg->charset, a, a_length, b, b_length,
				   (my_bool) ((nextflag & SEARCH_PREFIX) &&
					      next_key_length <= 0),
				   (my_bool)!(nextflag & SEARCH_PREFIX))))
          return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
        a=end;
        b+=length;
      }
      break;
    case HA_KEYTYPE_BINARY:
    case HA_KEYTYPE_BIT:
      if (keyseg->flag & HA_SPACE_PACK)
      {
        int a_length,b_length,pack_length;
        get_key_length(a_length,a);
        get_key_pack_length(b_length,pack_length,b);
        next_key_length=key_length-b_length-pack_length;

        if (piks &&
	    (flag=compare_bin(a,a_length,b,b_length,
                              (my_bool) ((nextflag & SEARCH_PREFIX) &&
                                         next_key_length <= 0),1)))
          return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
        a+=a_length;
        b+=b_length;
        break;
      }
      else
      {
        uint length=keyseg->length;
        if (piks &&
	    (flag=compare_bin(a,length,b,length,
                              (my_bool) ((nextflag & SEARCH_PREFIX) &&
                                         next_key_length <= 0),0)))
          return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
        a+=length;
        b+=length;
      }
      break;
    case HA_KEYTYPE_VARTEXT1:
    case HA_KEYTYPE_VARTEXT2:
      {
        int a_length,b_length,pack_length;
        get_key_length(a_length,a);
        get_key_pack_length(b_length,pack_length,b);
        next_key_length=key_length-b_length-pack_length;

        if (piks &&
	    (flag= mi_compare_text(keyseg->charset,a,a_length,b,b_length,
                                   (my_bool) ((nextflag & SEARCH_PREFIX) &&
                                              next_key_length <= 0),
				   (my_bool) ((nextflag & (SEARCH_FIND |
							   SEARCH_UPDATE)) ==
					      SEARCH_FIND &&
                                              ! (keyseg->flag &
                                                 HA_END_SPACE_ARE_EQUAL)))))
          return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
        a+= a_length;
        b+= b_length;
        break;
      }
      break;
    case HA_KEYTYPE_VARBINARY1:
    case HA_KEYTYPE_VARBINARY2:
      {
        int a_length,b_length,pack_length;
        get_key_length(a_length,a);
        get_key_pack_length(b_length,pack_length,b);
        next_key_length=key_length-b_length-pack_length;

        if (piks &&
	    (flag=compare_bin(a,a_length,b,b_length,
                              (my_bool) ((nextflag & SEARCH_PREFIX) &&
                                         next_key_length <= 0), 0)))
          return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
        a+=a_length;
        b+=b_length;
        break;
      }
      break;
    case HA_KEYTYPE_INT8:
    {
      int i_1= (int) *((signed char*) a);
      int i_2= (int) *((signed char*) b);
      if (piks && (flag = CMP_NUM(i_1,i_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a= end;
      b++;
      break;
    }
    case HA_KEYTYPE_SHORT_INT:
      s_1= mi_sint2korr(a);
      s_2= mi_sint2korr(b);
      if (piks && (flag = CMP_NUM(s_1,s_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 2; /* sizeof(short int); */
      break;
    case HA_KEYTYPE_USHORT_INT:
      {
        uint16 us_1,us_2;
        us_1= mi_sint2korr(a);
        us_2= mi_sint2korr(b);
        if (piks && (flag = CMP_NUM(us_1,us_2)))
          return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
        a=  end;
        b+=2; /* sizeof(short int); */
        break;
      }
    case HA_KEYTYPE_LONG_INT:
      l_1= mi_sint4korr(a);
      l_2= mi_sint4korr(b);
      if (piks && (flag = CMP_NUM(l_1,l_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 4; /* sizeof(long int); */
      break;
    case HA_KEYTYPE_ULONG_INT:
      u_1= mi_sint4korr(a);
      u_2= mi_sint4korr(b);
      if (piks && (flag = CMP_NUM(u_1,u_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 4; /* sizeof(long int); */
      break;
    case HA_KEYTYPE_INT24:
      l_1=mi_sint3korr(a);
      l_2=mi_sint3korr(b);
      if (piks && (flag = CMP_NUM(l_1,l_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 3;
      break;
    case HA_KEYTYPE_UINT24:
      l_1=mi_uint3korr(a);
      l_2=mi_uint3korr(b);
      if (piks && (flag = CMP_NUM(l_1,l_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 3;
      break;
    case HA_KEYTYPE_FLOAT:
      mi_float4get(f_1,a);
      mi_float4get(f_2,b);
      /*
        The following may give a compiler warning about floating point
        comparison not being safe, but this is ok in this context as
        we are bascily doing sorting
      */
      if (piks && (flag = CMP_NUM(f_1,f_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 4; /* sizeof(float); */
      break;
    case HA_KEYTYPE_DOUBLE:
      mi_float8get(d_1,a);
      mi_float8get(d_2,b);
      /*
        The following may give a compiler warning about floating point
        comparison not being safe, but this is ok in this context as
        we are bascily doing sorting
      */
      if (piks && (flag = CMP_NUM(d_1,d_2)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 8;  /* sizeof(double); */
      break;
    case HA_KEYTYPE_NUM:                                /* Numeric key */
    {
      int swap_flag= 0;
      int alength,blength;

      if (keyseg->flag & HA_REVERSE_SORT)
      {
        swap_variables(uchar*, a, b);
        swap_flag=1;                            /* Remember swap of a & b */
        end= a+ (int) (end-b);
      }
      if (keyseg->flag & HA_SPACE_PACK)
      {
        alength= *a++; blength= *b++;
        end=a+alength;
        next_key_length=key_length-blength-1;
      }
      else
      {
        alength= (int) (end-a);
        blength=keyseg->length;
        /* remove pre space from keys */
        for ( ; alength && *a == ' ' ; a++, alength--) ;
        for ( ; blength && *b == ' ' ; b++, blength--) ;
      }
      if (piks)
      {
	if (*a == '-')
	{
	  if (*b != '-')
	    return -1;
	  a++; b++;
	  swap_variables(uchar*, a, b);
	  swap_variables(int, alength, blength);
	  swap_flag=1-swap_flag;
	  alength--; blength--;
	  end=a+alength;
	}
	else if (*b == '-')
	  return 1;
	while (alength && (*a == '+' || *a == '0'))
	{
	  a++; alength--;
	}
	while (blength && (*b == '+' || *b == '0'))
	{
	  b++; blength--;
	}
	if (alength != blength)
	  return (alength < blength) ? -1 : 1;
	while (a < end)
	  if (*a++ !=  *b++)
	    return ((int) a[-1] - (int) b[-1]);
      }
      else
      {
        b+=(end-a);
        a=end;
      }

      if (swap_flag)                            /* Restore pointers */
        swap_variables(uchar*, a, b);
      break;
    }
#ifdef HAVE_LONG_LONG
    case HA_KEYTYPE_LONGLONG:
    {
      longlong ll_a,ll_b;
      ll_a= mi_sint8korr(a);
      ll_b= mi_sint8korr(b);
      if (piks && (flag = CMP_NUM(ll_a,ll_b)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 8;
      break;
    }
    case HA_KEYTYPE_ULONGLONG:
    {
      ulonglong ll_a,ll_b;
      ll_a= mi_uint8korr(a);
      ll_b= mi_uint8korr(b);
      if (piks && (flag = CMP_NUM(ll_a,ll_b)))
        return ((keyseg->flag & HA_REVERSE_SORT) ? -flag : flag);
      a=  end;
      b+= 8;
      break;
    }
#endif
    case HA_KEYTYPE_END:                        /* Ready */
      goto end;                                 /* diff_pos is incremented */
    }
  }
  (*diff_pos)++;
end:
  if (!(nextflag & SEARCH_FIND))
  {
    uint i;
    if (nextflag & (SEARCH_NO_FIND | SEARCH_LAST)) /* Find record after key */
      return (nextflag & (SEARCH_BIGGER | SEARCH_LAST)) ? -1 : 1;
    flag=0;
    for (i=keyseg->length ; i-- > 0 ; )
    {
      if (*a++ != *b++)
      {
        flag= FCMP(a[-1],b[-1]);
        break;
      }
    }
    if (nextflag & SEARCH_SAME)
      return (flag);                            /* read same */
    if (nextflag & SEARCH_BIGGER)
      return (flag <= 0 ? -1 : 1);              /* read next */
    return (flag < 0 ? -1 : 1);                 /* read previous */
  }
  return 0;
} /* ha_key_cmp */


/*
  Find the first NULL value in index-suffix values tuple

  SYNOPSIS
    ha_find_null()
      keyseg     Array of keyparts for key suffix
      a          Key suffix value tuple

  DESCRIPTION
    Find the first NULL value in index-suffix values tuple.
    TODO Consider optimizing this fuction or its use so we don't search for
         NULL values in completely NOT NULL index suffixes.

  RETURN
    First key part that has NULL as value in values tuple, or the last key part 
    (with keyseg->type==HA_TYPE_END) if values tuple doesn't contain NULLs.
*/

HA_KEYSEG *ha_find_null(HA_KEYSEG *keyseg, uchar *a)
{
  for (; (enum ha_base_keytype) keyseg->type != HA_KEYTYPE_END; keyseg++)
  {
    uchar *end;
    if (keyseg->null_bit)
    {
      if (!*a++)
        return keyseg;
    }
    end= a+ keyseg->length;

    switch ((enum ha_base_keytype) keyseg->type) {
    case HA_KEYTYPE_TEXT:
    case HA_KEYTYPE_BINARY:
      if (keyseg->flag & HA_SPACE_PACK)
      {
        int a_length;
        get_key_length(a_length, a);
        a += a_length;
        break;
      }
      else
        a= end;
      break;
    case HA_KEYTYPE_VARTEXT1:
    case HA_KEYTYPE_VARBINARY1:
      {
        int a_length;
        get_key_length(a_length, a);
        a+= a_length;
        break;
      }
    case HA_KEYTYPE_NUM:
      if (keyseg->flag & HA_SPACE_PACK)
      {
        int alength= *a++;
        end= a+alength;
      }
      a= end;
      break;
    case HA_KEYTYPE_INT8:
    case HA_KEYTYPE_SHORT_INT:
    case HA_KEYTYPE_USHORT_INT:
    case HA_KEYTYPE_LONG_INT:
    case HA_KEYTYPE_ULONG_INT:
    case HA_KEYTYPE_INT24:
    case HA_KEYTYPE_UINT24:
#ifdef HAVE_LONG_LONG
    case HA_KEYTYPE_LONGLONG:
    case HA_KEYTYPE_ULONGLONG:
#endif
    case HA_KEYTYPE_FLOAT:
    case HA_KEYTYPE_DOUBLE:
      a= end;
      break;
    }
  }
  return keyseg;
}

